JP2011147683A - Radiographic imaging apparatus and radiographic imaging system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiographic imaging apparatus wherein a data transfer period is shortened by reversibly compressing data while reducing the size of information on data compression processing. <P>SOLUTION: The radiographic imaging apparatus 1 is provided with: a detection part P; a reading circuit 17 for outputting an electric charge from the detection part P as read image data D; a compression processing part 49a for performing compression processing of the image data D using a static dictionary; an antenna apparatus 39 for transferring the image data; and a processed data size determination part 47 which, when the compression processing is performed, predicts and determines whether the data size of the image data of the whole of one image in transfer exceeds the data size of the whole of one image of the original image data before compression. The compression processing part 49a performs the compression processing only when the processed data size determination part 47 determines that the data size of the image data of the whole of one image after the compression processing does not exceed the data size of the whole of one image of the original image data before the compression. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a radiographic image capturing apparatus and a radiographic image capturing system, and more particularly to a radiographic image capturing apparatus that compresses and transfers image data and a radiographic image capturing system that receives the image data and restores the original image data.

  A so-called direct type radiographic imaging device that generates electric charges by a detection element in accordance with the dose of irradiated radiation such as X-rays and converts it into an electrical signal, or other radiation such as visible light with a scintillator or the like. Various so-called indirect radiographic imaging devices have been developed that convert charges to electromagnetic waves after being converted into electrical signals by generating electric charges with photoelectric conversion elements such as photodiodes in accordance with the energy of the converted and irradiated electromagnetic waves. Yes. In the present invention, the detection element in the direct type radiographic imaging apparatus and the photoelectric conversion element in the indirect type radiographic imaging apparatus are collectively referred to as a radiation detection element.

  This type of radiographic imaging apparatus is known as an FPD (Flat Panel Detector), and conventionally formed integrally with a support base (or a bucky apparatus) (see, for example, Patent Document 1). A portable radiographic imaging device in which an element or the like is housed in a housing has been developed and put into practical use (see, for example, Patent Documents 2 and 3).

  By the way, in such a radiographic imaging apparatus, a plurality of radiation detection elements are arranged in a two-dimensional shape (matrix shape) to form a detection unit. At this time, the number of radiation detection elements (that is, the number of pixels) is Usually, the number of pixels is several million to several tens of millions or more. Therefore, if the image data read from each radiation detection element is transferred to the external device without being compressed, the transfer time becomes longer. Further, in a portable radiographic imaging apparatus with a built-in battery, when the transfer time of image data becomes long, the power consumed at the time of transfer increases, leading to battery consumption.

  Therefore, as described in, for example, Patent Document 4 and Patent Document 5, the read image data is usually reversible compression (also referred to as lossless compression) or lossy compression (also referred to as lossy compression). The data is compressed by a data compression method and transferred to an external device such as a console or a server.

  Then, for example, the radiographic imaging device is used as a medical image imaging device that images a part of a body such as a patient's head, chest, and limbs as a subject and uses the acquired radiographic image as a medical image for diagnosis or the like. In this case, as a data compression method for compressing image data, in general, image data before compression and after restoration are compared with a lossy compression method in which a part of information included in the image data is lost by the compression. It is considered preferable to employ a lossless compression method in which compression is performed so that the image data completely matches.

JP-A-9-73144 JP 2006-058124 A JP-A-6-342099 JP 2000-275350 A JP 2005-287927 A

However, assuming that image data read from each radiation detection element after radiographic imaging is subjected to lossless compression using a static dictionary, for example, by a Huffman coding technique, the image data is 2 ¹⁶ (= 65536) floors, for example. when produced by the tone, that is, when the luminance value of the image data can take the values of 0 and 65535 does not have to take into Huffman code 2 ¹⁶ kinds prepared table (code for associating the image data and the Huffman code There is a problem that it is also a very large dictionary.

In addition, since the codes given to the processed image data in the Huffman encoding process must be unique, depending on the code, the amount of data is large, and if this is added to the image data, it will be more than the image data before processing. Can also become large.
In such a case, if the compression process is performed, the amount of image data increases, and there is a problem that it takes time to transfer, and this is particularly noticeable when the compression process is performed using a static dictionary.

That is, as a method for compressing image data, a compression process using a static dictionary that does not update the contents of the dictionary while the data is encoded, and a dictionary is created / updated while reading the original data without creating the dictionary in advance. There is a dynamic dictionary compression process that encodes data at the same time, but the static dictionary compression process is excellent in that it can be processed quickly without the need to create a dictionary for each image. ing.
On the other hand, in the case of using a static dictionary, however, there is a problem in that the image is not necessarily optimally encoded when compression processing is performed.
For example, if compression processing is performed on an image with a lot of noise components, the size of the image data after compression may exceed the size of the original image data. There is a possibility that time is wasted for useless compression processing.

  Therefore, the present invention has been made in view of the above circumstances, and when performing compression processing using a static dictionary, efficient data compression is achieved by reducing unnecessary transfer time and time required for compression processing. An object of the present invention is to provide a radiographic image capturing apparatus and a radiographic image capturing system capable of performing data transfer.

In order to solve the above-described problem, the radiographic imaging device of the present invention includes
A plurality of scanning lines and a plurality of signal lines arranged so as to intersect with each other; a plurality of radiation detecting elements arranged in a two-dimensional manner in each region partitioned by the plurality of scanning lines and the plurality of signal lines; A detector comprising:
A readout circuit that reads out charges from the radiation detection elements through the signal lines, converts the charges into electrical signals for each of the radiation detection elements, and outputs them as image data;
Compression means for compressing image data using a static dictionary;
Transfer means for transferring image data;
When the image data output from the radiation detection element is compressed by the compression means, the data size of the entire image data transferred by the transfer means is the original image data before compression. A post-processing data size determination means for predicting / determining whether or not the data size of the entire image is exceeded,
With
The compression means determines that the data size of the entire image data after compression processing by the post-processing data size determination means does not exceed the data size of the entire original image data before compression. Compression process only when
The transfer means transfers the image data after the compression processing when the compression processing is performed by the compression means, and the original image data when the compression processing is not performed. And

Moreover, the radiographic imaging system which is another aspect of this invention is the following.
The radiographic imaging device according to any one of claims 1 to 6,
A console for receiving image data transferred from the radiation image capturing apparatus;
With
The console includes a restoration unit that decompresses and restores the image data to the original image data when the compression processing by the compression unit is performed on the image data transferred from the radiation image capturing apparatus. It is characterized by that.

According to the radiographic image capturing apparatus and the radiographic image capturing system of the present invention, the compression processing is performed as to whether the data size of the compressed data does not exceed the data size of one whole image of the original image data before compression. If it is predicted and determined in advance and it is determined that the data size is equal to or exceeds the data size of the original image data before compression, the data is transferred as it is without performing the compression process.
As a result, when the data size is increased by performing compression processing, useless compression processing is prevented, and data larger than the data size of the original image data before compression is externally stored. Since transfer to the apparatus can be avoided, it is possible to reduce the time required for useless compression processing and data transfer, and to reduce power consumption accordingly.

It is an external appearance perspective view which shows the radiographic imaging apparatus in this embodiment. It is sectional drawing which follows the AA line in FIG. It is a top view which shows the structure of the board | substrate of a radiographic imaging apparatus. It is an enlarged view which shows the structure of the radiation detection element, TFT, etc. which were formed in the small area | region on the board | substrate of FIG. It is sectional drawing which follows the BB line in FIG. It is a side view explaining the board | substrate with which COF, a PCB board | substrate, etc. were attached. It is a block diagram showing the equivalent circuit of a radiographic imaging apparatus. It is a block diagram showing the equivalent circuit about 1 pixel which comprises a detection part. It is a figure explaining the state where the image data read from the radiation detection element at the same time by each readout IC is rearranged after being stored in the buffer memory and transmitted to the storage means. It is a graph showing. It is a block diagram showing the functional structure of the control means of a radiographic imaging apparatus. It is a graph which shows the range of the difference data by which Huffman code is matched and tabulated in this embodiment. It is a figure explaining the state in which difference data is calculated for every image data of a signal line direction. It is a figure explaining the state in which difference data is calculated for every image data of the direction of a scanning line. It is a figure explaining the structure of a difference calculation part, and the method of producing the difference data of the image data adjacent to the signal line direction connected to the same signal line. It is a figure explaining the state by which difference data is calculated from each image data read from each radiation detection element connected to the reference | standard data and the line L1 of a scanning line. (A)-(C) It is a figure explaining the method of producing the difference data of the image data adjacent to the signal line direction connected to the same signal line using one buffer register. Distribution of appearance frequency of difference data of image data output from adjacent radiation detection elements connected to (A) same signal line or (B) same scanning line when radiation image capturing apparatus is irradiated with radiation uniformly It is a graph which shows. When the radiation dose to the radiographic imaging device is increased, (A) the frequency of appearance of difference data of image data output from adjacent radiation detection elements connected to the same signal line or (B) the same scanning line It is a graph which shows distribution. It is a graph showing an example of distribution of the appearance frequency of the image data read from each radiation detection element. It is a figure which shows the structural example of the data for transfer when not performing a compression process. It is a figure which shows the structural example of the data for transfer at the time of performing a compression process. It is a graph which shows the range of the difference data considered to exceed predetermined code length in this embodiment. It is a figure which shows the whole structure of the radiographic imaging system in this embodiment. It is a flowchart which shows the compression and non-compression process in this embodiment. It is a flowchart which shows the compression and non-compression process in this embodiment.

  Embodiments of a radiographic image capturing apparatus and a radiographic image capturing system according to the present invention will be described below with reference to the drawings.

[Radiation imaging equipment]
First, the configuration of the radiographic image capturing apparatus according to the present embodiment will be described with reference to FIGS. 1 to 22. In the following description, the radiographic imaging device is a so-called indirect radiographic imaging device that includes a scintillator or the like and converts the irradiated radiation into electromagnetic waves of other wavelengths such as visible light to obtain an electrical signal. As will be described, the present invention can also be applied to a direct radiographic imaging apparatus. Although the case where the radiographic image capturing apparatus is portable will be described, the present invention is also applicable to a radiographic image capturing apparatus formed integrally with a support base or the like.

