JP7249567B2 - Dental X-ray CT imaging apparatus and X-ray CT imaging condition setting program - Google Patents

Description

The present invention relates to a technique for setting imaging conditions in a medical X-ray CT imaging apparatus.

Patent document 1 discloses that adult input or infant input is performed depending on whether the patient is an adult or an infant, and the age of the patient is input. Further, Patent Document 2 also discloses inputting top-priority targets such as exposure dose, image quality, and imaging speed. In the X-ray CT imaging apparatus of Patent Document 1, it is disclosed that optimum imaging conditions are automatically set based on adult/infant input and highest priority target input.

Patent Literature 2 discloses deriving CT scan parameters according to the patient's physique.

JP-A-2005-80748 Japanese Patent Publication No. 2014-528284

When performing X-ray CT imaging, it is preferable to reduce exposure to radiation as much as possible.

However, it may not be possible to obtain an appropriate CT image for the purpose of diagnosis by setting the imaging conditions according to whether the person is an adult or an infant, or depending on the body size. For example, even when performing X-ray CT imaging on an infant or a person with a small build, there are cases where it is desired to obtain a clear X-ray CT image of a local area. Also, when performing X-ray CT imaging on an adult or a person with a large build, it is sufficient if an X-ray CT image of a wide range can be obtained, and there are cases where such sharpness is not required.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to obtain an X-ray CT image of appropriate image quality according to the purpose of imaging while minimizing radiation exposure as much as possible.

In order to solve the above problems, a medical X-ray CT imaging apparatus according to a first aspect includes an X-ray generator that generates a cone beam, an X-ray detector, the X-ray generator and the X-ray detector a supporting portion that supports the X-ray generator and the X-ray detector in a facing state; a rotating driving portion that rotates the X-ray generator and the X-ray detector supported by the supporting portion; an imaging information reception unit that receives setting of an imaging area related to at least one of them; an X-ray output condition setting unit that automatically sets the output condition of the ray generator.

A second aspect is the medical X-ray CT imaging apparatus according to the first aspect, wherein the setting of the imaging region received by the imaging information receiving unit and the setting of the X-ray output condition setting unit It further comprises an image quality setting unit that automatically sets the image quality of the X-ray CT image according to at least one of the output conditions of the X-ray generator.

A third aspect is the medical X-ray CT imaging apparatus according to the first or second aspect, wherein the imaging information reception unit sets the size of the imaging region by setting the rotation axis of the rotation driving unit. receives the setting of the size of the photographing area on a plane orthogonal to .

A fourth aspect is the medical X-ray CT imaging apparatus according to any one of the first to third aspects, wherein the imaging information receiving unit sets the size of the imaging region to a first imaging A region and a second imaging region wider than the first imaging region can be set, and the X-ray output condition setting unit is based on a second output condition according to the size of the second imaging region. setting at least one set value that defines each of the first output condition and the second output condition such that the dose is smaller than the dose based on the first output condition corresponding to the size of the first imaging region; Set automatically.

A fifth aspect is the medical X-ray CT imaging apparatus according to the fourth aspect, wherein the imaging information receiving unit sets the maxillofacial region of the subject as the imaging region as the setting related to the size of the imaging region, It is possible to accept a setting in which a region in which a part of the teeth of the dental arch is accommodated is set as the first imaging region, and an entirety of the dental arch or a region in which all the teeth of the dental arch are accommodated is set as the second imaging region.

A sixth aspect is the medical X-ray CT imaging apparatus according to the fourth aspect, wherein the imaging information receiving unit has a boundary circle or a circumscribed circle with a diameter of R1 (mm) as the first imaging region. In addition to accepting the setting of the imaging area, it is possible to accept the setting of an imaging area whose diameter of the boundary circle or the circumscribed circle is R2 (mm) as the second imaging area, where 40 (mm) < k1 (mm )<70 (mm), R1 (mm)<k1 (mm)<R2 (mm) is satisfied.

A seventh aspect is the medical X-ray CT imaging apparatus according to the fourth aspect, wherein the imaging information receiving unit has a boundary circle or a circumscribed circle with a diameter of R1 (mm) as the first imaging region. In addition to accepting the setting of the imaging area, it is possible to accept the setting of the imaging area whose diameter of the boundary circle or the circumscribed circle is R2 (mm) as the second imaging area, where 80 (mm)<k2 (mm )<120 (mm), R1 (mm)<k2 (mm)<R2 (mm) is satisfied.

An eighth aspect is the medical X-ray CT imaging apparatus according to any one of the first to seventh aspects, wherein the imaging information reception unit is capable of receiving a setting of a physique, and the X-ray output The condition setting unit sets the imaging region according to at least one of the size of the imaging region received by the imaging information receiving unit, the purpose of imaging, and the body part to be imaged, and also sets the physique. , to automatically set the output conditions of the X-ray generator.

A ninth aspect is the medical X-ray CT imaging apparatus according to the eighth aspect, wherein the imaging information receiving unit sets the physique of the subject to be that of a child or exceeds that of a child. In response to the setting, the X-ray output condition setting unit exceeds the child so that the dose based on the output condition according to the physique exceeding the child is larger than the dose based on the output condition according to the physique of the child At least one set value is automatically set for each of the output condition according to the physique and the output condition according to the physique of the child.

A tenth aspect is the medical X-ray CT imaging apparatus according to any one of the first to ninth aspects, wherein the imaging information receiving unit receives the setting of the imaging purpose, and the X-ray output conditions A setting unit automatically sets output conditions of the X-ray generator in accordance with the imaging purpose received by the imaging information receiving unit.

An eleventh aspect is the medical X-ray CT imaging apparatus according to any one of the first to tenth aspects, wherein the imaging information reception unit receives the setting of the imaging region, and the X-ray output conditions A setting unit automatically sets output conditions of the X-ray generator in accordance with the radiographed region received by the radiographic information receiving unit.

A twelfth aspect is the medical X-ray CT imaging apparatus according to any one of the first to eleventh aspects, wherein the X-ray output condition setting unit sets the output condition of the X-ray generator to: At least one of the tube voltage of the X-ray generator, the tube current, and the time during which the X-ray generator emits X-rays is automatically set.

A thirteenth aspect is the medical X-ray CT imaging apparatus according to any one of the first to twelfth aspects, further comprising a mode setting reception unit that receives settings of the low dose mode and the high resolution mode, The X-ray output condition setting unit sets the output conditions of the X-ray generator in accordance with the imaging region accepted by the imaging information accepting unit when the low dose mode is accepted by the mode setting accepting unit. Set automatically.

A fourteenth aspect is the medical X-ray CT imaging apparatus according to any one of the first to thirteenth aspects, further comprising an output condition setting reception unit that receives manual setting of an output condition of the X-ray generator. wherein the X-ray output condition setting unit automatically sets the output conditions of the X-ray generator according to the imaging region received by the imaging information reception unit, and then manually sets the output conditions through the output condition setting reception unit. to change the output condition of the X-ray generator according to

In order to solve the above problems, a fifteenth aspect provides an X-ray generator that generates a cone beam, an X-ray detector, and a support that supports the X-ray generator and the X-ray detector in a facing state. and a turning drive section for turning the X-ray generator and the X-ray detector supported by the support section, in which the conditions for X-ray CT imaging are: A method for setting medical X-ray CT imaging conditions to be set, comprising: receiving imaging region settings related to at least one of imaging region size, imaging purpose, and imaging region; The output condition of the X-ray generator is automatically set according to at least one of the purpose and the imaging part.

In order to solve the above problems, a sixteenth aspect supports an X-ray generator that generates a cone beam, an X-ray detector, and the X-ray generator and the X-ray detector in a facing state. An X-ray CT imaging condition setting program for a medical X-ray CT imaging apparatus, comprising: a supporting section; and a turning driving section for turning the X-ray generator and the X-ray detector supported by the supporting section. (a) a step of receiving setting of an imaging region relating to at least one of the size of the imaging region, the purpose of imaging, and the region to be imaged to the computer for setting the X-ray CT imaging conditions of the medical X-ray CT imaging apparatus; and (b) the step of automatically setting the output conditions of the X-ray generator according to at least one of the accepted imaging region size, imaging purpose, and imaging region. It is a CT imaging condition setting program.

In order to solve the above problems, a seventeenth aspect is a medical X-ray CT imaging apparatus comprising an X-ray generator for generating a cone beam, an X-ray detector, the X-ray generator and the a support for supporting an X-ray detector facing each other; an actuator for rotating the X-ray generator and the X-ray detector supported by the support; The setting of the imaging region for at least one of the size of the region, the purpose of imaging, and the site to be imaged is input as imaging information, and the size of the imaging region, the purpose of imaging, and the size of the imaging region input when setting the conditions for X-ray CT imaging The output condition of the X-ray generator is automatically set according to at least one of the imaging parts.

An eighteenth aspect is the medical X-ray CT imaging apparatus according to the seventeenth aspect, wherein the processor sets the size of the imaging region to be a first imaging region and a size larger than the first imaging region. Information of setting with a wide second imaging region can be received, and the dose based on the second output condition according to the size of the second imaging region is the first output according to the size of the first imaging region At least one set value defining each of the first output condition and the second output condition is automatically set so as to be smaller than the dose based on the condition.

A nineteenth aspect is the medical X-ray CT imaging apparatus according to the seventeenth or eighteenth aspect, wherein the processor sets a first imaging purpose and a second imaging purpose as settings related to the imaging purpose. The first imaging purpose is an imaging purpose for observing in more detail than the second imaging purpose, and the dose based on the second output condition corresponding to the second imaging purpose is At least one set value defining each of the first output condition and the second output condition is automatically set so as to be smaller than the dose based on the first output condition corresponding to the first imaging purpose.

A twentieth aspect is the medical X-ray CT imaging apparatus according to any one of the seventeenth to nineteenth aspects, wherein the processor sets a first imaging region, a second imaging region, and a second imaging region as settings related to the imaging regions. It is possible to receive information of setting with a site, the first imaging site has a larger amount of hard tissue or a higher density of hard tissue than the second imaging site, and the second imaging site according to the second imaging site. At least one setting value that defines each of the first output condition and the second output condition such that the dose based on the output condition is smaller than the dose based on the first output condition corresponding to the first imaging region. automatically set.

A twenty-first aspect is the medical X-ray CT imaging apparatus according to any one of the seventeenth to twentieth aspects, wherein the processor sets the input imaging region and sets the X-ray generator and automatically sets the image quality of the X-ray CT image according to at least one of the output conditions.

According to the first aspect, by automatically setting the output conditions of the X-ray generator according to at least one of the size of the received imaging region, the purpose of imaging, and the body part to be imaged, radiation exposure is reduced as much as possible. be able to. In addition, although the size of the imaging region or the imaging region is usually set according to the imaging purpose, the output condition of the X-ray generator depends on at least one of the imaging region size, the imaging purpose, and the imaging region. is automatically set, it is possible to obtain an X-ray CT image with image quality as appropriate as possible according to the purpose of imaging.

Under X-ray output conditions aimed at a low dose, noise tends to be added to X-ray CT images. Therefore, noise can be reduced by automatically setting the image quality of the X-ray CT image according to at least one of the setting of the imaging region and the output condition of the X-ray generator, as in the second aspect.

According to the third aspect, the output condition of the X-ray generator can be automatically set according to the size in the plane orthogonal to the turning axis.

According to the fourth aspect, when a relatively small first imaging region is set, X-ray CT imaging can be performed under the first output condition in which the dose is relatively large. On the other hand, when a relatively large second imaging region is set, X-ray CT imaging can be performed under the second output condition with a relatively small dose.

According to the fifth aspect, when an area in which a part of the teeth of the dental arch is accommodated is set as the first imaging area, X-ray CT imaging can be performed under the first output condition in which the dose is relatively large. This enables observation with a relatively clear image. On the other hand, if the entire area of the dental arch or an area that accommodates all the teeth of the dental arch is set as the second imaging area, X-ray CT imaging can be performed under the second output condition in which the dose is relatively small. can.

According to the sixth aspect, X Line CT imaging can be performed. Therefore, when X-ray CT imaging is performed on a part of the dental arch, observation with a relatively clear image is possible. On the other hand, when R2 is larger than k1, X-ray CT imaging can be performed under the second output condition in which the dose is relatively small. Therefore, when X-ray CT imaging is performed on the entire dental arch or the like, X-ray CT imaging can be performed with a relatively low dose.

According to the seventh aspect, X Line CT imaging can be performed. Therefore, when X-ray CT imaging is performed on the entire dental arch or the like, it is possible to observe with a relatively clear image. On the other hand, when R2 is larger than k1, X-ray CT imaging can be performed under the second output condition in which the dose is relatively small. Therefore, when X-ray CT imaging is performed for the entire jaw or the like, X-ray CT imaging can be performed with a relatively low dose.

According to the eighth aspect, the X-ray output condition setting unit generates X-rays according to at least one setting of the physique, the purpose of imaging, and the region to be imaged, in addition to the imaging region received by the imaging information receiving unit. Automatically set the output conditions of the instrument. As a result, at least one of the physique, the purpose of imaging, and the body part to be imaged can be taken into account to reduce exposure to radiation as much as possible. In addition, an X-ray CT image with appropriate image quality can be obtained by considering at least one of physique, purpose of imaging, and body part to be imaged.

According to the ninth aspect, when the subject is set to have a child's physique as the physique setting, the radiation dose can be reduced to reduce the exposure dose. On the other hand, if the body size is set to exceed that of a child, the dose can be increased and a clear image can be obtained.

According to the tenth aspect, the output condition of the X-ray generator can be automatically set according to the set imaging purpose.

According to the eleventh aspect, the output condition of the X-ray generator can be automatically set according to the set imaging region.

According to the twelfth aspect, by setting at least one of the tube voltage and tube current of the X-ray generator, and the time during which the X-ray generator emits X-rays, it is possible to adjust the dose and the like.

According to the thirteenth aspect, when the low-dose mode is accepted, the output conditions of the X-ray generator are automatically set according to the accepted imaging region, thereby reducing exposure to radiation as much as possible and satisfying the imaging purpose. Accordingly, an X-ray CT image of appropriate image quality can be obtained.

According to the fourteenth aspect, the output condition of the X-ray generator set according to the imaging region can be changed by manual setting according to the operator's preference.

According to the fifteenth aspect, by automatically setting the output conditions of the X-ray generator according to at least one of the size of the imaging region accepted, the purpose of imaging, and the body part to be imaged, radiation exposure is reduced as much as possible. be able to. Moreover, although the size of the imaging region and the imaging region are usually set according to the imaging purpose, the output conditions of the X-ray generator are determined according to at least one of the imaging region size, the imaging purpose, and the imaging region. is automatically set, it is possible to obtain an X-ray CT image with image quality as appropriate as possible according to the purpose of imaging.

