JP2005308409A - Cassette for radiation detection - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accommodate a radiation solid state detector having as large size as possible in a cassette for radiation detection in which a radiation solid state detector is accommodated in a casing. <P>SOLUTION: In this cassette 15 for detecting radiation, the radiation solid state detector 30 as an image pickup device, and a power supply 40 or the like for supplying electric power to the radiation solid state detector 30 are accommodated in the casing 20. The power supply 40 is arranged at the back side (radiation non-incidence plane side) of the radiation solid state detector 30, therefore the size of the radiation solid state detector 30 accommodated in the casing 20 is not restrained. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a radiation detection cassette in which a radiation solid detector is accommodated in a housing.

  Today, in radiography for medical diagnosis and the like, a solid-state radiation detector that detects radiation transmitted through a subject and outputs an image signal representing a radiographic image related to the subject (mainly a semiconductor; hereinafter simply a detector) Various proposals and practical applications (Patent Document 1, Patent Document 2, etc.), and these radiation solid detectors and a power supply for supplying power to the detectors are accommodated in a case. Various types of cassettes for radiation detection have been proposed (Patent Document 3, etc.).

The radiation detection cassette as described above is relatively thin and can be transported. For example, for a patient who cannot move, the radiation is placed under the part that the patient wants to shoot while lying on the bed. Place the detection cassette, move the radiation source of the radiation imaging device to a position facing the radiation detection cassette and the patient, and take an image, or load it into an imaging device such as a breast radiography device It is possible to perform shooting with a very high degree of freedom such as shooting.
JP 2000-105297 A JP 2000-284056 A US Pat. No. 5,661,309

  By the way, in the cassette as described above, it is desired to enlarge the imaging area of the detector with respect to the size of the cassette so that the image can be captured to the edge of the cassette, that is, to form a frame.

  In particular, in breast radiography equipment, the subject's breast is fixed on an imaging table loaded with a cassette, and radiation is applied from the top of the breast to perform imaging from the chest wall to the breast, or imaging with a cassette loaded. In order to take a picture of the axilla of the subject by tilting the stand vertically and placing the arm on the side of the photography stand, not only the side arranged on the chest wall side of the cassette (front side of the photographing device) It is desired that the side adjacent to the side is also a sandwiched frame.

  Therefore, as in the cassette described in Patent Document 3 above, it is conceivable to concentrate and arrange a structure such as a power supply on the side of one side of the detector, but the size of the cassette is generally Since, for example, 193 mm in length, 266 mm in width, and 15 mm in thickness are determined in this manner, there is a problem in that the imaging area becomes narrow in addition to reducing the size of the detector.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to enable a radiation solid detector as large as possible to be accommodated in a radiation detection cassette in which a radiation solid detector is accommodated in a housing. It is what.

  A radiation detection cassette according to the present invention includes a flat radiation solid detector that receives image radiation to carry image information, records the image information, and outputs an image signal representing the recorded image information, and a radiation solid detector In the radiation detection cassette in which a power source for supplying power to the housing is housed in a casing, the power source is arranged on the radiation non-incident surface side of the radiation solid detector.

  In the present invention, the “radiation solid detector” is a detector that detects radiation (X-rays) carrying image information of a subject and outputs an image signal representing a radiation image related to the subject, and directly receives incident radiation. Alternatively, it is possible to obtain an image signal representing a radiographic image related to a subject by converting the light once into light and then converting it into electric charge and outputting the electric charge to the outside.

  There are various types of solid state detectors. For example, from the aspect of the charge generation process that converts radiation into electric charge, the photoconductive layer detects the fluorescence emitted from the phosphor when irradiated with radiation. The signal charge obtained in this way is temporarily stored in the power storage unit, and the stored charge is converted into an image signal (electrical signal) and output, or the photoconductive layer is irradiated with radiation. The signal charge generated in step 1 is collected by the charge collection electrode, temporarily stored in the power storage unit, and the stored charge is converted into an electrical signal and output, or the direct conversion type solid state detector that reads the stored charge to the outside From the aspect of the reading process, a TFT reading method that scans and reads a TFT (thin film transistor) connected to the power storage unit, or an optical reading method that reads the reading light (electromagnetic wave for reading) by irradiating the detector with the reading light. Such as those of news, there is such an improved direct conversion type which is proposed in the Patent Document 2 filed by the present applicant that combines the direct conversion type and the optical readout type.

