JP2010217498A - Radiation image detection cassette - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance impact-resistance, and to prevent the breakage of a cassette even if an impact is suddenly applied thereto. <P>SOLUTION: Provided that the thickness of a housing 3 in an irradiating direction of radioactive rays is denoted as D, a curvature radius of the round-chamfered corner part of the housing 3 is denoted as R, a relational expression of 0.18≤R/D is satisfied. Accordingly, the impact resistance of the radiation image detection cassette can be enhanced. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radiological image detection cassette.

  In recent years, a digital radiographic image detection apparatus has been used as a method of obtaining a radiographic image by irradiating a subject with radiation and detecting the radiation transmitted through the subject. As such a radiation image detection apparatus, there is a so-called FPD (Flat Panel Detector).

  As an example of an FPD, a plurality of detection elements are two-dimensionally arranged on a substrate, radiation that has passed through a subject is irradiated onto a phosphor (scintillator), and visible light that is emitted according to the amount of irradiated radiation is charged. There is one that obtains a radiographic image by reading the electric charge accumulated in the photoelectric conversion element by converting into the photoelectric conversion element. Such an FPD has immediacy that a radiographic image can be obtained immediately after imaging.

  The cassette-type FPD is transported to a predetermined location and used for radiographic imaging, but the cassette-type FPD is accidentally dropped while being transported to the predetermined location, In some cases, a shock may be applied to the cassette type FPD. If no measures are taken against this impact, the cassette-type FPD may be broken.

  Therefore, a technique that considers the impact resistance of the cassette type FPD has been proposed. In the technique described in Patent Document 1, a cap formed of an impact-resistant energy absorbing material such as nylon or polyethylene is provided at the corner of an X-ray detector that is a cassette type FPD. When a cap is provided at the corner of the X-ray detector, even if a sudden impact is applied to the corner of the X-ray detector, the impact can be absorbed by the cap, so that damage to the X-ray detector can be suppressed.

JP 2008-90304 A

  By the way, when a sudden impact is applied to the X-ray detector which is a cassette type FPD, stress concentration occurs in the corner (X region shown in FIG. 9) of the X-ray detector 100 shown in FIG. May occur and the X-ray detector may be damaged from the corner. The technique described in Patent Document 1 can absorb the impact applied to the corner of the X-ray detector in the cap, but does not take into account the occurrence of cracks at the corners due to stress concentration as described above. Further, sudden impacts applied to portions other than the corners of the X-ray detector cannot be absorbed, which is insufficient from the viewpoint of impact resistance. Further, in the prior art, detailed examination has not been made on the shape of the cassette type FPD in consideration of impact resistance.

  Accordingly, an object of the present invention is to provide a radiation image detection cassette having improved impact resistance due to the shape of the cassette itself.

A portable radiation image detection cassette that detects radiation irradiated toward a subject and obtains radiation image data,
A detector unit comprising: a scintillator that converts incident radiation into light; and a detector that receives the light converted by the scintillator and converts it into an electrical signal;
A housing containing the detector unit;
When the thickness of the casing in the radiation irradiation direction is D and the radius of curvature of the corner of the casing that is chamfered round is R, the following relational expression is satisfied.
0.18 ≦ R / D

  According to the radiation image detection cassette according to the present invention, impact resistance is improved, and damage to the cassette can be suppressed even when a sudden impact is applied.

It is a perspective view which shows a cassette type | mold detector. It is a disassembled perspective view of a housing. It is sectional drawing of the predetermined location which looked at the cassette type detector shown in FIG. 1 from the a direction. It is the fragmentary sectional view which expanded only the housing part of sectional drawing shown in FIG. It is a graph which shows the relationship between R / D and the maximum value of equivalent stress. It is the fragmentary sectional view which expanded only the housing part. It is explanatory drawing which shows the structure of a carbon fiber group. It is explanatory drawing which shows the direction of the bundle | flux of carbon fiber. It is a perspective view which shows the conventional X-ray detector.

[Outline of cassette type detector]
FIG. 1 is a perspective view of a cassette type detector. A cassette type detector 1 which is a radiation image detection cassette is a cassette type flat panel detector. The cassette-type detector 1 includes a radiation detection unit 2 (see FIG. 3 and the like) that detects irradiated radiation and acquires it as digital image data, and a housing (housing) 3 that incorporates the radiation detection unit 2. Yes.

  FIG. 2 is an exploded perspective view of the housing 3. As shown in FIG. 2, the housing 3 includes a hollow main body 31 having openings 311 and 312 at both ends, a first lid member 32 and a second lid 32 that close the openings 311 and 312 of the main body 31. And a lid member 33.

  The main body 31 is cylindrical and is formed so as to maintain the strength of the cassette type detector 1.