According to the sixteenth aspect, by automatically setting the output conditions of the X-ray generator according to at least one of the size of the imaging region accepted, the purpose of imaging, and the region to be imaged, radiation exposure is reduced as much as possible. be able to. Moreover, although the size of the imaging region and the imaging region are usually set according to the imaging purpose, the output conditions of the X-ray generator are determined according to at least one of the imaging region size, the imaging purpose, and the imaging region. is automatically set, it is possible to obtain an X-ray CT image with image quality as appropriate as possible according to the purpose of imaging.

According to the seventeenth aspect, by automatically setting the output condition of the X-ray generator according to at least one of the size of the imaging area, the purpose of imaging, and the body part to be imaged, it is possible to reduce exposure to radiation as much as possible. can. In addition, although the size of the imaging region or the imaging region is usually set according to the imaging purpose, the output condition of the X-ray generator depends on at least one of the imaging region size, the imaging purpose, and the imaging region. is automatically set, it is possible to obtain an X-ray CT image with image quality as appropriate as possible according to the purpose of imaging.

According to the eighteenth aspect, when a relatively small first imaging region is set, X-ray CT imaging can be performed under the first output condition in which the dose is relatively large. On the other hand, when a relatively large second imaging region is set, X-ray CT imaging can be performed under the second output condition with a relatively small dose.

According to the nineteenth aspect, the output condition of the X-ray generator can be automatically set according to the set imaging purpose.

According to the twentieth aspect, it is possible to automatically set the output conditions of the X-ray generator according to the radiographic regions having different amounts of hard tissue.

Under X-ray output conditions aimed at a low dose, noise tends to be added to X-ray CT images. Therefore, as in the twenty-first aspect, by automatically setting the image quality of the X-ray CT image according to at least one of the input setting of the imaging region and the set output condition of the X-ray generator, noise can be reduced.

1 is a schematic diagram showing an X-ray CT imaging apparatus according to a first embodiment; FIG. 4 is a flowchart showing processing by an X-ray output condition setting unit; FIG. 2 is an overall view showing the configuration of an X-ray CT imaging apparatus according to a second embodiment; FIG. 11 is a perspective view of the X-ray CT imaging apparatus according to the second embodiment when viewed obliquely from above; 1 is a functional block diagram of an X-ray CT imaging apparatus; FIG. 3 is a block diagram showing an electrical configuration of a body control section; FIG. It is a figure which shows the example of a display of an operation panel apparatus. It is a figure which shows the example of a display for a setting of an operation panel apparatus. It is a figure which shows the example of a display for a setting of an operation panel apparatus. It is a figure which shows the example of a display for a setting of an operation panel apparatus. It is a figure which shows the example of a display for a setting of an operation panel apparatus. It is a figure which shows the example of a display for a setting of an operation panel apparatus. It is a figure which shows the example of a display for a setting of an operation panel apparatus. It is a figure which shows an example of a reference table. 4 is a flow chart showing a processing example of the X-ray CT imaging apparatus; FIG. 10 is a diagram showing another example of a reference table; FIG. It is a figure which shows the example of a display for a setting of an operation panel apparatus. FIG. 10 is a diagram showing another example of a reference table; FIG. FIG. 10 is a diagram showing another example of a reference table; FIG. FIG. 10 is a diagram showing another example of a reference table; FIG.

{First embodiment}
A medical X-ray CT imaging apparatus, a medical X-ray CT imaging apparatus, a medical X-ray CT imaging condition setting method, and an X-ray CT imaging condition setting program based on the first embodiment will be described below. FIG. 1 is a schematic diagram showing an X-ray CT imaging apparatus 10. As shown in FIG.

The X-ray CT imaging apparatus 10 is an apparatus for performing X-ray CT (Computed Tomography) imaging of a subject P, and includes an X-ray generator 22, an X-ray detector 24, a support section 20, a turning drive section 30, It includes an imaging information reception unit 40 and an X-ray output condition setting unit 60 .

X-ray generator 22 generates an X-ray cone beam. The X-ray detector 24 detects the X-ray cone beam emitted from the X-ray generator 22 .

The support portion 20 supports the X-ray generator 22 and the X-ray detector 24 in a facing state. With the X-ray generator 22 and the X-ray detector 24 supported by the support portion 20, a space is provided between them so that the subject P can be arranged therebetween. The subject P is, for example, a human head. The X-ray cone beam emitted from the X-ray generator 22 passes through the subject P and enters the X-ray detector 24 . The X-rays incident on the X-ray detector 24 are converted into electric signals corresponding to the intensity of the X-rays for each unit pixel. An X-ray CT image or the like is generated based on these electrical signals.

The turning driving section 30 turns the X-ray generator 22 and the X-ray detector 24 supported by the supporting section 20 . For example, the turning drive unit 30 includes an electric motor and, if necessary, an acceleration/deceleration mechanism such as gears. The turning drive section 30 supports a shaft section 33 protruding from the support section 20 at a position between the X-ray generator 22 and the X-ray detector 24 so as to be rotatably driven. The support portion 20 is rotated by driving the rotation driving portion 30 with the central axis of the shaft portion 33 as the center of rotation. Along with this, the X-ray generator 22 and the X-ray detector 24 rotate around the object P. As shown in FIG.

The imaging information reception unit 40 is configured to be able to receive the setting of the imaging area. The imaging information receiving unit 40 can adopt a configuration that receives the setting of the imaging region by receiving an input operation by the operator through a touch panel, an operation switch, or the like, for example.

The setting of the imaging region includes information on at least one of the size of the imaging region desired for X-ray CT imaging of the subject P, the imaging purpose, and the imaging region.

For example, assuming that the medical X-ray CT apparatus is a dental X-ray CT apparatus, the size of the imaging area is a part of the row of teeth (for example, an area containing about 1 to 3 teeth). ), a setting including a size of an imaging region for specifying the entire dentition, a setting for specifying a size of an imaging region for specifying the entire jaw, and the like. The size of the imaging region can be set, for example, by setting the size of the radius indicating the size of the imaging region, or by setting the imaging region for the row of teeth or jaw region shown in the drawing.

Here, the imaging area will be described. The configuration of the present application can be suitably applied to a partial area of the entire subject as an individual organism. The entire subject includes partial regions such as the head, chest, and abdomen. Even in the head, there are more subdivided regions such as the maxillofacial region that is the target of dental care and the otolaryngological region that is the target of otolaryngology. In this way, there are partial areas in the entire subject individual, and the partial areas can also have size relationships.

Targeting the head of the whole individual, the head is the first layer partial area, the jaw area in it is the second layer partial area, the dental arch area in it is the third layer partial area, and the front teeth area in it. may be considered as the fourth layer partial region, and the size of the region may be considered according to the depth of the layer relative to the size of the region. In this case, a layer in a wide area may be considered a shallow layer, and a layer in a narrow area may be considered a deep layer. The hierarchy may be provided appropriately depending on the situation, and the partial areas in the dental arch, such as the first layer partial area, the anterior tooth area, and the molar tooth area, may be considered as the second layer partial areas. .

In the case of the otolaryngological region, an example may be considered in which the ear and nose region is set as the first layer partial region and the ossicular region is set as the second layer partial region.

In this way, partial areas may be set for each category of medical department.

The shallow layer partial region does not necessarily have to completely enclose the deep layer partial region, and the deep layer partial region may protrude from the shallow layer partial region.

In addition, the purpose of photography is to observe, for example, root fracture, endodontic therapy, periapical lesion, bone regeneration process of implant, periodontal, wisdom tooth, supernumerary tooth, impacted tooth, salivary stone, etc. is assumed.

The imaged region is assumed to be, for example, mandibular anterior teeth, mandibular molars, maxillary anterior teeth, maxillary molars, all teeth, temporomandibular joints, face, or the like.

The X-ray output condition setting unit 60 automatically sets the output conditions of the X-ray generator 22 according to the size of the imaging region received by the imaging information receiving unit 40 .

This X-ray output condition setting unit 60 includes at least one processor. For example, the X-ray output condition setting unit 60 is configured by a computer including at least one processor, a RAM (Random Access Memory), a storage unit, an input/output unit, and the like. The storage unit is composed of a nonvolatile storage device such as a flash memory or a hard disk device, and stores an X-ray CT imaging condition setting program 60P for setting X-ray output conditions. The RAM serves as a work area when at least one processor performs predetermined processing. Then, at least one processor performs predetermined arithmetic processing according to the X-ray CT imaging condition setting program 60P or the like stored in the storage unit to set the X-ray CT imaging conditions. In setting the X-ray CT imaging conditions, the output conditions of the X-ray generator 22 are automatically set according to the size of the imaging region received by the imaging information receiving unit 40 .

Here, the reason why the output condition of the X-ray generator 22 is automatically set according to the size of the imaging region is to adjust the radiation dose to the subject P according to the size of the imaging region. In other words, the output condition of the X-ray generator 22 is a condition that influences the dose to the subject P when performing X-ray CT imaging, for example.

Here, the dose may be defined from the output amount of X-rays from the X-ray tube, which is the X-ray source of the X-ray generator 22 . This output amount can be adjusted by the amount of energy applied to the X-ray tube. For example, if X-ray irradiation with a tube current of 40 mA and X-ray irradiation with a tube current of 50 mA are applied at the same tube voltage and for the same irradiation time, the output amount is larger at 50 mA than at 40 mA. 40 kV X-ray irradiation and 50 kV X-ray irradiation have the same tube current and the same irradiation time. The amount of output can also be adjusted from the irradiation time. For example, assuming that the same tube current and tube voltage are used for short-time X-ray irradiation and long-time X-ray irradiation, the longer the irradiation time, the larger the output amount. Assuming that the X-ray cone-beam shape adjustment unit 127 regulates the irradiated X-rays to have a cone-beam shape, it is assumed that the X-ray cone-beam path to be irradiated is between the X-ray generator 22 and the X-ray detector 24. If there is nothing to block the X-ray detector 24, the amount of light received by the detection surface of the X-ray detector 24 increases as the amount of output increases.

The amount of X-rays irradiated to a unit three-dimensional area of a three-dimensional area geometrically formed between the X-ray tube focus and the X-ray receiving surface may be used as the dose. If a cylindrical region with a diameter of 40 mm and a height of 40 mm is targeted for X-ray irradiation, the X-ray cone beam shape adjustment unit 127 regulates the X-ray irradiation so that the X-rays are irradiated only to this region. It is assumed that the detection surface of the line detector 24 has a width of 60 mm and a height of 60 mm. A three-dimensional quadrangular pyramidal area is geometrically formed between the X-ray tube focus of the X-ray generator 22 and the light receiving surface of 60 mm in width and 60 mm in height. If the light-receiving surface is further subdivided into a unit area of 1 mm in width and 1 mm in height, for example, the unit area of 1 mm in width and 1 mm in height is interposed between the X-ray tube focus and the unit area of 1 mm in width and 1 mm in height. A dimensional area is formed. The amount of X-rays applied to each unit three-dimensional area may be defined as the dose. As will be described later, the unit area may be a pixel unit forming the detection surface of the X-ray detector 24 (128).

The dose does not change whether or not the subject exists in this unit three-dimensional area. When an object exists, the X-rays irradiated into the unit three-dimensional area are absorbed by the object and do not reach the detection surface of the X-ray detector 24, or reach the detection surface after being attenuated. On the other hand, when there is no subject, all the X-rays irradiated into the unit three-dimensional area are received by the detection surface of the X-ray detector 24 (the amount absorbed by the air is so small that it can be ignored). . In any case, as long as the X-rays are irradiated under the same conditions, the amount of X-rays irradiated into the unit three-dimensional area is the same. For example, if we irradiate X-rays with large and small output amounts, and measure the dose in a unit three-dimensional area, we find that the measured dose of X-ray irradiation with a large output amount is higher than that of X-ray irradiation with a small output amount. growing.

In this example, assuming that the same part range of the same subject positioned in the same posture is irradiated with X-rays with both a large output amount and a small output amount, as a result, if the output amount of X-rays is large, the subject The X-ray energy absorbed by the unit mass portion of P is also large, and if the X-ray output amount is small, the X-ray energy absorbed by the unit mass portion of the subject P is also small.

In setting the X-ray output conditions, it is not always necessary to obtain a specific dose measurement value. This is because, for example, it is possible to set an appropriate output amount if the output amount for obtaining a good X-ray image is obtained as knowledge theoretically, experimentally, and empirically. It is sufficient if it is possible to assemble based on the prediction that if the dose is measured, the expected result will be obtained.

In addition, the dose may be considered to be the amount of X-ray energy absorbed by a unit mass portion of the subject P when the subject P exists within the X-ray irradiation range. may be represented. When performing X-ray CT imaging, for example, if the tube voltage of the X-ray tube constituting the X-ray generator 22 is increased, the absorbed dose will be increased, and if the tube current is increased, the absorbed dose will be increased. Also, if the X-ray irradiation time is lengthened when performing X-ray CT imaging, the absorbed dose increases. For this reason, the output conditions of the X-ray generator 22 are, for example, tube voltage, tube current, X-ray irradiation time, etc. when performing X-ray CT imaging. Note that the X-ray irradiation time is, for example, the speed (rotational speed) at which the X-ray generator 22 and the X-ray detector 24 are rotated by the rotating drive unit 30, the X-ray generator 22 and the X-ray It can be set by the extent to which the detector 24 is swiveled (eg, 360° swivel, 180° swivel, etc.). Appropriate dose adjustment is achieved by appropriately setting these output conditions. As described above, when the object P is present in the X-ray irradiation range, increasing the output amount of X-rays from the X-ray tube results in the amount of X-rays absorbed by the unit mass of the object P. Since it increases, there is some overlap between this definition and the previous definition.

FIG. 2 is a flowchart showing processing by the X-ray output condition setting unit 60. As shown in FIG.

That is, when X-ray CT imaging is performed, setting of an imaging region by the operator is received through the imaging information receiving unit 40 in step T1. Acceptance is done, for example, by input. The settings regarding the imaging region include settings regarding at least one of information regarding the size of the imaging region, the imaging purpose, and the imaging region.

After that, in the next step T2, the output condition of the X-ray generator is automatically set according to at least one of the information regarding the size of the imaging region, the purpose of imaging, and the region to be imaged.

As for the size of the photographing area, for example, as shown in FIG. 1, the photographing area E1 and the photographing area E2 wider than the photographing area E1 can be considered.

