JP6728092B2 - Bone densitometer - Google Patents

Description

The present invention relates to a bone density measuring device, and more particularly to a bone density measuring device including a measuring groove into which a forearm is inserted.

The bone density measuring device is a device for measuring bone density (bone mineral content) using X-rays. The forearm can be mentioned as a site for measuring the bone density, and specifically, the radius of the forearm and the like can be mentioned. The forearm bone density measuring device generally has a measurement groove (measurement space, accommodation space) into which the forearm is inserted. An X-ray generator is provided on one side of the measurement groove, and an X-ray detector is provided on the other side of the measurement groove. The forearm is irradiated with the X-ray from the X-ray generator, and the X-ray transmitted through the forearm is detected by the X-ray detector. The bone density distribution is calculated according to the DEXA (Dual Energy X-ray Absorptiometry) method based on the X-ray detection data obtained thereby. If necessary, the bone densitometer is supported by the support device. The bone densitometry system comprises a bone densitometer and a support device.

Patent Document 1 discloses a conventional bone density measuring system. The system includes a bone density measuring device having a measuring groove and a leg supporting the bone density measuring device. In the bone density measuring device, a measurement groove is formed parallel to the bottom surface. On the other hand, the upper surface of the leg is inclined, and the bone density measuring device is installed on the upper surface. As a result, the measuring groove is inclined. Then, the forearm is inserted into the measurement groove. A mechanism for assisting the bone density measurement is provided in the measurement groove. The mechanism includes a removable grip and a pair of elbow pads. The detachable grip is attached to an unused elbow pad. The elbow pad is a member provided so as to be slidable, and is for measuring the forearm length.

Patent Document 2 discloses a bone density measuring system similar to the above. Patent Document 3 discloses a bone density measuring device including an X-ray marker. Patent Document 4 discloses a bone mineral content measuring device capable of changing the position of a table on which a test site is placed.

JP, 2008-22960, A JP, 2008-22958, A JP, 2009-106425, A Japanese Patent Publication No. 2008-44439

When the bone density measuring device has a measurement groove parallel to the bottom surface, in order to reduce the burden on the subject, in order to make the measurement groove in an inclined posture, a special leg having an inclined mounting surface is used. You have to use it. The work of installing the bone densitometer on such a special leg is not easy. When the bone density measuring device is used alone, it is difficult to realize the inclined posture of the measurement groove.

An object of the present invention is to make it possible to naturally form an inclined posture of a measurement groove without using a special leg. Alternatively, an object of the present invention is to functionalize the form or structure of the bone density measuring device on the assumption of the inclined posture of the measurement groove. Alternatively, it is to utilize the underground space that occurs under the X-ray generator.

The bone density measuring device according to the embodiment is composed of a front side portion and a back side portion, a lower portion having a bottom surface, an upper portion formed of a front side portion and a back side portion, and a back side portion of the lower portion. An intermediate portion connected to the back side portion of the upper portion, the front side portion of the lower portion constitutes a lower hollow structure containing an X-ray generator, and the front side portion of the upper portion is an X-ray detector. The upper hollow structure that accommodates the upper hollow structure is formed, and between the lower hollow structure and the upper hollow structure, a measurement groove is formed which has a tilted posture from the front side to the back side and into which the forearm is inserted. When the direction orthogonal to the bottom surface is defined as the vertical direction, the thickness of the lower hollow structure in the vertical direction is gradually reduced from the front side to the back side. ..

According to the above configuration, when the bone density measuring device is installed on a horizontal plane, the measurement groove is naturally inclined (upwardly viewed from the side of the subject). Therefore, it is not necessary to use a special leg having an inclined upper surface when forming the inclined posture of the measurement groove. In the lower hollow structure, the vertical thickness thereof gradually decreases from the front side to the back side, and a space margin is generated in the front side portion of the lower hollow structure. Thereby, for example, the ventilation space around the X-ray generator can be increased, or a space for installing a cooling fan or the like under the X-ray generator can be secured. The upper surface of the lower hollow structure functions as a mounting surface on which the forearm is mounted, and the mounting surface is an inclined surface that is lowered from the front side to the back side. If the forearm is placed on the placement surface, the forearm will naturally come into contact with the structure provided on the back side of the measurement groove. The front side is the front side of the apparatus, that is, the side on which the subject is present. The back side is the opposite side of the front side.

In the embodiment, the central axis of the X-ray beam connecting the X-ray generator and the X-ray detector is inclined inward with respect to the vertical direction. With this configuration, the posture of the X-ray beam with respect to the forearm can be optimized. In the embodiment, the X-ray generator, the X-ray detector, and a frame connecting them constitute an internal moving body, and an inner bottom plate inclined parallel to the measurement groove is provided inside the lower hollow structure. And a slide mechanism which is provided on the inner bottom plate and slides the internal moving body in the left-right direction while keeping the inclined posture. According to this configuration, the internal moving body is scanned according to the measurement coordinate system based on the measurement groove or the X-ray beam central axis.

In the embodiment, a wedge-shaped underground space is formed between the bottom plate having the bottom surface and the inner bottom plate, and a fan for cooling the X-ray generator is installed in the underground space. With this configuration, it is possible to effectively use the space generated due to the use of the inclined posture of the measurement groove. For example, if a fan, which is conventionally provided on the front side of the X-ray generator, is moved to the lower side of the X-ray generator, it becomes possible to bring the X-ray generator closer to the subject, or the lower side. It is possible to reduce the width of the hollow structure in the depth direction. In either case, inserting the forearm into the measurement groove becomes easier. If the space around the X-ray generator can be expanded, the air cooling effect can be enhanced. In an embodiment, the inner bottom plate has a plurality of ventilation holes. Each vent is a through hole. The inner bottom plate is inclined with respect to the bottom plate, and the underground space between them has a shape similar to a wedge. The shape can be called a trapezoidal triangle when viewed from the side.

In the embodiment, a back plate as a vertical plate is provided across the lower portion, the intermediate portion, and the upper portion. With this configuration, the back plate can be brought close to the wall surface or the like.