  The first lid member 32 and the second lid member 33 include lid body portions 321 and 331 and insertion portions 322 and 332, and are formed of aluminum.

  Engagement pieces 324 and 334 that engage the first lid member 32 and the second lid member 33 and the main body 31 are inserted into the openings 311 and 312 on the side surfaces of the insertion portions 322 and 332, respectively. Extends in the direction. Engagement projections 325 and 335 are provided on the outer surfaces of the engagement pieces 324 and 334, respectively. When the first lid member 32 and the second lid member 33 are inserted into the main body portion 31, the engagement convex portions 325 and 335 engage with the engagement concave portions 315 and 316 installed in the main body portion 31.

  An antenna device 9 for transmitting and receiving information wirelessly between the cassette type detector 1 and an external device is embedded in one side surface of the lid main body portion 321 of the first lid member 32. 9 includes a pair of flat radiation plates 91 and 92 made of metal, and a power feeding unit 93 that feeds power to the pair of radiation plates 91 and 92.

  In addition, when charging the rechargeable battery 24 (see FIG. 3 and the like) provided inside the housing 3 on one surface of the lid main body 321 on the same surface as the surface on which the antenna device 9 is formed. A charging terminal 45 connected to an external power source or the like and a power switch 46 for switching ON / OFF of the power source of the cassette type detector 1 are provided. Furthermore, the corner 47 formed by the surface on which the antenna device 9 is formed and the surface on the radiation incident side is composed of, for example, an LED or the like, and is an indicator 47 that displays the charging status of the rechargeable battery 24 and various operation statuses. Is provided.

[Internal structure of cassette type detector]
Next, the internal structure of the cassette type detector 1 will be described. FIG. 3 is a cross-sectional view of a predetermined portion of the cassette type detector 1 shown in FIG.

  As shown in FIG. 3, the radiation detection unit 2 includes a detector unit 21, a base 22, and electrical components (a relay board 23A, a control board 23B, a rechargeable battery 24, etc.). In this embodiment, the detector unit 21 is attached to the upper surface of the base 22 via the shielding member 25, and a plurality of control boards 23B, rechargeable batteries 24, and the like are provided on the lower surface of the base 22. Electrical parts are installed.

  The base 22 is flexible and is made of a thin resin. The thickness is about 1 mm, and the material is, for example, a resin in which polycarbonate and ABS are mixed.

  The detector unit 21 includes a scintillator layer 211, a sensor array substrate 212, a counter substrate 213, a reinforcing member 214, and the like. The basic structure of the detector unit 21 will be described. A detection unit 151 is supported on a sensor array substrate 212, and a scintillator layer 211 is provided above the detection unit 151. A counter substrate 213 is provided above the scintillator layer 211, and the scintillator layer 211 is sandwiched between the counter substrate 213 and the sensor array substrate 212.

  The scintillator layer 211 has a function of converting incident radiation into light. The scintillator layer 211 has, for example, a phosphor as a main component, and outputs an electromagnetic wave having a wavelength of 300 nm to 800 nm, that is, an electromagnetic wave (light) ranging from ultraviolet light to infrared light centering on visible light, based on incident radiation. It is like that.

  A detection unit 151 is formed below the scintillator layer 211. The detection unit 151 converts electromagnetic waves (light) output from the scintillator layer 211 into electric energy and accumulates the electric signal based on the accumulated electric energy. Output.

  Both the sensor array substrate 212 and the counter substrate 213 are glass substrates having a thickness of about 0.6 mm.

  A reinforcing member 214 is installed below the sensor array substrate 212 to reinforce the protruding portion of the sensor array substrate 212 with respect to the counter substrate 213. A protective member 215 that protects the counter substrate 213 is provided above the counter substrate 213.

  An electric signal extraction unit 216 for extracting an electric signal generated by the detection unit 151 is provided at an end of the sensor array substrate 212. The electric signal extraction unit 216 and the first relay substrate 23A are connected by a flexible harness 26. Has been.

  In the present embodiment, an electric double layer capacitor is used as the rechargeable battery 24 attached to the lower surface of the base 22.

  As described above, by using the cassette type detector 1 as shown in FIGS. 1 to 3, it is possible to detect a radiographic image of a subject.

[Housing shape]
Next, the shape of the housing 3 in consideration of impact resistance will be described in detail.

  FIG. 4 is a partial cross-sectional view in which only the housing portion of the cross-sectional view shown in FIG. 3 is enlarged. “D” shown in FIG. 4 indicates the thickness of the housing 3 in the radiation irradiation direction, and “R” indicates the radius of curvature of the corner Y of the housing 3 that is rounded and chamfered. “T” indicates the thickness of the wall of the housing 3.

