JP2011229797A - Radiographic imaging apparatus and radiographic imaging system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiographic imaging apparatus which can shorten the data transfer time by reversibly compressing data saving size of information relative to data compression processing.SOLUTION: The radiographic imaging apparatus 1 includes: a detection part P; a readout circuit 17 which reads out an electric charge from the detection part P and outputs it as image data D; a calculation means 491 which creates difference data; a compression processing part 49a which performs compression processing of the image data D by using a static dictionary; and an antenna device 39 which transfers data. The static dictionary prepares conversion codes comprising encoding codes or special codes for all the difference data.

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

Generally, when compression processing is performed by reversible compression, the values indicated by the image data are concentrated on some numerical values as compared with the case where the values (pixel values) indicated by the image data output from each radiation detection element are distributed over a wide range. In such a case, more efficient compression processing can be performed.
However, when a part of the body such as a patient's head, chest, or limb is photographed as a subject, the values indicated by the image data output by each radiation detection element are widely dispersed according to the shade of each part of the image. In many cases, it is difficult to efficiently perform compression processing of image data based on a radiation image.
For this reason, when the image data is transferred from the radiation imaging apparatus to the outside due to the above problem, the transfer time cannot be shortened sufficiently, the power saving becomes insufficient, and the battery consumption is sufficiently reduced. I could not.

Also, in the field of radiographic images, in order for the captured image to reproduce the actual image more faithfully, it is necessary to increase the number of gradations of the luminance value of the image data. The number of codes required for the process is also increased, which increases the time required for the compression process and increases the storage capacity for storing the table for associating the image data with the codes. .
Furthermore, when the number of gradations of the image data increases, there is a problem that the processing time increases not only at the time of compression but also at the time of restoration.

  The present invention has been made in view of the above points, and provides a radiographic imaging apparatus and a radiographic imaging system capable of performing lossless compression processing of efficient data and speeding up the processing. Objective.

In order to solve the above problem, a radiographic imaging apparatus according to the present invention is divided by a plurality of scanning lines and a plurality of signal lines arranged so as to cross each other, and the plurality of scanning lines and a plurality of signal lines. A plurality of radiation detection elements arranged two-dimensionally in each region, and a charge is read from the radiation detection element through the signal line, and the charge is converted into an electrical signal for each radiation detection element. A readout circuit that outputs the data as image data, a calculation unit that calculates difference between adjacent data in a certain arrangement direction in the image data or thinned data created by thinning out the image data, and creates difference data; A compression means for compressing the difference data using a static dictionary; and a transfer means for transferring data,
The static dictionary stores conversion codes after processing by the compression means for the difference data in the entire range, and stores encoded codes after compression processing as conversion codes for some difference data, and others For the difference data, a special code indicating that compression processing is not performed is stored as a conversion code,
The compression means converts the partial difference data into the encoded code by the static dictionary and compresses the difference data without performing compression processing on the other difference data. Add a special code to the image data or thinned data,
The transfer means transfers the difference data compressed by the compression means and the difference data to which the special code is added or the original image data or thinned data.

Moreover, the radiographic imaging system which is another side surface of this invention receives the data transferred from the radiographic imaging apparatus as described in any one of Claims 1-3, and the said radiographic imaging apparatus. And a console to
When the data transferred from the radiographic imaging device is differential data subjected to compression processing by the compression unit, the console stores the data based on the same static dictionary as the radiographic imaging device. The image processing apparatus includes a restoration unit that restores the difference data and calculates image data from the difference data.

  According to the radiographic image capturing apparatus and the radiographic image capturing system of the present invention, difference data is obtained from a difference between adjacent data in a certain arrangement direction in thinned data created by thinning out image data or the image data, and statically Since differential data is compressed using a dictionary, it is possible to perform compression with high efficiency using differential data that shows a distribution tendency of appearance frequency that is more suitable for compression than image data, and to increase data transmission speed Thus, it is possible to save power in the radiation image capturing apparatus.

In addition, the static dictionary of the radiographic imaging apparatus stores the conversion codes after compression processing for all the values that can be taken by the difference data, and also stores the encoded codes as conversion codes for some of the difference data. For other differential data, a special code indicating that compression processing is not performed is stored as a conversion code.
For this reason, in order to reduce the data capacity of the static dictionary, the difference to be processed at the time of compression processing is used as in the case of using a static dictionary that stores only encoded codes corresponding to some difference data. Unlike the case where a process for confirming whether or not the encoded code corresponding to the data exists in the static dictionary is required, the confirmation process is not required, so the present invention speeds up the compression process. It becomes possible to plan.