In this case, for example, the first output condition is set when the imaging region E1 is relatively narrow (first extent), and the first output condition is set when the imaging region E2 is relatively wide (second extent). 2 output conditions are set. For example, let the dose under the first output condition be the first dose, let the dose under the second output condition be the second dose, and set the first output condition and the second dose so that the first dose is greater than the second dose. 2 output conditions are set. When the imaging region E1 is relatively narrow, X-ray CT imaging is usually performed for the purpose of observing the local area in detail. Therefore, X-ray CT imaging is performed under the first output condition in which the dose is relatively large. Thus, a relatively sharp image can be obtained. Also, when the imaging region E2 is relatively large, X-ray CT imaging is usually performed for the purpose of overall observation, so X-ray CT imaging is performed under the second output condition in which the dose is relatively small. Therefore, low radiation exposure can be achieved.

Further, for example, when (observation of) any one of root fracture, endodontic therapy, periapical lesion, and implant bone regeneration process is set as the first imaging purpose, the first output condition is If any of periodontal, wisdom teeth, supernumerary teeth, impacted teeth, and salivary calculus (observation) is set as the second imaging purpose, the second output condition is set. For example, the first output condition and the second output condition are set such that the dose under the first output condition is greater than the dose under the second output condition. When the imaging purpose is to observe any of root fractures, endodontic therapy, periapical lesions, or the bone regeneration process of implants, X-ray CT imaging is usually performed for the purpose of observing the target site in detail. Therefore, a relatively clear image can be obtained by performing X-ray CT imaging under the first output condition in which the dose is relatively large. In addition, when the purpose is to observe any of the periodontal, wisdom teeth, supernumerary teeth, impacted teeth, or salivary stones, X-ray CT imaging is usually performed for the purpose of overall observation and understanding, so the dose is high. By performing X-ray CT imaging under the second output condition, which is relatively small, it is possible to achieve low radiation exposure.

When detailed observation is the purpose, such as observation of root fracture, endodontic therapy, periapical lesion, or bone regeneration process of implants, this purpose is called the purpose of detailed observation. When the objective is to observe the overall situation or to observe the situation in general, such as observation of teeth, impacted teeth, or salivary stones, this purpose is usually called observation purpose.

X-ray CT imaging for achieving the purpose of detailed observation will be referred to as detailed observation CT imaging, and X-ray CT imaging for achieving the purpose of normal observation will be referred to as normal observation CT imaging. An operating state in which detailed observation CT imaging is possible is called a detailed observation CT imaging mode, and an operating state in which normal observation CT imaging is possible is called a normal observation CT imaging mode.

When imaging the same region in the same size of X-ray CT imaging area, it is conceivable to change the output conditions according to the purpose of imaging. For example, when X-ray CT imaging is performed for the same region (with the same size) including the mandibular anterior teeth with the first imaging purpose being the diagnosis of root fracture, the first output condition is set, and salivary stone observation is performed. When X-ray CT imaging is performed with the purpose of the second imaging purpose, it is conceivable to set the second output condition. In this way, it is possible to reduce the exposure dose to the mandibular anterior tooth region during salivary stone observation. In addition, when diagnosing root fracture, a relatively clear and detailed image suitable for observation can be obtained.

Further, for example, when any one of the mandibular anterior teeth, the mandibular molars, the maxillary anterior teeth, and the maxillary molars is set as the first imaging region, the first output condition is set, all teeth, all teeth to jaw A second output condition is set when either the wide area extending to the joints or the face is set as the second imaging region. In the case of this example, since the first imaging region and the second imaging region have wide and narrow regions, there is also a relationship between the imaging region of the first spread and the imaging region of the second spread. Then, for example, the first output condition and the second output condition are set such that the dose under the first output condition is larger than the dose under the second output condition. If any part of the mandibular anterior teeth, the mandibular molars, the maxillary anterior teeth, or the maxillary molars is to be imaged, X-ray CT imaging is usually performed for the purpose of observing a relatively narrow imaging part in detail. A relatively clear image can be obtained by performing X-ray CT imaging under the first output condition in which the dose is relatively large. In addition, when all teeth, a wide area extending from all teeth to the temporomandibular joint, or the face is to be imaged, X-ray CT imaging is performed for the purpose of overall observation, so the dose is relatively small. By performing X-ray CT imaging under the second output condition, low radiation exposure can be achieved.

It is also conceivable to change the output conditions when imaging different parts in the same size CT imaging area. For example, an area including the temporomandibular joint where the base of the skull exists in the path of the X-ray cone beam (first imaging site) and an area including the mandibular anterior teeth where the base of the skull is out of the path of the X-ray cone beam (second imaging site). Assume that a CT imaging region of the same size is set. In this case, the shooting purpose may or may not be set. When the shooting purpose is set, it may be the same purpose. Then, the irradiation condition for the former, that is, the temporomandibular joint region, and the latter, that is, the irradiation condition for the mandibular anterior tooth region are set, and the first output condition is set for the temporomandibular joint region, and the second output condition is set for the mandibular anterior tooth region. In this way, the exposure dose to the mandibular anterior tooth region can be reduced. In addition, a clear image of the temporomandibular joint, in which the base of the skull exists in the path of the X-ray cone beam, can be obtained regardless of the presence of the base of the skull.

Another classification may be used when different parts are imaged in the same size CT imaging area. For example, assuming that a cylindrical region with a diameter of 40 mm and a height of 40 mm is targeted for X-ray CT imaging, it is classified into a molar region and an anterior tooth region according to the amount of hard tissue, and the molar region is regarded as a region with a large amount of hard tissue and is output as the first output. The first output condition and the second You may make it set an output condition.

In addition, even in the same anterior tooth region, there is a difference between the maxillary anterior tooth region and the mandibular anterior tooth region in that the upper anterior tooth region has more surrounding hard tissue, and the mandibular anterior tooth region has less surrounding hard tissue. Even in the same molar region, there is a difference between the maxillary molar region and the mandibular molar region in that the maxillary molar region has more surrounding hard tissue, and the mandibular molar region has less surrounding hard tissue.

Focusing on this, for example, the maxillary molar region is classified into the first group, the mandibular molar region and the maxillary anterior tooth region are classified into the second group, and the mandibular anterior tooth region is classified into the third group. classified into

In the relationship between the first set and the second set, the first set is the first imaging site, the second set is the second imaging site, and the dose based on the first output condition corresponding to the first imaging site is The first output condition and the second output condition are defined so as to be larger than the dose based on the second output condition corresponding to the second imaging region.

In the relationship between the second set and the third set, the second set is the first imaging region, the third set is the second imaging region, and the dose based on the first output condition corresponding to the first imaging region is The first output condition and the second output condition are defined so as to be larger than the dose based on the second output condition corresponding to the second imaging region.

A setting example in FIG. 20, which will be described later, is such a setting example.

In addition to the setting based on the amount of hard tissue, the setting may also be performed based on the density of the hard tissue.

In the above example, an example in which the output condition is set based on one of the information on the size of the imaging region, the purpose of imaging, and the region to be imaged has been described. The output condition may be set based on a combination of the two, or based on a combination of all of the size of the imaging region, imaging purpose, and imaging region.

When the output conditions of the X-ray generator are automatically set according to at least one of the information regarding the size of the imaging region, the imaging purpose, and the imaging region, the setting process regarding the X-ray output conditions ends.

The X-ray CT imaging apparatus 10 irradiates an X-ray cone beam from the X-ray generator 22 according to the set output conditions of the X-ray generator, and detects the X-ray cone beam transmitted through the subject P to the X-ray detector 24 . , the rotation driving unit 30 rotates the X-ray generator 22 and the X-ray detector 24 around the object P to perform X-ray CT imaging.

An X-ray CT image is generated based on the data detected by the X-ray detector 24 .

According to the X-ray CT imaging apparatus 10, the medical X-ray CT imaging condition setting method, and the X-ray CT imaging condition setting program 60P configured as described above, according to at least one of the received information regarding the imaging purpose and imaging region, By automatically setting the output condition of the X-ray generator 22 using the X-ray generator 22, it is possible to reduce exposure to radiation as much as possible. Also, normally, the sizes of the imaging regions E1 and E2, the imaging region, and the like are set according to the imaging purpose. By automatically setting the output conditions of the ray generator 22, it is possible to obtain an X-ray CT image with image quality that is as appropriate as possible according to the purpose of imaging.

For example, in the case of a relatively small imaging region E1, a relatively clear X-ray CT image can be obtained by performing X-ray CT imaging under the first output condition in which the dose is relatively large. Usually, in the case of X-ray CT imaging for a relatively narrow imaging range E1 targeting a part of the teeth of the dental arch, X-ray CT for the purpose of treatment etc. of a part of the teeth of the dental arch Filming takes place. Therefore, by obtaining a relatively clear X-ray CT image, a clear image suitable for treatment can be obtained. Further, for example, in the case of a relatively large imaging region E2, X-ray CT imaging can be performed under low exposure conditions by performing X-ray CT imaging under the second output condition in which the dose is relatively small. can. Generally, in the case of X-ray CT imaging for a relatively wide imaging region E2, which targets the entire dental arch, the entire jaw region, etc., X-ray CT imaging is used for the purpose of observing the overall shape of teeth and skeletons. done. Therefore, an X-ray CT image suitable for such overall observation can be obtained under low-exposure X-ray CT imaging conditions.

Further, for example, when root fracture, endodontic therapy, periapical lesion, bone regeneration process of implants, etc. are set as imaging purposes, X-ray CT imaging is performed under the first output condition where the dose is relatively large. By doing so, a relatively clear image can be obtained. In addition, when any of periodontal disease, wisdom tooth, supernumerary tooth, impacted tooth, or salivary calculus is set, X-ray CT imaging is usually performed under the second output condition with a relatively small dose, thereby reducing exposure to radiation. can be planned.

Further, for example, when any of the mandibular anterior teeth, the mandibular molars, the maxillary anterior teeth, and the maxillary molars, which are part of the dental arch, is set as the imaging region, X A relatively clear image can be obtained by performing linear CT imaging. In addition, when any of all teeth, temporomandibular joints, or the face, which is wider than the entire dental arch, is set as the imaging region, X-ray CT imaging is performed under the second output condition with a relatively small dose. , low exposure can be achieved.

{Second embodiment}
An X-ray CT imaging apparatus according to the second embodiment will be described.

<Overall configuration>
FIG. 3 is an overall view showing the configuration of an X-ray CT imaging apparatus 110 according to the second embodiment, and FIG. 4 is a perspective view of the X-ray CT imaging apparatus 110 according to the second embodiment when viewed obliquely from above. is. In each figure, for convenience of explanation, an XYZ coordinate system may be set in the entire space in which the X-ray CT imaging apparatus 110 exists. In this XYZ coordinate system, the right direction is the X (+) direction, the left direction is the X (-) direction, and the front is the Y (+) direction, with reference to the head P supported by the X-ray CT imaging apparatus 110. The rearward direction is the Y(-) direction, the upward direction is the Z(+) direction, and the downward direction is the Z(-) direction.

The X-ray CT imaging apparatus 110 has an imaging unit 120 and an image processing device 180 . The imaging unit 120 is a device that acquires X-ray projection data by performing X-ray imaging of the subject P. As shown in FIG. The imaging unit 120 is housed in, for example, an X-ray-proof room 146 and used. The image processing device 180 processes the X-ray projection data acquired by the imaging unit 120 to generate various X-ray images (specifically, panoramic images, CT images, cephalometric images, etc.).

Of course, the imaging unit 120 only needs to perform X-ray CT imaging of the subject P, and the image processing device 180 processes the X-ray projection data collected by the imaging unit 120 to generate an X-ray CT image. Anything that does. In the following, the configuration for performing CT imaging by the X-ray CT imaging apparatus 110 will be mainly described.

The imaging unit 120 includes an X-ray generator 126, an X-ray detector 128, a swivel support unit 124, and a body control unit 150 (see FIGS. 5 and 6 described later, not shown in FIG. 3).

The X-ray generator 126 has an X-ray tube, which is an X-ray source that generates X-rays. An X-ray cone beam is emitted from the X-ray generator 126 . The intensity (output intensity) of the X-ray cone beam is controlled by changing at least one of the tube voltage and tube current supplied to the X-ray generator 126 . Control of the X-ray generator 126 (more specifically, control of at least one of tube voltage and tube current) is performed by an X-ray generator drive control section 152h of the main body control section 150. FIG.

An X-ray cone beam shape adjusting unit 127 is provided on the side of the X-ray generator 126 where the X-ray cone beam is irradiated. The X-ray generator 126 and the X-ray cone beam shape adjusting section 127 are supported by one end of the turning support section 124 .

The X-ray cone beam shape adjustment unit 127 regulates the spread of the X-ray cone beam emitted from the X-ray generator 126, and adjusts the X-ray cone beam to a shape according to the purpose of imaging. The X-ray cone beam shape adjusting unit 127 is, for example, a member in which an X-ray regulation hole is formed. Allows the passage of the part and shields the outside of the passage range. This limits the range of the x-ray beam that travels to the x-ray detector 128 . This X-ray cone beam shape adjusting unit 127 is, for example, provided with a plurality of types of X-ray restricting holes and switching the X-ray restricting holes for restricting X-rays, or moving a member forming the X-ray restricting holes. The amount of X-rays generated from the X-ray generator 126 that are shielded, that is, the amount of regulation, is adjusted by adjusting the opening width of the X-ray regulation hole. The X-ray cone beam shape adjusting section 127 is controlled by the X-ray generator driving control section 152h.

X-ray detector 128 detects the X-ray cone beam emitted from X-ray generator 126 . The X-ray detector 128 can be composed of a flat panel detector (FPD) having a flat detection surface, an X-ray fluorescence intensifier (I.I.: Image Intensifier), or the like.

A plurality of detection elements arranged on the detection surface of the X-ray detector 128 convert the intensity of incident X-rays into electrical signals. Then, the electrical signal is input to the main body control unit 150 or the image processing device 180 as an output signal, and an X-ray projection image is generated based on the signal.

The X-ray detector 128 is supported at the other end of the swivel support section 124 so as to face the X-ray generator 126 with a gap therebetween. A detection surface of the X-ray detector 128 is irradiated with an X-ray cone beam emitted from the X-ray generator 126 .

