JP2010162059A - Radiation image capturing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation image capturing system capable of accurately performing image processing by the same operation in both cases of using a radiation solid-state detector and a stimulable phosphor sheet for radiation image capturing. <P>SOLUTION: The radiation image capturing system 50 includes: the radiation solid-state detector 1 for detecting radiation by a plurality of radiation detection elements 7 and generating first image data proportional to the dose of the radiation; a reader 61 for reading second image data proportional to the logarithm of the dose of the radiation from the stimulable phosphor S; and a console 58 capable of image-processing both of the first image data and the second image data. When the image data are the first image data, the console 58 performs correction processing of correcting the first image data and logarithm conversion processing of logarithm-converting the first image data on the basis of read efficiency from the radiation detection elements 7, and performs gradation processing predetermined for each capturing object part which is an object in common to the second image data and the corrected and logarithm-converted first image data. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radiographic imaging system.

  For the purpose of disease diagnosis and the like, radiographic images taken using radiation typified by X-ray images are widely used. Conventionally, such medical radiographic images have been taken using a screen / film, but in order to digitize radiographic images, CR (Computed) using a stimulable phosphor sheet or a stimulable phosphor plate is used. Radiography) imaging devices have been developed.

  In a CR imaging apparatus, radiation is generally transmitted by irradiating a photostimulable phosphor sheet stored in a cassette (hereinafter referred to as a CR cassette) or the like with radiation that has passed through an imaging target region of a patient's body as a subject. Is stored in a stimulable phosphor sheet, and the stimulable phosphor sheet is loaded in a reader, and the stimulable phosphor is irradiated with excitation light by the reader. Image data is generated by detecting the stimulated light emitted according to the energy.

  In recent years, a radiation panel detector (FPD) has been developed in which irradiated radiation is detected by radiation detectors arranged two-dimensionally and generated as digital image data. Conventionally, a radiation solid-state imaging device has been integrally formed with a support base or the like (see, for example, Patent Document 1). However, in recent years, a portable radiation solid has been made portable by housing a radiation detection element or the like in a housing. An imaging device has been developed and put into practical use (for example, see Patent Document 2).

  However, there are still many cases where CR imaging devices are still used for radiographic imaging. A radiation solid-state detector integrally formed with a support stand or a portable radiation solid-state imaging device (FPD). When the is introduced, a mixed state of a so-called CR imaging device and a radiation solid-state imaging device may occur in the imaging room. Therefore, a radiographic imaging system has been proposed for constructing an environment in which such CR imaging devices and solid-state radiographers coexist with high efficiency and easy operation for operators such as radiographers. (See Patent Document 3).

JP-A-9-73144 JP 7-246199 A JP 2006-122723 A

  By the way, the radiation solid state detector is usually a so-called direct type radiation solid state detector in which the radiation that has passed through the subject is directly incident on the radiation detecting element and detected, and the radiation that has passed through the subject is once incident on the scintillator. Thus, the radiation is roughly classified into so-called indirect radiation solid state detectors that convert the electromagnetic waves into electromagnetic waves of other wavelengths and make the converted electromagnetic waves incident on the radiation detection element for detection.

  In the radiation solid state detector, when the incident radiation or the electromagnetic wave converted from the radiation by the scintillator is incident on the radiation detection element, the radiation dose in the radiation detection element or the amount of the converted electromagnetic wave proportional to it is changed. Since charges are generated in proportion, image data proportional to the radiation dose is read from each radiation detection element. Hereinafter, the image data proportional to the radiation dose is referred to as first image data.

  On the other hand, the image data read by detecting the photostimulated light emitted from the photostimulable phosphor sheet or the photostimulable phosphor plate when irradiated with the excitation light is usually a photostimulable phosphor sheet or the like. It is read in a form proportional to the logarithm (log) of the dose of radiation irradiated to each pixel. Hereinafter, the image data proportional to the logarithm of the radiation dose is referred to as second image data.

  Therefore, when these image data are subjected to image processing to obtain a final radiation image, it is necessary to perform different image processing between the first image data and the second image data. However, how to perform image processing when radiographic imaging is performed using a radiation solid state detector (FPD) and when radiographic imaging is performed using a CR cassette containing a stimulable phosphor sheet or the like. Is inconvenient when an operator such as a radiologist performs image processing.

  In addition, when a diagnosis is performed based on a final radiographic image obtained by performing erroneous image processing on the first image data and the second image data, a lesioned part captured in the radiographic image is overlooked. As a result, misdiagnosis may occur.