In the embodiment, a partition plate is provided across the inside of the lower portion, the inside of the intermediate portion, and the inside of the upper portion, and between the back plate and the partition plate, a back side space that spreads from above to below is provided. The power supply unit is arranged in the inner space. The power supply unit is relatively heavy, and if the power supply unit is arranged in the rear part and in the lower part, the position of the center of gravity can be moved inward and downward, so that the posture of the bone density measuring device is stabilized.

According to the present invention, it is possible to naturally form the inclined posture of the measurement groove without using a special leg. Alternatively, according to the present invention, the form or structure of the bone density measuring device can be functionalized on the premise of the inclined posture of the measurement groove. Alternatively, according to the present invention, an underground space in which a fan or the like can be installed can be generated below the X-ray generator in the lower part of the bone densitometer.

It is a perspective view showing a bone density measuring system concerning an embodiment. It is another perspective view showing the bone density measuring system concerning an embodiment. It is a perspective view showing a bone density measuring device concerning an embodiment. It is a side view showing a bone density measuring device concerning an embodiment. It is a figure for explaining change of the height of a measurement slot. It is a perspective view which shows the trolley|bogie which concerns on embodiment. It is a figure which shows operation at the time of setting the rising edge height. It is a figure which shows a stepwise change of a rising end height. It is a figure which shows the structural example of a limitation mechanism. It is a figure which shows the relationship between a handle and a lever. It is sectional drawing which shows an unlocking mechanism. It is a figure which shows a bone density measuring system and a wheelchair near it. It is a schematic sectional drawing of a bone density measuring device. It is a top view which shows a measurement assistance mechanism. It is a top view which shows the state in which the forearm was mounted on the mounting surface. It is a perspective view showing a measurement assist mechanism. It is a figure which shows the grip in the state of falling down. It is a figure which shows the grip in an upright state. It is a figure which shows the structure of the assembly for right arms. It is a figure which shows a regulation state. It is a figure which shows a non-regulation state. It is a figure which shows the example of arrangement|positioning of a sensor. It is a block diagram showing a bone density measuring device. It is a figure which shows the judgment and control according to two grip states. It is a figure which shows the positional relationship of a fan beam and a marker. It is a figure which shows an X-ray transmission image and an average value profile. It is a flowchart which shows a bone density measuring process. It is a flow chart which shows the example of control of a bone density measuring device.

Embodiments of the present invention will be described below with reference to the drawings.

(1) Bone Density Measuring System and Bone Density Measuring Device FIG. 1 shows a bone density measuring system 10 according to an embodiment. The bone density measuring system 10 is a medical device for measuring the bone density (bone mineral density) of a subject in a medical institution such as a hospital. The bone density is calculated based on the DEXA method. The site to be measured is the subject's forearm, and more specifically, the radius in the forearm. The ulna or other bone may be the measurement target.

The bone density measuring system 10 includes a bone density measuring device 12 and a carriage 14 as a supporting device. The bone densitometer 12 may be used by itself, or the bone densitometer 12 may be mounted on another supporting device. The bone density measuring device 12 has a measurement groove 18 having an inclined posture (obliquely upward posture). The forearm (forearm of the right hand or forearm of the left hand) is inserted into the measurement groove 18. The measurement groove 18 has a front opening, a right opening, and a left opening.

In addition, in FIG. 1, the X direction is the front-back direction or the depth direction. The Y direction is the left-right direction. The Z direction is the vertical (vertical) direction. In the X direction, the side closer to the subject is the front side, and the side farther from the subject is the back side. The front opening of the measurement groove 18 is an opening opened to the front side. The back side of the bone densitometry system 10 is shown in FIG.

Only the bone densitometer 12 is shown in FIG. The bone density measuring device 12 has a housing 16 as a housing. The housing 16 is roughly divided into a lower portion 20, an upper portion 22 and an intermediate portion 24. A measuring groove 18 is formed between the lower portion 20 and the upper portion 22. The bottom surface of the measurement groove 18 (that is, the upper surface of the lower portion 20) constitutes the mounting surface 26. A measurement assist mechanism 28 is provided in the measurement groove 18. The details will be described later.

FIG. 4 shows a schematic side view of the bone densitometer. The above-mentioned measurement assist mechanism is not shown. As described above, the housing includes the lower portion 20, the upper portion 22 and the middle portion 24. The lower part 20 comprises a front part 30 and a rear part 32. An X-ray generator is provided in the front part 30. The front portion 30 will be referred to as a lower hollow structure 30. The upper portion 22 includes a front portion 34 and a rear portion 36. An X-ray detector is provided in the front portion 34. The front portion 34 will be referred to as the upper hollow structure 34. An intermediate portion 24 is formed between the rear portion 32 of the lower portion 20 and the rear portion 36 of the upper portion 22.

The measurement groove 18 is formed between the lower hollow structure 30 and the upper hollow structure 34. The measurement groove 18 has an inclined posture (diagonal upward posture). The lower portion 20 has a bottom surface 37A as a horizontal plane. The measurement groove 18 is inclined with respect to the bottom surface 37A. The bottom surface of the measurement groove 18, that is, the upper surface of the lower hollow structure 30 constitutes a mounting surface 26, and the mounting surface 26 descends from the front side to the back side, which is an inclined surface. The thickness of the lower hollow structure 30 in the vertical direction (Z direction) gradually decreases from the front side to the back side (along the X direction). For example, the thickness T2 on the back side is smaller than the thickness T1 on the front side. Incidentally, the thickness T1 is defined as the distance from the surface 37B obtained by horizontally extending the bottom surface 37A to the mounting surface 26.

As described above, in the bone density measuring device according to the present embodiment, the measurement groove 18 having the inclined posture in the natural state is configured. Therefore, if the bone density measuring device is installed on a horizontal pedestal, the measuring groove 18 is naturally inclined. It is not necessary to install the bone densitometer on a special leg with an inclined mounting surface. Since the measurement groove 18 has an obliquely upward posture, it is possible to naturally guide the forearm to the back side of the measurement groove 18 when the forearm is placed on the mounting surface 26. The lower surface of the upper hollow structure 34 constitutes a ceiling surface 38 facing the mounting surface 26. The mounting surface 26 and the ceiling surface 38 are parallel to each other. The internal structure of the bone densitometer will be described later in detail.