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 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. (A)-(C) 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. 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. FIG. 4 is a diagram for explaining a method of creating difference data between image data adjacent to each other in the signal line direction connected to the same signal line using two buffer registers. It is a graph showing an example of distribution of the appearance frequency of the image data read from each radiation detection element. 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. FIG. 5 is a graph showing the distribution of the appearance frequency of difference data of image data output from adjacent radiation detection elements connected to the same signal line when the radiation imaging apparatus is uniformly irradiated with radiation, and a predetermined threshold value A case in which a plurality of regions exceeding 1 is generated is illustrated. 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 figure which shows the structural example of the data for transfer at the time of performing a compression process. 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 explanatory drawing which showed reading of the transfer data in the decompression | restoration process performed in the conventional radiographic imaging system illustrated as a reference example in order of execution. It is a conceptual diagram of the list data of the code length of the conversion code. It is explanatory drawing which showed reading of the transfer data of the decompression | restoration process performed with the console in this embodiment in order of execution. It is a flowchart which shows the process of the decompression | restoration 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 after calculating difference data ΔD described later, the radiation image capturing apparatus 1 does not illustrate the data. The case where the compression process is performed on the difference data ΔD when transferring to the external device will be described. However, the image data D read from each radiation detection element 7 is not stored in the data memory 46 or the data memory 46. It is also possible to perform a difference calculation and compression process on each image data D or the like as a separate process in parallel with the storage to store the image data directly.

[Control means]
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.

  The FPGA 24 constituting the control means 22 is provided with a buffer memory 45, 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 readout circuit 17 and stores the original image data (that is, the raw signal value). , Pixel values) are sent to the data memory 46, and the original image data is sequentially stored in the data memory 46.

[Compression processing section]
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 one buffer register 491a (see FIG. 13), reads the original image data D stored in the data memory 46, and calculates difference data ΔD for the image data D. It is a calculation means.

  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 one buffer register 491a is illustrated, but the number of buffer registers provided in the difference calculation unit 491 is not particularly limited. For example, two 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. 11, 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 one buffer register 491a as shown in FIG. When calculating the difference value and generating the difference data ΔD, as shown in FIG. 14A, the difference calculation unit 491 detects, from the data memory 46, each radiation detection 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 scanning line direction read from the element 7 are read and temporarily stored in the buffer register 491a. .
Then, the control means 22 stores 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 in the data memory 46. Are sequentially read out and stored in the buffer register 491a while sequentially replacing the corresponding image data D (n, 1), D (n, 2), D (n, 3),. At that time, as shown in FIGS. 14B and 14C, 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 sequentially replaced while the difference data ΔD is sequentially calculated for each image data D (n + 2, 1), D (n + 2, 2), D (n + 2, 3),. .

  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 out from each radiation detection element 7 connected to the line L1 of the scanning line 5 from the data memory 46. The image data D (1,1), D (1,2),... Arranged in the scanning line direction are sequentially read, and the difference ΔD is obtained as the difference data ΔD (1,1), ΔD (1,2),. Is calculated as

  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. .

The difference calculation unit 491 may be configured to calculate the difference data ΔD by calculating the difference between the image data D adjacent in the signal line direction similar to the above even when a plurality of buffer registers are provided. Is possible.
That is, as shown in FIG. 16, a case where two buffer registers 491a and 491b are provided in the difference calculation unit 491 will be described as an example. When the difference value is calculated and the difference data ΔD is generated, the difference is calculated. The calculation unit 491 reads from the data memory 46 the image data D (n, 1) and D (n, 2) arranged in the scanning line direction read from the radiation detecting elements 7 connected to the line Ln of the scanning line 5. ), D (n, 3),... Are read and temporarily stored in the buffer register 491a. Further, the image data D (n + 1, 1), 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 data memory 46. (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, the difference calculation unit 491 calculates the difference data ΔD between 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. , Each image data D (n + 1,1), D (n + 1,2), D (n + 1,3),... Is moved from the buffer register 491b to the buffer register 491a, and the next adjacent scan to the buffer register 491b which has become empty. The image data D (n + 2, 1), D (n + 2, 2), D (n + 2, 3),... Aligned in the scanning line direction of the line Ln + 2 of the 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.

  With this configuration, even when there are a plurality of buffer registers 491a and 491b, the signals are 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.

[Encoding processing section]
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.