  FIG. 1 is an external perspective view of the radiographic image capturing apparatus according to the present embodiment, and FIG. 2 is a cross-sectional view taken along the line AA in FIG. As shown in FIGS. 1 and 2, the radiographic image capturing apparatus 1 according to the present embodiment is configured by housing a scintillator 3, a substrate 4, and the like inside a housing 2.

  The housing 2 is formed of a material such as a carbon plate or plastic that at least the radiation incident surface R transmits radiation. 1 and 2 show a case where the housing 2 is a so-called lunch box type formed by the frame plate 2A and the back plate 2B, but the shape of the housing 2 is not limited to this. . It is also possible to use a so-called monocoque type in which the housing 2 is integrally formed in a rectangular tube shape.

  As shown in FIG. 1, the side surface of the housing 2 is opened and closed for replacement of a power switch 36, an indicator 37 composed of LEDs and the like, and a battery 41 (not shown) (see FIG. 7 described later). A possible lid member 38 and the like are arranged. In the present embodiment, an antenna device 39 that is a transfer means for wirelessly transferring image data or the like to an external device such as a console 58 (see FIG. 23) described later is embedded in the side surface of the lid member 38. It is. It is also possible to transfer the image data or the like to an external device in a wired manner. In this case, for example, as a transfer means, a connection terminal or the like for connecting by inserting a cable or the like is used as radiation. It is provided on the side surface of the image capturing apparatus 1 or the like.

  As shown in FIG. 2, a base 31 is disposed inside the housing 2 via a thin lead plate or the like (not shown) on the lower side of the substrate 4. The disposed PCB substrate 33, the buffer member 34, and the like are attached. In the present embodiment, a glass substrate 35 for protecting the substrate 4 and the radiation incident surface R of the scintillator 3 is disposed.

  The scintillator 3 is attached to a detection unit P, which will be described later, of the substrate 4. As the scintillator 3, for example, a scintillator 3 that has a phosphor as a main component and converts it into an electromagnetic wave having a wavelength of 300 to 800 nm, that is, an electromagnetic wave centered on visible light when it receives incident radiation, is used.

  In the present embodiment, the substrate 4 is formed of a glass substrate. As shown in FIG. 3, a plurality of scanning lines 5 and a plurality of signal lines are provided on a surface 4 a of the substrate 4 facing the scintillator 3. 6 are arranged so as to cross each other. In each small region r defined by the plurality of scanning lines 5 and the plurality of signal lines 6 on the surface 4 a of the substrate 4, radiation detection elements 7 are respectively provided.

  Thus, the entire region r in which a plurality of radiation detection elements 7 arranged in a two-dimensional manner are provided in each small region r partitioned by the scanning line 5 and the signal line 6, that is, shown by a one-dot chain line in FIG. The region is a detection unit P.

  In the present embodiment, a photodiode is used as the radiation detection element 7, but other than this, for example, a phototransistor or the like can also be used. Each radiation detection element 7 is connected to the source electrode 8s of the TFT 8 serving as a switching element, as shown in the enlarged views of FIGS. The drain electrode 8 d of the TFT 8 is connected to the signal line 6.

  The TFT 8 is turned on when an on-voltage is applied to the connected scanning line 5 and applied to the gate electrode 8g by a scanning driving means 15 (see FIG. 7) described later, and the radiation detection element 7 is turned on. The electric charge generated and accumulated therein is discharged to the signal line 6. Further, the TFT 8 is turned off when the off voltage is applied to the connected scanning line 5 and the off voltage is applied to the gate electrode 8g, and the emission of the charge from the radiation detecting element 7 to the signal line 6 is stopped. The charges generated in the radiation detection element 7 are held and accumulated in the radiation detection element 7.

  Here, the structure of the radiation detection element 7 and the TFT 8 in this embodiment will be briefly described with reference to the cross-sectional view shown in FIG. FIG. 5 is a sectional view taken along line BB in FIG.

  As shown in FIG. 5, a gate electrode 8g of a TFT 8 made of Al, Cr, or the like is formed on the surface 4a of the substrate 4 so as to be integrally laminated with the scanning line 5, and the gate electrode 8g and the surface 4a. The radiation detecting element 7 is disposed above the gate electrode 8g on the gate insulating layer 81 made of silicon nitride (SiNx) or the like laminated on the semiconductor layer 82 made of hydrogenated amorphous silicon (a-Si) or the like. The source electrode 8 s connected to the first electrode 74 and the drain electrode 8 d formed integrally with the signal line 6 are laminated.

  The source electrode 8s and the drain electrode 8d are divided by a first passivation layer 83 made of silicon nitride (SiNx) or the like, and the first passivation layer 83 covers the electrodes 8s and 8d from above. In addition, ohmic contact layers 84a and 84b formed in an n-type by doping hydrogenated amorphous silicon with a group VI element are stacked between the semiconductor layer 82 and the source electrode 8s and the drain electrode 8d, respectively. The TFT 8 is formed as described above.

  In the radiation detecting element 7, an auxiliary electrode 72 is formed by laminating Al, Cr, or the like on the insulating layer 71 formed integrally with the gate insulating layer 81 on the surface 4 a of the substrate 4. A first electrode 74 made of Al, Cr, Mo or the like is laminated on the auxiliary electrode 72 with an insulating layer 73 formed integrally with the first passivation layer 83 interposed therebetween. The first electrode 74 is connected to the source electrode 8 s of the TFT 8 through the hole H formed in the first passivation layer 83.

  On the first electrode 74, an n layer 75 formed in an n-type by doping a hydrogenated amorphous silicon with a group VI element, an i layer 76 which is a conversion layer formed of hydrogenated amorphous silicon, and a hydrogenated amorphous A p layer 77 formed by doping a group III element into silicon and forming a p-type layer is formed by laminating sequentially from below.

  When radiation enters from the radiation incident surface R of the housing 2 of the radiographic imaging apparatus 1 and is converted into an electromagnetic wave such as visible light by the scintillator 3, and the converted electromagnetic wave is irradiated from above in the figure, the electromagnetic wave is detected by radiation. The electron hole pair is generated in the i layer 76 by reaching the i layer 76 of the element 7. In this way, the radiation detection element 7 converts the electromagnetic waves irradiated from the scintillator 3 into electric charges.

  On the p layer 77, a second electrode 78 made of a transparent electrode such as ITO is laminated and formed so that the irradiated electromagnetic wave reaches the i layer 76 and the like. In the present embodiment, the radiation detection element 7 is formed as described above. The order of stacking the p layer 77, the i layer 76, and the n layer 75 may be reversed. Further, in the present embodiment, a case where a so-called pin-type radiation detection element formed by sequentially stacking the p layer 77, the i layer 76, and the n layer 75 as described above is used as the radiation detection element 7. However, it is not limited to this.

  A bias line 9 for applying a bias voltage to the radiation detection element 7 is connected to the upper surface of the second electrode 78 of the radiation detection element 7 via the second electrode 78. The second electrode 78 and the bias line 9 of the radiation detection element 7, the first electrode 74 extended to the TFT 8 side, the first passivation layer 83 of the TFT 8, that is, the upper surfaces of the radiation detection element 7 and the TFT 8 are The upper side is covered with a second passivation layer 79 made of silicon nitride (SiNx) or the like.

  As shown in FIGS. 3 and 4, in this embodiment, one bias line 9 is connected to a plurality of radiation detection elements 7 arranged in rows, and each bias line 9 is connected to a signal line 6. Are arranged in parallel with each other. Further, each bias line 9 is bound to the connection 10 at a position outside the detection portion P of the substrate 4.

  In this embodiment, as shown in FIG. 3, each scanning line 5, each signal line 6, and connection 10 of the bias line 9 are input / output terminals (also referred to as pads) provided near the edge of the substrate 4. 11 is connected. As shown in FIG. 6, a COF (Chip On Film) 12 in which a chip such as an IC 12a is incorporated in each input / output terminal 11 is an anisotropic conductive adhesive film (Anisotropic Conductive Film) or anisotropic conductive paste (Anisotropic paste). It is connected via an anisotropic conductive adhesive material 13 such as Conductive Paste).

  The COF 12 is routed to the back surface 4b side of the substrate 4 and connected to the PCB substrate 33 described above on the back surface 4b side. Thus, the board | substrate 4 part of the radiographic imaging apparatus 1 is formed. In FIG. 6, illustration of the electronic component 32 and the like is omitted.

Here, the circuit configuration of the radiation image capturing apparatus 1 will be described.
FIG. 7 is a block diagram showing an equivalent circuit of the radiographic imaging apparatus 1 according to the present embodiment, and FIG. 8 is a block diagram showing an equivalent circuit for one pixel constituting the detection unit P.

  As described above, each radiation detection element 7 of the detection unit P of the substrate 4 has the bias line 9 connected to the second electrode 78, and each bias line 9 is bound to the connection 10 to the bias power supply 14. It is connected. The bias power supply 14 applies a bias voltage to the second electrode 78 of each radiation detection element 7 via the connection 10 and each bias line 9. The bias power source 14 is connected to a control unit 22 described later, and the control unit 22 controls a bias voltage applied to each radiation detection element 7 from the bias power source 14.

  In the present embodiment, the current detection means 43 for detecting the amount of current flowing through the connection 10 (bias line 9) is provided in the connection 10 of the bias line 9. As described above, when the radiation imaging apparatus 1 is irradiated with radiation, electron-hole pairs are generated in the i layer 76 (see FIG. 5) of each radiation detection element 7, and this is the bias line 9 or the connection. The current detection means 43 can detect the start and end of radiation irradiation by detecting the increase or decrease of the current flowing through the connection 10. In the present invention, the current detection means 43 is not necessarily provided.

  As shown in FIGS. 7 and 8, in this embodiment, it can be seen that the bias line 9 is connected via the second electrode 78 to the p-layer 77 side (see FIG. 5) of the radiation detection element 7. In addition, the bias power supply 14 supplies a voltage equal to or lower than a voltage applied to the second electrode 78 of the radiation detection element 7 via the bias line 9 as a bias voltage on the first electrode 74 side of the radiation detection element 7 (that is, a so-called reverse bias voltage). Is applied.

  The first electrode 74 of each radiation detection element 7 is connected to the source electrode 8s of the TFT 8 (indicated as S in FIGS. 7 and 8), and the gate electrode 8g of each TFT 8 (FIGS. 7 and 8). Are respectively connected to the lines L1 to Lx of the scanning line 5 extending from the gate driver 15b of the scanning driving means 15 to be described later. Further, the drain electrode 8 d (denoted as D in FIGS. 7 and 8) of each TFT 8 is connected to each signal line 6.