(2) Bogie FIG. 5 shows the operation of the support mechanism (elevating mechanism) 40 provided on the carriage 14. A state in which the height of the bone density measuring device 12 is lowered is indicated by reference numeral 10A. The state in which the height of the bone density measuring device 12 is increased is indicated by reference numeral 10B. In either case, the inclination angle θ1 of the measurement groove is the same. That is, even if the bone density measuring device 12 is moved up and down, the tilted posture of the measurement groove remains unchanged. Incidentally, θ1 is set within the range of 6 degrees to 14 degrees, for example, 10 degrees. The dolly 14 has a support mechanism 40. The support mechanism 40 includes a fixed column 42 as a fixed member and a movable column 44 also as a vertically movable member. The movable column 44 is held by the fixed column 42 so as to be able to move up and down.

The dolly will be described in more detail with reference to FIG. The dolly has a pedestal 46, a support mechanism 40, and legs 49. The pedestal 46 has a pedestal surface as a horizontal plane, on which the bone density measuring device is placed. The support mechanism 40 has a fixed column 42, a movable column 44, and a gas spring 50. The gas spring 50 is provided inside the fixed column 42 and the movable column 44, straddling them. The lower end of the fixed pillar 42 is fixed to the leg portion 49, and the fixed pillar 42 holds the movable pillar 44 so that it can be moved up and down. The upper end of the movable column 44 is connected to the pedestal 46. The leg 49 is provided with four casters 51 which can be swiveled.

The gas spring 50 functions as a push-up mechanism that exerts a push-up force on the pedestal 46. Specifically, the gas spring 50 has a lock function (unlock function). In the locked state, the entire length of the gas spring 50 is held, and in the unlocked state, upward pushing force is exerted. .. In the present embodiment, in the entire stroke range of the pedestal 46, at the height corresponding to about 80% from the lowest height (base height), the total load (force from above) and the pushing force (from below) of the movable portion. The action of the gas spring 50 is adjusted so as to be balanced with Here, the movable part is the entire part that moves up and down, and the total load includes the load of the bone density measuring device, the load of the pedestal 46, and the load of the movable column 44. Furthermore, the load relating to the subject such as the forearm may be considered.

It is also possible to make settings or adjustments so that the above balance is established at the highest point or intermediate point of the entire stroke range. As will be described later, the gas spring 50 has a cylindrical body and a shaft body, and an elastic force that pushes out the shaft body is generated by the pressure of the gas in the cylinder body. A pin that is biased forward is provided at the tip of the shaft. A locked state is formed with the pin protruding, and an unlocked state is formed by pushing the pin back.

The pedestal 46 has four handles 54a, 54b, 54c, 54d which are spread in the horizontal direction. They are formed around the pedestal surface, and project and are exposed to the outside of the densitometer when the bone densitometer is mounted. The base 46 is provided with a lock release mechanism 52. The lock release mechanism 52 has arms 56a and 56b and levers 58a and 58b. Details of the lock release mechanism 52 will be described later. A lever 58a exists below the handle 54a, and when the lever 58a is pulled up, the lever 58a comes close to the handle 54a, and when viewed from above, they are in a superposed state. Similarly, the lever 58b exists below the handle 54b, and when the lever 58b is pulled up, the lever 58b comes close to the handle 54b, and they are in a superposed state when viewed from above. With such a configuration, while the levers 58a and 58b are pulled up by the fingers of the hand (unlocked state), at the same time, the palms are put on the handles 54a and 54b and the weight is applied to them. Is possible.

The support mechanism 40 includes a limiting mechanism 48. The limiting mechanism 48 is a mechanism for limiting the ascending motion exceeding the ascending end height when the ascending end height is selected from a plurality of (three in the present embodiment) ascending end heights. Here, the rising end height refers to the pedestal 46 (particularly the pedestal surface), but since the pedestal 46 and the bone density measuring device integrally move up and down, the rising end height is the bone density measuring device or It is also about measuring grooves.

FIG. 7 shows a knob 60 that is operated when setting or selecting the rising end height. The knob 60 is a rotary operator provided on the back side of the fixed column 42. Utilizing this, the inspector can select any one of the three rising edge height candidates. When the rising end height is set, the stroke range that is effective at that time is from the bottom height (base height) to the rising end height. The limiting mechanism 48 prohibits the ascending movement of the movable body (directly, the movable column) exceeding the ascending end height set by the operation of the knob 60. The knob 60 is operated by the inspector and is not operated by the examinee, and rather should be avoided from an easy operation or contact by the examinee. Therefore, the knob 60 is provided on the rear side of the fixed column 42. 60 is provided. Near the knob 60, three numerical values for identifying the three rising edge height candidates are displayed.

FIG. 8 illustrates three types of rising end heights. In the state shown on the left side, the rising end height of the pedestal surface of the pedestal 46A is indicated by H3. In the state shown in the center, the rising end height of the pedestal surface of the pedestal 46B is indicated by H2. In the state shown on the right side, the rising end height of the pedestal surface of the pedestal 46C is indicated by H1. H0 indicates the base height, that is, the bottom height. When H3 is selected as the rising end height, the range (large range) from H0 to H3 is the effective stroke range. When H2 is selected as the rising end height, the effective stroke range is the range from H0 to H2 (medium range). When H1 is selected as the rising end height, the range (small range) from H0 to H1 is the effective stroke range. For example, the distance between H3 and H2 is in the range of 4-6 cm, similarly, the distance between H2 and H1 is in the range of 4-6 cm, and the distance between H1 and H0 is 2-5 cm. Is within the range of. Each numerical value is merely an example. In either state, the base height H0 is the same, and the rising end height is selectively changed. Instead of the stepwise switching method of the rising end height, a continuous switching method may be adopted. The movable column 44 is provided with a scale 62, and the effective stroke range can be recognized in relation to the upper end level of the fixed column 42 on the scale 62.