The swivel support portion 124 is suspended from the horizontal arm 123 via the rotation shaft portion 125 . The swivel support portion 124 extends in the horizontal direction while being suspended. A housing 124 a is attached to one end of the swivel support portion 124 , and a housing 124 b is attached to the other end of the swivel support portion 124 . An X-ray generator 126 and an X-ray cone beam shape adjusting section 127 are accommodated and supported in the housing 124a. The X-ray generator 126 irradiates an X-ray cone beam from one end of the swivel support 124 to the other end. The X-ray detector 128 is accommodated in the housing 124b with the X-ray detection surface facing the X-ray generator 126 side. As a result, the swivel support portion 124 supports the X-ray generator 126 on one end side and supports the X-ray detector 128 on the other end side.

The swivel support portion 124 is supported via a column 121 and a horizontal arm 123 .

The column 121 is supported in a vertical posture on a base 121B placed on a floor surface or the like. An elevating unit 122 is provided on the column 121 so as to be capable of being driven up and down. The lifting section 122 is driven up and down by a lifting drive mechanism. As the elevation drive mechanism, a moving mechanism including a ball screw mechanism, a motor, and the like, and a linear actuator such as a linear motor are used, which are incorporated in the column 121 and drive the elevation section 122 up and down. A horizontal arm 123 is supported by the elevation unit 122 so as to extend in the horizontal direction. A turning drive mechanism 130 is incorporated in the tip of the horizontal arm 123 .

The turning drive mechanism 130 is a mechanism for turning the turning support portion 124 . In this embodiment, the turning drive mechanism includes a turning shaft moving mechanism 134 and a turning mechanism 132 movably supported by the turning shaft moving mechanism 134 .

The turning shaft moving mechanism 134 is a mechanism for moving the rotating shaft portion 125 together with the turning mechanism 132 in a direction (here, horizontal direction) crossing the turning axis X1 of the rotating shaft portion 125 . As the turning axis moving mechanism 134, for example, an XY table mechanism in which two linear actuators are combined in directions orthogonal to each other can be adopted. The rotating shaft moving mechanism 134 moves the rotating shaft portion 125 along the horizontal direction together with the rotating mechanism 132, so that the rotating shaft portion 125 can be arranged at a desired position. The pivot axis of the line detector 128 can be set at any position.

The turning mechanism 132 includes a turning driving actuator, specifically a motor 132a, as a turning driving section, and is supported by the turning shaft moving mechanism 134 so as to be movable in the horizontal direction. An upper end portion of a rotating shaft portion 125 protruding upward from an intermediate portion in the extending direction of the turning support portion 124 is supported by a turning mechanism 132 so as to be rotatably driven. Rotational motion of a motor provided in the turning mechanism 132 is transmitted to the rotating shaft portion 125, so that the turning support portion 124 and the X-ray generator 126 and the X-ray detector 128 supported by the turning support portion 124 turn. do. Rotational motion of the motor provided in the turning mechanism 132 is transmitted to the rotating shaft portion 125 via a transmission mechanism such as gears and pulleys as necessary.

In this embodiment, the X-ray generator 126 and the X-ray detector 128 are attached to both ends of the U-shaped turning support 124, but the X-ray generator and the X-ray detector are You may support by the annular member in the opposing state. Such an annular member can be rotatably supported by providing a shaft portion on a part of the annular member in the circumferential direction or on a supporting member that traverses the interior of the annular member. Further, in the present embodiment, the X-ray generator 126 and the X-ray detector 128 are rotatably supported around a vertical axis, but they are supported rotatably around an axis oblique to the vertical direction. may have been

The swivel support part 124 can be moved up and down according to the height of the head P by the elevating part 122 . The swivel drive mechanism 130 can also swivel the swivel support 124 so that the X-ray generator 126 and the X-ray detector 128 swivel around the head P. As shown in FIG.

Further, a lifting part 141A for a head fixing device is provided on the post 121 so as to be driven up and down. The elevating section 141</b>A for the head fixing device is provided below the elevating section 122 . The head fixing device arm 141 is provided so as to extend in the same direction as the horizontal arm 123 from the head fixing device elevating section 141A. Head fixator arm 141 extends through the underside of horizontal arm 123 toward a lower position between X-ray generator 126 and X-ray detector 128 . A head fixing device 142 is provided at the tip of the head fixing device arm 141 . Head fixation device 142 is located between x-ray generator 126 and x-ray detector 128 . The head fixing device 142 includes a chin rest 142a on which the chin of the subject's head P can be placed and supported, and a holding portion 142b that sandwiches and retains the subject's head P from both outer sides. The jaw of the head P is supported on the chin rest 142a, and the head P is sandwiched between the holding portions 142b, so that the head P is positioned between the X-ray generator 126 and the X-ray detector 128. held in place. The head fixing device 142 may comprise at least one of the chin rest 142a and the holding portion 142b.

In addition, an arm 143 for suspending the head fixing device for cephalometric imaging is provided so as to extend in the horizontal direction on the side opposite to the side where the horizontal arm 123 extends from the column 121. This arm 143 for suspending the head fixing device for cephalometric imaging A cephalometric imaging head fixing device 144 is supported in a suspended state. The head fixing device 144 for cephalometric imaging incorporates an X-ray detector 128b for cephalometric imaging. A mechanism including cephalometric head fixing device suspension arm 143, cephalometric head fixing device 144, cephalometric X-ray detector 128b, and other peripheral components as necessary, Configure the detection mechanism. A mechanism including the horizontal arm 123, the swivel support 124, the housing 124a, the X-ray generator 126, and other peripheral components as required for cephalometric imaging constitutes an X-ray generating mechanism for cephalometric imaging. The cephalometric X-ray detection mechanism and the cephalometric X-ray generation mechanism constitute a cephalometric imaging mechanism.

In this embodiment, each part for cephalometric imaging, for example, the cephalometric imaging head fixing device hanging arm 143, the cephalometric imaging head fixing device 144, the cephalometric imaging X-ray detector 128b, etc., may be omitted. good.

A body control section 150 including an operation panel device 158 is provided at an intermediate portion in the extending direction of the head fixing device arm 141 .

When X-ray imaging is performed, the head P, which is the subject, is fixed by the head fixing device 142, and X-ray imaging is performed with the swivel support section 124 stopped or rotated according to the desired imaging mode. take a picture. In particular, the X-ray image data necessary for generating an X-ray CT image or the like can be obtained by rotating the turning support part 124 and turning the X-ray generator 126 and the X-ray detector 128 around the subject P. be able to. Also, by performing X-ray imaging with the swivel support portion 124 rotated within a certain range, a panorama photographed image can be obtained. The X-ray CT imaging apparatus 110 can also perform X-ray imaging for obtaining cephalometric images and pseudo intraoral images. For example, the head P is positionally fixed to the cephalometric imaging head fixing device 144 supported by the cephalometric imaging head fixing device suspending arm 143 extending in the horizontal direction from the support 121 while the turning support part 124 is stopped. A cephalometric image can be obtained by irradiating X-rays from the X-ray detector 128 and performing X-ray imaging.

The body control unit 150 is configured by a computer or the like, and is configured to be able to receive various instructions to the imaging unit 120 and to control each operation of the imaging unit 120 . The body control unit 150 is fixed to a head fixing device arm 141 extending horizontally from the support 121 . The body control section 150 is provided with an operation panel device 158 for displaying various information from the body control section 150 and for receiving various commands to the body control section 150 . Here, the operation panel device 158 is a touch panel that includes a display device such as a liquid crystal display panel and a touch detection section provided on the display screen of the display device. By detecting the user's touch operation on the display screen with the touch detection unit, the X-ray CT imaging apparatus 110 is configured to be able to receive the operation. A push button or the like may be provided near the operation panel device 158 or the like. Also, the display device and the input device that receives the user's operation may be provided separately.

A push-button switch called a deadman switch connected to the main control unit 150 is provided on the outside of the wall of the X-ray proof room 146 that accommodates the imaging unit 120 . X-ray irradiation is performed only while the operator is pressing the deadman's switch.

The image processing apparatus 180 includes an information processing main unit 182 configured by, for example, a computer, workstation, etc., and is connected to the imaging unit 120 via a communication cable so that various data can be transmitted and received. However, data may be transmitted and received between the imaging unit 120 and the image processing device 180 by wireless communication. This information processing main unit 182 can execute various image processing and the like based on the data transmitted from the photographing unit 120 .

The image processing device 180 is connected to a display unit 184a including a display device such as a liquid crystal monitor, and an operation unit 184b including a keyboard, mouse, and the like. The operator can give various commands to the information processing main unit 182 by operating a pointer or the like using a mouse or the like on characters or images displayed on the display unit 184a. Note that the display unit 184a may be composed of a touch panel.

A part or all of the processing of the image processing device 180 may be executed by the main control unit 150 . Alternatively, part or all of the processing of the body control unit 150 may be executed by the image processing device 180 . In other words, each process of the main body control unit 150 and the image processing device 180 may be executed by a single computer provided at any location, or distributed by a plurality of processors provided at any location. may be processed by

<About the block diagram of the X-ray CT apparatus>
FIG. 5 is a functional block diagram of the X-ray CT imaging apparatus 110, and FIG. 6 is a block diagram showing the electrical configuration of the main body controller 150. As shown in FIG.

The body control unit 150 controls the X-ray imaging operation of the imaging unit 120, and includes a CPU (Central Processing Unit) 150a as an example of a processor, a RAM (Random Access Memory) 150b, a storage unit 150c, and an input/output unit 150d. , an operation input unit 150e, an image output unit 150f, and the like are configured by computers interconnected via a bus line 150g (see FIG. 6). The storage unit 150c is composed of a non-volatile storage device such as a flash memory or a hard disk device. It stores an imaging program 151 and the like for controlling operations when line CT imaging is performed. The imaging program 151 includes an X-ray CT imaging condition setting program 151a for automatically setting the output conditions of the X-ray generator 126 in accordance with the X-ray imaging settings received through the operation panel device 158 or the like. It is included.

The storage unit 150c also stores a reference table 152 in which the output conditions of the X-ray generator 126 are associated with settings related to X-ray imaging. An example of this reference table 152 will be described later.

The RAM 150b is used as a working area when the CPU 150a performs predetermined processing. The input/output unit 150d is connected to a motor included in the turning drive mechanism 130 of the imaging unit 120, the X-ray generator 126, the X-ray detector 128, and the like. The operation input unit 150 e is connected to the touch detection unit of the operation panel device 158 , and the image output unit 150 f is connected to the display unit of the operation panel device 158 .

In the body control unit 150, the CPU 150a performs arithmetic processing according to the procedure described in the imaging program 151 and the instructions received through the operation panel device 158 and the like, thereby controlling the display on the operation panel device 158 and Accept various settings. In addition, the CPU 150a performs arithmetic processing in accordance with the procedure described in the imaging program 151 and received instructions regarding imaging, thereby driving and controlling the turning drive mechanism 130, the X-ray generator 126, the X-ray detector 128, and the like. . As a result, the X-ray generator 126 and the X-ray detector 128 rotate around the object P, and the X-ray cone beam emitted from the X-ray generator 126 passes through the object P and enters the X-ray detector 128. do. Then, based on the data detected by the X-ray detector 128, an X-ray CT image can be generated.

As shown in FIG. 5, the main body control unit 150 includes a support unit drive control unit 152a, a mode setting reception unit 152b, an imaging information reception unit 152c, an X-ray output condition setting unit 152d, an output condition setting reception unit 152e, an X-ray imaging It has a data processing unit 152f, an X-ray detection unit drive control unit 152g, an X-ray generator drive control unit 152h, and an image quality setting unit 152i. Each of these control units is a function realized by a CPU (general purpose circuit) operating according to the imaging program 151 . It should be noted that some or all of these functions may be implemented in hardware by configuring a dedicated circuit or the like. Moreover, each of the above functions may be distributed and processed by a plurality of computers. The mechanical entity of the function realized by the CPU operating according to the program is the electrical signal as the program and the circuit functioning according to the program.

The support drive control section 152 a controls the turning of the turning support section 124 by controlling the turning drive mechanism 130 . Specifically, the support unit drive control unit 152a rotates the X-ray generator 126 and the X-ray detector 128 supported by the turning support unit 124 around the rotation axis X when performing X-ray CT imaging. Thereby, the X-ray generator 126 and the X-ray detector 128 are rotated around the subject P. The support unit drive control unit 152a can control the rotation speed and rotation range (rotation angle) of the X-ray generator 126 and the X-ray detector 128 in accordance with the output conditions set by the X-ray output condition setting unit 152d, which will be described later. may be

The mode setting reception unit 152b receives the setting of the low dose mode and the high resolution mode through the operation panel device 158. FIG. As will be described later, the low-dose mode is a mode in which X-ray CT imaging is performed with a low dose depending on the imaging region according to at least one of the imaging region size, imaging purpose, and imaging region. That is, the X-ray CT imaging apparatus 110 can perform low-dose X-ray CT imaging and high-resolution X-ray CT imaging, as will be described later. Low-dose X-ray CT imaging is imaging in which X-ray CT imaging is performed in a state where the dose of X-rays emitted from the X-ray generator 126 is suppressed. Become. The high-resolution mode is a mode for high-resolution X-ray CT imaging. High-resolution X-ray CT imaging is imaging in which X-ray CT imaging is performed with a higher dose than in the case of low-dose X-ray CT imaging. image can be obtained. Output conditions of the X-ray detector 128 are set according to each of the low dose mode and the high resolution mode. This setting is defined in the reference table 152, for example. This point will be described later.

The low dose mode is a specific example of the normal observation CT imaging mode, and the high resolution mode is a specific example of the detailed observation CT imaging mode.

In the X-ray CT imaging apparatus 110, switching between both the low dose mode and the high resolution mode is not essential. For example, the configuration may be such that only the low dose mode can be executed.

The imaging information receiving unit 152c receives, via the operation panel device 158, imaging information regarding at least one of the size of the imaging region, the imaging purpose, and the imaging region. The imaging information contains settings related to at least one of the size of the imaging region, the purpose of imaging, and the body part to be imaged. Acceptance is done, for example, by input. In the present embodiment, an example in which the imaging information reception unit 152c receives the size of the imaging region and the imaging part through the operation panel device 158 will be described. An example in which the photographing information receiving unit 152c receives the purpose of photographing will be described later in a modified example.

Here, the photographing information reception unit 152c also receives the setting of the physique through the operation panel device 158. FIG. More specifically, the imaging information receiving unit 152c receives, as the setting of the physique, whether the subject has the physique of a child or exceeds that of a child.