  In the present embodiment, the scanning drive unit 15 includes a power supply circuit 15a that supplies an on voltage and an off voltage to the gate driver 15b, and a voltage applied to each of the lines L1 to Lx of the scanning line 5 between the on voltage and the off voltage. A gate driver 15b that switches between the on state and the off state of each TFT 8 is provided.

  Each signal line 6 is connected to each readout circuit 17 formed in the readout IC 16. Note that the readout IC 16 is provided with one readout circuit 17 for each signal line 6.

  The readout circuit 17 includes an amplifier circuit 18, a correlated double sampling circuit 19, an analog multiplexer 21, and an A / D converter 20. 7 and 8, the correlated double sampling circuit 19 is represented as CDS. In FIG. 8, the analog multiplexer 21 is omitted.

  In the present embodiment, the amplifier circuit 18 is configured by a charge amplifier circuit, and is configured by connecting a capacitor 18b and a charge reset switch 18c in parallel to the operational amplifier 18a and the operational amplifier 18a. In addition, a power supply unit 18 d for supplying power to the amplifier circuit 18 is connected to the amplifier circuit 18.

  The signal line 6 is connected to the inverting input terminal on the input side of the operational amplifier 18a of the amplifier circuit 18, and the reference potential V0 is applied to the non-inverting input terminal on the input side of the amplifier circuit 18. Yes. The reference potential V0 is set to an appropriate value, and in this embodiment, for example, 0 [V] is applied.

  The charge reset switch 18c of the amplifier circuit 18 is connected to the control means 22 described later, and is controlled to be turned on / off by the control means 22. When the image data is read from each radiation detection element 7, when the charge reset switch 18c is turned off and the TFT 8 of the radiation detection element 7 is turned on (that is, the scanning line 5 is applied to the gate electrode 8g of the TFT 8). When an on-voltage for signal readout is applied via the signal), the electric charge released from the radiation detection element 7 flows into the capacitor 18b and is accumulated, and a voltage value corresponding to the accumulated electric charge is output from the operational amplifier 18a. Output from the side.

  In this way, the amplifier circuit 18 outputs a voltage value according to the amount of charge output from each radiation detection element 7 and converts the charge voltage. When the charge reset switch 18c is turned on, the input side and the output side of the amplifier circuit 18 are short-circuited, and the charge accumulated in the capacitor 18b is discharged to reset the amplifier circuit 18. ing. Note that the amplifier circuit 18 may be configured to output a current in accordance with the charge output from the radiation detection element 7.

  At the time of reading the image data from each radiation detection element 7, the charge is read from each radiation detection element 7, and the voltage value that is output after being subjected to charge-voltage conversion by the amplifier circuit 18 is sampled by the correlated double sampling circuit 19. It is processed and output downstream as image data. The image data of each radiation detection element 7 output from the correlated double sampling circuit 19 is transmitted to the analog multiplexer 21 (see FIG. 7), and is sequentially transmitted from the analog multiplexer 21 to the A / D converter 20. Then, the A / D converter 20 sequentially converts the image data into digital values, which are output to the storage means 40 and sequentially stored.

  In the present embodiment, when the image data is read from each radiation detection element 7, the lines L1 to Lx of the scanning line 5 to which the ON voltage is applied are sequentially switched, and the above-described respective A process for reading image data from the radiation detection element 7 is performed.

  In the present embodiment, for example, 128 signal lines 6 are processed by one readout IC 16. That is, one read IC 16 corresponds to each signal line 6 with 128 read circuits 17 (that is, amplifier circuit 18 and correlated double sampling circuit 19 etc.), one analog multiplexer 21, and one A / D. It is formed by a converter 20 or the like.

  If the number of signal lines 6 is 2048, for example, 2048/128 = 16 readout ICs 16 are arranged in parallel to form a readout unit. Hereinafter, the number of readout circuits 17 formed in one readout IC 16, that is, the number of signal lines 6 connected to one readout IC 16 is 128, and the total number of signal lines 6 is 2048. However, the present invention is not limited to this case.

  As shown in FIG. 9, when an on-voltage is applied to the line L <b> 1 of the scanning line 5, for example, when the image data is read out, each radiation detection element (1, 1) connected to the line L <b> 1 of the scanning line 5. ) To (1,2048) are simultaneously read out and sent to the reading ICs 16 in parallel.

  Then, each read circuit 17 (not shown in FIG. 9) of each read IC 16 performs charge-voltage conversion and the like, and each of the 128 image data transmitted in parallel is converted into each analog multiplexer 21 (in each read IC 16). The image data is serially transferred to the A / D converter 20 (not shown) sequentially and digitized image data is temporarily stored in the buffer memory 45 from the A / D converter 20.

  That is, when image data corresponding to each radiation detection element (x, y) is represented as D (x, y), first, from each readout IC 16, D (1, 1), D (1, 129), D ( 1, 257),..., D (1, 1921) are transmitted and stored in the buffer memory 45, and then D (1, 2), D (1, 130), D (1, 258). ,..., D (1, 1922) are transmitted and stored in the buffer memory 45.

  Then, the image data D (1, 1) to D (1, 2048) from the radiation detection elements (1, 1) to (1, 2048) connected to the line L1 of the scanning line 5 are stored in the buffer memory 45. Are stored, the image data D are rearranged in the order of image data D (1,1), D (1,2), D (1,3), D (1,4),. The image data D (difference data ΔD based on the image data D) is sequentially transmitted and stored in the data memory 46 in this order.

  In addition, the reading process of each image data D (1,1) to D (1,2048) from each radiation detection element (1,1) to (1,2048) connected to the line L1 of the scanning line 5 is completed. Then, the line of the scanning line 5 to which the ON voltage is applied is subsequently switched to L2. Similarly, the image data D (2,1) to D (2,2048) are transmitted to the buffer memory 45 for each readout IC 16 and rearranged, and then sequentially transmitted to the data memory 46 and stored. The

  The reading process and the storing process in the data memory 46 are sequentially repeated for each of the lines L1 to Lx of the scanning line 5 so that the reading process of the image data D from all the radiation detection elements 7 is performed. It has become.

  The rearrangement process of the image data D is normally performed by converting the image data D into D (1,1), D (1,1) regardless of the external device (not shown) that transfers the image data D. 2), D (1,3), D (1,4),... Can be handled by transferring them in this order. Therefore, the image data D is generally used at the stage of storing the image data D in the data memory 46. This is a process for rearranging and storing D in the above order.

  Accordingly, when the order of transferring the image data D from the radiation image capturing apparatus 1 to the external apparatus can be determined in advance, the image data D can be rearranged according to the determined order. .

  In addition, each image data D is preliminarily output from the radiation imaging apparatus 1 to the external device, for example, in the order of output from each readout IC 16, D (1, 1), D (1, 129),..., D (1, 1921), If it is determined that the data is transferred in the order of D (1,2), D (1,130),..., D (1,1922),. It is also possible to directly transmit and store the data directly in the data memory 46 without going through 45.

  Further, when the image data D is rearranged as described above, the image data D is rearranged when the image data D is read from the data memory 46, not when the image data D is stored in the data memory 46. It is also possible to configure so that

  In the present embodiment, the image data D read from each radiation detection element 7 as described above is temporarily stored in the data memory 46 and then transferred from the radiation image capturing apparatus 1 to an external device (not shown). A case where compression processing is performed on D or the like will be described. However, each image data D read from each radiation detection element 7 is not stored in the data memory 46, or is separately stored in parallel with the storage in the data memory 46. It is also possible to configure such that each image data D or the like is subjected to compression processing and transferred directly as processing.

Here, the structure of the control means 22 in this embodiment is demonstrated, referring FIG.7 and FIG.10. In FIG. 10, the outline of the processing flow of the image data read from the reading circuit 17 is indicated by a broken line.
As shown in FIG. 10, in this embodiment, the control means 22 includes a main body control unit 23, an FPGA (Field Programmable Gate Array) 24, a data memory 46, and the like.
The control means 22 may be constituted by a dedicated control circuit.

In the present embodiment, the control means 22 is connected to a storage means 40 constituted by a DRAM (Dynamic RAM) or the like and the antenna device 39 described above.
Further, as shown in FIG. 7, a battery 41 for supplying power to each member such as the detection unit P, the scanning drive unit 15, the readout circuit 17, the storage unit 40, and the bias power supply 14 is connected to the control unit 22. Has been. The battery 41 is provided with a connection terminal 42 for charging the battery 41 by supplying power to the battery 41 from a charging device (not shown) such as a cradle.

  As described above, the control unit 22 (main body control unit 23) controls the bias power supply 14 to set a bias voltage to be applied to each radiation detection element 7 from the bias power supply 14, or to the amplification circuit 18 of the readout circuit 17. Various processes such as on / off control of the charge reset switch 18c and transmission of a pulse signal to the correlated double sampling circuit 19 to control on / off of the sample hold function are executed. ing.

  In addition, the control means 22 (main body control unit 23) applies to the scanning drive means 15 at the time of reset processing of each radiation detection element 7 or at the time of reading the image data D from each radiation detection element 7 after radiographic imaging. A pulse signal for switching the voltage applied to the gate electrode 8g of each TFT 8 between the on-voltage and the off-voltage is transmitted from the scanning drive means 15 via each scanning line 5.

The main body control unit 23 is a computer configured by a CPU (Central Processing Unit) 23a, a ROM (Read Only Memory) 23b, a RAM (Random Access Memory) 23c, and the like, and performs operations of each functional unit of the radiographic image capturing apparatus 1 and the like. It comes to control.
In the ROM 23b, for example, a program for performing data compression processing, information relating to data compression processing, that is, a table of Huffman codes Hc used for Huffman coding in this embodiment, threshold values for determining whether or not to perform compression processing are stored. (Details will be described later) are stored.
Various programs, information, and the like are not limited to being stored in the ROM 23b of the main body control unit 23, and a separate program memory or the like may be provided and stored therein.