FIG. 9 shows a configuration example of the limiting mechanism 48. The limiting mechanism 48 acts between the fixed column 42 and the movable column 44, and includes a guide mechanism 64, a stopper 68, a lift limiting block 70, and the like. The guide mechanism 64 is fixed to the fixed column 42, and it has a guide 66. The guide 66 guides the horizontal movement of the stopper 68. The lifting limit block 70 is fixed to the movable column 44 and moves up and down together with it. The rising limiting block 70 has two upward faces 72 and 74 having different heights.

The guide mechanism 64 is a mechanism that converts the rotational movement of the knob 60 into the linear movement of the stopper 68. In FIG. 9, the rising end height H1 (see FIG. 8) is selected, and the stopper 68 is most advanced. In this state, the upper surface 72 is in contact with the lower surface of the tip portion of the stopper 68, and further upward movement of the upward movement limiting block 70 is limited. When the rising end height H2 (see FIG. 8) is selected by rotating the knob 60, the stopper 68 moves one step to the right in the drawing. As a result, the ascending movement of the ascending limiting block 70 is allowed, and the ascending movement is limited when the upward surface 74 hits the lower surface of the tip portion of the stopper 68. When the rising end height H3 (see FIG. 8) is selected by further rotation of the knob 60, the stopper 68 further moves to the right in the drawing, and the hitting relationship between the stopper 68 and the rising limiting block 70 is substantially. The movable column 44 is allowed to ascend until it physically disappears and reaches another mechanically raised end. As described above, according to the present embodiment, it is possible to form a plurality of rising ends with a very simple mechanism. An illustration of the slide mechanism that straddles the fixed column 42 and the movable column 44 is omitted.

The knob 60 may be rotated only when the base is at a specific height, and the knob 60 may not be rotated otherwise. The specific height may be, for example, the above H0 or the above H1. When such a configuration is adopted, for example, if a mechanism is provided that allows the sliding movement of the stopper 68 when the movable column 44 is at a specific position and prohibits the sliding movement of the stopper 68 in other cases. Good. The mechanism may be incorporated in the guide mechanism 64.

FIG. 10 is an enlarged view showing the relationship between the handle 54b, the lever 58b, and the arm 56b. The lever 58b is in a tilted state. When viewed from above, the handle 54b and the lever 58b are in a superposed relationship. By lifting the lever 58b, it becomes horizontal. In this state, the lever 58b comes close to the handle 54b with a certain gap. This makes it easy to operate the handle 54b with one hand while maintaining the lifted state of the lever 58b. For example, it becomes easy to apply weight to the handle 54b through the palm while lifting the lever 58b with a finger.

FIG. 11 illustrates the gas spring 50 and the lock release mechanism 52. In this embodiment, a gas spring with a lock function is used as the gas spring 50. Specifically, the gas spring 50 has a cylindrical body 77 as a main body and a shaft body 76 held by the cylindrical body 77. The lower end of the cylindrical body 77 is attached to the fixed column or the leg portion. The upper end portion of the shaft body 76 is attached to the pedestal 46. A pin 78 is provided at the tip of the shaft body 76. The pin 78 is always biased in the protruding direction. By applying a pressing force larger than the urging force to the pin 78, the pin 78 sinks. When the pin 78 projects, a locked state is formed, and the tubular body 77 holds the shaft body 76, and the two are integrated. When the pin 78 is depressed, the locked state is released, that is, the unlocked state is formed, and the pushing force is transmitted from the tubular body 77 to the shaft body 76. That is, a force that pushes up the movable portion including the pedestal 46 is generated.

The lock release mechanism 52 is a mechanism for pressing the pin 78 to form an unlocked state. Specifically, the lock release mechanism 52 includes a horizontal shaft 80, a pair of arms (only one arm 56b is shown in FIG. 11) connected to both ends of the horizontal shaft 80, and a pair of arms provided at the tips of the pair of arms. It has a lever (only one lever 58b is shown in FIG. 11) and a pressing piece 84 fixed to the horizontal shaft 80. The working end (the left end in FIG. 11) of the pressing piece 84 is in contact with the top of the pin 78.

In the above configuration, when holding one or both of the pair of levers and pulling the pair of levers upward (see reference numeral 86), the pair of arms changes from the inclined posture to the horizontal posture, and the horizontal shaft 80 rotates ( It rotates clockwise in FIG. 11). As a result, the pressing piece 84 pushes the pin 78, and an unlocked state is formed.

The unlocked state is maintained as long as the paired levers are maintained in the pulled-up state. In the unlocked state, a push-up force of the gas spring 50 is generated, and the movable portion can naturally move upward unless a force is applied downward. Height adjustment can be performed by utilizing the ascending movement. Alternatively, in the unlocked state, it is possible to lower the height of the movable portion by applying a pressing force larger than the pushing force to the movable portion. If the pair of levers are released after the height adjustment, the pair of arms returns to the inclined posture, and at the same time, the pressing piece 84 returns to the original posture and the pin 78 returns to the protruding state. As a result, the locked state is formed. That is, the height of the movable portion at that time is firmly held.

The pushing force F1 of the gas spring 50 changes according to the amount of advance of the shaft 76. If there is a height (equilibrium height) in which the pushing-up force F1 of the gas spring 50 and the total load F2 of the movable portion are balanced within the entire stroke range, the current height at the time when the unlocked state is reached. If the height is lower than the equilibrium height, the movable part naturally rises gently to the equilibrium height. On the contrary, if the current height at the time of becoming the unlocked state is higher than the equilibrium height, the movable part naturally descends gently to the equilibrium height. Therefore, in order to improve usability, it is desirable to appropriately determine the balanced height according to the usage situation. For example, the balanced height may be set at 40%, 60%, 80% or 100% of the entire stroke range as viewed from the base height. Further, the balanced height may be set according to the frequency of use of the height of each rising end. Alternatively, the balanced height may be set in consideration of secular change of the gas spring 50. The load from the forearm may be included when calculating the total load on the moving part. In any case, it is desirable to determine various conditions so as to enhance safety and workability during height adjustment and bone density measurement. Equipment (for example, a gas damper) other than the gas spring 50 may be used as the pushing-up mechanism.