The X-ray output condition setting unit 152d sets the X-ray output conditions according to at least one of the size of the imaging region, the purpose of imaging, and the region to be imaged received by the imaging information receiving unit 152c. In this embodiment, an example in which the imaging information reception unit 152c sets the X-ray output condition according to the size of the imaging region will be described. An example in which the X-ray output condition setting unit 152d sets the X-ray output condition according to the purpose of imaging, the part to be imaged, etc. will be described later in a modified example.

Here, the X-ray output condition setting unit 152d sets the imaging region regarding at least one of the imaging region size, the imaging purpose, and the imaging region received by the imaging information receiving unit, and also sets the imaging region according to the physique. The output conditions of the X-ray generator 126 are automatically set according to the setting, more specifically, depending on whether the subject has a physique of a child or a physique exceeding that of a child. When the output condition is manually set in the output condition setting reception unit 152e described below, the output condition setting reception unit 152e changes the automatically set output condition according to the content of the manual setting.

The output condition setting reception unit 152 e receives manual setting of the output condition of the X-ray generator 126 by the operator through the operation panel device 158 . That is, when the operator wishes to arbitrarily change and adjust the output conditions for the output conditions automatically set by the X-ray output condition setting unit 152d, the operator can change the automatically set output conditions through the operation panel device 158. Adjustments can be entered.

A manual setting function for automatically set output conditions may be omitted.

The X-ray imaging data processing unit 152f performs image processing such as noise reduction processing on the data detected by the X-ray detector 128 . As the noise reduction process, a median filter that uses the value of each pixel as the median value of surrounding pixels, a moving average filter that uses the average value of the surrounding pixels as the value of each pixel, or the like can be used.

The X-ray detection unit drive control unit 152g controls driving of the X-ray detector 128 . The X-ray detection unit drive control unit 152g may be capable of controlling ON/OFF of a binning function for collectively processing a plurality of pixels of the X-ray detector 128 as one pixel, and control of the unit of pixels grouped by the binning function.

The X-ray generator drive control unit 152h controls at least one of the tube voltage and the tube voltage of the X-ray generator 126 according to the X-ray output conditions automatically set by the X-ray output condition setting unit 152d. On/off control of the line generator 126 and the like are performed.

The image quality setting unit 152i performs X-ray CT according to at least one of the setting of the imaging region received by the imaging information receiving unit 152c and the output condition of the X-ray generator 126 automatically set by the X-ray output condition setting unit 152d. Automatically set image quality. Here, the image quality setting unit 152 i automatically sets the image quality of the X-ray CT image by adjusting the voxel size when reconstructing the X-ray CT image based on the image obtained by the X-ray detector 128 . For example, in the output conditions, there are a first dose and a second dose, the first dose is larger than the second dose, and the first output condition sets the first dose. If the second output condition is to set the second dose, and if the second output condition is automatically set, noise is likely to be present. Set the size relatively large. Further, for example, when the first output condition is automatically set, noise is less likely to appear, so the voxel size is made smaller than in the above case to obtain a high-resolution and clear image. Further, for example, when the relatively wide imaging area E2 is imaged under the second output condition compared to the relatively narrow imaging area E1, the voxel size may be set relatively large.

The image quality setting unit 152i may automatically set the image quality of the X-ray CT image according to the received imaging region setting information regardless of the set output conditions of the X-ray generator 126 . For example, it is possible to reduce the voxel size when there is a request for detailed observation as described above, and to increase the voxel size when there is a request for normal observation as described above. The voxel size may be reduced when there is an acceptance of a relatively narrow first expanse imaging area, and may be increased when an acceptance of a relatively wide second expanse imaging area is received. .

A set value (for example, a voxel value) in the image quality setting unit 152 i is given to the image processing device 180 . The image processing device 180 reconstructs an X-ray CT image based on the set voxel values. That is, three-dimensional data is generated based on data detected by the X-ray detector 128, and an X-ray CT image is generated by cutting out a tomographic image from this three-dimensional data. The voxel value is a three-dimensional unit when generating the three-dimensional data.

An example of image quality setting by the image quality setting unit 152i is not limited to the above example. The role of the image quality setting unit 152i is to eliminate the influence of noise as much as possible because noise tends to occur when an output condition with a relatively small dose is automatically set. Conversely, when the output condition with a relatively large dose is automatically set, the boundary itself is relatively clear and data with little noise can be obtained. Although image quality adjustment is not necessary, the smaller the degree of image quality adjustment, the better.

As the image quality setting process by the image quality setting unit 152i, other than adjusting the voxel size as described above can be employed.

For example, the image quality setting unit 152i may adjust the unit of pixels to be combined by turning on/off the binning function of the X-ray detector 128 or by the binning function. For example, the binning function may be turned on when the output condition of relatively low dose is automatically set, and the binning function may be turned off when the output condition of relatively high dose is automatically set. Further, for example, when an output condition with a relatively small dose is automatically set, the pixel unit to be combined by the binning function is higher than the pixel unit to be combined by the binning function when an output condition with a relatively large dose is automatically set. You can make it bigger. Turning the binning function on instead of turning it off, or increasing the pixel unit grouped by the binning function is called high-binning.

Also, the image quality setting unit 152i may adjust the detection sensitivity of the X-ray detector 128 to set the image quality. For example, when an output condition with a relatively small dose is automatically set, the sensitivity may be increased, and when an output condition with a relatively large dose is automatically set, the detection sensitivity may be decreased. As a specific example, a capacitor element (capacitor) that receives a pixel signal on the detection surface is prepared in a plurality of types or variable capacitively, and configured to be switchable or changeable, and an output condition with a relatively small dose is achieved. The volume is decreased when the setting is automatically performed, and the volume is increased when the output condition with a relatively large dose is automatically set. The evaluation of the strength of the signal in each capacity is configured to be performed in multiple stages (same number of stages common to each capacity, eg 16 bits).

The image quality setting unit 152i may also adjust the slice thickness when reconstructing the X-ray CT image. That is, three-dimensional data is generated based on the data detected by the X-ray detector 128, slices are cut out from this three-dimensional data, and one slice or multiple slices are superimposed to obtain an X-ray CT. Generate an image. Increasing the thickness of the slice contributes to noise reduction, which leads to averaging the values in the thickness direction. Therefore, when the output condition with a relatively small dose is automatically set, the thickness of the slice is set large, and when the output condition with a relatively large dose is automatically set, the thickness of the slice is set small. good too. The slice thickness automatic setting value is provided to the image processing device 180 . The image processing device 180 reconstructs an X-ray CT image based on the set slice thickness.

Also, noise reduction processing such as smoothing operation filters such as median filters and moving average filters for at least one of the data obtained by the X-ray detector 128, the three-dimensional image based on the data, and the X-ray CT image You may adjust whether to apply or not to apply. For example, when an output condition with a relatively small dose is automatically set, noise reduction processing is performed, and when an output condition with a relatively large dose is automatically set, noise reduction processing may not be performed. good. The intensity of noise processing may be changed between the two. Instructions on whether or not to execute noise processing and on selection are given from the body control unit 150 to the image processing device 180 .

Further, when executing each of the processes described above, particularly when executing the processes as the mode setting reception unit 152b, the X-ray output condition setting unit 152d, and the output condition setting reception unit 152e, the main body control unit 150 uses the operation panel device It controls the display contents in 158 and accepts touch operations on the operation panel device 158 . In this regard, the operation panel device 158 includes a mode setting operation section 158a for performing setting operations on the mode setting reception section 152b, an imaging information setting operation section 158b for performing setting operations on the X-ray output condition setting section 152d, and an output It can function as an output condition setting operation unit 158c for performing a setting operation on the condition setting reception unit 152e.

Here, the above-described processing for increasing the voxel size, noise reduction processing using a filter or the like, binning processing, processing for increasing the slice thickness, etc. are processing in the direction of combining the signal of a certain pixel and the signals of neighboring pixels. This is called pixel signal coupling type processing.

Of these, signal processing on the X-ray detector side, such as binning switching of the X-ray detector 128, is called pixel signal coupling type detection signal processing, and image processing on the image processing apparatus side, such as processing for increasing the slice thickness, is performed. The processing is called pixel signal combination type image processing.

As an example of control, the following control can be considered. The first imaging area and the second imaging area are considered as imaging target areas. Comparing the sizes, the first imaging area is narrow and the second imaging area is wide. X-ray CT imaging is performed for a first imaging region under a first output condition and for a second imaging region under a second output condition. The first output condition and the second output condition are set by the X-ray output condition setting unit 152d, the dose under the first output condition is the first dose, and the dose under the second output condition is the second dose. Comparing the magnitudes, the first dose is large and the second dose is small.

First projection image data is obtained by X-ray CT imaging of the first imaging region, and second projection image data is obtained by X-ray CT imaging of the second imaging region.

The image quality setting unit 152i sets the image quality of the generated X-ray CT image. For example, high-binning is performed during X-ray CT imaging of the second imaging region, or pixel signal combination type processing is performed on the second projection image data.

The body control unit 150 is communicably connected to the image processing device 180 via a communication I/F (interface) 154 .

The image processing device 180 is configured by a computer, workstation, or the like. That is, the image processing apparatus 180 includes a CPU as an example of a processor that performs various kinds of arithmetic processing, a ROM that is a read-only memory that stores basic programs, and a RAM that is a readable/writable memory that stores various information. The CPU functions as the control unit 181 by operating according to the control program. The control section 181 is connected to the image processing section 181 a and the storage section 183 . The image processing unit 181a processes an X-ray transmission image generated based on the signal output from the X-ray detector 128 when the imaging unit 120 executes X-ray CT imaging, and generates an X-ray CT image. . Storage unit 183 stores applications or data.

The image processing unit 181a is a function implemented by an image processor. The image processing unit 181a may be a function realized by the CPU of the control unit 181 operating according to an application program.

For example, when X-ray CT imaging is performed by the imaging unit 120, the image processing unit 181a performs predetermined preprocessing, filter processing, backprojection processing, and the like on a plurality of acquired projection images to obtain 3 images. A dimensional image is generated, and a CT image of each tomogram obtained by slicing the imaging region based on the three-dimensional image is generated. For example, a plurality of projection images obtained by X-ray CT imaging are processed as frame data, three-dimensional mesh data consisting of three-dimensional voxel data (three-dimensional pixels in image processing) is constructed, and from the three-dimensional mesh data The extracted slice data is visualized as a tomographic image, or the three-dimensional mesh data is processed as a volume rendering image. An X-ray CT image is thus generated.

The control unit 181 is connected to a display unit 184a that displays images showing various types of information, and an operation unit 184b that allows an operator to perform operation input. Also, the image processing device 180 is connected to the main control unit 150 via the communication I/F 185 so as to be able to communicate information.

<Various setting examples>
An example in which body control unit 150 receives various settings through operation panel device 158 will be described.

FIG. 7 is a diagram showing a display example of the operation panel device 158. As shown in FIG.

As shown in the figure, the operation panel device 158 displays imaging mode selection images 201, 202, and 203 corresponding to a plurality of X-ray imaging modes. Here, shooting mode selection images 201 , 202 , 203 and 204 are displayed above the display area of the operation panel device 158 .

More specifically, the imaging mode selection images 201, 202, and 203 are a panoramic imaging mode selection image 201 corresponding to the panoramic imaging mode, a cephalometric imaging mode selection image 202 corresponding to the cephalometric imaging mode, and a CT imaging mode. and a CT imaging mode selection image 203 .

Here, the panorama imaging mode is an imaging mode executed to acquire one image of the entire mouth (or part of the mouth) along the dentition. In this mode, X-ray imaging is performed in a rotated state. An image representing the characters “Pan” is displayed as the panorama shooting mode selection image 201 . An X-ray generator 126 and an X-ray detector 128 are used for panoramic radiography.

The cephalometric imaging mode is an imaging mode that is executed to perform cephalometric imaging, i.e., X-ray standard photography of the head. This is the mode for shooting. As the cephalometric imaging mode selection image 202, an image representing the characters "Ceph" is displayed. The cephalometric imaging mechanism described above is used for cephalometric X-ray photography.

The CT imaging mode is an imaging mode that is executed to obtain a tomographic image of the entire dentition (or part of the dentition). be. An image representing the characters “CT” is displayed as the CT imaging mode selection image 203 . An X-ray generator 126 and an X-ray detector 128 are used for CT imaging.

The images displayed as the shooting mode selection images 201, 202, and 203 are not limited to the above example, and may be, for example, an illustration of each shooting mode.

The display screen of the operation panel device 158 is provided with a touch detection section as a two-dimensional position detection section that detects a touch position on the display outer surface. Then, when the user touches one of the shooting mode selection images 201, 202, and 203, the touch detection unit accepts a selection operation for one of the shooting mode selection images 201, 203, and 203. When this selection operation is accepted, one imaging mode selection image corresponding to the selection operation is preferably displayed so as to be visually identifiable from other imaging area selection images. Accordingly, main body control portion 150 accepts the selection of the shooting mode. Note that when a selection operation for one of the shooting mode selection images 201, 203, and 203 is accepted, the selected one of the shooting mode selection images 201, 203, and 203 is displayed in a different color ( (including the case where the shade of color is different), and may be made identifiable from others.

Further, an image 210 for designating a photographing position is displayed on the operation panel device 158 . Here, an image showing a dental arch is displayed as the imaging position designation image 210 . The photographing position designation image 210 is displayed in a large size in the central portion of the display screen of the operation panel device 158 . The image for specifying the imaging position may be an X-ray image, such as a cephalometric image, obtained by separately imaging a subject who is actually subjected to X-ray imaging. An image 211 (here, a circle) indicating the shooting position is superimposed on the shooting position specifying image 210 and displayed. An image 211 indicates the shooting position in the shooting position designation image 210 . It can be considered that the image 210 for specifying the shooting position and the image 211 indicating the shooting position constitute a scout image for setting the shooting position.

In FIG. 7, three sizes of images 211, 211a, 211b are shown. The image 211, which is the smallest circle, is a region for photographing a part of the dental arch (about 5-6 teeth on the anterior side, about 2-3 teeth on the molar side). showing. Image 211a, which is a medium-sized circle, shows the area for imaging the entire dental arch. The image 211b, which is the largest circle, represents the area for imaging the entire maxillofacial area (the area including all the left and right teeth from the anterior teeth to the molars and both temporomandibular joints). As the images 211, 211a, and 211b, one image having a size corresponding to the setting of the imaging area setting image 234, which will be described later, is displayed.

When the user touches a desired position on the image 210 for specifying the shooting position, the setting of the shooting position in the image 210 for specifying the shooting position is accepted. Alternatively, the shooting position may be set using a direction key or the like.