  Since the above radiation solid state detector is usually driven at a very high voltage (2 to 4 kV), a cable for supplying power to the radiation solid state detector is generally thick and inflexible. However, when such a cable is directly connected to the radiation incident surface side of the radiation solid detector, the gap on the radiation incident surface side of the radiation solid detector in the housing increases, and the distance from the subject to the radiation solid detector becomes long. Therefore, there is a problem that the image quality is deteriorated, such as blurring of the image.

  Therefore, connect the power connection located on the radiation incident surface side of the radiation solid detector to one end of the flexible cable or metal tape, and connect the other end of the flexible cable or metal tape to the radiation non-incident surface of the radiation solid detector. It is preferable that it is arranged on the side and connected to a power supply cable on the radiation non-incident surface side.

  At this time, the flexible cable or the metal tape is preferably provided with a shield.

  According to the radiation detection cassette of the present invention, a flat radiation solid detector for receiving image radiation that carries image information, recording the image information, and outputting an image signal representing the recorded image information, and a radiation solid In a radiation detection cassette in which a power source for supplying power to the detector is housed in a housing, the power source that has been conventionally arranged on the side surface of the radiation solid detector is connected to the radiation non-incident surface side of the radiation solid detector Therefore, the size of the radiation solid detector accommodated in the housing can be increased by this amount of space.

  Also, connect the power connection located on the radiation incident surface side of the radiation solid detector to one end of the flexible cable or metal tape, and connect the other end of the flexible cable or metal tape to the radiation non-incident surface of the radiation solid detector. By disposing it on the side and connecting to the power supply on the radiation non-incident surface side, the gap on the radiation incident surface side of the radiation solid detector can be reduced in the housing, thus preventing image quality degradation. can do.

  Furthermore, by using a flexible cable or metal tape with a shield, electromagnetic noise from the flexible cable or metal tape to the outside, and electromagnetic noise from entering the flexible cable or metal tape from the outside can be prevented. be able to.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an example of a breast radiography apparatus using a radiation detection cassette according to the present invention, FIG. 2 is a schematic diagram of the inside of the radiation detection cassette, and FIG. 3 is a detector of the radiation detection cassette. FIG. 4 is an enlarged schematic diagram of the radiation detection cassette as viewed from above.

  The breast radiography apparatus 1 includes an X-ray source storage unit 3 that stores an X-ray source 2 therein, and an imaging table 8 that holds a radiation detection cassette 15 that stores a radiation solid detector 30 that is an imaging device. Are connected by an arm 5 so as to face each other, and this arm 5 is attached to a base 6. The arm 5 rotates in the direction of an arrow about a joint portion 6a with the base 6 as an axis. Further, a compression plate 7 is attached to the arm 5 to hold the breast 9 of the subject against the imaging table 8 from above.

  The radiation detection cassette 15 is provided with a connector 21 for outputting an image signal acquired by the radiation solid detector 30 to the outside. The connector 21 is used for acquiring an image signal provided in the mammography apparatus 1. The connection terminal 12 of the cable 13 is connected.

  X-rays emitted from the X-ray source 2 are applied to the imaging table 8 and applied to the radiation solid detector 30 in the radiation detection cassette 15 loaded in the cassette loading unit 8 a of the imaging table 8. X-ray imaging by the breast radiography apparatus 1 is performed in a state where the subject is located between the X-ray source storage unit 3 connected to the arm 5 and the imaging table 8. Then, the X-ray imaging is performed while the arm 5 rotates according to the X-ray imaging purpose and the arm 5 is inclined at various angles.

  The radiation detection cassette 15 is configured such that a radiation solid state detector 30, which is an imaging device, a power supply 40, and the like are accommodated in a housing 20.