FIG. 12 exemplifies a situation in which bone density measurement is performed on a subject who uses a wheelchair. However, illustration of the subject is omitted. As described above, the bone density measuring system 10 includes the bone density measuring device 12 and the carriage 14. In the carriage 14, the front side of the support mechanism (fixed column, movable column) is open. The central axis of the support mechanism substantially coincides with the center of gravity of the movable part. A line 92 indicates the tip position (the maximum position in the negative direction of the X axis) of the leg portion of the carriage 14. The tip position of the lower portion 20 (maximum position in the negative direction of the X-axis) in the bone densitometer 12 is indicated by a line 90. The lower part of the lower part of the lower part 20 has a roundness, and the tangent line to it is a line 94. The line 92 is on the X axis positive side of the line 90. The line 93 indicates the inclination angle or the central axis of the measurement groove.

As a result of the bone densitometry system 10 being configured as described above, it is possible to bring the wheelchair 88 fairly close to the bone densitometer 12, as shown. In particular, a space is formed below the lower portion 20 to receive the wheels 89 of the wheelchair 88. Moreover, it is possible to adjust the height of the inclined measuring groove. This greatly reduces the burden on the subject using a wheelchair when inserting his or her forearm into the measurement groove. Since the mounting surface that forms the bottom of the measurement groove is inclined from the front side to the back side, the inserted arm can be naturally guided to the back side. The same advantage can be obtained when the measurement is performed on the subject sitting in the chair.

In addition, since a pair of levers are provided and the unlocked state can be formed by operating any of the levers, a situation particularly shown in FIG. 12 (where the inspector wraps around the system front side) It is possible to improve workability or operability when there is no situation.

(3) Structure of Bone Density Measuring Device FIG. 13 shows an internal structure of the bone density measuring device as a schematic sectional view. As already described with reference to FIG. 4, the housing 16 includes a lower portion, an upper portion, and an intermediate portion. The lower hollow structure is configured as the lower front portion, and the upper hollow structure is configured as the upper front portion. More specifically, the housing 16 includes a bottom plate 37, a front plate 100, a top plate 102, a back wall 103, a ceiling plate 104, a top plate 106, and a back plate 108. The bottom plate 37 is configured as a horizontal plate except for the front part thereof. The front plate 100 is configured as a rounded curved plate. The top plate 102 is inclined downward from the front side to the back side, and the inclination angle is θ1. The back wall 103 has a posture tilted from the vertical axis (vertical axis) to the back side, and the tilt angle is θ1. The ceiling plate 104 is provided in parallel with the top plate 102. As shown in FIG. 13, the top plate 102 and the ceiling plate 104 are orthogonal to the back wall 103. The upper surface plate 106 constitutes the upper surface of the housing, which constitutes a gentle curved surface. The back plate 108 stands upright. For example, during storage, the entire back surface of the bone density measuring device can be brought close to or against a vertical wall surface. As a result, useless space is unlikely to occur.

The inside of the housing 16 is hollow. The cavity is roughly divided into a lower internal space 20A, an upper internal space 22A, and an intermediate internal space 24A. An inner bottom plate 110 is arranged in the internal space 20A. The inner bottom plate 110 is lowered from the front side to the back side, that is, has an inclined posture. The inclination angle is θ1. A partition plate 116 is provided from the lower part to the vicinity of the upper part via the intermediate part. The partition plate 116 is inclined to the back side similarly to the back wall 103, and the tilt angle is θ1.

A wedge-shaped underground space 20B is formed between the inner bottom plate 110 and the bottom plate 37. In the underground space 20B, the thickness in the vertical direction gradually decreases from the front side to the back side. A back chamber 24B is formed between the partition plate 116 and the back plate 108. The lateral width (width in the direction from the front side to the back side (X direction)) of the back chamber 24B generally gradually widens from the upper side to the lower side.

A slide mechanism is arranged on the inner bottom plate 110, and the slide mechanism is composed of a pair of rail mechanisms 120 and 122. Each of the rail mechanisms 120 and 122 includes, for example, a rail fixed to the inner bottom plate 110 and extending in the left-right direction (Y direction), and a slider that engages with the rail and moves in the left-right direction. The slide mechanism is a mechanism that guides the horizontal movement of the internal unit (internal moving body) 118.

The internal unit 118 includes an X-ray generator 126, a filter unit 128, a connection frame 130, and a support plate 132. They are integrated and move inside the housing 16. The X-ray generator 126 has an X-ray generation tube. In the illustrated configuration example, a plurality of sliders are attached to the X-ray generator 126 side. An X-ray detector 134 is attached to the support plate 132. The X-ray generator 126 forms the fan beam 136 as an X-ray beam. The X-ray detector 134 is composed of a plurality of sensors lined up in the direction of fan beam spread. A two-dimensional irradiation area is formed by mechanically scanning the fan beam 136 in the left-right direction (Y direction). Reference numeral 136A indicates the central axis of the fan beam 136. The central axis 136A is tilted to the back side and has a tilted posture, and the tilt angle is θ1.

A cooling fan 138 is arranged in the underground space 20B. Specifically, the fan 138 is fixed to the front side of the lower surface of the inner bottom plate 110. When the underground space 20B is a narrow space, it is difficult to arrange the fan 138 there. In the present embodiment, the distance between the bottom plate 37 and the inner bottom plate 110 is increased on the near side, and a space for installing the fan 138 is created. A ventilation space is secured around the fan 138, and a ventilation space is secured on the front side of the X-ray generator 126. By the way, the inner bottom plate 110 and the partition plate 116 have a large number of through holes, that is, have air permeability. With such a configuration, the fan 138 can be used to effectively suppress the temperature rise of the X-ray generator 126.

The power supply unit 140 is disposed below the back chamber 24B. The power supply unit 140 is a relatively heavy member, and if the power supply unit 140 is arranged on the back side and the lower side, the center of gravity of the device can be moved to the back side and downward.

The expansion of the space is recognized on the front side of the underground space 20B, and members such as the fan 138 can be installed there. Therefore, it is not necessary to install a fan or the like on the front side of the X-ray generator 126. This makes it possible to bring the X-ray generator 126 and the front plate 100 close to each other. By bringing the fan beam 136 close to the subject, the burden on the subject can be reduced.