Further, an irradiation mode setting image 220 for setting the irradiation mode is displayed on the operation panel device 158 . Here, the irradiation mode setting image 220 is an image simulating a gear, and is displayed below the imaging mode selection image 201 . When the user touches the main irradiation mode setting image 220, as shown in FIG. 8, the characters "low dose noise reduction mode" and "ON" and "OFF" are displayed. When the user touches the character "ON", the "low dose noise reduction mode" is turned on, and the setting of the low dose mode is accepted. When the user touches "OFF", the setting of the high resolution mode is accepted. After the setting, after a predetermined time has passed, or by touching another area (for example, "low dose noise reduction mode"), it is possible to set the screen to return to the original display screen. By turning on the low-dose noise reduction mode, the low-dose mode can be selected, and even when performing low-dose X-ray CT imaging, noise reduction processing as described above is performed so that strong noise is not superimposed. mode.

Further, on the operation panel device 158, as imaging condition setting images corresponding to the CT imaging mode, a region of interest setting image 231, a patient size selection image 232, a CT imaging position-attached mode selection image 233, and an imaging region setting image are displayed. 234, a scan mode selection image 235 is displayed. In this embodiment, these images 231 , 232 , 233 , 234 and 235 are displayed in the right area of the display screen of the operation panel device 158 . Depending on the setting contents of the region-of-interest setting image 231, presence/absence of display of the other images 232, 233, 234, and 235 may be changed or changed to other images.

The region-of-interest setting image 231 is an image in which an illustration image of the region of interest is added next to the letters "ROI". A user can set a region of interest (ROI) through the region-of-interest setting image. When the user touches the region-of-interest setting image 231, a plurality of region-of-interest setting images 231A, 231B, and 231C are displayed as shown in FIG. The plurality of region-of-interest setting images 231A, 231B, and 231C are a tooth-row setting image 231A whose region of interest is the dental arch, a temporomandibular joint setting image 231B whose region of interest is the temporomandibular joint, and a region of interest of the maxillofacial surface. and a maxillofacial setting image 231C. When the user touches one of the region-of-interest setting images 231A, 231B, and 231C while these images 231A, 231B, and 231C are displayed side by side, the setting of the region of interest is accepted. Depending on which one of the dentition setting images 231A, 231B, and 231C is selected, the content of the displayed imaging area setting image 234, which will be described later, can be changed.

The patient size setting image 232 is an image for setting the physique. Here, an illustration image showing the upper half of the body and a letter indicating the size (here, "M") are added next to the letter "Size". is. The user can set the patient size (physique) through the patient size setting image 232 . When the user touches the patient size setting image 232, multiple patient size selection images 232A, 232B, 232C, and 232D are displayed as shown in FIG. The plurality of patient size selection images 232A, 232B, 232C, and 232D include a plurality of patient size display illustration images representing upper body contours with mutually different sizes. More specifically, the patient size selection image 232A is an image obtained by adding “c” (the initial letter of child) to the smallest patient size display illustration image, and the patient size selection image 232B is an image of the next smallest patient size. The image for patient size selection 232C is an image obtained by adding "S" (initial letter for small) to the image for size selection, and the image for patient size selection 232C is the next smaller image for patient size selection with "M" (initial letter for middle). , and the patient size selection image 232D is an image obtained by adding “L” (the first letter of large) to the largest patient size selection image. When the user touches one of the images 232A, 232B, 232C, and 232D displayed side by side, the setting of the patient size (physique) is accepted. In particular, when the patient size selection image 232A is selected, a setting indicating that the physique is a child is accepted, and when the patient size selection images 232B, 232C, and 232D are selected, the physique exceeds that of a child. The setting to that effect is accepted.

The CT imaging position-attached mode selection image 233 is an image for changing the mode for position setting. By manipulating this CT position-attached mode selection image 233, it is possible to set an imaging region based on a panorama image or scout images in two directions, in addition to setting an imaging position using a dental arch.

The imaging area setting image 234 is an image for setting the size of the imaging area. Here, the imaging area setting image 234 is an illustration (for example, a cylindrical shape) that stereoscopically expresses the shape of the imaging area. , and an image of numerical values (diameter, height, etc.) representing its size is added. When the user touches the shooting area setting image 234, a plurality of shooting area setting images 234A to 234H are displayed as shown in FIG. The imaging area setting images 234A to 234H are a plurality of CT imaging area candidate images representing mutually different CT imaging area sizes. That is, the imaging region setting images 234A to 234H are for setting CT imaging regions having different diameters, heights, or imaging region shapes. Note that the display example of the imaging region setting images 234A to 234H in FIG. 11 is a display example when the row of teeth setting image 231A is selected from the region of interest setting image 231 described above. For example, when the maxillofacial setting image 231C is selected from the region-of-interest setting image 231, the number of imaging-region setting images 234 is reduced, and the size of the region of interest can be reduced by imaging the maxillofacial. There may be only one setting, and only the height of the region of interest is valued. Assuming a general tooth and jaw size, the relatively narrow imaging area setting images 234A and 234B target a range with a diameter of 40 mm, and select and designate a local CT imaging mode in which about three teeth can be imaged. It is an image for The relatively wide imaging area setting images 234C, 234D, and 234E target a range of about 80 mm in diameter, and are images for selecting and specifying a CT imaging mode targeting almost all teeth and jaws. Also, the imaging region setting images 234F, 234G, and 234H for selecting and designating the wide region setting screen CT imaging mode have a triangular imaging region with rounded corners, so that all teeth including the molars are completely captured. It is an image for selecting and designating an imaging region targeting the jaw. When the user touches one of the displayed images 234A to 234H, setting of the CT imaging area size is accepted. Note that if the size setting acceptance is not changed, the current region of interest remains unchanged and the process proceeds to the next step. Incidentally, the numbers written on the right side of each illustration indicate the diameter (mm) of the region of interest at the top and the height (mm) of the region of interest at the bottom. When the height of the region of interest is 80, the upper and lower jaws can be imaged, and when the height is 40 or 50, either the upper jaw or the lower jaw can be imaged, thereby enabling imaging with reduced radiation dose. .

Note that the imaging region setting image 234 can be changed depending on the setting of the region of interest setting image 231 . For example, when the maxillofacial region is set as the region of interest, the imaging region setting image 234 sets a range of a size covering the entire maxillofacial region, for example, a diameter of 150 mm, as the imaging region. image.

The scan mode selection image 235 is an image for setting the turning angle of the turning support part 124 required for X-ray CT imaging. This is an image for setting a mode for line CT imaging.

The operation panel device 158 displays an irradiation setting image 241, a tube voltage setting image 242, a tube current setting image 243, and a sensitivity setting image 244 as imaging condition setting images. Here, these images are displayed on the lower portion of the operation panel device 158 .

The irradiation setting image 241 is an image in which the character “M” representing manual setting is added below the character “Exp”. Manual setting of the tube voltage, tube current, resolution, etc., and turning off the X-rays (set when the arm is rotated without irradiation) using the setting by the irradiation setting image 241. ), etc. can be set. What is currently selected may be indicated by the content displayed under the word "Exp". If the letter "M" is displayed as shown, then the current selection is manual setting. Other options may be displayed by touching the letter "M". For example, manual setting, automatic setting, and X-ray off may be selected, and the character "M", character "A", and character "Off" may be displayed according to this selection. As an automatic setting, it is possible to set a pattern that varies the intensity of X-ray irradiation during X-ray imaging, and another character may be displayed when this pattern with intensity is selected.

Further, when the manual setting is selected, the above-described low dose mode may be left and the same irradiation conditions may be applied regardless of the imaging information such as the imaging area. For example, if manual setting is selected for a certain imaging area and the tube current is set to 8mA, the same tube current of 8mA is applied even if an imaging area of a different size is set. You may do so. Here, a mode in which the same irradiation conditions are applied is called a multi-condition mode, and the low dose mode and the multi-condition mode may be selectable. At least one of the low dose mode, high resolution mode, and multi-condition mode may be selected. These selections may be configured to be performed by operating the irradiation mode setting image 220 .

The tube voltage setting image 242 is an image in which a number representing the tube voltage setting value is added below the characters "kV" representing the tube voltage unit. When the user touches the tube voltage setting image 242, a tube voltage adjustment image 242A is displayed as shown in FIG. The tube voltage adjustment image 242A includes a "+" sign for increasing the tube voltage, a "-" sign for decreasing the tube voltage, and a numerical display portion indicating the tube voltage. When the user touches the "+" sign, the set value of the tube voltage increases, and when the user touches the "-" sign, the set value of the tube voltage decreases, and each set value is displayed as a numerical value. Is displayed. While the tube voltage adjustment image 242A is being displayed, the characters "OK" are displayed. disappears, and the tube voltage setting image 242 is displayed in a state in which the setting values are reflected.

The tube current setting image 243 is an image in which a number representing the tube current set value is added below "mA" representing the tube current unit. As shown in FIG. 13, when the user touches the tube current setting image 243, a tube current adjustment image 243A is displayed. The tube voltage adjustment image 243A includes a "+" symbol for increasing the tube current, a "-" symbol for decreasing the tube current, and a numerical display portion indicating the tube current. When the user touches the "+" sign, the set value of the tube current increases, and when the user touches the "-" sign, the set value of the tube current decreases. Is displayed. In the state where the tube current adjustment image 243A is displayed, the characters "OK" are displayed. disappears, and the tube current setting image 243 is displayed in a state in which the setting values are reflected.

The sensitivity setting image 244 is an image for manually setting the sensitivity per unit area of the detection surface of the X-ray detector 128 . For example, standard sensitivity and high sensitivity can be selected, and characters "SD" may be displayed in the case of standard, and characters "HR" in the case of high resolution.

The display position of each image is not limited to the example shown in FIG. 7, and can be set to any position.

<Reference table example>
An example of the reference table will be described with reference to FIG.

In this lookup table, the low dose mode and the high resolution mode are set separately. In addition, in each mode, children and adults (body size exceeding children) are set separately.

Regarding the physique of an adult in the low-dose mode, the output conditions of the X-ray generator 126 are set at a tube voltage of 100 kV and a tube current of 8 mA when the diameter of the imaging region is 40 mm. Also, the voxel size is set to 80 μm as a setting related to image quality. The size of the imaging area may be set as the size of the imaging area on a plane perpendicular to the turning axis of the turning drive unit 30 (that is, a plane parallel to the floor). Also, when the imaging area on the plane is circular, it is defined as the diameter of the circle, and when the imaging area on the plane is non-circular, it is preferably defined as the diameter of the circle circumscribing the imaging area.

On the other hand, when the diameter of the imaging region is 80 mm or 100 mm, the difference is that the tube current is set to 7 mA compared to the above output conditions. Another difference is that the voxel size is set to 125 μm as a setting related to image quality.

Therefore, when the diameter of the imaging region is 80 mm or 100 mm, the output conditions are set so that the dose is smaller than when the diameter of the imaging region is 40 mm. In addition, when the diameter of the imaging region is 80 mm or 100 mm, the voxel size is set larger than when the diameter of the imaging region is 40 mm. As a result, the resolution is rough, but the noise is reduced. It is set for image quality.

Furthermore, when the diameter of the imaging region is 150 mm, the tube current is set to 6 mA compared to when the diameter of the imaging region is 40 mm, 80 mm, or 100 mm. Another difference is that the voxel size is set to 320 μm as a setting related to image quality.

Therefore, when the diameter of the imaging region is 150 mm, the output conditions are set so that the diameter of the imaging region reduces the dose as compared with the above examples. Also, when the diameter of the imaging area is 150 mm, the voxel size is set larger than in each of the above examples, and as a result, the resolution becomes coarser, but the image quality is set so that noise is further reduced. It is

Here, assuming that an imaging region with a diameter of 40 mm is the first imaging region and an imaging region with a diameter of 80 mm or 100 mm is the second imaging region, a first output condition corresponding to the size of the first imaging region (tube voltage 100 kV, tube current 8 mA) is larger than the dose based on the second output condition (tube voltage 100 kV, tube current 7 mA) according to the size of the second imaging region (relatively Considering that, each of the first output condition and the second output condition is defined such that the dose based on the second output condition is smaller than the dose based on the first output condition. Based on the reference table 152, the X-ray output condition setting unit 152d automatically sets the first output condition and the second output condition so that the above conditions are satisfied.

Considering that an imaging region with a diameter of 80 mm or 100 mm is the first imaging region and an imaging region with a diameter of 150 mm is the second imaging region, a first output condition ( The dose based on the tube voltage of 100 kV, the tube current of 7 mA) is larger than the dose based on the second output condition (tube voltage of 100 kV, the tube current of 6 mA) according to the size of the second imaging region (considered relatively and the dose based on the second output condition is smaller than the dose based on the first output condition). Based on the reference table 152, the X-ray output condition setting unit 152d automatically sets the first output condition and the second output condition so that the above conditions are satisfied.

The imaging region with a diameter of 150 mm is set to be the maxillofacial region of the subject P, and the imaging region with a diameter of 40 mm is the first imaging region where some teeth of the dental arch are accommodated. , and the imaging region with a diameter of 80 mm or 100 mm can be regarded as an example of a region in which the entire dental arch or all the teeth of the dental arch are accommodated.

However, the size of each imaging area does not have to be the above example.

For example, let us consider a case where a part of the dental arch is used as the imaging area and a case where the entire dental arch is used as the imaging area are distinguished by the size of the imaging area. In this case, the imaging information receiving unit 152c receives the setting of an imaging region whose diameter is R1 (mm) for the boundary circle or circumscribed circle as the first imaging region, and the diameter of the boundary circle or circumscribed circle is R1 (mm) for the second imaging region. If it is possible to accept the setting of the imaging area R2 (mm), then R1 (mm) < k1 (mm) < R2 ( mm).

Also, for example, consider a case where the imaging region is determined to cover as much of the entire dental arch as possible and the imaging region includes the entire jaw as much as possible, which is distinguished by the size of the imaging region. In this case, the imaging information receiving unit 152c receives the setting of an imaging region whose diameter is R1 (mm) for the boundary circle or circumscribed circle as the first imaging region, and the diameter of the boundary circle or circumscribed circle is R1 (mm) for the second imaging region. If it is possible to accept the setting of the imaging region R2 (mm), then R1 (mm) < k2 (mm) < R2 ( mm).