  The radiation solid detector 30 includes a first conductive layer 36 made of a-Si TFT on a glass substrate 31, a photoconductive layer 37 that exhibits conductivity by generating electric charges upon receiving X-ray irradiation, and a second conductive layer 37. The radiation detection unit 35 is formed by laminating the conductive layer 38 and the insulating layer 39 in this order.

  The first conductive layer 36 is formed with a plurality of TFTs corresponding to each pixel, and a signal line for detecting image information recorded in an area corresponding to each TFT as an image signal, Scanning lines for switching readout TFTs in the longitudinal direction of the signal lines are arranged in a matrix so as to cross each other.

  Among the signal lines of each TFT, odd-numbered signal lines from the end are sequentially passed through the TAB film 22a for every several to hundred scanning lines on one side of the two sides adjacent to the chest wall 10 side. Are connected to the printed circuit board 22 arranged on the back side (radiation non-incident surface side) of the radiation solid detector 30, and the even-numbered signal line from the end is also of the two sides adjacent to the chest wall 10 side. On the other side, the printed circuit board 22 disposed on the back side of the radiation solid state detector 30 is connected via the TAB film 22a for every several to hundred scanning lines.

  Further, the scanning lines of the TFTs are printed boards arranged on the back side of the radiation solid detector 30 via the TAB film 23a for every several to hundred scanning lines that are sequentially adjacent on the side facing the chest wall 10 side. 23.

  On the printed circuit board 22, an output amplifier (not shown) for reading out signal charges transferred from the radiation solid state detector 30 via a signal line for each column to the outside, an A / D converter (not shown), and a memory (Not shown) etc. are provided.

  On the printed circuit board 23, a sub-scanning pulse generator (not shown) connected in common via the gates of the TFTs and scanning lines is provided for each row.

  In the radiation solid detector 30, when an electric field is formed between the first conductive layer 36 and the second conductive layer 38, when the photoconductive layer 37 is irradiated with X-rays, the photoconductive layer A charge pair is generated in 37, and a latent image charge corresponding to the amount of the charge pair is accumulated in the first conductive layer. When the accumulated latent image charge is read, the TFTs of the first conductive layer 36 are sequentially driven to read the latent image charge corresponding to each pixel, so that the electrostatic latent image carried by this latent image charge is read. Can be read.

  The power supply 40 for supplying power to the radiation solid detector 30 is arranged on the back side (radiation non-incident surface side) of the radiation solid detector 30 and restricts the size of the radiation solid detector 30 accommodated in the housing 20. I don't want to do that.

  Since the radiation solid detector 30 is usually driven at a very high voltage (2 to 4 kV), a cable for supplying power to the radiation solid detector 30 is generally thick and inflexible. However, when such a cable is directly connected to the front side (radiation incident surface side) of the radiation solid state detector 30, the gap on the front side of the radiation solid state detector 30 is widened in the housing, and the distance from the subject to the radiation solid state detector 30 is increased. Since the distance becomes long, there is a problem that the quality of the image deteriorates, such as blurring of the image.

  Therefore, the power connection part located on the front side of the radiation solid detector 30 is connected to one end of the flexible cable 45, the other end of the flexible cable 45 is arranged on the back side of the radiation solid detector 30, and the radiation solid detector 30. The radiation solid detector 30 and the power source 40 are connected by connecting the cable 41 and the other end of the flexible cable 45 on the back side of the cable. As a result, it is possible to prevent the gap on the front side of the radiation solid detector 30 in the housing 20 from being widened, so that it is possible to prevent the image quality from deteriorating.

  In addition, a metal shield 50 having a substantially U-shaped cross section and connected to GND is fitted around the flexible cable 45, thereby radiating electromagnetic noise from the flexible cable 45 to the outside and from the outside. Intrusion of electromagnetic noise into the flexible cable 45 can be prevented.

  The cable 41 and the conductive portion 45b of the flexible cable 45 are bonded so as to completely cover the conductive wire exposed portion of the cable 41 and the conductive portion 45b with an insulating adhesive 46, and the shield 50 is bonded to this insulating adhesive. The power source is configured not to be short-circuited so as to contact only the agent 46 and the insulating portion 45 a of the flexible cable 45.