  Therefore, when radiographic imaging is performed, image processing is accurately performed with the same operation regardless of whether a solid state detector (FPD) is used or a CR cassette containing a stimulable phosphor sheet is used. In addition, radiographic imaging capable of automatically determining whether image data to be subjected to image processing is first image data or second image data and performing image processing accurately It is desirable to build a system.

  In addition, it is assumed that the number of cases where radiation solid state detectors (FPDs) will be introduced later into facilities configured with existing CR imaging devices is expected to increase in the future. It is desirable to enable smooth introduction and not affect the diagnostic ability of the lesion.

  The present invention has been made in view of the above-mentioned problems, and it is possible to perform the same operation and accuracy regardless of whether a radiation solid state detector or a stimulable phosphor sheet (CR cassette) is used for radiographic imaging. Another object of the present invention is to provide a radiographic imaging system capable of performing image processing.

In order to solve the above-described problem, the radiographic imaging system of the present invention includes:
A radiation generator for irradiating the subject with radiation;
A radiation solid state detector in which a plurality of radiation detection elements are arranged in a two-dimensional manner, and radiation that has passed through a subject is detected by each of the radiation detection elements to generate first image data proportional to the radiation dose,
A reading device for reading second image data proportional to the logarithm of the radiation dose from a stimulable phosphor irradiated with radiation transmitted through a subject;
A console capable of image processing both the transmitted first image data and the second image data;
With
The console is
When the transmitted image data is the first image data, a correction process for correcting the first image data based on the reading efficiency from each of the radiation detection elements according to the dose of irradiated radiation; Preprocessing means for performing logarithmic conversion processing for logarithmically converting the first image data;
For the transmitted second image data and the first image data corrected by the preprocessing means and logarithmically converted, a gradation process predetermined for each imaging target part that is a subject is commonly performed. Gradation processing means to perform;
It is characterized by providing.

  According to the radiographic imaging system of the system as in the present invention, when the imaging apparatus used for radiographic imaging is a radiation solid state detector (FPD), the first image data is read efficiently from the radiation detection element. The radiation solid state detector and the CR cassette are configured so that gradation processing is performed in the same manner as the second image data obtained using the CR cassette after performing preprocessing based on logarithmic conversion. In any case, an operator such as a radiologist can perform the same image processing operation to obtain final image data.

  Moreover, since it becomes possible to image-process the 1st image data image | photographed with the radiation solid detector by operation similar to operation in CR imaging device, operators, such as a radiographer, use a radiation solid detector. Image processing can be performed by the same operation when radiographic imaging is performed and when radiographic imaging is performed using a CR cassette. Therefore, the radiographic imaging system of the system as in the present invention is convenient for the operator.

  Further, when the imaging device used for radiographic imaging is a radiation solid state detector, preprocessing for correcting the first image data based on the reading efficiency from the radiation detection element and logarithmic conversion is performed, In the gradation processing that is performed in common for the first image data and the second image data, gradation processing that is predetermined for each imaging target portion that is a subject is performed.

  Therefore, even when a radiation solid state detector (FPD) is added to a CR cassette operating facility, the gradation characteristics defined to match the diagnostic resolution established in the conventional screen / film system are maintained. . At the same time, since it is possible to perform image processing accurately so that the imaging target site where the information such as the lesion is imaged is appropriately displayed on the radiographic image, the diagnostic ability cultivated by doctors ( The detection of a lesion part based on contrast in each part is maintained, and an appropriate diagnosis can be made without causing a misdiagnosis by overlooking the lesion part taken in the radiographic image.

It is a figure which shows the whole structure of the radiographic imaging system which concerns on this embodiment. It is a perspective view showing a radiation solid detector concerning 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 which concerns on this embodiment. FIG. 5 is an enlarged view showing a configuration of an imaging element, a thin film transistor, and the like formed in a small region on the substrate of FIG. 4. It is a side view explaining the board | substrate with which COF, a PCB board | substrate, etc. were attached. It is a figure showing the equivalent circuit schematic of the radiation solid detector concerning this embodiment. It is a figure which shows the structure of the reading part of a reader. (A) Histogram representing signal value distribution of second image data, (B) Histogram representing signal value distribution of normalized second image data. It is a graph which shows an example of the normalization LUT of the signal value of 2nd image data. It is a graph which shows an example of the gradation LUT set for every imaging | photography object site | part. It is a graph which shows the relationship between the dose of a radiation, and the reading efficiency from a radiation detection element.