  The cassette type detector 1 is transported to a predetermined location and used for radiographic imaging, but the cassette type detector 1 may be accidentally dropped while being transported to the predetermined location. There is a case where a sudden impact is applied to the cassette type detector 1 by colliding with another object. When a sudden impact is applied to the cassette type detector 1, stress concentration occurs at the corner Y of the housing 3. However, the stress concentration at the corner Y is reduced by chamfering the corner Y as shown in FIG. It can be made.

  By the way, if the value of the thickness D of the housing 3 increases, the mass of the cassette detector 1 increases and the impact force due to the drop also increases. Therefore, in order to reduce the stress concentration due to the impact force, Need to be larger. On the other hand, if the value of the thickness D of the housing 3 decreases, the mass of the cassette-type detector 1 decreases and the impact force due to the drop also decreases. That is, considering the impact resistance of the cassette type detector 1, the value of R / D, which is the ratio of the thickness D of the housing 3 and the radius of curvature R of the corner Y, may be optimized. Therefore, an appropriate range of R / D was examined by experiment. The result is shown in FIG.

  FIG. 5 is a graph showing the relationship between R / D and the maximum value of equivalent stress. The horizontal axis shows the value of R / D, and the vertical axis shows the maximum value of equivalent stress. The maximum value of equivalent stress is the maximum value of stress when a predetermined impact force is applied to the housing 3, and is the maximum value at the corner Y of the housing 3.

As shown in FIG. 5, when the value of R / D increases (for example, when the radius of curvature R is larger than the thickness D), the maximum value of equivalent stress decreases, that is, stress concentration at the corner Y of the housing 3. And the impact resistance of the cassette type detector 1 is improved. If the maximum value of the equivalent stress is higher than 0.4 MPa through the experiment, it is found that there is a problem in the impact resistance of the cassette type detector 1, and it is necessary that R / D satisfies the following formula (1). It is.
0.18 ≦ R / D (1)
For example, the thickness D of the housing 3 conforms to a JIS standard (JIS Z 4905; an international standard corresponding to JIS Z 4905 is IEC 60406) (13 to 16 mm ((15-2) mm to (15 + 1) mm)), the radius of curvature R is preferably about 3 mm or more. In this embodiment, the thickness D of the housing 3 is 15 mm, and the radius of curvature of the corner Y is 4 mm.

  As described above, by selecting the thickness D of the housing 3 and the radius of curvature R of the corner Y so as to satisfy the above formula (1), the stress concentration at the corner Y of the housing 3 is reduced, and the cassette The impact resistance of the mold detector 1 can be improved.

  Further, if the radius of curvature R of the corner Y is increased with respect to the thickness D of the housing 3, there is no problem from the viewpoint of impact resistance, but the housing 3 has a very round shape as shown in FIG. The area of the flat portion Z on the side wall 3 is reduced. When the cassette-type detector 1 is set on the imaging table, the flat portion Z on the side wall of the housing 3 is set by rubbing against the support portion of the imaging table, but when the area of the flat portion Z decreases, the imaging is performed. The rubbing location with the support portion of the base is reduced, and the side wall of the housing 3 is easily worn.

  Further, when the housing 3 is rounded, the space inside the housing 3 is reduced, and the arrangement of the detector unit 21 and electric components incorporated in the housing 3 is limited. Furthermore, when the housing 3 is rounded, the user easily slips when carrying the cassette-type detector 1 with a rounded portion, and the cassette-type detector 1 is easily dropped.

Then, when the numerical value of R / D was examined from the said viewpoint, it was able to grasp | ascertained through experiment that R / D satisfied | fulfilled the following (2) Formula.
R / D ≦ 0.47 (2)
For example, the thickness D of the housing 3 conforms to a JIS standard (JIS Z 4905; an international standard corresponding to JIS Z 4905 is IEC 60406) (13 to 16 mm ((15-2) mm to (15 + 1) mm)), the curvature radius R is preferably about 6 mm or less.

  As described above, by selecting the thickness D of the housing 3 and the radius of curvature R of the corner portion Y that satisfy the above expression (2), the wear of the side wall of the housing 3 is suppressed, The degree of freedom of arrangement can be increased. Also, the portability of the cassette type detector 1 can be improved.

[Thickness of housing wall]
Next, the wall thickness of the housing 3 in consideration of impact resistance will be described. Although the thickness t of the wall of the housing 3 shown in FIG. 3 is increased, the strength of the housing 3 increases and the damage of the housing 3 can be suppressed as the value of the thickness t increases.

  By the way, if the value of the thickness D of the housing 3 is increased, the mass of the cassette type detector 1 is increased and the impact force due to the drop is also increased. good. On the other hand, if the value of the thickness D of the housing 3 decreases, the mass of the cassette type detector 1 decreases and the impact force due to dropping also decreases, so that the impact force can be endured even if the wall thickness t is reduced. That is, in consideration of the impact resistance of the cassette type detector 1, in addition to the optimization of R / D, the value of t / D which is the ratio of the thickness D of the housing 3 to the thickness t of the wall of the housing 3 Should be optimized.