At the time of compression, the difference data ΔD indicating each value is converted into a code having a smaller number of bits as the appearance frequency increases. As a result, more differential data ΔD is converted into a smaller number of bits than the original data, and the entire data capacity is compressed. Therefore, more efficient compression can be realized by showing a tendency that the appearance frequency concentrates on a part of the difference data ΔD.
The distribution of the appearance frequency F of the image data D read from each radiation detection element 7 is a distribution as shown in FIG. 17, for example, and the application frequency F tends to be distributed over a wide range. On the other hand, FIG. 18A 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. 18B is a graph showing the distribution of the appearance frequency F, and FIG. 18B is outputted 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. In any difference data ΔD, the appearance frequency is concentrated around the difference value 0, and it is possible to realize more efficient compression by compressing the difference data ΔD than when directly compressing the image data D. ing.
Even if the image data D is compressed by Huffman coding, it is possible to compress the image data D. However, as described above, Huffman coding is applied to the difference data ΔD indicating the tendency that the appearance frequency F is concentrated on some values as described above. The more efficient compression can be realized by performing the compression according to. Accordingly, the encoding processing unit 492 performs compression processing on the difference data ΔD calculated by the difference calculation unit 491.

As shown in FIG. 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 centered on ΔD = 0. The distribution is 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. 18B, the distribution of 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 is a normal distribution. However, it has a distribution that can be called a trapezoidal shape.

  According to the study by the inventors of the present application, the main cause of the distribution of the appearance frequency F of the difference data ΔD as shown in FIG. 18B is as described above, as shown in FIG. In this case, the image data D is read from each radiation detection element 7 by a different readout circuit 17, but the output characteristics of each readout circuit 17 are different for each readout circuit 17 and the output characteristics of each readout circuit 17 vary. It is considered to be.

  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. It is considered that the width of the distribution is wider than the case 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 shown in FIG.

Accordingly, in the main body control unit 23, the difference calculation unit 491 calculates the difference data ΔD between the image data D output from the adjacent radiation detection elements 7 connected to the same signal line 6, and the encoding processing unit 492 Compression processing is performed on the difference data ΔD.
However, even when the difference calculation unit 491 calculates the difference data ΔD between the image data D output from the adjacent radiation detection elements 7 connected to the same scanning line 5 and the encoding processing unit 492 compresses the image data. Can be compressed with sufficiently high efficiency as compared with the case of directly compressing. Therefore, the difference data ΔD between the image data D output from the adjacent radiation detection elements 7 connected to the same scanning line 5 may be a compression target.

  Further, 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 stores the difference data ΔD. The compression processing is performed by assigning the Huffman code Hc and coding it.

When the luminance gradation of the image data D read from each radiation detection element 7 is, for example, 2 ¹⁶ (= 65536) gradations, the range of values that the difference data ΔD can take is doubled, and all the difference data ΔD. If a Huffman code (encoded code) is prepared for, the number of codes becomes enormous, and at the same time, an encoded code having a large number of bits must be prepared. For example, in a typical Huffman coding technique must take into prepared twice 2 ¹⁷ different Huffman code Hc of the luminance gradation, image data D (difference data ΔD thereunder) and the Huffman code Hc The corresponding table is also very large.

Therefore, in the radiographic imaging apparatus 1 according to the present embodiment, Huffman encoding (compression processing) is performed only on a part of the difference data ΔD, instead of performing Huffman encoding on all the difference data ΔD. It has become.
That is, the table of the Huffman code Hc prepares conversion codes for all the difference data ΔD that can be taken by the difference of the image data D, but not all the conversion codes are Huffman codes Hc. That is, the Huffman code Hc table stores a part of the difference data ΔD to be compressed so as to be associated with the Huffman code Hc individually, but the difference data ΔD to be excluded from the compression is Huffman. The code Hc is not prepared, and all of them are stored so as to be associated with the same special code.

Then, the encoding processing unit 492 can read the Huffman code Hc corresponding to the part of the difference data ΔD to be compressed by the table of the Huffman code Hc, and the corresponding Huffman code Hc. And is sent to the main body control unit 23.
In addition, when the differential data ΔD that is not subject to compression is processed, a special code is read from the table of the Huffman code Hc, and in this case, the encoding processing unit 492 causes the differential data ΔD to be read. The original image data (that is, the raw signal value) is read out, and a special code is added thereto and sent to the main body control unit 23.
Further, the compressed difference data ΔD (Huffman code Hc) or the image data D to which the special code is added sent to the main body control unit 23 is transferred from the main body control unit 23 to the external device. .