Here, a table of the Huffman code Hc will be described.
The Huffman code Hc table is a static dictionary used for image data compression processing in this embodiment. The static dictionary is not limited to the Huffman code Hc table, and a static dictionary corresponding to this is prepared when another method is used as the compression processing method.
In this embodiment, a Huffman code Hc table is created in advance and stored in a memory such as the ROM 23b.

Specifically, first, image data D is read from each radiation detection element 7 by changing various imaging conditions such as an imaging region such as a chest and abdomen of a patient's body as a subject and a radiation dose, and the same signal line 6 is read out. The difference between the image data D of the adjacent radiation detection elements 7 connected to is calculated as difference data ΔD, and the appearance frequency F of each difference data ΔD is plotted as shown in FIG. Then, for example, a table is created in advance by associating the difference data ΔD with the Huffman code Hc for the difference data ΔD in the range of X to Y in the figure that appears at the appearance frequency F equal to or higher than the threshold.
In the present embodiment, a case where one table of Huffman codes Hc is provided will be described. Since the table of the Huffman code Hc has a relatively large amount of data, when one table is used as described above, the memory capacity necessary for storing the table can be reduced accordingly. It is. Note that a plurality of types of tables may be prepared according to the imaging region and the like, and an optimum table may be selected as appropriate to perform compression processing.

Note that in what range the table is created (that is, how many threshold values are set) may be set in advance by default, or may be arbitrarily set by the user.
If a table is created for a wide range of difference data ΔD, the amount of data that can be encoded by compression processing increases accordingly. However, if a table is created by importing data with a low appearance frequency F, the code length of the Huffman code Hc is increased. Even if the compression process is performed and the difference data ΔD is replaced with the Huffman code Hc, the compression effect is not so much improved, or conversely, the data amount may be larger than the original image data. For this reason, it is preferable that the setting of the threshold value is determined in consideration of the compression efficiency. Then, as will be described later, a special code process for attaching a special code indicating that the original image data is not subjected to the compression process is not performed on the portion below the threshold value and the Huffman code Hc is not assigned. Respond by doing.

  The FPGA 24 constituting the control means 22 is provided with a buffer memory 45, a post-processing data size determination unit 47, a compression ON / OFF switch 48, a transfer data generation unit 49, a register unit 49d, and the like.

  In the present embodiment, the buffer memory 45 temporarily stores the original image data (that is, the raw signal value and the pixel value) read from the reading circuit 17, and calculates the difference of the post-processing data size determination unit 47. The original image data (ie, raw signal values and pixel values) is sent to the data memory 46 as it is, and the original image data is sequentially stored in the data memory 46.

The transfer data generation unit 49 is a functional unit that generates transfer data to be transferred to an external device based on the difference data ΔD.
The transfer data generation unit 49 adds compression section 49a as compression means in the present invention that performs compression processing on the difference data ΔD, and adds information on the delimiter position of the data to the compressed data for each line. An information adding unit 49b and a data generation unit 49c that generates transfer data for each line are provided.

The compression processing unit 49a is a compression unit that performs compression processing of image data using a static dictionary.
In the present embodiment, the compression processing unit 49a performs a difference calculation unit 491 that calculates the difference data ΔD for the image data D, and a compression process by Huffman coding described later on the difference data ΔD generated by the difference calculation unit 491. And an encoding processing unit 492 that performs the processing.

  The difference calculation unit 491 includes at least two buffer registers 491a and 491b (see FIG. 14), reads the original image data D stored in the data memory 46, and outputs the difference data ΔD for the image data D. It is a calculation means for calculating.

  In the present embodiment, a case where the difference calculation unit 491 is provided in the FPGA 24 will be described as an example. However, an existing register in the main body control unit 23 that is a computer may be used as the difference calculation unit 491. Is possible. Furthermore, in this embodiment, the case where the difference calculation unit 491 is provided with two buffer registers 491a and 491b is illustrated, but the number of buffer registers provided in the difference calculation unit 491 is not particularly limited. For example, one buffer register may be provided, or three or more buffer registers may be provided.

Here, a method for calculating the difference value for the image data D by the difference calculation unit 491 and generating the difference data ΔD will be described.
In the present embodiment, as described below, the difference data ΔD generated by the difference calculation unit 491 is output to the encoding processing unit 492, and the encoding processing unit 492 performs compression processing on the difference data ΔD. After that, a case will be described in which the difference data ΔD sent to the main body control unit 23 and stored in the storage means 40 of the radiographic image capturing device 7 is stored (see the broken line shown in FIG. 10), but the compression processing has been performed. The difference data ΔD can also be configured to be transferred from the antenna device 39 to the external device wirelessly without being stored in the storage unit 40.

  Note that the order in which the image data D is processed when creating the difference data ΔD is not particularly limited. However, as shown in FIG. When each line Ln is stored in the data memory 46 or the like in the order of D (n, 1), D (n, 2), D (n, 3), D (n, 4),. Each image data can be easily read by configuring the storage and reading to 46 and the like in the same order.

  Therefore, in the present embodiment, as shown in FIG. 12, the difference between the image data D output from the adjacent radiation detection elements 7 connected to the same signal line 6 while reading each image data D in the above order. Is calculated as difference data ΔD. That is, the difference between the image data D from each radiation detection element 7 adjacent to the extending direction of the signal line (hereinafter referred to as the signal line direction) represented by the vertical arrow in the figure is calculated as difference data ΔD. It is supposed to be.

  For example, when the difference between the image data D output from the adjacent radiation detection elements 7 connected to the same scanning line 5 is calculated as the difference data ΔD, as shown in FIG. Are calculated in the above order, the difference between the image data D from each radiation detection element 7 adjacent in the direction of the scanning line 5 (the horizontal arrow direction in the figure) is calculated, and the difference data ΔD is calculated. be able to.

Specifically, in the present embodiment, the difference calculation unit 491 is provided with at least two buffer registers 491a and 491b as shown in FIG.
When the difference value is calculated and the difference data ΔD is generated, the difference calculation unit 491 scans the buffer memory 45 read from each radiation detection element 7 connected to the line Ln of the scanning line 5. The image data D (n, 1), D (n, 2), D (n, 3),... Arranged in the line direction are read out and temporarily stored in the buffer register 491a. Further, the image data D (n + 1, 1) and D arranged in the scanning line direction read from the radiation detecting elements 7 connected to the line Ln + 1 adjacent to the line Ln of the scanning line 5 from the buffer memory 45. (N + 1, 2) and D (n + 1, 3) are read out and temporarily stored in the buffer register 491b.

  Then, by calculating the difference ΔD (ie, ΔD (n + 1,1), ΔD (n + 1,2), ΔD (n + 1,3),...) Between the image data D at the same address in the buffer registers 491a and 491b, The difference data ΔD between the image data D of the radiation detecting elements 7 adjacent to each other in the signal line direction connected to the same signal line 6 is calculated.

  At that time, if the image data D arranged in the scanning line direction for two adjacent lines is read from the data memory 46 every time in order to calculate the difference data ΔD, the reading control becomes troublesome.

  Therefore, in the present embodiment, the difference calculation unit 491 performs the difference between the image data D arranged in the scanning line direction read from the radiation detection elements 7 connected to the lines Ln and Ln + 1 of the adjacent scanning line 5. When the data ΔD is calculated, the image data D (n + 1, 1), D (n + 1, 2), D (n + 1, 3),... Are transferred from the buffer register 491b to the buffer register 491a, and the empty buffer register 491b is transferred. Next, the image data D (n + 2, 1), D (n + 2, 2), D (n + 2, 3),... Arranged in the scanning line direction of the line Ln + 2 of the adjacent scanning line 5 are accumulated.

  When the difference data ΔD (n + 2, 1), ΔD (n + 2, 2),... Is calculated, the image data D (n + 2, 1), D (n + 2, 2),... Are transferred from the buffer register 491b to the buffer register 491a. The image data D (n + 3, 1), D (n + 3, 2),... Are accumulated in the buffer register 491b. In this way, the process of calculating the difference ΔD between the image data D at the same address in the buffer registers 491a and 491b while transferring each image data D from the buffer register 491b to the buffer register 491a is repeated to sequentially calculate the difference data ΔD. It has come to do.

  When configured in this way, the image data D (1,1), D (1,2), D arranged in the scanning line direction read from the radiation detecting elements 7 connected to the line L1 of the scanning line 5 .. Are required as data for calculating the difference data ΔD (1,1), ΔD (1,2), ΔD (1,3),. Therefore, in this embodiment, preset reference data Dc (1), Dc (2), Dc (3),... Are stored in advance in a memory such as a ROM.

  Then, when calculating the difference data ΔD (1,1), ΔD (1,2), ΔD (1,3),..., The difference calculation unit 491 reads from the memory as shown in FIG. The reference data Dc (1), Dc (2), Dc (3),... Are accumulated in the buffer register 491a and read from each radiation detection element 7 connected to the line L1 of the scanning line 5 read from the buffer memory 45. The image data D (1,1), D (1,2),... Arranged in the scanning line direction is accumulated in the buffer register 491b, and the difference ΔD is obtained as the difference data ΔD (1,1), ΔD ( 1, 2),...

  At this time, the respective values of the reference data Dc (1), Dc (2),... May be set to the same value, or may be set to different values from each other, and are set appropriately in advance. .

  Even when only one buffer register 491a is provided in the difference calculation unit 491, the difference data ΔD is calculated by calculating the difference between the image data D adjacent in the signal line direction similar to the above. It is possible.

  That is, as shown in FIG. 16A, scanning is performed among the image data D arranged in the scanning line direction read from the radiation detecting elements 7 connected to the lines Ln and Ln + 1 of the adjacent scanning line 5. When the image data D (n, 1), D (n, 2), D (n, 3),... Aligned in the scanning line direction of the line Ln of the line 5 are accumulated in the buffer register 491a, the control means 22 Are sequentially read from the buffer memory 45 from the image data D (n + 1,1), D (n + 1,2), D (n + 1,3),... Arranged in the scanning line direction of the line Ln + 1 of the adjacent scanning line 5. , Each corresponding image data D (n, 1), D (n, 2), D (n, 3),... Is stored in the buffer register 491a while being sequentially replaced. At this time, as shown in FIGS. 16B and 16C, the difference data ΔD between the corresponding image data D is calculated and then replaced.