  Embodiments of a radiation image capturing system according to the present invention will be described below with reference to the drawings. However, the present invention is not limited to the following illustrated examples.

  In the following embodiments, a so-called indirect radiation that includes a scintillator or the like as a radiation solid state detector, converts the emitted radiation into electromagnetic waves of other wavelengths such as visible light, and obtains an electrical signal by the radiation detection element. Although the solid state detector will be described, the present invention can also be applied to a so-called direct type radiation solid state detector in which radiation is directly detected by a radiation detecting element without using a scintillator or the like.

  Further, in the following embodiment, a case where the radiation solid detector is a portable radiation solid detector and is mounted in a Bucky device or used alone will be described. However, the radiation solid detector is integrated with a support base or the like. The present invention can also be applied to the case where it is formed as a whole.

  FIG. 1 is a diagram illustrating an overall configuration of a radiographic image capturing system according to the present embodiment. The radiographic imaging system 50 of this embodiment is a system that assumes radiographic imaging performed in, for example, a hospital or clinic, and can be employed as a system that captures medical diagnostic images as radiographic images.

  As shown in FIG. 1, the radiographic imaging system 50 includes, for example, an imaging room R <b> 1 that irradiates radiation and images a subject (part of a patient to be imaged) that is a part of a patient (not shown), and a radiographer or doctor. The operator is arranged in the front chamber R2 for performing various operations such as control of radiation applied to the subject and image processing of the acquired radiation image. The imaging room R1 is often shielded with lead or the like so that radiation does not leak outside.

  In the present embodiment, the radiographing room R1 includes a bucky device 51 that can be loaded with a radiation solid detector 1 to be described later, a radiation generation device 52 that includes an X-ray tube (not shown) that generates radiation to irradiate a subject, a radiation solid A wireless access point (base station) 54 provided with a wireless antenna 53 that relays these communications when the detector 1 and the console 58 communicate wirelessly is provided.

  In the anterior chamber R2, an operation console 56 that controls irradiation of radiation provided with a switch means 55 for instructing the start of irradiation of radiation from the radiation generating device 52, and the radiation solid state detector 1 described later. A tag reader 57 that detects tags and a console 58 that controls the entire radiographic imaging system 50 are provided. The console 58 is connected to storage means 59 composed of a hard disk or the like.

  First, the radiation solid detector 1 will be described. FIG. 2 is an external perspective view of the radiation solid state detector according to the present embodiment, and FIG. 3 is a cross-sectional view taken along the line AA of FIG. The radiation solid detector 1 according to the present embodiment is a cassette-type portable radiation solid detector in which a scintillator 3, a substrate 4, and the like are housed in a housing 2 as shown in FIGS. 2 and 3. It is configured.

  The housing 2 is formed of a material such as a carbon plate or plastic that transmits radiation at least on a surface R (hereinafter referred to as a radiation incident surface R) that receives radiation. 1 and 2 show a case where the housing 2 is a lunch box type formed by the frame plate 2A and the back plate 2B, but the housing 2 is formed integrally, for example, A so-called monocoque type, such as the X-ray imaging apparatus described in Japanese Unexamined Patent Publication No. 2002-31526, can also be used.

  Further, a power switch 37 of the radiation solid state detector 1 and an indicator 38 for displaying various operation statuses are provided on the short side surface portion on one side of the housing 2. Also, a lid member 39 for replacing an internal battery (not shown) is provided on the side surface portion, and the radiation solid detector 1 transmits and receives data and signals to and from an external device in a wireless manner. An antenna device 40 for performing is embedded and provided.

  The location where the antenna device 40 is provided is not limited to one short side surface portion of the housing 2 as in the present embodiment, and may be provided at another position. Further, the number of antenna devices 40 is not necessarily limited to one, and a necessary number is provided as appropriate.

  As shown in FIG. 3, a base 31 is disposed on the lower side of the substrate 4 inside the housing 2, and a PCB substrate 33 on which electronic components 32 and the like are disposed and a buffer member are disposed on the base 31. 34 etc. are attached. In the present embodiment, the radiation that has entered the lower surface side of the base 31 and the PCB substrate 33 from the radiation incident surface R side of the radiation solid detector 1 and has passed through the scintillator 3, the substrate 4, the base 31, etc. A radiation sensor 35 for detection is attached. A glass substrate 36 for protecting the substrate 4 and the scintillator 3 on the radiation incident surface R side is disposed.