  Further, in the Huffman code Hc table, the range of the difference data ΔD is subjected to compression processing, and the range of which is not compressed, that is, the difference data ΔD is assigned the Huffman code Hc. The selection of the correlation data and the difference data ΔD to be associated with the special code is the distribution of the appearance frequency F of the difference data ΔD calculated from the image data D read from each radiation detection element 7 of the radiographic imaging device 1. Based on the above.

  In the Huffman coding process, since data having a higher appearance frequency is associated with a Huffman code Hc having a smaller number of bits, the compression efficiency is improved. Therefore, the selection of whether to perform compression is performed by setting a predetermined threshold value for the appearance frequency. The difference data ΔD having an appearance frequency that is less than the threshold value is excluded from the compression target.

  For example, when the distribution of the appearance frequency F of the difference data ΔD is as shown in FIGS. 18A and 18B described above, for example, the difference in the range h in which the appearance frequency F is equal to or greater than the threshold value α. A table in which a special code is associated with each difference data ΔD that is individually associated with the data ΔD and is not included in the range h (the appearance frequency F is less than the threshold value α) is created.

Further, as described above, the difference data ΔD usually shows a tendency that the distribution of the appearance frequency F is concentrated around the difference value 0.
However, when there are various factors, for example, those in which each radiation detection element 7 performs an abnormal output due to a defect in the element itself or an element that performs an abnormal output due to the influence of external noise, these abnormalities are included. In many cases, the output is 0 or the maximum output, and when such an abnormal output occurs to some extent, the appearance frequency F may exceed the above-described threshold value α for the difference data ΔD greatly deviating from the difference value 0. In such a case, as shown in FIG. 19, a plurality of regions where the appearance frequency F exceeds the threshold value α are generated, but the Huffman code Hc table is included in each of these regions h1 to h3. The difference data ΔD is associated with the Huffman code Hc corresponding to the appearance frequency F, and the difference data ΔD included in each region ho where the appearance frequency F is less than the threshold α is associated with the same special code. It will be.

  In the above example, the case where there is an abnormality in the output of each radiation detection element 7 is exemplified as a factor that causes a plurality of regions in which the appearance frequency F of the difference data ΔD is equal to or greater than the threshold value α. Even when there may be a plurality of regions where the distribution of the appearance frequency distribution of ΔD may occur, the table is created so that the Huffman code Hc is associated with the difference data ΔD belonging to each region.

  Also, the special code associated with the difference data ΔD whose appearance frequency F is less than the threshold value α is added to the head of the image data D that is the source of the difference data ΔD and transmitted to the external device together with the image data D. This is a code indicating that 16-bit data below the special code is the raw image data D that has not been subjected to compression processing. Therefore, in order to prevent 16-bit data from being erroneously interpreted as the Huffman code Hc at the transmission destination, the special code has a longer code length than the normal Huffman code Hc. In this case, the code has a data amount of 24 bits. Therefore, the data subjected to the special code process (special code + image data D) is 40-bit data in which the 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.
In the case where the compression processing is not performed, a special code is added to the difference data ΔD that is not compressed (that is, uncompressed difference data ΔD, so-called raw difference data ΔD) instead of the image data D, and this is added to the main body. You may make it transfer to the control part 23 grade | etc.,.

Note that if the imaging conditions are changed during radiographic imaging, the distribution characteristics of the appearance frequency F of the difference data ΔD also change.
For example, when the dose of radiation irradiated to the radiographic imaging apparatus 1 is increased, the distribution of the appearance frequency F of the difference data ΔD changes as shown in FIGS. 20A and 20B, and FIG. , (B), the width of the distribution is slightly widened as can be seen. 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, for the Huffman code Hc table, which is information related to data compression processing, the appearance frequency F corresponds to the characteristics of the distribution of the appearance frequency F of the difference data ΔD under various imaging conditions, for example, a plurality of doses of irradiated radiation. Characteristics of a plurality of Huffman codes Hc that define a threshold value α or a range of difference data ΔD to be compressed and uncompressed, and distribution of appearance frequency F of difference data ΔD in various imaging regions of a patient's body as a subject A plurality of Huffman code Hc tables that define the threshold value α of the appearance frequency F or the range of the difference data ΔD to be compressed and uncompressed corresponding to the above may be prepared in advance in the memory of the control means 22 for each shooting condition. . In that case, when the difference data ΔD is subjected to data compression processing by the control means 22, a table corresponding to the set photographing condition is selected, and data compression processing is performed on the difference data ΔD with reference to the selected table. It may be configured.
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.