  Further, the image data D (n + 1, 1), D (n + 1, 2), D (n + 1, 3),... Stored in the buffer register 491a while the difference data ΔD is calculated and replaced in this way are now represented. Are replaced while the difference data ΔD is sequentially calculated for each of the image data D (n + 2, 1), D (n + 2, 2), D (n + 2, 3),... Sequentially read from the buffer memory 45. .

  With this configuration, even when there is only one buffer register 491a, it is output from the adjacent radiation detection elements 7 connected to the same signal line 6 in the same manner as shown in FIGS. The difference data ΔD between the image data D can be calculated, and the calculation processing of each difference data ΔD can be easily performed continuously.

The encoding processing unit 492 is a functional unit that performs compression processing on the difference data ΔD calculated by the difference calculation unit 491.
As described above, when the radiographic image capturing apparatus 1 is used as a medical image capturing apparatus for capturing a part of a patient's body as a subject and using the acquired radiographic image as a medical image for diagnosis or the like, compression is performed. As a method, it is preferable to employ a lossless compression method in which compression is performed so that the difference data ΔD before compression and the difference data ΔD after restoration completely match.

  In the present embodiment, a Huffman coding method is employed as a lossless compression method. In the following, a case where the differential data ΔD is compressed by the Huffman coding method will be described. However, the compression method is not necessarily required by the Huffman coding, and the loss data of the differential data ΔD can be obtained using another lossless compression method. It is also possible to perform a compression process.

  As described above, a table of the Huffman code Hc as a static dictionary is stored in the memory such as the ROM 23b, and the encoding processing unit 492 refers to the table of the Huffman code Hc and adds the Huffman code to the difference data ΔD. A compression process is performed by assigning and encoding the code Hc. In data compression by Huffman coding, as is well known, data having a higher appearance frequency F (see FIG. 11 and the like) is assigned a shorter Huffman code Hc.

Here, the Huffman coding (Huffman coding) process will be described in detail with reference to FIGS.
When the luminance gradation of the image data D read from each radiation detection element 7 is, for example, 2 ¹⁶ (= 65536) gradations, for example, in the normal Huffman coding method, 2 ¹⁶ for each luminance gradation. Various types of Huffman codes Hc must be prepared, and the table for associating the image data D (difference data ΔD based thereon) with the Huffman codes Hc becomes very large.

  Therefore, as described above, in the radiographic imaging device 1 according to the present embodiment, not all the difference data ΔD is subjected to Huffman coding, but the image data D output from the adjacent radiation detection elements 7 is exchanged. Only a part of the difference data ΔD calculated as the difference is compressed.

  As described above, the ROM 23b of the main body control unit 23 stores a table associating a part of the difference data ΔD, which is information related to data compression processing for performing compression processing, with the Huffman code Hc.

  Then, when the difference data ΔD does not belong to the part of the difference data ΔD, the encoding processing unit 492 does not perform compression processing on the data, and the difference data ΔD becomes the part of the difference data ΔD. The compression process is performed with reference to the table only when belonging to the group. Then, the encoding processing unit 492 controls the main body by combining the compressed difference data ΔD when compression is performed, and the original image data (that is, the raw signal value) of the difference data ΔD when compression is not performed. The data is sent to the unit 23 and transferred from the main body control unit 23 to the external device.

  Of the difference data ΔD, which range is compressed and which range is uncompressed, that is, which difference data ΔD is associated with the Huffman code Hc and tabulated, and which difference data ΔD Is selected based on the distribution of the appearance frequency F (see FIG. 11 and the like) of the difference data ΔD calculated from the image data D read from each radiation detection element 7 of the radiographic imaging device 1. It is determined.

  That is, for example, in the distribution of the appearance frequency F of the difference data ΔD, the Huffman code Hc is applied to the difference data ΔD only for the difference data ΔD having a high appearance frequency F, that is, for the difference data ΔD that is higher than the threshold value for which the appearance frequency F is set. Create a table in association. No table is created for the difference data ΔD other than the difference data ΔD.

  Specifically, when the compression or non-compression target is the difference data ΔD, the distribution of the appearance frequency F of the difference data ΔD that is the difference between the image data D read from the adjacent radiation detection elements 7 is, for example, FIG. The distribution is as shown in A) and (B). In this case, for example, a table is created only for the difference data ΔD that appears at the appearance frequency F equal to or higher than the threshold.

  FIG. 17A shows the difference data ΔD of the image data D output from the adjacent radiation detection elements 7 connected to the same signal line 6 when the radiation image capturing apparatus 1 is uniformly irradiated with radiation. FIG. 17B is a graph showing the distribution of the appearance frequency F, and FIG. 17B is output from the adjacent radiation detection elements 7 connected to the same scanning line 5 when the radiation image capturing apparatus 1 is uniformly irradiated with radiation. 6 is a graph showing a distribution of appearance frequency F of difference data ΔD of image data D. Even when the radiation image capturing apparatus 1 is irradiated with radiation through the subject, the distribution of the appearance frequency F of each difference data ΔD is substantially symmetric around ΔD = 0 as in FIGS. 17A and 17B. I know that

  When the object to be compressed or uncompressed is the difference data ΔD, the distribution of the appearance frequency F of the difference data ΔD is shown in FIG. 18A when the radiation dose irradiated to the radiographic imaging apparatus 1 is increased. As shown in FIGS. 17A and 17B, the width of the distribution is slightly widened. Although not shown, the distribution width is widened or narrowed even when the photographing conditions including the photographing part of the patient's body as the subject are different.

  Therefore, even when the target of compression or non-compression is the difference data ΔD, a plurality of tables of Huffman codes Hc, which are information related to data compression processing, are stored in advance in the memory of the control means 22 for each shooting condition, and control is performed. When the data compression processing is performed on the difference data ΔD by the means 22, a table corresponding to the set photographing condition is selected, and the data compression processing is performed on the difference data ΔD with reference to the selected table. Is possible.

  However, according to the study by the inventors of the present application, as shown in FIGS. 17A and 17B and FIGS. 18A and 18B, the same signal line 6 and the same scanning line 5 are connected. It is known that when the difference data ΔD that is the difference between the image data D output from the adjacent radiation detection elements 7 is calculated, the difference data ΔD is distributed in a relatively narrow range.

  Further, in the study by the inventors of the present application, even if the imaging condition including the imaging region is variously changed and the width of the distribution of the appearance frequency F of the difference data ΔD is widened, for example, the difference data that appears at the appearance frequency F equal to or higher than the threshold value. It has been found that the range of ΔD falls within a part of the entire range of values that can be taken by the difference data ΔD (−65535 to 65535 in this embodiment).

  Therefore, one of the distributions of the appearance frequency F of the difference data ΔD that is created by setting in advance the range of the difference data ΔD that associates the Huffman code Hc, that is, the range of the difference data ΔD that creates a table (information on data compression processing). It is possible to use only a table, and this embodiment will be described in this embodiment.

  As shown in FIGS. 17A and 18A, the appearance frequency F of the difference data ΔD between the image data D output from the adjacent radiation detection elements 7 connected to the same signal line 6 is , ΔD = 0 becomes a distribution with a normal distribution. This is considered to be due to manufacturing variation of each radiation detection element 7 that occurs when each radiation detection element 7 is formed by stacking each layer as shown in FIG.

  On the other hand, as shown in FIG. 17B and FIG. 18B, the appearance frequency F of the difference data ΔD between the image data D output from the adjacent radiation detection elements 7 connected to the same scanning line 5. The distribution of is not a normal distribution but a distribution that can also be called a trapezoid.

  According to the study by the present inventors, the main cause of the distribution of the appearance frequency F of the difference data ΔD as shown in FIGS. 17B and 18B is shown in FIG. As described above, in the above case, the image data D is read from the radiation detection elements 7 by the different readout circuits 17, but the output characteristics of the readout circuits 17 are different for each readout circuit 17, and the output of each readout circuit 17 is different. This is thought to be due to variations in characteristics.

  Then, the distribution of the output characteristics of each readout circuit 17 and the distribution of the normal distribution of the difference data ΔD itself are superimposed, so that the distribution of the appearance frequency F of the difference data ΔD has a substantially trapezoidal shape, and FIG. If the width of the distribution is wider than the difference data ΔD between the image data D output from the adjacent radiation detection elements 7 connected to the same signal line 6 shown in FIG. Conceivable.

The distribution of the appearance frequency F of the image data D read from each radiation detection element 7 is, for example, a distribution as shown in FIG. 19, and the distribution width of the appearance frequency F is wider than the difference data ΔD. In the case of performing compression processing, it is known that the compression efficiency is improved when the distribution width of the appearance frequency F is narrow.
Therefore, in the present embodiment, the difference data ΔD in which the distribution width of the appearance frequency F is narrower than that in the case of the image data D is used, and further connected to the same signal line 6 in which the distribution width becomes narrower as described above. The description will be made on the assumption that the difference data ΔD between the image data D output from the adjacent radiation detection elements 7 is used. However, when the image data D is used or when the difference data ΔD between the image data D output from the adjacent radiation detection elements 7 connected to the same scanning line 5 is used, the distribution width of the appearance frequency F is different. The rest is the same as that described in the present embodiment, and substantially the same description is valid.

In this embodiment, only one Huffman code Hc table is prepared in the memory of the ROM 23b, and the compression processing unit 49a refers to this table and performs the compression process regardless of the type of shooting. As will be described, a plurality of tables may be provided for each imaging condition including the imaging region of the patient's body, which is the subject, as the Huffman code Hc table. In this case, for example, when information such as imaging conditions is input to the radiographic imaging apparatus 1 by an operator such as a radiographer, the compression processing unit 49a is input from the table stored in the memory. A table to be used is selected based on the shooting conditions, and the difference data ΔD is compressed with reference to the selected table.
It is also possible to transmit the information of the table to be used from the external device to the radiographic image capturing device 1, and the compression processing unit 49a may select the table accordingly. Further, the Huffman code Hc table suitable for the radiographic imaging conditions is transmitted from the external device to the radiographic imaging device 1 for storage or rewriting every time radiographic imaging is performed, and the compression processing unit 49a is transmitted. It is also possible to perform a compression process on the difference data ΔD with reference to the table of the Huffman code Hc.

  On the other hand, since the Huffman code Hc is not prepared for the appearance frequency F below the predetermined threshold as described above, the compression processing unit 49a calculates the difference in which the calculated difference data ΔD is associated with the Huffman code Hc. If it is not within the range of the data ΔD, that is, within the target range not less than the lower limit value X and not more than the upper limit value Y (see FIG. 11), the compression process is not performed (that is, uncompressed). Special code processing for adding a special code to image data (that is, raw signal value, pixel value) is performed.