The lower hollow structure (the front part in the lower part) housing the X-ray generator 126 has a trapezoidal shape when viewed from the side (see reference numeral 30 in FIG. 4 ). As described above, the vertical thickness of the lower hollow structure gradually decreases from the front side to the back side. Although the bottom plate 37 is provided with a plurality of legs, they are not shown in FIG. Further, a drive source for mechanically scanning the internal unit 118 is provided inside the housing 16, but this is also omitted in the drawing.

(4) Measurement Assist Mechanism The measurement assist mechanism 28 will be described with reference to FIGS. 14 to 22. FIG. 14 is a top view of the measurement assist mechanism 28. The measurement assist mechanism 28 has a function of optimizing the forearm posture and maintaining the posture, and a function of measuring the forearm length. Specifically, the measurement assist mechanism 28 includes a right hand grip 148, a left hand grip 150, a left hand elbow rest member 152, and a right hand elbow rest member 154. Each of the grips 148 and 150 is a non-detachable grip, and selectively takes a tilted posture that is an operating posture and a standing posture that is a retracted posture. In the tilted posture, the grips 148 and 150 are formed so as to closely face the mounting surface 26. Note that, in FIG. 14, a combined state of the grip 150 and the elbow rest piece of the elbow rest member 154 is shown.

The panel 142 forming a part of the top plate is formed of a member that does not cause X-ray attenuation so much. A two-dimensional irradiation area is formed by scanning the fan beam. The irradiation region includes a subject irradiation region 144 and an air value acquisition region 146. The forearm needs to be correctly positioned with respect to the subject irradiation region 144. The air value acquisition region 146 is a region for acquiring the air value required when performing the bone density calculation based on the DEXA method. It corresponds to the detected value of the X-ray that does not pass through the subject.

The measurement assist mechanism 28 has a housing 160. Two slits 162 and 164 are formed in the housing 160, and the markers 166 and 168 pass through the slits 162 and 164. The ends of the markers 166 and 168 enter the X-ray irradiation space (particularly the air value acquisition space). The marker 168 slides in conjunction with the slide movement of the rod 156. An elbow rest member 152 is attached to the end of the rod 156. The marker 166 slides in conjunction with the slide movement of the rod 158. An elbow rest member 154 is attached to the end of the rod 158. Details thereof will be described later.

FIG. 15 schematically shows a state (measurement state) in which the forearm (the left forearm) is properly positioned on the mounting surface 26. The grip 150 is gripped by the left hand. An elbow rest piece 152A of the elbow rest member 152 is in contact with the left elbow. The housing has two overhangs 180, 182 against which the forearm rests. The unused grip 148 is in an upright posture (however, it is slightly inclining forward). The front surface (inclined surface) 148a also hits the forearm and functions in positioning the forearm. The elbow rest piece of the elbow rest member 154 is housed in the slit of the grip 150, that is, in the united state.

FIG. 16 is a perspective view of the measurement assist mechanism 28. The configuration of the measurement assist mechanism 28 will be described in detail including the elements already described. In FIG. 16, the X′ direction is the front-back direction of the inclined mounting surface and is the direction inclined from the X direction. The Y'direction coincides with the Y direction. The Z'direction is the direction of the fan beam center axis, and is the direction inclined from the Z direction.

The measurement assist mechanism 28 includes a grip 148 for the right arm, a grip 150 for the left arm, an assembly 176 for the left arm, an assembly 178 for the right arm, and a housing 160. Slits 148A and 150A are formed in the grips 148 and 150, respectively. The assembly 176 includes an elbow rest member 152 and a rod 156. A part of the elbow pad member 152 is an elbow pad piece 152A. The assembly 178 includes an elbow rest member 154 and a rod. Part of the elbow rest member 154 is an elbow rest piece 154A.

The housing 160 has an inclined surface 184, and two slits 162, 164 arranged in the Y'direction are formed therein. Some of the markers 166 and 168 project from the slits 162 and 164. The markers 166 and 168 are composed of members that greatly attenuate X-rays. The housing 160 has bulging portions 180 and 182 that bulge toward the front side. The slope 184 has an angle parallel to the hypotenuse of the fan beam. The rotary shafts of the individual grips 148 and 150 are not shown.

FIG. 17 shows the grip 150 in the collapsed posture. FIG. 17 also shows the relationship between the X direction and the X′ direction and the relationship between the Z direction and the Z′ direction. The center axis of the grip 150 is indicated by a line 190 in the tilted posture. The line 192 shows the inclination angle of the mounting surface. An angle difference is generated between the line 192 and the line 190. The grip 150 is in a slightly upward posture with respect to the mounting surface. The elbow pad is housed in the slit of the grip 150, and a part (lower part) of the elbow pad is exposed in the housed state. The longitudinal direction (or lower side) of the elbow pad is parallel to the line 192. FIG. 18 shows the grip 150 in a standing posture. In that state, the elbow pad 154A is completely exposed.

FIG. 19 shows a configuration example of the left arm assembly 176. In FIG. 19, the back side of the housing 160 is shown. An elbow rest member 152 is attached to the end of the rod 156. The rod 156 slides in the Y direction. A rack 202 is provided on the rod 156. The conversion unit 200 is provided inside the housing 160. The conversion unit 200 has a plurality of pinions 204 and a rack 206. A plurality of pinions 204 convert the movement amount between the rack 202 and the rack 206. Specifically, the conversion unit 200 has a function of moving the marker 168 by, for example, ¼ of the amount of movement of the rod 156. This makes it possible to identify the position of the elbow rest member 152 from the position of the marker 168. That is, it is possible to specify the position of the elbow rest member 152 by image analysis without providing an encoder or the like for detecting the linear movement distance of the rod 156. This has the advantage of reducing the number of parts. In FIG. 19, the grip 148 is in a standing state. The right arm assembly has a symmetrical configuration with the left arm assembly 176. The measurement assist mechanism of this embodiment has two regulation mechanisms.

FIG. 20 shows the regulation mechanism 210A in the regulated state. FIG. 21 shows the regulation mechanism 210B in the non-regulated state. The restricting mechanisms 210A and 210B allow the grips 148 and 150 to fall down only when the assembly is in the home position (the position most retracted into the housing), and restrict the fall of the grips 148 and 150 in other states ( It is a mechanism to prohibit).