  However, according to the study by the inventors of the present application, as shown in FIGS. 18A and 18B and FIGS. 20A and 20B, 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, 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, it is possible to use only one table that allows the difference in the distribution characteristics of the appearance frequency F of the difference data ΔD due to the above-described changes in various shooting conditions. The case where it has the table of one Huffman code Hc is illustrated.

[Information addition processing]
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. This is because when compression processing is performed, the compression ratio varies depending on the type of image, and therefore, the delimiter code cannot be specified unless the delimiter code is added. 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.

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.

[Header part addition processing]
When the data with the delimiter code added thereto 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 to obtain the data size of the data for one line. A process of writing (appending) to the header portion of the data is performed.

FIG. 21 shows a configuration example of transfer data. In the transfer data, header data is added to the head (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. 22). It is simply replaced with “Hc”. Also, for the difference data ΔD that is not subject to encoding with the Huffman code Hc, a special code indicating that the original image data D is uncompressed is added.
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 the special code processing has a data size that exceeds the original image data D, such as 40 bits. However, the radiation detection element 7 to be subjected to the special code processing has a low appearance frequency and is converted into another Huffman code. In general, the data size of the entire data for one line, and thus the entire image, becomes smaller than the original image data D by canceling out with the radiation detecting element 7.

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.

[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. 22 is a diagram showing an overall configuration of a radiographic image capturing system in the present embodiment. As shown in FIG. 22, the radiographic imaging system 50 includes, for example, an imaging room R <b> 1 that performs imaging of a subject 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.

  22 shows the case where the portable radiographic imaging device 1 is used by being loaded into the cassette holding portion 51a of the bucky device 51. However, the radiographic imaging device 1 includes the bucky device 51, a support base, and the like. It may be integrally formed. Further, as shown in FIG. 22, the radiographic imaging apparatus 1 and the base station 54 can 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 capturing room R1 or on a bucky apparatus 51B for supine 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.
Further, the ROM stores the same Huffman code Hc table as that of the radiation image capturing apparatus 1 and list data of the code lengths of all the conversion codes stored in the Huffman code Hc table. That is, the ROM of the console 58 functions as a storage unit that stores a list of code lengths of conversion codes.
Then, when the compressed difference data ΔD and the image data D to which the special code is added are transferred, the CPU of the console 58 removes the header data and the delimiter code, and the Huffman code stored in the ROM or the like. Based on this table and the list data of the code length of the conversion code, processing for restoring the original image data is performed. That is, the CPU of the console 58 functions as restoration means.
The details of the list data of the code length of the conversion code described above will be described later.

The console 58 is connected to the above-described base station 54, console 57, storage means 59 composed of a hard disk, etc., and a cradle 55 etc. are connected via the base station 54, and the console 58 is connected. A radiation generating device 52 and the like are connected via 57. Then, the compressed image data D and the special code added to the storage unit 59 are transferred from the radiographic imaging apparatus 1 via the antenna device 39 and the cable via the base station 54 and the like. Is memorized. In the following description, the difference data ΔD and the image data D are collectively referred to as transfer data.
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.

[Image data compression processing of radiation imaging equipment]
Next, image data compression processing by the control means 22 of the radiation image capturing apparatus 1 will be described with reference to the flowchart shown in FIG. Here, the processing for the image data of the radiation detection elements 7 for one line connected to the same scanning line 5 is illustrated.
First, the image data of each radiation detection element 7 of the line Ln is accumulated in the buffer register 491a, and the image data of each radiation detection element 7 of the line Ln + 1 whose line Ln is adjacent to the line Ln is sequentially read, and the address is Differences ΔD are calculated as difference data ΔD (n + 1, 1), ΔD (n + 1, 2), ΔD (n + 1, 3)... In order (step S1). When the image data compression process is started from the first line L1, the difference calculation unit 491 reads the reference data Dc (1), Dc (2), Dc (3),... From a memory such as a ROM. Are stored in the buffer register 491a, and the image data D (1,1), D (1,2), D (1,3),...

Next, the encoding processing unit 492 reads the conversion code associated with the difference data ΔD with reference to the Huffman code Hc table (step S2).
Then, it is determined whether or not the difference data ΔD generated in the difference calculation unit 491 by the read conversion code is a compression target (step S3).
Specifically, the encoding processing unit 492 determines whether or not the conversion code associated with the difference data ΔD is the Huffman code Hc. If the conversion code is Huffman code Hc, the encoding processing unit 492 uses the Huffman code Hc as the information adding unit 49b. (Step S4).
On the other hand, if the conversion code read from the Huffman code Hc table is a special code, the information addition unit adds the special code to the original image data of the difference data ΔD without compressing the difference data ΔD. Special code processing to be output to 49b is performed (step S5).