  Further, if the wall thickness t of the housing 3 is larger than the thickness D of the housing 3, the space inside the housing 3 is reduced, and the arrangement of the detector unit 21 and electrical components built in the housing 3 is reduced. It will be restricted.

Therefore, when considering the impact resistance and securing the space in the housing 3, it was understood that it is preferable that t / D satisfies the following expression (3).
0.075 ≦ t / D ≦ 0.170 (3)
For example, the thickness D of the housing 3 is set to a size (13 to 16 mm ((15-2) mm to (15 + 1) corresponding to JIS Z 4905; an international standard corresponding to JIS Z 4905 is IEC 60406). ) Mm)), the wall thickness t is preferably in the range of about 1.2 mm to 2.2 mm. In the present embodiment, the wall thickness t of the housing 3 is 1.6 mm.

  As described above, the shock resistance of the cassette type detector 1 can be further improved by selecting the thickness D of the housing 3 and the thickness t of the wall of the housing 3 so as to satisfy the above expression (3). The degree of freedom of arrangement in the housing 3 can be increased.

[Housing material]
Next, the material of the housing 3 will be described. The housing 3 which is an exterior part of the cassette type detector 1 includes the carbon fiber group C shown in FIG. 7A, and the carbon fiber group C is laminated and entirely made of a resin material (for example, epoxy resin, phenol resin, etc.). It is hardened.

  As shown in FIG. 7 (a), the carbon fiber group C is formed by weaving a bundle C1 of carbon fibers arranged in one direction and a bundle C2 of carbon fibers arranged in a direction perpendicular to the bundle C1 of carbon fibers. It has a strong structure. FIG. 7B schematically shows a cross section of the carbon fiber bundles C1 and C2, and the carbon fiber bundles C1 and C2 are configured in a form in which a plurality of carbon fibers CS are densely packed.

  Since the cassette type detector 1 is irradiated with radiation or set on the imaging table a plurality of times, the strength of the housing 3 tends to decrease due to deterioration over time. However, the cassette type detector 1 is woven together with the shape of the housing 3 described above. By having the carbon fiber group C formed inside, the strength of the housing 3 can be maintained. Further, by having the woven carbon fiber group C inside, even when the wall of the housing 3 is thin, a certain strength can be maintained. FIG. 8 shows a top view of the cassette-type detector 1. The carbon fiber bundles C1 and C2 may be perpendicular to the vertical and horizontal directions as shown in FIG. 8 (a), or as shown in FIG. 8 (b). It is also possible to adopt a form orthogonal to the oblique direction. In this way, by weaving the carbon fiber bundle C1 and the carbon fiber bundle C2 so that the fiber directions intersect vertically and horizontally, the carbon fiber bundle C1 group and the bundle C2 group are mutually affected by impact and the like. In addition, the reinforcing function can be exhibited to prevent the housing 3 from cracking.

  As mentioned above, although this invention was demonstrated by embodiment shown in FIGS. 1-8, this invention is not limited to the said embodiment, Even if there exists a change and addition in the range which does not deviate from the summary of this invention. It is included in the present invention.

DESCRIPTION OF SYMBOLS 1 Cassette type detector 2 Radiation detection part 3 Housing 21 Detector unit 22 Base 31 Main body part 32 1st cover member 33 2nd cover member 151 Detection part 211 Scintillator layer C Carbon fiber group

Claims (4)

A portable radiation image detection cassette that detects radiation irradiated toward a subject and obtains radiation image data,
A detector unit comprising: a scintillator that converts incident radiation into light; and a detector that receives the light converted by the scintillator and converts it into an electrical signal;
A housing containing the detector unit;
A radiation image detection cassette satisfying the following relational expression, where D is the thickness of the casing in the radiation irradiation direction and R is the radius of curvature of the corner of the casing that is chamfered round:
0.18 ≦ R / D The radiographic image detection cassette according to claim 1, wherein the R / D satisfies the following relational expression.
R / D ≦ 0.47 The radiographic image according to claim 1, wherein the following relational expression is satisfied, where D is a thickness of the housing in the radiation irradiation direction and t is a wall thickness of the housing in the radiation irradiation direction. Detection cassette.
0.075 ≦ t / D ≦ 0.170   The said housing | casing contains the carbon fiber group woven by the bundle | flux of the carbon fiber arranged in one direction, and the bundle | flux of the carbon fiber arranged in the direction orthogonal to the said bundle. The radiation image detection cassette according to any one of the above.

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