In FIG. 20, the grip 148 has a standing posture. An opening 212 is formed in the grip 148, and the protrusion 220 of the rotating body 214 is inserted into the opening 212. Due to the engagement, the fall of the grip 148 is restricted. The rotating body 214 has a groove 216. On the other hand, the elbow rest member 152 has a hook 218. When the assembly is pulled into the housing (B direction in FIG. 20) and reaches the home position, the tip of the hook 218 enters the groove 216, and rotates the rotating body 214 in the clockwise direction. Then, the protrusion 220 of the rotating body 214 is disengaged from the opening 212, and the rotational movement (falling movement) of the grip 148 becomes possible. In order to move the assembly in the opposite direction (direction A in FIG. 20), it is necessary to return the grip 148 to the standing state.

FIG. 21 shows the grip 150 in a non-regulated state. In the illustrated example, the rotating body 230 rotates counterclockwise, and the protrusion 228 of the rotating body 230 is disengaged from the opening 226. When the grip 150 falls down to the mounting surface side, the elbow pad piece naturally enters the slit formed in the grip 150. This uniting strengthens the grip 150 structurally.

As shown in FIG. 22, a detector 231 for detecting the attitude of the grip 150 is provided. The detector 231 has a light emitting device and a light receiving device, and the light output signal changes when a light shielding plate is inserted between them. As a result, it is detected whether or not the light-shielded state has occurred (that is, the leaning posture or the standing posture). The shading plate is configured as a moving piece attached to the base of the grip 150. A similar detector is provided on the other grip. A micro switch or the like may be used as the detector 231.

As described above, according to each of the restricting mechanisms, the unused elbow pad piece is accommodated in the slit of the grip, and the combined state of the two is naturally formed. In order to tilt the grip to be used, it is necessary to push the unused assembly, so that it is possible to prevent the situation where the bone density measurement is performed with the unused assembly protruding halfway. The assembly used is, of course, allowed to slide. However, in that case, since the standing posture of the unused grip is forced, the unused grip does not interfere with the measurement.

(5) Data Processing and Control FIG. 23 is a block diagram of the bone density measuring device. The internal unit 237 includes an X-ray generator 234 and an X-ray detector 236. The internal unit 237 is mechanically scanned by the scanning mechanism 238. Low-energy X-rays and high-energy X-rays are generated alternately by switching filters that act on X-rays. The low-energy X-ray detection value and the high-energy X-ray detection value are stored in the memory 240 for each pixel. The processor 242 includes a marker position calculation unit 244, a measurement site calculation unit 245, a bone density image forming unit 246, a control unit 247, and the like. Note that, in FIG. 23, the input unit and the display unit are not shown.

The marker position calculation unit 244 calculates the position of the marker by image analysis based on a two-dimensional image (transmission image) composed of a plurality of low-energy X-ray detection values, for example. A two-dimensional image composed of a plurality of high-energy X-ray detection values may be the analysis target. The measurement part calculation unit 245 has a function of specifying a reference position based on the two-dimensional image, a function of calculating a forearm length from the reference position and the marker position, a function of calculating a measurement part based on the reference position and the forearm length, and the like. Have. The reference position is, for example, the ulnar styloid process. A measurement site (average bone density calculation site) is determined centered on a position distant from the reference position by 1/n (n is 3, 6, 10) of the forearm length.

The bone density image forming unit 246 calculates the bone density according to the DEXA method on a pixel-by-pixel basis based on the data in the memory 240, thereby forming a bone density image. The bone density image is referred to when calculating the average bone density. The control unit 247 controls the operations of the scanning mechanism 238, the X-ray generator 234, and the like.

FIG. 24 shows the control content of the control unit. The row 300 shows the grip state for the right arm. The row 302 shows the grip state for the left arm. Each grip state is determined from the output signals of the two detectors. A column 304 shows the determination result or control content.

As shown in the row 306, when the standing posture of the right arm grip and the falling posture of the left arm grip are detected, the left arm is determined as the measurement target, and the bone density measurement for the left arm is executed. As shown in line 308, when the tilted posture of the right arm grip and the standing posture of the left arm grip are detected, the right arm is determined as the measurement target, and the bone density measurement for the right arm is executed. As shown in line 310, when the standing posture of the right arm grip and the standing posture of the left arm grip are detected, the measurement is prohibited. As shown in row 312, measurement is also prohibited when the tilted posture of the right arm grip and the tilted posture of the left arm grip are detected. Safety can be enhanced by such control.

A method of calculating the marker position will be described with reference to FIGS. 25 and 26. In FIG. 25, the fan beam region 250 includes an air value region 254 at the end. Reference numeral 251 indicates all reception channels (sensor array). A part 252 of them becomes a channel group for air value acquisition. When the markers 166 and 168 enter the fan beam region 250, the influence appears in a part of the channel group for air value acquisition.

In FIG. 26, a two-dimensional image (transmission image) 256 and an average value profile 265 are shown. The two-dimensional image 256 is composed of, for example, a plurality of low energy X-ray detection values. In the entire range 251A in the X'direction, the end area is the air value acquisition area 252A. The marker images 262 and 264 appear in the air value acquisition area 252A. Specifically, the marker images 262 and 264 appear in the thin strip-shaped region 257A. The average value profile 265 is obtained by plotting the average detected value (average value) for each Y coordinate in the area 257A. As shown, two valleys 266, 268 occur corresponding to the two marker images 262, 264. By specifying the centers 270 and 272 of the valleys, the position (Y coordinate) of each marker is specified.

In practice, if the measurement target arm is the left arm, the Y coordinate of the marker image 264 is calculated, and if the measurement target arm is the right arm, the Y coordinate of the marker image 262 is calculated. By the way, the moving ranges of the marker images 262 and 264 are indicated by reference numerals 258 and 260. The position of each marker may be calculated by a method other than the above. Note that the two marker images are excluded when calculating the air value.