When the encoding processing unit 492 performs compression processing or special code processing based on each difference data ΔD, the information adding unit 49b adds a delimiter code to the end of the data for one line (step S6).
Then, the data generation unit 49c generates compressed data transfer data (step S7), and the transfer data is transferred to the main body control unit 23 (step S8).
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 is added as data (step S9).
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 S6), the process of generating transfer data (step S7), and the process of adding header data to the beginning of the data (step S8) 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.

[Console image data restoration processing]
Next, the data restoration process performed by the console 58 that has acquired the transfer data transferred from the radiographic imaging apparatus 1 will be described in detail.
When performing the restoration process, the console 58 reads the transfer data received from the radiation image capturing apparatus 1 from the storage unit 59 and collates which conversion code in the table of the Huffman code Hc. Then, based on the result of the collation, the difference data ΔD or the image data is restored.

FIG. 24 is an explanatory diagram showing the reading of the transfer data in the restoration process performed in the conventional radiographic imaging system exemplified as a reference example in the order of execution. As shown in the figure, conventionally, reading of transfer data from the radiographic imaging apparatus 1 from the storage unit 59 is executed in 1-bit units, and each time 1-bit transfer data is read, the data is stored in the Huffman code Hc. It was checked whether it matches one of the conversion codes prepared in the table.
However, the Huffman codes Hc in Huffman coding are not necessarily prepared for all the numbers of bits. Rather, each Huffman code Hc is stepwise, that is, skipped from the viewpoint of the efficiency or certainty of collation at the time of restoration. It was common to prepare with the number of bits.
As a result, as before, when the transfer data is read and verified in 1-bit units in the restoration process, the number of bits for which no conversion code exists is also collated, which is restored due to a reduction in processing efficiency. The processing was slowed down.

Therefore, in the radiographic image capturing system 50, the list of code lengths of conversion codes is prepared in the storage means 59 to solve the above problem.
FIG. 25 is a conceptual diagram of the list data of the code lengths of the conversion codes, and FIG.
As shown in FIG. 25, the list data stores the conversion code and the number of bits indicating the code length in association with each other. In this list data, the number of bits of the conversion code is in order from the shortest. It is remembered. The list data conversion code includes not only the Huffman code Hc but also special data.
In the restoration process, the transfer data is read with the stepwise bit number indicated in the code length list data of the conversion code, and the read transfer data and the read bit number are supported. A match with the conversion code is determined.
For example, as shown in FIG. 25, when the number of bits is recorded in the list data of the code length of the conversion code in the order of 4, 7, 7, 9, 9, and 11, as shown in FIG. The transfer data stored in the means 59 is also read for 4 bits first, and a match with the corresponding conversion code is determined. If there is no match, the number of bits is stepwise, such as 7 bits, 9 bits, and 11 bits. Read to increase. As a result, the transfer data can be read efficiently, and the restoration process can be performed at high speed.

FIG. 27 is a flowchart showing the restoration process in the console 58. The restoration process will be described in detail with reference to FIG.
First, the console 58 refers to the code length list data of the conversion code, reads the number of bits recorded at the head (step S21), and reads the transfer data corresponding to the number of read bits from the storage means 59 (step S21). Step S22).

Then, it is determined whether or not the transfer data that has been read matches the conversion code associated with the number of read bits (step S23), and if not, the process returns to step S21 to return the code length of the conversion code. The next number of bits is read from the list data and the same processing as steps S22 and S23 is executed again.
On the other hand, if the read transfer data matches the conversion code, it is determined whether the transfer data is a Huffman code Hc or a special code (step S24).

In the above determination, if the transfer data is a special code, the restoration is completed by further reading the image data D following the transfer data (step S25).
On the other hand, when the transfer data is the Huffman code Hc, the difference data ΔD associated with the Huffman code Hc is specified with reference to the Huffman code Hc table (step S26).

  When the difference data ΔD is obtained, an addition process with the image data D already obtained for the adjacent radiation detection elements 7 connected to the same signal line 6 is performed, and the source of the difference data ΔD is obtained. Image data D is calculated. The ROM of the console 58 stores the same reference data Dc (1), Dc (2), Dc (3),. Therefore, when the difference data ΔD is the image data D output from each radiation detection element 7 connected to the line L1 of the scanning line 5, the reference data having the same address is read and added to the difference data ΔD. Thus, the image data D is calculated (step S27). This completes the restoration.