  Even when the compression process is not performed, a special code is added to the uncompressed difference data ΔD (that is, uncompressed difference data ΔD, so-called raw difference data ΔD), and this is added to the main body control unit 23 or the like. You may make it forward to.

  This special code is a code indicating that 16-bit data below the special code is raw image data D that has not been subjected to compression processing, and the 16-bit data is erroneously interpreted as Huffman code Hc. This is a code to prevent this. The special code has a longer code length than the normal Huffman code Hc, and in this embodiment, the special code is a code having a data amount of 24 bits. For this reason, the pixel subjected to the special code processing is 40-bit data in which a 24-bit special code is added to the 16-bit original image data D which is the main body.

  The compression processing unit 49a performs uncompressed image data D to which each Huffman code Hc assigned to each differential data ΔD is added when compression processing is performed, and special code is added when special code processing is performed (that is, The 40-bit data) is sequentially sent to the information adding unit 49b.

  The information adding unit 49b secures an area to be a header portion at the head of the data for each line and also sends data sent from the compression processing unit 49a (that is, uncompressed data to which a Huffman code Hc or a special code is added). The original image data D) is sequentially arranged and functions as delimiter information adding means for adding information on the delimiter position of the data to the end of the data for one line.

  In the present embodiment, the information adding unit 49b adds a delimiter code to the end of the data for one line as delimiter information. The delimiter information added to the data by the information adding unit 49b is not limited as long as the delimiter position of the data for one line can be determined, and the type, mode, and the like are not limited.

The information added by the information adding unit 49b is not limited to the delimiter information.
For example, in the present embodiment, as will be described later, the header data added to the head header portion of the data is described as being added by the CPU 23a of the main body control unit 23, but the header data is added in the information addition unit 49b. May be added. The header data includes, for example, data size information of data for one line, but is not limited thereto.
Furthermore, in this embodiment, as will be described later, when compression processing is not performed, the CPU 23a of the main body control unit 23 sets short information (a code of about 1 bit) indicating no compression at the head of data for one line. Although the case of adding will be described as an example, the information adding unit 49b may add the non-compressed code.

Data to which information such as a delimiter code is added by the information adding unit 49b is sent to the data generating unit 49c, and is formatted as transfer data for each line and then sent to the main body control unit 23. .
The data size information of each transfer data for one line is also sent to the register unit 49d and held in the register unit 49d.

In the present embodiment, the FPGA 24 is provided with a compression ON / OFF switch 48 that switches whether or not to perform compression processing on each difference data ΔD.
When the compression ON / OFF switch 48 is turned on and compression processing is performed on the data of the entire image, the compression processing unit 49a performs the compression processing of the difference data ΔD, and the information addition unit 49b delimits the data. A delimiter code is added as position information. Thereafter, data for transfer is generated by the data generation unit 49 c and is sent to the main body control unit 23.
On the other hand, when the compression ON / OFF switch 48 is turned OFF and compression processing is not performed on the entire data of the one image, the original image data stored in the data memory 46 is sent from the data generation unit 49c. D (that is, raw signal value, raw pixel value) is sent as it is to the main body control unit 23 as transfer data.

  When the Huffman code Hc to which the delimiter code is added is sent from the data generation unit 49c, the CPU 23a of the main body control unit 23 refers to the register unit 49d of the FPGA 24 and acquires the data size of the data for one line. A process of writing (adding) this to the header portion of the data is performed. If all the data for one line is 16 bits, it is determined that the data is not compressed, and only short information (about 1 bit) indicating no compression is added to the head of the data for one line. It comes to add.

FIG. 20 is a configuration example of transfer data when compression processing is not performed, and FIG. 21 is a configuration example of transfer data when compression processing is performed.
As described above, when compression processing is not performed (see FIG. 20), a code indicating no compression is added to the head (header portion) of one line of data consisting of 16-bit image data per pixel. .
On the other hand, when compression processing is performed, as shown in FIG. 21, header data is added to the beginning (header portion) of data for one line, and a delimiter code is added to the end of the data. In addition, as a result of encoding with the Huffman code Hc, the original image data (difference data ΔD before the compression process) has a data of 16 bits per pixel converted to a Huffman code Hc of 6 bits, 7 bits, etc. (FIG. 21). It is simply replaced with “Hc”. In addition, a special code indicating that is added to pixel data that could not be Huffman coded.
21 exemplifies a case where the data size of the original image data D per pixel (that is, the raw signal value and the raw pixel value) is 16 bits and the special code is 24 bits as described above. However, the size of the original image data D and the size of the special code are not limited to those exemplified here.
The data subjected to special code processing in this way has a data size that exceeds the original image data D, such as 40 bits, but the pixels that are subject to special code processing appear less frequently, and other Huffman-coded pixels By canceling out, it is general that the data size of the entire data for one line, and hence the entire image, is smaller than the original image data D (see FIGS. 20 and 21).

  Note that when compression processing is performed, the compression ratio varies depending on the type of image, and therefore, it is not possible to specify the data separation position for one line without adding header data and a delimiter code. On the other hand, when the original image data D is transferred as it is without performing compression processing, the length of the data is fixed to the number of pixels constituting 16 bits × 1 line per pixel. The data delimiter position can be correctly recognized in the transfer destination apparatus (for example, the console 58) without adding data indicating the data delimiter position as in the embodiment. Therefore, in this case, by not adding the header data and the delimiter code, the data for one line can be reduced correspondingly, and the data transfer time can be shortened. Even when compression processing is not performed, the header data and the delimiter code may be added uniformly.

Then, the CPU 23a temporarily stores and saves these data in the storage means 40 for each line in a state where the data can be identified on which line, and appropriately stores the external device via the antenna device 39. (Sequentially transferred to the console 58, for example).
In this embodiment, since data for each line is stored in the storage unit 40 in this way, even if an abnormality occurs in the data transfer process, or a problem occurs in the data at the transfer destination, one line is stored. It becomes possible to respond to a retransmission request every time.

  Further, in the FPGA 24, when data compression processing is performed by the compression processing unit 49a which is a compression unit, the data size of the entire image data transferred through the antenna device 39 is the original size before compression. A post-processing data size determination unit 47 is provided as post-processing data size determination means for predicting / determining whether the data size of the entire image data exceeds the data size.

The post-processing data size determination unit 47 includes a difference calculation unit 44 and a counter 47a. When the compression processing is performed, it is determined that the code length of the assigned Huffman code Hc exceeds a predetermined length. The counter 47a is sequentially counted up. If the counter 47a exceeds a predetermined threshold value, the post-processing data size determination unit 47 predicts that the data after compression processing is the same as or exceeds the size of the original image data. judge.
The configuration and operation of the difference calculation unit 44 are the same as those of the difference calculation unit 491 of the compression processing unit 49a, and thus description thereof is omitted.

  In this embodiment, the difference calculation unit 491 of the compression processing unit 49a and the difference calculation unit 44 of the post-processing data size determination unit 47 are configured to include two difference calculation units. Only one of the units 44 is provided, and the difference data ΔD calculated and generated there is used as the difference data ΔD for performing post-processing data size determination processing and the difference data ΔD for performing compression processing. You may comprise.

When the post-processing data size determination unit 47 predicts / determines that the data after the compression processing is smaller than the size of the original image data, the above-described compression ON / OFF switch 48 is switched to ON, The entire image data is subjected to compression processing by the compression processing unit 49a, and processing is performed to transfer the compressed image data (that is, difference data ΔD after compression processing).
On the other hand, when the post-processing data size determination unit 47 predicts / determines that the data after the compression processing is the same as or exceeds the size of the original image data, the compression ON / OFF switch 48 is switched OFF, The entire image data is processed so that the original image data D (that is, raw signal values and raw pixel values) stored in the data memory 46 is transferred without being compressed. The

  When the compression process is performed as described above, the data size of the compressed data is generally smaller than the size of the original image data before the compression. However, if there is a large amount of image data to be subjected to special code processing or Huffman code Hc having a long code length, the compressed data size may be larger than the uncompressed data size. . Therefore, whether or not the data size of the compressed data exceeds the data size of one whole image of the original image data before compression is predicted and determined before performing the compression process, and the original image data before compression is determined. If the data size is predicted to be the same as or larger than the data size, the original image data D (that is, the raw signal value, the raw pixel value) is transferred without performing the compression process. By preventing redundancy in data size due to compression processing, it is possible to reduce the burden of data transfer, and it is possible to eliminate time loss due to unnecessary compression processing.

FIG. 22 is a graph showing a distribution example of difference data ΔD for one entire image.
As described above, in the Huffman code Hc, a code having a short code length is assigned to an element having a high appearance frequency F, and a code having a long code length is assigned as the appearance frequency F decreases. Although it is possible to prepare codes for all the elements and form a table, in this case, the code length of the Huffman code Hc becomes long, and the compression efficiency does not increase much even if compression processing is performed. Therefore, in the present embodiment, as shown in FIG. 22, a table of Huffman codes Hc is prepared for a certain range (for example, the range of X to Y shown in FIGS. 22 and 11), and the table does not fall within this range. Is processed with a special code attached so as not to perform compression processing.

In this embodiment, the code added to the data whose code length exceeds a predetermined length is counted up by the counter 47a of the post-processing data size determination unit 47. Here, data whose code length is longer than a predetermined length (represented as data exceeding a predetermined code length in FIG. 22) is data that is a target of special code processing for giving a special code, In addition, even in the range where the table of the Huffman code Hc is prepared, it refers to data whose code length exceeds a predetermined length, for example, data having a lower limit value A or less or an upper limit value B or more in FIG. is there.
Note that the prediction / determination processing by the post-processing data size determination unit 47 is sequentially performed on the difference data ΔD calculated and generated by the difference calculation unit 44. Note that after the difference data ΔD is calculated and generated by the difference calculation unit 44 and is once stored in the data memory 46 or the like, the difference data ΔD may be read from the data memory 46 or the like and processed.