  Further, the cable 41 for supplying electric power generates strong electromagnetic noise, and is therefore arranged in the space between the printed circuit boards 22 and 23 so as not to affect the driving of the TFT of the radiation solid state detector 30.

  A moving grid 8b for removing scattered rays is built in the imaging table 8 above the cassette loading portion 8a. Further, a grid driving means (not shown) for driving the moving grid 8b is installed in the imaging table 8. ing. Further, an X-ray dose detector 8c for detecting the X-ray dose irradiated to the radiation detection cassette 15 is built in the lower part of the cassette loading unit 8a. The X-ray source 2 is controlled so that X-rays are not excessively irradiated to the X-ray. However, if various members such as a printed board and a power source are interposed between the X-ray source 2 and the X-ray dose detector 8c, The detection accuracy of the X-ray dose of the dose detector 8c is lowered.

  Therefore, as shown in FIG. 4, in the radiation detection cassette 15, members other than the radiation solid detector 30 are arranged in the region 20 a located above the X-ray dose detector 8 c when mounted on the imaging table 8. Thus, the detection of the X-ray dose by the X-ray dose detector 8c is not hindered.

  A connector 21 for outputting an image signal acquired by the radiation solid detector 30 to the outside is provided at the opposite end of the chest wall 10 on two sides adjacent to the chest wall 10 side. It is configured so that the connection terminal 12 and the cable 13 do not get in the way when performing imaging of the axilla, that is, MLO imaging (Mediolateral Oblique).

  In this embodiment, the connector 21 is provided on both the side on the chest wall 10 side and two adjacent sides, and the connector 21 that can be easily connected according to the posture of the arm 5 is used for convenience. However, the connector 21 may be provided only on one of the two sides adjacent to the chest wall 10 side.

  Next, the operation of the radiation imaging apparatus for breast 1 will be described.

  First, the radiation detection cassette 15 configured as described above is loaded into the cassette loading portion 8 a of the imaging table 8. Then, the arm 5 in the photographing apparatus main body rotates in the arrow direction to a predetermined position according to the photographing purpose. Next, X-rays are emitted from the X-ray source 2 in a state where the subject is positioned between the X-ray source storage unit 3 connected by the arm 5 and the imaging table 8, and the X-rays pass through the subject, The radiation that has passed through the subject is irradiated on the radiation image detector 30 in the radiation detection cassette 15. Then, charges corresponding to the radiation dose are generated in the photoconductive layer 37 of the radiation image detector 30 as described above, and X-ray images are recorded by accumulating the charges.

  After recording the radiation image, the TFTs of the first conductive layer 36 are sequentially driven, the latent image charge corresponding to each pixel is read to obtain an image signal, and the image signal is output from the connector 21 to the outside of the cassette.

Schematic which shows an example of the radiography apparatus for breasts in which the cassette for radiation detection by this invention is used Schematic view of the radiation detection cassette Enlarged view of the connection part between the detector of the radiation detection cassette and the power source Schematic configuration diagram seen from the top surface of the radiation detection cassette

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Breast radiography apparatus 2 Radiation source 3 Radiation source storage part 5 Arm 6 Base 7 Compression board 8 Imaging stand 8b X-ray dose detector 15 Radiation detection cassette 20 Case 30 Radiation solid state detector 40 Power supply 41 Power cable 45 Flexible Cable 50 shield

Claims (3)

A plate-shaped radiation solid detector that receives irradiation of radiation carrying image information, records the image information, and outputs an image signal representing the recorded image information, and a power source that supplies power to the radiation solid detector In a cassette for radiation detection that is housed in a housing,
A radiation detection cassette, wherein the power source is disposed on a radiation non-incident surface side of the radiation solid detector. A power connection located on the radiation incident surface side of the radiation solid detector is connected to one end of a flexible cable or a metal tape,
2. The radiation detection cassette according to claim 1, wherein the other end of the flexible cable or the metal tape is disposed on the radiation non-incident surface side of the radiation solid detector.   The radiation detection cassette according to claim 2, wherein the flexible cable or the metal tape includes a shield.

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