(6) Measurement Process FIG. 27 shows the bone density measurement process as a flow chart. In S10, the ascending end height is selected (reset) by the inspector, if necessary. For example, the rising edge height is selected according to the target group of subjects. In S12, the inspector adjusts the height of the measurement groove according to the subject. At that time, an unlocked state is formed, and the height is adjusted in that state. After the height adjustment, the locked state is formed, and the adjusted height is maintained. In S14, the grip to be used is tilted down by the inspector. At that time, an unused elbow pad is housed in the grip. In S16, the inspector performs an operation of sliding the elbow pad to be used far away. Then, in S18, the grip is gripped by the hand of the arm to be measured, and at the same time, the arm is abutted against the projecting portion. This positions the arm. After that, the inspector applies an elbow pad to the olecranon of the arm to be measured. In S20, bone density measurement is executed.

FIG. 28 shows a flow chart of an example of a control method of the bone density measuring device. The control method is executed by the control unit shown in FIG. In S30, the specific target (right arm or left arm) is specified based on the output signals of the two detectors. If the measurement target cannot be properly specified at this stage, the measurement is prohibited as shown in S31. In S32, the internal unit is conveyed to the scan start position corresponding to the measurement target. The scanning start position is selected from the scanning start position for the right arm (the scanning origin on the left side of the device) and the scanning start position for the left arm (the scanning origin on the right side of the device) according to the measurement target. This is because scanning from the distal end side of the forearm to the opposite side is usually required.

In S34, irradiation and scanning are started. In S36, the marker detection process is executed in real time, that is, in parallel with the data acquisition. In this marker detection process, it is determined whether or not the transmission image formed up to that point includes the entire marker image, and if it does, the marker position is calculated. The measurement site is calculated based on the marker position. A necessary scanning range (a range in which fan beam scanning is required) is determined as a range that covers the measurement site. In addition, if scanning of the entire range is required regardless of the measurement site, the entire range is the required scanning range.

In S38, it is determined whether or not the scanning for the required scanning range is completed. If it is not completed, the steps after S36 are repeatedly executed. When it is determined in S38 that the scanning for the required scanning range is completed, the control for ending the irradiation and scanning is executed in S40.

(7) Modified Example The bone density measuring device may be mounted on a supporting device other than the dolly. Alternatively, the bone density measuring device and the carriage may be integrated. The adjusted height may be recorded for each subject, and the recorded height may be used when the bone density measurement is performed again for the same subject. For example, the height may be displayed. It is also conceivable to use the recorded height for automatic height adjustment. It is also possible to obtain a standard or standard height from the information about the subject (age, sex, height, etc.) and display it.

Although the fan beam is used in the above embodiment, a pencil beam or a cone beam may be used instead. The ulnar styloid process is used to calculate the forearm length. Instead of specifying the position of the ulnar styloid process by image processing, the position may be specified by manually aligning the laser marker with the ulnar styloid process.

When both the two grips are in the collapsed posture, the internal unit may be positioned at the center in the left-right direction. According to this, when the measurement is restarted, the movement time becomes the same regardless of which scanning start position the internal unit is moved to. Further, according to such control, the weight balance of the device can be improved during transportation. It is also conceivable to automatically move the assembly including the elbow rest. It is also possible to automate the posture change of the grip.

In the above embodiment, the marker position is detected in real time, but a temporary transmission image may be acquired by prescanning and the marker position may be specified based on that. Alternatively, the marker position may be specified based on the transmission image after the full range scan is executed.

10 Bone Density Measuring System, 12 Bone Density Measuring Device, 14 Carriage, 16 Case, 18 Measuring Groove, 20 Lower Part, 22 Upper Part, 24 Intermediate Part, 26 Mounting Surface, 28 Measurement Assist Mechanism, 40 Support Mechanism, 48 Restriction Mechanism , 50 gas spring, 52 unlocking mechanism, 110 inner bottom plate, 118 internal unit, 120, 122 rail mechanism (slide mechanism), 126 X-ray generator, 134 X-ray detector, 148, 150 grip, 152, 154 elbow rest Members, 166, 168 markers, 176 left arm assembly, 178 right arm assembly, 210A, 210B restriction mechanism.

Claims (7)

A lower part having a bottom surface, which is composed of a front part and a back part,
An upper part composed of a front part and a back part,
An intermediate portion that is continuous with the back side portion of the lower portion and the back side portion of the upper portion,
Including
The lower front part constitutes a lower hollow structure containing an X-ray generator,
The front side portion of the upper portion constitutes an upper hollow structure containing an X-ray detector,
Between the lower hollow structure and the upper hollow structure, a measurement groove is formed into which the forearm is inserted having an inclined posture that is lowered from the front side to the back side,
When the direction orthogonal to the bottom surface is defined as a vertical direction, the thickness of the lower hollow structure in the vertical direction is gradually reduced from the front side to the back side,
A bone density measuring device characterized by the above. The device of claim 1, wherein
An X-ray beam central axis connecting the X-ray generator and the X-ray detector is inclined inward with respect to the vertical direction,
A bone density measuring device characterized by the above. The device according to claim 2,
The X-ray generator, the X-ray detector, and the frame connecting them constitute an internal moving body,
Inside the lower hollow structure, an inner bottom plate inclined parallel to the measurement groove, and a slide mechanism provided on the inner bottom plate for sliding the inner moving body in the left-right direction in an inclined posture. Provided,
A bone density measuring device characterized by the above. The device according to claim 3,
A wedge-shaped underground space is formed between the bottom plate having the bottom surface and the inner bottom plate,
A fan for cooling the X-ray generator is installed in the underground space,
A bone density measuring device characterized by the above. The device according to claim 3,
The inner bottom plate has a plurality of ventilation holes,
A bone density measuring device characterized by the above. The device of claim 1, wherein
A back plate as a vertical plate is provided across the lower part, the intermediate part and the upper part.
A bone density measuring device characterized by the above. The device according to claim 6,
A partition plate is provided across the inside of the lower portion, the inside of the intermediate portion and the inside of the upper portion,
Between the back plate and the partition plate, a back side space spreading from the upper side to the lower side is formed,
A power supply unit is arranged in the back space,
A bone density measuring device characterized by the above.