It should be noted that in the range of data, the compression processing is performed with the counter 47a counted up (that is, how many lower limit values A and B are set), and when the counter 47a becomes more than a threshold value. Whether or not to determine whether to determine whether or not may be set in advance by default, or may be arbitrarily set by the user.
In the present embodiment, the counter 47a is sequentially counted up for those for which it is determined that the code length of the Huffman code Hc assigned when the compression processing is performed exceeds the predetermined length. For example, when the data size of the original image data is 16 bits, the original image data exceeds 16 bits. The number of counters 47a or more is set as the threshold value when, for example, one-third or more of the data constituting the entire image exceeds 16 bits.
In this way, by determining whether or not the number of difference data ΔD, which has a data amount exceeding the Huffman code, exceeds a certain amount, based on the 16-bit data size of the original image data. Thus, it is possible to determine whether or not the compression process should be performed by a simple determination method using the counter 47a, and it is possible to shorten the time required for the determination and perform a quick process.

[Radiation imaging system]
Next, the configuration of the radiographic image capturing system in the present embodiment will be described. The radiographic imaging system is a system that assumes radiographic imaging performed in, for example, a hospital or a clinic, and can be employed as a system that captures a medical diagnostic image as a radiographic image, but is not necessarily limited thereto. .

  FIG. 23 is a diagram showing an overall configuration of the radiographic image capturing system in the present embodiment. As shown in FIG. 23, the radiographic imaging system 50 includes, for example, an imaging room R1 that performs imaging of a subject (a patient's imaging target region) that is a part of a patient by irradiating radiation, and an operator such as a radiographer. Are arranged in the anterior chamber R2 for performing various operations such as control of radiation applied to the subject, and outside thereof.

  In the radiographing room R1, a bucky device 51 that can be loaded with the radiographic imaging device 1 described above, a radiation generating device 52 that includes an X-ray tube (not shown) that generates radiation to irradiate a subject, the radiographic imaging device 1 and a console. A base station 54 provided with a wireless antenna 53 that relays these communications when wirelessly communicating with 58 is provided.

  FIG. 23 shows a case where the portable radiographic image capturing device 1 is used by being loaded into the cassette holding portion 51a of the bucky device 51. However, the radiographic image capturing device 1 includes a bucky device 51, a support base, and the like. It may be integrally formed. Further, as shown in FIG. 23, the radiographic imaging apparatus 1 and the base station 54 may be connected by a cable so that data can be transmitted by wired communication via the cable.

  In the present embodiment, the cradle 55 that reads the cassette ID from the radiographic image capturing apparatus 1 and notifies the console 58 via the base station 54 when the radiographic image capturing apparatus 1 is inserted into the radiographing room R1. Is provided. The cradle 55 may be configured to charge the radiographic image capturing apparatus 1 or the like.

  The anterior room R2 is provided with an operation console 57 for controlling radiation irradiation, which includes a switch means 56 for instructing the radiation generator 52 to start radiation irradiation and the like.

  The configuration of the radiographic image capturing apparatus 1 is as described above. The radiographic image capturing apparatus 1 may be used by being loaded into the bucky device 51 as described above, but it is not loaded into the bucky device 51. It can also be used in a single state.

  That is, the radiation image capturing apparatus 1 is disposed on the upper surface side in a single state, for example, on a bed provided in the imaging room R1 or a bucky apparatus 51B for lying position photographing as shown in FIG. (See FIG. 1) The patient's hand, which is the subject, can be placed on the top, or the patient's waist, legs, etc. lying on the bed can be inserted between the bed and the bed. It has become. In this case, for example, radiation image capturing is performed by irradiating the radiation image capturing apparatus 1 with radiation from a portable radiation generating device 52B or the like via a subject.

  In this embodiment, the console 58 that controls the entire radiographic imaging system 50 is provided outside the imaging room R1 and the front room R2. For example, the console 58 is configured to be provided in the front room R2. Is also possible.

  The console 58 is constituted by a computer or the like in which a CPU, a ROM, a RAM, an input / output interface and the like (not shown) are connected to a bus. A predetermined program is stored in the ROM, and the console 58 reads out the necessary program, expands it in the work area of the RAM, executes various processes according to the program, and controls the entire radiographic imaging system 50 as described above. Is supposed to do.

  The console 58 is connected to the above-described base station 54, console 57, storage means 59 composed of a hard disk or the like, and a cradle 55 or the like is connected via the base station 54. The radiation generating device 52 and the like are connected via this. The console 58 is provided with a display screen 58a composed of a CRT (Cathode Ray Tube), an LCD (Liquid Crystal Display), or the like, and other input means such as a keyboard and a mouse are connected thereto.

  When the console 58 is notified of the cassette ID of the radiographic imaging apparatus 1 from the cradle 55 via the base station 54, the console 58 saves it in the storage means 59, and the radiographic imaging apparatus 1 existing in the imaging room R1. To manage. In the console 58, each image data D is restored from the Huffman code by the method described in the present embodiment, and image processing such as offset correction and gain correction is performed on the restored image data D to obtain a final result. Image data is generated.

Further, in the memory such as a ROM of the computer constituting the console 58 and the storage means 59, the same information as the data compression processing information such as a Huffman code table stored in the memory of the control means 22 of the radiographic image capturing apparatus 1 is stored. It is remembered.
When the image data subjected to the compression process is transferred, the CPU of the console 58 converts the image data into the original image based on information relating to the data compression process such as a Huffman code table stored in the ROM or the like. It functions as a restoration means for decompressing and restoring data.

The operation of this embodiment will be described with reference to FIGS.
In the present embodiment, as shown in FIG. 12, the difference calculation unit 44 reads out each image data D from the buffer memory 45 in order, and outputs images output from adjacent radiation detection elements 7 connected to the same signal line 6. The difference between the data D is calculated as difference data ΔD. That is, the difference between the image data D from each radiation detection element 7 adjacent in the signal line extending direction (signal line direction) represented by the vertical arrow in the figure is calculated as difference data ΔD. (Step S1 in FIG. 24).

  Next, the post-processing data size determination unit 47 determines whether the code length of the code added when the difference calculation unit 44 compresses the difference data ΔD every time the difference data ΔD is calculated exceeds a predetermined range. If not (Step S2), if it exceeds (Step S2; YES), the counter 47a of the post-processing data size determination unit 47 is incremented by one (Step S3).

  In this case, since it takes time to determine the Huffman code Hc corresponding to the difference data ΔD with reference to the table, for example, the values A and B in FIG. The lower limit value and the upper limit value in a range not exceeding the upper limit value are stored, and the post-processing data size determination unit 47 calculates the difference data ΔD if the difference data ΔD calculated by the difference calculation unit 44 is equal to or lower than the lower limit value and the upper limit value. It is preferable that the counter 47a is incremented by one by determining that the code length of the code attached when the data is compressed exceeds the predetermined range.

The post-processing data size determination unit 47 always determines whether or not the counter has reached a certain threshold (step S4). If the counter has not reached the threshold (step S4; NO), the data of one entire image is determined. It is determined whether the determination has been completed for all (step S5).
If the determination for the data for the entire image has not been completed (step S5; NO), the process returns to step S2 to repeat the determination process, and the determination for the data for the entire image has been completed (step S5). ; YES), the post-processing data size determination unit 47 does not exceed the data size of one whole image data of the original image data before compression (compression processing). It is determined that the subsequent data size <the data size before compression) (step S6).

In this case, the compression ON / OFF switch 48 is switched ON (step S7), and the compression processing unit 49a of the transfer data generation unit 49 receives the image data D of the entire image from the data memory 46. For example, one line is read and sent to the difference calculation unit 491. Then, the difference processing unit 492 performs compression processing on the difference data ΔD generated by the difference calculation unit 491 (step S8).
Specifically, the encoding processing unit 492 of the compression processing unit 49a determines whether or not the difference data ΔD is in the Huffman code Hc table. If it is replaced with the corresponding Huffman code Hc and it is not in the table, special code processing is performed for adding the special code to the original image data of the difference data ΔD without compressing the pixel data. At this time, it takes time to determine whether or not the difference data ΔD is in the Huffman code Hc table with reference to the Huffman code Hc table. The X and Y values in the table, that is, the lower limit value and the upper limit value of the data for which the Huffman code Hc table is prepared are stored, and the compression processing unit 49a determines whether or not the difference data ΔD is to be compressed. It is preferable to determine whether or not the difference data ΔD is a value not less than the lower limit value and not more than the upper limit value.

When the encoding processing unit 492 performs compression processing on the difference data ΔD, the information adding unit 49b adds a delimiter code to the end of the compressed data (step S9 in FIG. 25).
Then, the data generation unit 49c generates compressed data transfer data (step S10), and the transfer data is transferred to the main body control unit 23 (step S11).
Information such as the data size of the transfer data is stored in the register unit 49d, and the main body control unit 23 obtains the data size information of the transferred transfer data from the register unit 49d and adds a header to the header portion of the transfer data. It adds as data (step S12).
The main body control unit 23 stores the transfer data in the storage unit 40 and transfers the data to an external device such as the console 58 via the antenna device 39 as appropriate.
Note that the order of the process of adding a delimiter code (step S9), the process of generating transfer data (step S10), and the process of adding header data to the head of data (step S12) is not limited to that described here. . For example, a delimiter code and header data may be added to the data by the information adding unit 49b and then transferred to the main body control unit 23.

On the other hand, when the counter 47a reaches a certain threshold (step S4 in FIG. 24; YES), the post-processing data size determination unit 47 uses the entire one image after compression processing for the data of the entire one image. It is determined that the data size of the image data is equal to or greater than the data size of the entire image of the original image data before compression (data size after compression processing ≧ data size before compression) (step S13).
In this case, the compression ON / OFF changeover switch 48 is turned OFF (step S14), and the data generation unit of the transfer data generation unit 49 is not subjected to compression processing for the data of the entire image. 49c reads the original image data D of the entire image from the data memory 46, and generates transfer data without header information or delimiter code (step S15 in FIG. 25). The generated transfer data is transferred to the main body control unit 23 (step S16), and the main body control unit 23 adds an uncompressed code as header information to the header portion of the transfer data (step S17).
Then, the main body control unit 23 stores the transfer data in the storage unit 40 and transfers the data to an external device such as the console 58 via the antenna device 39 as appropriate.
Note that the process of adding the uncompressed code to the head of the data (step S17) may be performed by the information adding unit 49b. In this case, the data to which the code without compression is added is transferred to the main body control unit 23.