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

  In the present embodiment, the substrate 4 is formed of a glass substrate. As shown in FIG. 4, 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 of the small regions r defined by the plurality of scanning lines 5 and the plurality of signal lines 6 on the surface 4a of the substrate 4, radiation detection elements 7 that are photoelectric conversion elements in the present embodiment are provided. In this way, the radiation detection elements 7 are two-dimensionally arranged on the substrate 4, and the entire region r in which the plurality of radiation detection elements 7 are provided, that is, the region indicated by the alternate long and short dash line in FIG. P.

  In the present embodiment, as the radiation detection element 7, the radiation incident from the radiation incident surface R is converted by the scintillator 3 and output, according to the amount of electromagnetic waves (increased according to the radiation dose incident on the scintillator 3). For example, a phototransistor or the like can also be used.

  As shown in the enlarged views of FIGS. 4 and 5, one of the pair of electrodes of each radiation detection element 7 (an electrode (not shown in the figure)) is a source of a TFT (thin film transistor) 8 that is a switch element. The drain electrode 8 d of the TFT 8 is connected to the signal line 6. When the TFT 8 is turned on, that is, when a voltage for signal readout is applied to the gate electrode 8g and the gate of the TFT 8 is opened, the charge accumulated in the radiation detection element 7 is applied to the signal line 6. It is supposed to be released.

  Further, a bias line 9 for applying a reverse bias voltage to the radiation detection element 7 is connected to the other electrode (front electrode in the figure) of the radiation detection element 7 via this electrode. As shown in FIGS. 4 and 5, in the present 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. In addition, each bias line 9 is bound to one connection 10 at a position outside the detection portion P of the substrate 4.

  In the present embodiment, the connection lines 10 of the scanning lines 5, the signal lines 6, and the bias lines 9 are respectively connected to input / output terminals (also referred to as pads) 11 provided near the edge of the substrate 4. 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.

  Here, the circuit configuration of the radiation solid state detector 1 will be described. FIG. 7 is an equivalent circuit diagram of the radiation solid state detector 1 according to the present embodiment.

  As described above, in each radiation detection element 7 of the detection unit P of the substrate 4, one electrode 78 is connected to the bias line 9, and the connection 10 of the bias line 9 is connected to the reverse bias power supply 14. . The reverse bias power supply 14 supplies a reverse bias voltage to be applied to each radiation detection element 7 via the connection 10 and each bias line 9. The reverse bias power supply 14 is connected to the control means 22, and the control means 22 controls the reverse bias voltage applied to each radiation detection element 7 from the reverse bias power supply 14.

  The other electrode 74 of each radiation detection element 7 is connected to a source electrode 8s (denoted as S in FIG. 7) of the TFT 8, and a gate electrode 8g (denoted as G in FIG. 7) of each TFT 8. Is connected to each scanning line 5 extending from the scanning drive circuit 15. Further, the drain electrode 8 d (denoted as D in FIG. 7) of each TFT 8 is connected to each signal line 6.

  When a signal readout voltage is applied from the scanning drive circuit 15 to the gate electrode 8g of the TFT 8 via the scanning line 5, the gate of the TFT 8 is turned on, and an irradiation line is irradiated by radiographic imaging to detect the radiation detection element. The charge generated and accumulated in the pixel 7 is read from the drain electrode 8d to the signal line 6 via the source electrode 8s of the TFT 8. Each signal line 6 is connected to each readout circuit 17 formed in the readout IC 16.

  The readout circuit 17 includes an amplifier circuit 18, a correlated double sampling circuit 19, and an A / D converter 20, and one circuit is provided for each signal line 6. However, in the present embodiment, the A / D converter 20 is common to a plurality of circuits, and each electric signal output from each correlated double sampling circuit 19 is sequentially supplied to the A / D converter 21 via the analog multiplexer 21. The data is transmitted to the D converter 20 and is sequentially converted into a digital value by the A / D converter 20.

  In this way, in the readout circuit 17, charges are read from the radiation detection elements 7 through the signal lines 6, and the charges are converted into electric signals by charge-voltage conversion and amplification for each radiation detection element 7, It is output as digital image data.

  The correlated double sampling circuit 19 is represented as CDS in FIG. In this case, the image data output as a digital value is generated in proportion to the radiation dose and the electromagnetic wave converted by the scintillator 3 in proportion to the radiation dose in the radiation detection element 7 as described above. Due to the electric charge, each radiation detection element 7 reads out image data proportional to the radiation dose, that is, first image data.