  From then on, the console 58 executes the same processing for each line along all the scanning lines 5, thereby developing one screen of image data in the development area of the storage means 59 by one buffer register 581. Is possible.

  By performing the above process on the radiation detection elements 7 connected to all the lines in order from the radiation detection element 7 connected to the line L1 of the scanning line 5, all the image data D for one screen is restored.

[Effect of the embodiment of the invention]
As described above, in the radiographic image capturing apparatus 1 shown in the present embodiment, the difference data ΔD is obtained from the image data D of the radiation detection elements 7 adjacent to each other, and the difference is obtained using the Huffman code Hc table that is a static dictionary. Data ΔD is compressed. In the plurality of radiation detection elements 7 arranged in a matrix, since the two adjacent radiation detection elements 7 are close to each other, it is unlikely that the dose and the incident state incident on them are greatly different. Therefore, the difference data between two adjacent radiation detection elements 7 occupies most of the data indicating 0 or a value close thereto (see FIG. 18). On the other hand, when the Huffman compression process is performed, it is possible to compress more efficiently when the variation in data is small and the appearance frequency F of the difference data ΔD having a common value increases. That is, by performing the Huffman compression process on the difference data ΔD between the adjacent radiation detection elements 7, the compression can be performed with high efficiency, the data transmission can be performed more quickly, and the radiation image capturing apparatus 1. It is possible to save power.

  Moreover, in the radiographic imaging device 1, since the difference calculation unit 491 calculates the difference data ΔD between the radiation detection elements 7 adjacent along the extending direction of the signal line 6, more difference data ΔD is included within the narrower difference value range. The appearance frequency F can be concentrated, and the compression efficiency can be further increased.

Also, the encoding processing unit 492 uses the Huffman code Hc table to select a part of the difference data ΔD as a compression target, and does not perform the compression process on the remaining part of the difference data ΔD, and corresponds to the difference data ΔD. A process of adding a special code indicating non-compression to the image data of the radiation detecting element 7 is performed. For this reason, the difference data ΔD deviating from the value near the difference value 0 where the difference data ΔD is concentrated can be excluded from the compression processing targets. For this reason, the number of codes used in the Huffman code can be reduced, and highly efficient compression can be performed.
Further, by reducing the number of codes used in the Huffman code, it is possible to reduce the data capacity of the Huffman code Hc table.

In addition, the Huffman code Hc table of the radiographic image capturing apparatus 1 stores conversion codes after compression processing for values in the entire range that can be taken by the difference data ΔD, and a part of the difference data ΔD as conversion codes. A Huffman code Hc is stored, and for other difference data ΔD, a special code indicating that compression processing is not performed is stored as a conversion code.
For example, in order to reduce the data capacity of the table, Huffman codes Hc are not prepared for all numerical ranges that can be taken by the difference data ΔD, and only Huffman codes corresponding to only a part of the difference data ΔD to be compressed are provided. Although it is possible to use a table, in this case, when compressing the difference data ΔD for one screen, whether or not the Huffman code Hc corresponding to each difference data ΔD exists in the table is compressed. In this case, a confirmation process is required, and there is a disadvantage that the compression process is slowed down.
However, in the case where conversion codes are prepared for all the difference data ΔD that are not to be compressed as in the Huffman code Hc table in the radiographic imaging system 50 of the present embodiment, the above confirmation process is unnecessary. Therefore, it is possible to increase the speed of the compression process.

  Furthermore, as described above, when a table having conversion codes is used for all the difference data ΔD, the distribution tendency between the difference data ΔD and its appearance frequency F tends to vary depending on the shooting conditions, shooting targets, and the like. Even if they are different, it is possible to optimize the table by correcting some conversion codes, so it is possible to realize compression processing that can easily and flexibly cope with various shooting conditions, etc. It becomes.

In addition, the console 58 stores the list data of the code lengths of all the conversion codes held in the Huffman code Hc table, and the bit stored in the code length list data of the conversion codes for reading the transfer data in the restoration process. It is done step by step for each number.
For this reason, compared to the case where the transfer data is read bit by bit and compared with the conversion code of the Huffman code Hc table each time, it is possible to drastically shorten the transfer data reading and verification processing time. Thus, the restoration process can be speeded up.

  A table of Huffman codes Hc, which is a static dictionary, is prepared in advance by storing a plurality of tables for each imaging condition including an imaging region of a patient's body, which is a subject, and according to a specified imaging region or imaging condition. By making this selectable, data compression can be realized more effectively.