Also, regarding the physique of a child in the low dose mode, the tube voltage is set to 90 kV, which is smaller than in each of the above examples. Therefore, in the reference table 152, the output condition corresponding to the physique exceeding that of a child is set so that the dose based on the output condition corresponding to the physique exceeding that of a child is larger than the dose based on the output condition corresponding to the physique of a child. and at least one set value that defines each of the output conditions according to the physique of the child. Therefore, based on the reference table 152, the X-ray output condition setting unit 152d sets the dose based on the output condition corresponding to the physique exceeding that of a child to be larger than the dose based on the output condition corresponding to the physique of the child. , at least one set value that defines an output condition corresponding to a physique exceeding that of a child and an output condition corresponding to a physique of a child can be automatically set.

The dose during X-ray CT imaging can be adjusted by the tube voltage, the tube current, the irradiation time of the X-ray generator 126, and the like. For example, if the irradiation time of the X-ray detector 128 is shortened, the dose will be reduced, and if the irradiation time is lengthened, the dose will be increased. The setting of the irradiation time can be adjusted, for example, by adjusting the speed at which the X-ray generator 126 is rotated. Also, the dose can be switched by adjusting the angle of rotation of the X-ray generator 126 (for example, switching between 180° rotation and 360° rotation).

The dose during X-ray CT imaging can be set theoretically, experimentally, and empirically by adjusting the tube voltage, tube current, irradiation time, etc. of the X-ray generator 126 in combination.

Also, in the high resolution mode, the tube current is uniformly set to 8 mA compared to the dose mode. In addition, the voxel size is uniformly set to 80 μm as a setting related to image quality. Therefore, in the high resolution mode, a clear X-ray CT image can be uniformly obtained with a relatively high dose. The tube current may be uniformly set to 9 mA, and a difference may be made between the low-dose mode and the high-resolution mode even for an imaging region having a diameter of 40 mm. Numerical values in the reference table may be adapted to accept an operator's operation to access and arbitrarily rewrite them.

Further, for example, for an imaging region of diameter 40 mm for an adult physique in the low resolution mode, the output conditions for the maxillary molar region are a tube voltage of 100 kV and a tube current of 7.5 mA, and imaging of a diameter of 40 mm for a child physique. For the region, the output conditions for the maxillary molar region may be attenuated compared to the same region in the high resolution mode, such as a tube voltage of 90 kV and a tube current of 7.5 mA. By weakening the tube current, the voxel size in the image quality setting may be increased to 90 μm.

Furthermore, an output condition setting for each imaging part may be added. For example, for an imaging region with a diameter of 40 mm in the low-resolution mode, the output conditions for the maxillary molar region are a tube voltage of 100 kV and a tube current of 8 mA, and the output conditions for the mandibular anterior tooth region are a tube voltage of 100 kV and a tube current of 5 mA. , may be changed for each part.

<Action>
The operation of the X-ray CT imaging apparatus 110 will be described with reference to FIG. 15, focusing on the X-ray CT imaging operation.

First, in step S1, the user touches any of the imaging mode selection images 201, 202, and 203 to selectively accept any one of the panorama imaging mode, cephalometric imaging mode, and CT imaging mode (FIG. 7). reference). If the panorama photography mode setting is accepted, the process advances to step S11 to execute the panorama photographing process. If the cephalometric photographing mode setting is accepted, the process advances to step S12 to execute the cephalometric photographing process. When the setting of the CT imaging mode is accepted, the process proceeds to step S2 and subsequent steps.

In step S2, it is determined that the mode is for CT imaging.

In the next step S3, the irradiation mode setting is accepted using the irradiation mode setting image 220 and the like (see FIGS. 7 and 8).

In the next step S4, the setting of the region of interest is accepted through the image 231 for setting the region of interest (see FIG. 9).

In the next step S5, setting of the patient size (physique) is accepted through the patient size setting image 232 (see FIG. 10). As already mentioned, setting the patient size (physique) includes setting whether the physique is pediatric or super-pediatric.

In the next step S6, position setting is accepted through the imaging region setting image 234, the imaging position designation image 210, and the like (see FIG. 7). Thereby, the setting of the shooting position is accepted.

In the next step S7, the size of the imaging area is set through the imaging area setting image 234 (see FIG. 11).

In the next step S8, the output conditions of the X-ray generator 126 are automatically set. Here, referring to the reference table 152 shown in FIG. 14, the output condition of the X-ray generator 126 is set based on the size of the imaging region and whether the physique is that of a child or of a size exceeding that of a child (that is, an adult). Set automatically.

After this automatic setting, the process advances to step S9 to determine whether or not the output conditions have been manually set. When it is determined that the user has manually set the tube voltage and tube current through the tube voltage setting image 242 and the tube current setting image 243, etc., the process proceeds to step S13, and the output conditions are set based on the manual setting. and return to step S9. The determination in step 9 after step 8 is for determining whether manual setting operation has been performed, and the determination in step 9 after step 13 is for determining whether manual setting operation has been newly added.

If it is determined in step S9 that there is no manual setting of the output conditions, the process proceeds to step S10.

In step S10, X-ray CT imaging is performed according to the set output conditions. An X-ray CT image is generated based on the data thus obtained. When generating an X-ray CT image, the X-ray CT image is generated in accordance with the image quality setting (here, voxel size setting). The above steps can be changed as appropriate. For example, the order of steps 6 and 7 may be interchanged.

<Effects, etc.>
According to the medical X-ray CT imaging apparatus 110, the medical X-ray CT imaging condition setting method, and the X-ray CT imaging condition setting program 151a configured as described above, the X-ray generator 126, the X-ray detector 128, Equipped with a turning support section 124 and a motor 132a as a turning driving section, and in the X-ray CT imaging apparatus 110, the setting of the imaging area regarding at least one of the imaging area size, the imaging purpose, and the imaging site is received, By automatically setting the output conditions of the X-ray generator 126 according to at least one of the size of the received imaging region, imaging purpose, and imaging site, radiation exposure can be reduced as much as possible. In addition, although the size of the imaging region or the imaging region is usually set according to the imaging purpose, the output of the X-ray generator 126 depends on at least one of the imaging region size, the imaging purpose, and the imaging region. By automatically setting the conditions, it is possible to obtain an X-ray CT image with image quality that is as appropriate as possible according to the purpose of imaging.

In addition, under X-ray output conditions aimed at a low dose, noise is likely to appear in the X-ray CT image. By automatically setting the image quality of the X-ray CT image according to at least one of the setting of the imaging region and the automatically set output condition of the X-ray generator 126, the X-ray output condition especially aimed at a low dose can be obtained. Noise can be reduced when line CT imaging is performed.

In particular, by setting the size of the received imaging area to be the size in a plane perpendicular to the turning axis, the output conditions of the X-ray generator can be automatically set according to the spread of the imaging area on that plane. .

Also, usually, a relatively small imaging area is set when one wants to observe details in detail, and a relatively large imaging area is set when one wants to observe the entire object. Therefore, as a setting related to the size of the photographing area, a setting of a first photographing area and a second photographing area wider than the first photographing area is accepted, and a second output corresponding to the size of the second photographing area is received. At least one set value that defines each of the first output condition and the second output condition such that the dose based on the condition is smaller than the dose based on the first output condition corresponding to the size of the first imaging region. With automatic setting, X-ray CT imaging can be performed under appropriate output conditions according to the purpose.

Considering the above-described first imaging region and second imaging region, if a region in which a part of the teeth of the dental arch is accommodated is set as the first imaging region, the first output in which the dose is relatively large X-ray CT imaging can be performed under these conditions, and it is possible to observe some teeth in the dental arch with relatively clear images. On the other hand, when the entire area of the dental arch or the area in which all the teeth of the dental arch are accommodated is set as the second imaging area, X-ray CT is performed on the dental arch under the second output condition in which the dose is relatively small. You can take pictures.

Further, by automatically setting the output condition of the X-ray detector 128 in accordance with the setting of the physique in addition to the accepted imaging region, exposure to radiation can be reduced as much as possible.

Specifically, when the physique is set to be that of a child, the dose can be reduced to reduce the exposure dose. On the other hand, if the body size is set to exceed that of a child, the dose can be increased and a clear image can be obtained.

Also, as the output condition of the X-ray detector 128, at least one of the tube voltage and tube current of the X-ray generator 126, and the time during which the X-ray generator 126 emits X-rays is automatically set to adjust the dose. can do.

In addition, the low dose mode and the high resolution mode can be switched, and when the low dose mode is accepted, the output conditions of the X-ray generator are automatically set according to the received information on the imaging area. It is possible to obtain an X-ray CT image with image quality that is as appropriate as possible according to the purpose of imaging while reducing radiation exposure. Also, when the high-resolution mode is accepted, a clear X-ray CT image can be obtained regardless of the accepted information about the imaging region. Moreover, after automatically setting the output conditions of the X-ray generator 126 according to the received information about the imaging region, the conditions can be changed by manual setting according to the operator's preference.

Here, an example of controlling the output conditions of the X-ray generator 126 will be described from the irradiation X-ray dose side.

As described above, the detection surface of the X-ray detector 128 is composed of pixels. When each pixel is square, the shape of the X-ray beam irradiated to each pixel from the focal point of the X-ray tube is substantially quadrangular pyramid. For example, if the tube current is increased, the irradiation X-ray dose included in the space formed by the substantially quadrangular pyramidal X-ray beam for each pixel is increased, and if the tube current is decreased, the irradiation X-ray dose is decreased. Similarly, for example, when the tube voltage is increased, the irradiation X-ray dose included in the space formed by the substantially quadrangular pyramidal X-ray beam for each pixel is increased, and when the tube voltage is decreased, the irradiation X-ray dose is decreased. Similarly, for example, when the X-ray irradiation time is lengthened, the irradiation X-ray dose included in the space formed by the substantially quadrangular pyramid-shaped X-ray beam for each pixel when evaluated over the entire irradiation time increases, and the X-ray dose increases. Shortening the exposure time reduces the exposure x-ray dose when evaluated over the entire exposure time.

Considering this on the side of the X-ray detector 128, if there is no attenuation element such as a subject between the X-ray generator 126 and the X-ray detector 128, the amount of light received by each pixel is increases, and decreases as the tube current is lowered. In the same way, the amount of light received by each pixel increases as the tube voltage increases, and decreases as the tube voltage decreases. In the same way, the amount of light received by each pixel increases as the X-ray irradiation time increases, and decreases as the X-ray irradiation time decreases. If the irradiation conditions including the tube current, the tube voltage and the irradiation time are not changed in X-ray irradiation a plurality of times, the amount of light received by each pixel will be the same.

In this way, it is conceivable to change the output conditions so as to increase or decrease the irradiation X-ray dose per unit area of the detection surface of the X-ray detector 128. It is also an increase or decrease in the X-ray dose passing through the unit space.). Assuming that there is no attenuation element such as a subject between the X-ray generator 126 and the X-ray detector 128, increasing or decreasing the irradiation X-ray dose per unit area of the detection surface of the X-ray detector 128 is equivalent to increasing or decreasing the X-ray dose. It is synonymous with increasing or decreasing the amount of light received per unit area of the detection surface of the line detector 128 .

As the unit area, the area of each pixel unit, the area of each binning unit when a plurality of pixels can be binning, and the like can be considered.

Therefore, as an example of automatically setting the output conditions of the X-ray generator according to at least one of the size of the imaging region, the purpose of imaging, and the part to be imaged received by the imaging information receiving unit, a certain imaging region AR1 An example can be adopted in which the output of X-ray irradiation to the other imaging area AR2 is made smaller than the output of X-ray irradiation to the other imaging area AR2. For example, the tube current can be made lower for the imaging region AR2 than for the imaging region AR1, so that the irradiation X-ray dose per unit area can be made smaller for the imaging region AR2 than for the imaging region AR1 (assuming that Assuming that an attenuation element such as a subject is retracted from between the X-ray generator 126 and the X-ray detector 128, the amount of light received per unit area is greater for the imaging area AR2 than for the imaging area AR1. becomes smaller). Similarly, for example, the tube voltage can be made lower for the imaging area AR2 than for the imaging area AR1, so that the irradiation X-ray dose per unit area can be made smaller for the imaging area AR2 than for the imaging area AR1. Similarly, for example, the irradiation time for the imaging area AR2 can be made shorter than that for the imaging area AR1, so that the irradiation X-ray dose per unit area can be made smaller for the imaging area AR2 than for the imaging area AR1. Of course, by adjusting the combination of the tube current, the tube voltage, and the irradiation time, the irradiation X-ray dose per unit area can be made smaller for the imaging area AR2 than for the imaging area AR1.

Further, making the output of X-ray irradiation to the imaging region AR1 and the output of X-ray irradiation to the imaging region AR2 equal means to equalize the irradiation X-ray dose per unit area (assuming that the X-ray generator Assuming that an attenuation element such as a subject is retracted from between 126 and X-ray detector 128, the amount of light received per unit area remains the same unless the irradiation conditions including the tube current are changed.).

{Modification}
The modification shown in FIG. 16 shows an example of a reference table when the irradiation time is changed among the setting values that define the output conditions of the X-ray generator 126 .

As shown in the figure, the size of the imaging range with a diameter of 40 mm and the size of the imaging range with a diameter of 80 mm or 100 mm are the same with a tube voltage of 100 kV and a tube current of 8 mA. By setting the time to 17.9 s and the irradiation time of the latter to 9.4 s, the former is set to have a larger radiation dose during X-ray CT imaging than the latter. Assuming that the rotation angle of the X-ray detector 128 (or the rotation support portion 124) is the same range AG1, the time required for rotation of this angle AG1 is switched between an irradiation time of 17.9 s and an irradiation time of 9.4 s. The irradiation time may be changed by switching the rotation angle of the X-ray detector 128 (or the rotation support section 124). For example, the turning angle is switched between 360° and 180°. In this case, setting the irradiation time to 17.9 s means that the rotation angle of the X-ray detector 128 is 360°, and setting the irradiation time to 9.4 s means that the rotation angle of the X-ray detector 128 is 180°. It can be considered that there is For the size of the imaging range with a diameter of 150 mm, the irradiation time is 9.4 s and the tube current is 6 mA. are also set to reduce the dose during X-ray CT imaging.

In the above embodiment, the example in which the output conditions of the X-ray detector 128 are set mainly according to the size of the imaging range has been mainly described. and the X-ray generator according to at least one of the size of the imaging region, the purpose of imaging, and the part to be imaged received by the imaging information receiving unit. output conditions may be set automatically.

For example, as shown in FIG. 17, the operation panel device 158 is provided with a setting screen for the purpose of imaging, and observation is made on the setting screen for "root fracture, endodontic therapy, periapical lesion, bone regeneration process of implant". A purpose selection image 300 that enables selection of a purpose and a purpose selection image 302 that enables selection of observation purposes of “periodontal/wisdom tooth/supernumerary tooth/impacted tooth/salivary stone” are displayed. When the user touches one of the purpose selection images 300 and 302, the body control unit 150 can accept the setting of the purpose of photographing.