When the transfer data is transferred, the console 58 identifies the transfer image data for each line based on the header information and delimiter code, the presence or absence of compression processing, and the like. If the data has been compressed, it is decoded to restore the original image data.
Then, necessary image processing is performed as appropriate to generate diagnostic image data.

  As described above, according to the present embodiment, the data size of the entire image data transferred when the compression process is performed exceeds the data size of the entire image of the original image data before compression. Whether or not the post-processing data size determination unit 47 predicts / determines whether or not the data size after the compression processing is equal to or larger than the original image data. By transferring the image data as it is, it is possible to reduce the time required for useless compression processing and data transfer.

  Further, in this embodiment, the compression processing unit 49a performs compression processing for each signal line on each image data output from a plurality of radiation detection elements connected to the same signal line. Good compression processing can be performed.

  In the present embodiment, difference calculation is performed for calculating difference between image data of adjacent radiation detection elements for each image data output from a plurality of radiation detection elements connected to the same signal line. Since the compression processing unit 49a includes the unit 44 and the compression processing unit 49a performs compression processing on the difference data ΔD created by the difference calculation unit 44, the compression processing unit 49a can perform compression processing with higher compression efficiency.

  Further, in the present embodiment, a table of Huffman codes Hc for compression processing is provided in advance as a static dictionary, and the compression processing unit 49a refers to this table to perform Huffman coding (Huffman coding) of the difference data ΔD. Since the compression process is performed on the difference data ΔD for each radiation detection element, the compression process can be performed easily and quickly.

  Further, in the present embodiment, the compression processing unit 49a performs the compression process only when the difference data ΔD is a predetermined value (a value within the range of X to Y shown in FIGS. 22 and 11). In the case where the Huffman code Hc corresponding to all data is tabulated in order to perform special code processing for adding a special code indicating that compression processing is not performed on the difference data ΔD. The amount of data in the table can be reduced compared to

  In addition, when the compression process is not performed, the data delimiter position is clear without adding a delimiter code. Therefore, in the present embodiment, the information adding unit 49b is only applied when the compression process is performed by the compression process unit 49a. Thus, a delimiter code, which is data delimiter information indicating the data delimiter position, is added to the image data after compression processing, and no delimiter code is added when compression processing is not performed. For this reason, when compression processing is not performed, the amount of data can be reduced by not attaching a delimiter code, and the transfer time when transferring to an external device such as the console 58 is shortened.

  Needless to say, the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist of the present invention.

For example, in the present embodiment, the difference calculation unit 44 calculates and generates the difference data ΔD for the image data D, and performs prediction / determination of the data size after compression processing based on the difference data ΔD, or calculates the difference. The case where the difference data ΔD is calculated and generated for the image data D in the unit 491 and the compression process is performed on the difference data ΔD has been described as an example. However, the original data is not generated without generating the difference data ΔD. Based on the image data D, the data size after compression processing may be predicted and determined, or compression processing may be performed.
When compression processing is performed on the image data D, a table for associating a part of the image data D with the Huffman code Hc is prepared.
Specifically, when the compression or non-compression target is the image data D, the distribution of the appearance frequency F of the image data D read from each radiation detection element 7 is, for example, as shown in FIG. Distribution. In this case, for example, a table is created only for the image data D within the range of X to Y in the figure that appears at the appearance frequency F equal to or higher than the threshold.

  The distribution of the appearance frequency F of the image data D shown in FIG. 19 is usually that the imaging part of the body of the patient as the subject is the chest (front, side, the same applies hereinafter), skull, abdomen (lumbar vertebra), arm , Leg portions, hands, and the like. In addition, the distribution differs depending not only on the imaging region but also on the imaging conditions such as the size of the radiographic imaging device 1 being different, or the radiation field irradiated from the radiation generating device 52 to the radiographic imaging device 1 being narrowed or not narrowed.

  For this reason, a plurality of tables of Huffman codes Hc, which are information relating to data compression processing, are stored in advance in the memory of the control means 22 for each imaging condition including the imaging part of the patient's body, which is the subject, and control that constitutes the compression means When the image data D is subjected to data compression processing by the means 22, a table corresponding to the set photographing condition is selected, and the data compression processing is performed on the image data D with reference to the selected table. Is possible.

  Further, for example, a distribution including the distribution of the appearance frequency F of the image data D in all the imaging regions or the main imaging region is calculated, and the range of the image data D to which the Huffman code Hc is associated, that is, a table (information on data compression processing) It is also possible to set the range of the image data D to create) and use only one created table.

In this embodiment, the determination by the post-processing data size determination unit 47 is based on 16 bits that is the data size of the original image data, and the difference data ΔD that has a data amount exceeding this when Huffman coding is performed. Although the case where the determination is made based on whether the number exceeds a certain amount (for example, one third of the pixels constituting one whole image) has been described, the determination method by the post-processing data size determination unit 47 is here. It is not limited to what was illustrated.
For example, the compression processing unit 49a performs a compression process for converting the data into a Huffman code only when the difference data ΔD is a predetermined value (a value in the range of X to Y shown in FIGS. 22 and 11). Special code processing that cannot be converted to Huffman code when special code processing that adds a special code indicating that compression processing has not been performed on the difference data ΔD when the processing is not performed is performed. The number of necessary difference data ΔD is counted up by the counter 47a, and the determination is made based on whether or not this number exceeds a predetermined amount (for example, 1/20 of the pixels constituting one entire image). Good.
In this way, the post-processing data size determination unit 47 counts the number of difference data ΔD to be subjected to special code processing, and when this number exceeds a predetermined threshold, the image of one entire image after compression processing By determining that the data size of the data exceeds the data size of one whole image of the original image data before compression, the determination process can be performed more easily and quickly.
Further, when each difference data ΔD is converted into a Huffman code, it is determined how much the code length of the Huffman code Hc is assigned, and by calculating and adding the data amount, data data of one whole image is obtained. It may be determined whether the amount exceeds the data amount of one whole image of the original image data.
In addition, the determination may be performed by combining these methods.

  Also, in the present embodiment, whether or not to perform compression processing depending on whether or not the data size of image data of one entire image after compression processing exceeds the data size of one image of original image data before compression. However, the determination unit for determining whether or not to perform compression processing is not limited to this. For example, it is determined whether or not the data size of the image data after compression processing for each line exceeds the data size of the original image data before compression, and if so, the main body is not subjected to compression processing for that line. You may comprise so that it may send to the control part 23.

  In the present embodiment, when the post-processing data size determination unit 47 determines that the compression processing is not performed and the compression ON / OFF switch 48 is turned OFF, the delimiter code as delimiter position information is not added. Data is generated, but whether or not compression processing is performed on the entire data of one image or data for one line is determined by information sent from an external device such as the console 58, and compression processing is not performed. In this case, the delimiter code may not be added to the transfer data.

DESCRIPTION OF SYMBOLS 1 Radiation imaging device 5 Scanning line 6 Signal line 7 Radiation detection element (pixel)
17 Reading circuit 22 Control means 23 Main body control unit 24 FPGA
39 Antenna device (transfer means)
40 storage means 44 difference calculation unit (calculation means)
45 buffer memory 46 data memory 47 post-processing data size determination unit 47a counter 48 compression ON / OFF switch 49 transfer data generation unit 491 difference calculation unit 492 encoding processing unit 49a compression processing unit (compression means)
49b Information adding section 49c Data generating section 49d Register section 50 Radiation imaging system 58 Console 59 Storage means D Image data Hc Huffman code P Detection section r Region D Image data ΔD Difference ΔD Difference data

Claims (7)

A plurality of scanning lines and a plurality of signal lines arranged so as to intersect with each other; a plurality of radiation detecting elements arranged in a two-dimensional manner in each region partitioned by the plurality of scanning lines and the plurality of signal lines; A detector comprising:
A readout circuit that reads out charges from the radiation detection elements through the signal lines, converts the charges into electrical signals for each of the radiation detection elements, and outputs them as image data;
Compression means for compressing image data using a static dictionary;
Transfer means for transferring image data;
When the image data output from the radiation detection element is compressed by the compression means, the data size of the entire image data transferred by the transfer means is the original image data before compression. A post-processing data size determination means for predicting / determining whether or not the data size of the entire image is exceeded,
With
The compression means determines that the data size of the entire image data after compression processing by the post-processing data size determination means does not exceed the data size of the entire original image data before compression. Compression process only when
The transfer means transfers the image data after the compression processing when the compression processing is performed by the compression means, and the original image data when the compression processing is not performed. A radiographic imaging device.   The said compression means performs a compression process for every said signal line with respect to each said image data output from the said several radiation detection element connected to the said same signal line. Radiographic imaging device. For each of the image data output from the plurality of radiation detection elements connected to the same signal line, a calculation unit that calculates a difference between the image data of the adjacent radiation detection elements to create difference data is provided. ,
The radiographic image capturing apparatus according to claim 1, wherein the compression unit performs a compression process on the difference data created by the calculation unit. The compression means performs compression processing only when the image data or the difference data has a predetermined value, and does not perform compression processing on the image data when the compression processing is not performed. Special code processing for adding a special code representing the image data to the image data,
The post-processing data size determination means counts the number of the image data or the difference data that is the target of the special code processing, and when this number exceeds a predetermined threshold, The data size of the first image data is determined to exceed the data size of one whole image of the original image data before compression. 4. Radiographic imaging device. A table of Huffman codes for the compression process is provided in advance as the static dictionary,
The compression unit performs Huffman encoding of the image data or the difference data with reference to the table, and performs compression processing on the image data or the difference data for each of the radiation detection elements. The radiographic imaging apparatus as described in any one of Claims 1-4. Only when compression processing is performed by the compression means, it includes delimiter information adding means for adding data delimiter information indicating a data delimiter position to the image data after compression processing,
6. The transfer unit according to claim 1, wherein when the data delimiter information is added to the image data by the delimiter information adding unit, the transfer unit transfers the data delimiter information together with the image data. A radiographic imaging apparatus according to claim 1. The radiographic imaging device according to any one of claims 1 to 6,
A console for receiving image data transferred from the radiation image capturing apparatus;
With
The console includes a restoration unit that decompresses and restores the image data to the original image data when the compression processing by the compression unit is performed on the image data transferred from the radiation image capturing apparatus. A radiographic imaging system characterized by that.

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