When the problem to be solved is to speed up the restoration process, the Huffman code Hc table need not be limited to assigning conversion codes to all the difference data ΔD.
That is,
“A plurality of scanning lines and a plurality of signal lines arranged so as to cross each other, and a plurality of radiation detection elements arranged in a two-dimensional manner in each region partitioned by the plurality of scanning lines and the plurality of signal lines” A detection unit 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;
Calculating means for calculating difference between the image data output from the radiation detection elements adjacent to each other in a certain arrangement direction in the detection unit, and creating difference data;
Compression means for compressing the difference data using a static dictionary;
A transfer means for transferring data;
A radiographic imaging device comprising:
A console for receiving data transferred from the radiation imaging apparatus;
With
When the data transferred from the radiographic imaging device is differential data subjected to compression processing by the compression unit, the console stores the data based on the same static dictionary as the radiographic imaging device. A restoring means for restoring the difference data and calculating image data from the difference data;
A storage unit for storing a list of code lengths of all conversion codes held by the static dictionary;
The restoration means reads the data transferred from the radiographic imaging apparatus based on the code length of the conversion code defined in the list data, and performs a restoration process based on the static dictionary. Characteristic radiographic imaging system "
Even in this case, it is possible to solve the problem of speeding up the restoration process.

  Moreover, although the case where the radiographic imaging device 1 and the external device (for example, the console 58) described above perform data transmission and reception wirelessly using an antenna device has been illustrated, for example, these are performed by a wired communication unit (LAN or the like). You may connect and send and receive data.

In the radiographic imaging apparatus 1, the difference data ΔD is obtained from the difference between the image data D actually output by the radiation detection elements adjacent to each other in the detection unit P. However, the present invention is not limited to this.
For example, when data is transferred from the radiation image capturing apparatus 1 to an external device such as the console 58, the resolution consisting only of the image data of the radiation detection elements 7 separated by a certain interval is dropped before the normal image data. However, in such a case, the difference data ΔD is not obtained between the adjacent radiation detection elements 7 but is arranged at the thinning interval. The difference data ΔD between the radiation detection elements 7 is obtained (in the case of skipping three lines, the difference data of the first line, the fifth line, the fifth line, the ninth line,. Send to device.
In other words, as long as the data at the time of transmission is obtained, the difference data ΔD of data adjacent to each other along a predetermined direction (row direction or column direction) may be obtained.

  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.

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 45 buffer memory 46 data memory 491 difference calculation section (calculation means)
492 Encoding processing unit 49a Compression processing unit (compression means)
50 Radiation imaging system 58 Console (restoration means, storage unit)
59 Storage means D Image data Hc Huffman code P Detection unit r Region D Image data ΔD Difference data

Claims (5)

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;
Calculating means for calculating difference between data adjacent to each other in a certain arrangement direction in the image data or thinned data created by thinning out the image data; and
Compression means for compressing the difference data using a static dictionary;
A transfer means for transferring data;
With
The static dictionary stores conversion codes after processing by the compression means for the difference data in the entire range, and stores encoded codes after compression processing as conversion codes for some difference data, and others For the difference data, a special code indicating that compression processing is not performed is stored as a conversion code,
The compression means converts the partial difference data into the encoded code by the static dictionary and compresses the difference data without performing compression processing on the other difference data. Add a special code to the image data or thinned data,
The radiographic imaging apparatus, wherein the transfer unit transfers the differential data compressed by the compression unit and the differential data to which the special code is added or the original image data or thinned data.   The calculation means calculates difference based on image data output from radiation detection elements connected to the same signal line in the detection unit or thinned data created by thinning out the image data, and creates difference data. The radiographic imaging apparatus according to claim 1. A table of Huffman codes for the compression process is provided in advance as the static dictionary,
The radiographic image capturing apparatus according to claim 1, wherein the conversion code of the partial difference data is a Huffman code. The radiographic imaging device according to any one of claims 1 to 3,
A console for receiving data transferred from the radiation imaging apparatus;
With
When the data transferred from the radiographic imaging device is differential data subjected to compression processing by the compression unit, the console stores the data based on the same static dictionary as the radiographic imaging device. A radiographic imaging system comprising: a restoration unit that restores to difference data and calculates image data from the difference data. The console is
A storage unit for storing a list of code lengths of all conversion codes held by the static dictionary;
The restoration means reads the data transferred from the radiographic imaging apparatus based on the code length of the conversion code defined in the list data, and performs a restoration process based on the static dictionary. The radiographic imaging system according to claim 4, wherein

Images