As a reference table, as shown in FIG. 18, when imaging purposes of "root fracture, endodontic therapy, periapical lesion, bone regeneration process of implant" are set, clear X-ray CT imaging is performed. Since it is preferable to obtain an image, it is preferable to set the output condition so that the dose is relatively large. Here, the tube voltage is set to 100 kV and the tube current is set to 8 mA.

In addition, when the purpose of imaging is set for periodontal, wisdom teeth, supernumerary teeth, impacted teeth, and salivary calculus, it is sufficient to make rough observations. It is recommended to set the output condition to be smaller than the target. Here, the tube voltage is set to 100 kV and the tube current is set to 6 mA.

Thereby, the output condition of the X-ray generator 126 can be automatically set according to the set imaging purpose.

Further, for example, like the reference table shown in FIG. 19, the output conditions of the X-ray detector 128 may be automatically set according to the imaging region in the imaging range designated in the imaging position designation image 210 . The designation of the imaging region may be performed by designation of the X-ray image obtained by cephalometric imaging, in addition to designation of the dental arch. Determining the imaged part can be performed by determining the range of teeth included in the designated imaging range.

Here, when the imaging parts of "mandibular anterior teeth, mandibular molars, maxillary anterior teeth, maxillary molars" are set, the base of the skull, which has a large X-ray absorption coefficient, does not enter the path of the X-ray cone beam. , the output condition is set to a relatively small dose so that the exposure dose can be made as small as possible. Here, the tube voltage is set to 100 kV and the tube current is set to 6 mA.

Also, when the imaging region of ".temporomandibular joint" is set, the base of the skull enters the path of the X-ray cone beam, so the output condition is set so that the dose is relatively large. The tube voltage is set to 100 kV and the tube current is set to 8 mA.

Thereby, the output condition of the X-ray generator 126 can be automatically set according to the set imaging region.

Also, the output conditions of the X-ray generator 126 may be automatically set according to a plurality of combinations of the size of the imaging region, the purpose of imaging, and the region to be imaged. In this case, for example, as shown in FIG. 20, as a reference table, an imaging purpose and an imaging region are specified as necessary with respect to the size of the imaging region, and for each combination, the X-ray generator 126 What is necessary is just to prepare what the output conditions and image quality were set. FIG. 20 shows an example in which the output conditions of the X-ray generator 126 and the image quality are set for a combination of the imaging purpose and the imaging region for an imaging area of 40 mm in diameter. The output condition and image quality of the X-ray generator 126 may be set for the region and for the combination of the imaging purpose and imaging region.

In addition, each configuration described in each of the above-described embodiments and modifications can be appropriately combined as long as they do not contradict each other. For example, each unit described in the second embodiment can be combined with the configuration described in the first embodiment.

Although the present invention has been described in detail as above, the above description is illustrative in all aspects, and the present invention is not limited thereto. It is understood that numerous variations not illustrated can be envisioned without departing from the scope of the invention.

REFERENCE SIGNS LIST 10, 110 X-ray CT imaging apparatus 13 rotation drive mechanism 20 support section 22 X-ray generator 24 X-ray detector 30 rotation drive section 40 imaging information reception section 60 X-ray output condition setting section 60P X-ray CT imaging condition setting program 120 Imaging Unit 121 Post 123 Horizontal Arm 124 Rotating Support Unit 126 X-ray Generator 128 X-ray Detector 130 Rotating Drive Mechanism 132 Rotating Mechanism 150 Body Control Unit 150a CPU
150c Storage unit 150e Operation input unit 150f Image output unit 151 Imaging program 151a X-ray CT imaging condition setting program 152 Reference table 152a Support unit drive control unit 152c Imaging information reception unit 152d Line output condition setting unit 152e Output condition setting reception unit 152f X Radiographic data processing unit 152g X-ray detection unit drive control unit 152h X-ray generator drive control unit 152i Image quality setting unit 158a Code setting operation unit 158b Imaging information setting operation unit 158c Output condition setting operation unit 180 Image processing device 181 Control unit 181a image processing unit 182 information processing main unit 183 storage unit 220 irradiation mode setting image 231, 231A region of interest setting image 231A tooth row setting image 231B temporomandibular joint setting image 231C maxillofacial setting image 232, 232A, 232B, 232C Patient size selection image 234, 234A, 234B, 234C, 234D, 234E, 234F, 234G, 234H Imaging area setting image 235 Scan mode selection image 241 Irradiation setting image 242 Tube voltage setting image 242A Adjustment image 243 Tube Current setting image 243A Adjustment images 300, 302 Purpose selection images E1, E2 Imaging area P Head (subject)

Claims (13)

an X-ray generator that produces a cone beam;
an X-ray detector;
a support portion that supports the X-ray generator and the X-ray detector in a facing state;
a turning drive unit for turning the X-ray generator and the X-ray detector supported by the support;
an imaging information reception unit that receives setting of an imaging region related to at least one of the size of the imaging region, the purpose of imaging, and the region to be imaged;
an X-ray output condition setting unit that automatically sets output conditions of the X-ray generator according to at least one of the size of the imaging region, the purpose of imaging, and the part to be imaged received by the imaging information receiving unit;
with
The imaging information receiving unit is capable of receiving settings of a first imaging area and a second imaging area wider than the first imaging area as settings related to the size of the imaging area,
The imaging information reception unit further receives a setting for positioning the imaging region through the imaging position designation image, using a non-X-ray image, a cephalometric image, or a panoramic image showing the dental arch as an imaging position designation image. ,
The X-ray output condition setting unit sets the size of the imaging region to be the maxillofacial region of the subject as the imaging region, sets the region in which a part of the teeth of the dental arch is accommodated as the first imaging region, and determines the size of the imaging region. It is possible to receive a setting as the second imaging region for the entire area of the arch or the region where all the teeth of the dental arch are accommodated,
further comprising a mode setting reception unit for receiving the setting of the X-ray CT imaging mode,
The mode setting reception unit performs normal observation CT imaging for the purpose of general observation or general observation for observing any one of periodontal, wisdom teeth, supernumerary teeth, impacted teeth, and salivary calculus. Detailed observation for the purpose of observing any of root fracture, endodontic treatment, periapical lesion, or bone regeneration process of implants in imaging mode and at a dose higher than that in normal observation CT imaging. Receiving a detailed observation CT imaging mode, which is a mode for performing CT imaging,
In the normal observation CT imaging mode, the X-ray output condition setting unit sets the dose based on the second output condition according to the size of the second imaging region to the first X-ray output condition according to the size of the first imaging region. automatically setting at least one setting value defining each of the first output condition and the second output condition so as to be smaller than the dose based on the output condition; and in the detailed observation CT imaging mode, the first imaging A dental X-ray CT imaging apparatus, wherein the dose is uniformly set for both the area and the second imaging area. The dental X-ray CT imaging apparatus according to claim 1,
The image quality of the X-ray CT image is automatically set according to at least one of the setting of the imaging region received by the imaging information receiving unit and the output condition of the X-ray generator set by the X-ray output condition setting unit. 1. A dental X-ray CT imaging apparatus, further comprising an image quality setting unit for The dental X-ray CT imaging apparatus according to claim 1 or claim 2,
A dental X-ray CT imaging apparatus, wherein the imaging information receiving unit receives, as a setting related to the size of the imaging region, a setting of the size of the imaging region in a plane perpendicular to the turning axis of the turning drive unit. The dental X-ray CT imaging apparatus according to any one of claims 1 to 3 ,
The imaging information receiving unit receives the setting of an imaging area having a diameter of R1 (mm) of the boundary circle or the circumscribed circle as the first imaging area, and the diameter of the boundary circle or the circumscribed circle as the second imaging area. It is possible to accept the setting of the imaging area that is R2 (mm),
Here, for a value k1 that satisfies 40 (mm) < k1 (mm) < 70 (mm),
R1 (mm) < k1 (mm) < R2 (mm)
A dental X-ray CT imaging device that satisfies The dental X-ray CT imaging apparatus according to any one of claims 1 to 4 ,
The imaging information reception unit is capable of receiving a physique setting,
The X-ray output condition setting unit sets the imaging region regarding at least one of the size of the imaging region received by the imaging information receiving unit, the purpose of imaging, and the body part to be imaged. A dental X-ray CT imaging apparatus that automatically sets output conditions of the X-ray generator according to settings. The dental X-ray CT imaging apparatus according to claim 5 ,
The imaging information receiving unit receives, as the setting of the physique, a setting as to whether the subject has a physique of a child or a physique exceeding that of a child;
The X-ray output condition setting unit sets the output condition according to the physique exceeding that of a child so that the dose based on the output condition corresponding to the physique exceeding that of a child is greater than the dose based on the output condition that corresponds to the physique of a child. and a dental X-ray CT imaging apparatus that automatically sets at least one set value that defines each of the output conditions according to the physique of the child. The dental X-ray CT imaging apparatus according to any one of claims 1 to 6 ,
The imaging information reception unit receives the setting of the imaging part,
A dental X-ray CT imaging apparatus, wherein the X-ray output condition setting unit automatically sets the output condition of the X-ray generator in accordance with the imaging region received by the imaging information receiving unit. The dental X-ray CT imaging apparatus according to any one of claims 1 to 7 ,
The X-ray output condition setting unit automatically sets at least one of a tube voltage, tube current, and X-ray irradiation time of the X-ray generator as the output condition of the X-ray generator. A dental X-ray CT imaging apparatus. The dental X-ray CT imaging apparatus according to any one of claims 1 to 8 ,
further comprising an output condition setting reception unit that receives manual setting of the output condition of the X-ray generator,
The X-ray output condition setting unit automatically sets the output conditions of the X-ray generator according to the imaging region received by the imaging information reception unit, and then according to the manual setting through the output condition setting reception unit. a dental X-ray CT apparatus for changing the output conditions of the X-ray generator. an X-ray generator that produces a cone beam;
an X-ray detector;
a support portion that supports the X-ray generator and the X-ray detector in a facing state;
a turning drive unit for turning the X-ray generator and the X-ray detector supported by the support;
An X-ray CT imaging condition setting program for a dental X-ray CT imaging apparatus comprising
In the computer for setting the X-ray CT imaging conditions of the dental X-ray CT imaging apparatus,
(a) a step of receiving imaging region settings relating to at least one of imaging region size, imaging purpose, and imaging region;
(b) automatically setting the output conditions of the X-ray generator in accordance with at least one of the accepted size of the imaging region, imaging purpose, and imaging region;
and
moreover,
a step of receiving settings of a first imaging area and a second imaging area wider than the first imaging area as settings related to the size of the imaging area, wherein the setting related to the size of the imaging area is The maxillofacial region is defined as the imaging region, the region containing a part of the teeth of the dental arch is defined as the first imaging region, and the region containing the entire dental arch or all the teeth of the dental arch is defined as the second imaging region. receiving a setting to
a step of receiving a position setting of the imaging region through the imaging position specifying image, which is a non-X-ray image, a cephalometric image, or a panoramic image showing a dental arch;
As the setting of the X-ray CT imaging mode, perform normal observation CT imaging for the purpose of general observation and general observation to observe any of the periodontal, wisdom teeth, supernumerary teeth, impacted teeth, or salivary calculus. For the purpose of detailed observation for observing any of root fracture, endodontic treatment, periapical lesion, and implant bone regeneration process with a higher dose than in the normal observation CT imaging mode and the normal observation CT imaging mode. a step of accepting a detailed observation CT imaging mode, which is a mode for performing detailed observation CT imaging;
In the normal observation CT imaging mode, the dose based on the second output condition corresponding to the size of the second imaging region is smaller than the dose based on the first output condition corresponding to the size of the first imaging region. automatically sets at least one set value that defines each of the first output condition and the second output condition, and in the detailed observation CT imaging mode, both in the first imaging region and in the second imaging region a step of uniformly setting the dose,
An X-ray CT imaging condition setting program for executing A dental X-ray CT apparatus,
an X-ray generator that produces a cone beam;
an X-ray detector;
a support portion that supports the X-ray generator and the X-ray detector in a facing state;
an actuator that rotates the X-ray generator and the X-ray detector supported by the support;
with a processor and
The processor receives, as imaging information, an imaging region setting related to at least one of imaging region size, imaging purpose, and imaging region, and the input imaging region size when setting X-ray CT imaging conditions. automatically setting the output conditions of the X-ray generator according to at least one of the purpose of imaging and the part to be imaged ;
moreover,
a step of receiving settings of a first imaging area and a second imaging area wider than the first imaging area as settings related to the size of the imaging area, wherein the setting related to the size of the imaging area is The maxillofacial region is defined as the imaging region, the region containing a part of the teeth of the dental arch is defined as the first imaging region, and the region containing the entire dental arch or all the teeth of the dental arch is defined as the second imaging region. settings are input,
A non-X-ray image, a cephalometric image, or a panoramic image showing a dental arch is used as an image for specifying an imaging position, and setting of positioning of the imaging region is input through the image for specifying an imaging position,
As the setting of the X-ray CT imaging mode, perform normal observation CT imaging for the purpose of general observation and general observation to observe any of the periodontal, wisdom teeth, supernumerary teeth, impacted teeth, or salivary calculus. For the purpose of detailed observation for observing any of root fracture, endodontic treatment, periapical lesion, and implant bone regeneration process with a higher dose than in the normal observation CT imaging mode and the normal observation CT imaging mode. A detailed observation CT imaging mode, which is a mode for performing detailed observation CT imaging, is input,
In the normal observation CT imaging mode, the dose based on the second output condition corresponding to the size of the second imaging region is smaller than the dose based on the first output condition corresponding to the size of the first imaging region. automatically sets at least one set value that defines each of the first output condition and the second output condition, and in the detailed observation CT imaging mode, both in the first imaging region and in the second imaging region and a dental X-ray CT imaging apparatus in which the dose is uniformly set. The dental X-ray CT imaging apparatus according to claim 11 ,
The processor is capable of receiving setting information of a first imaging region and a second imaging region as settings related to the imaging regions, and the first imaging region has a larger amount of hard tissue than the second imaging region. The above-mentioned A dental X-ray CT imaging apparatus that automatically sets at least one set value that defines each of the first output condition and the second output condition. The dental X-ray CT imaging apparatus according to claim 11 or claim 12 ,
A dental X-ray CT imaging apparatus in which the processor automatically sets the image quality of the X-ray CT image according to at least one of the input setting of the imaging region and the set output condition of the X-ray generator.

Images