  The control means 22 is composed of a microcomputer equipped with a CPU (Central Processing Unit) or the like, or a dedicated control circuit, and controls the operation of each member of the radiation solid state detector 1. The control means 22 is connected to a storage means 23 composed of a RAM (Random Access Memory) or the like. Then, as described above, the control means 22 stores the first image data output for each radiation detection element 7 in the storage means 23 in association with the radiation detection element 7.

  Further, as described above, the control unit 22 controls the reverse bias power supply 14 to control the reverse bias voltage applied to each radiation detection element 7 or scans to apply a signal readout voltage from the scan drive circuit 15. The electrical signal is read from each radiation detection element 7 by switching the line 5 or controlling the amplification circuit 18 and the correlated double sampling circuit 19 in each readout circuit 17.

  Further, the antenna device 40 described above is connected to the control means 22, and the control means 22 transmits the first image data to the console 58 via the wireless access point 54 (see FIG. 1). Yes. The transmission of the first image data from the radiation solid detector 1 to the console 58 can be configured to be transmitted in response to a transmission request signal from the console 58. By operating the radiation solid detector 1, It is also possible to configure to send the first image data to the console 58.

  Further, a battery 41 (see FIG. 7) for supplying electric power to each member such as each radiation detection element 7 is connected to the control means 22. Thus, the battery 41 is built in the housing 2 of the radiation solid state detector 1, and the battery 41 has a connection terminal 42 for charging the battery 41 by supplying power from the external device to the battery 41. It is attached.

  The control unit 22 is connected to the radiation sensor 35 described above. In the present embodiment, as described above, the start and end of radiation irradiation to the radiation solid detector 1 are detected based on the radiation dose detected by the radiation sensor 35. However, instead of providing the radiation sensor 35, when the radiation solid detector 1 is irradiated with radiation, a current flowing out from each radiation detection element 7 to the bias line 9 or the connection 10 is detected to detect radiation to the radiation solid detector 1. It is also possible to configure to detect the start and end of irradiation.

  Moreover, it is also possible to notify the radiation solid-state detector 1 of the start and end of radiation irradiation via an antenna device 40 from an external device such as a console 56 of the radiation generator 52 described later.

  Further, as described above, the control means 22 causes the radiation that has passed through the subject during radiographic imaging to enter the scintillator 3, and electromagnetic waves of other wavelengths converted from the radiation by the scintillator 3 receive the radiation detection elements 7. In addition to performing readout processing for reading out the charges generated by being incident on the first image data, reset processing for releasing extra charges from each radiation detection element 7 and each readout circuit 17 is performed as necessary. ing.

  In addition, in the radiation detection element 7, a charge (that is, an electric charge generated by radiation of the radiation detection element 7 itself (ie, heat generated by radiation of the radiation (or electromagnetic waves converted from the radiation)) (ie, thermal excitation by heat of the radiation detection element 7 itself) The first image data read out as described above includes an offset due to the dark charge. Then, true first image data is obtained by subtracting the offset from the first image data.

  In order to calculate the offset due to the dark charge, there is a case where a dark reading process is performed in which the radiation solid detector 1 is left for a predetermined time without radiation and the dark charge accumulated in each radiation detection element 7 is read. However, this dark reading process is appropriately performed also in the radiation solid state detector 1 according to the present embodiment. Then, the control means 22 calculates an offset for each radiation detection element 7 based on the dark reading value obtained by the dark reading process.

  Although the basic configuration of the radiation solid detector 1 is as described above, in the present embodiment, the radiation solid detector 1 further has the following configuration.

  Specifically, a tag (not shown) is incorporated in the radiation solid detector 1. In this embodiment, a tag called a so-called RFID (Radio Frequency IDentification) tag is used as a tag, and the tag stores a control circuit that controls each part of the tag and a storage that stores unique information of the radiation solid state detector 1. The part is built in compactly. The unique information includes, for example, a cassette ID, scintillator type information, size information, resolution, and the like as identification information assigned to the radiation solid detector 1.

  Moreover, in this embodiment, the radiation solid state detector 1 is configured in a size conforming to JIS Z 4905 (corresponding international standard is IEC 60406) in a conventional screen / film cassette. That is, the thickness in the radiation incident direction is within a range of 15 mm + 1 mm to 15 mm-2 mm, and is 8 inches × 10 inches, 10 inches × 12 inches, 11 inches × 14 inches, 14 inches × 14 inches, 14 inches × 17 inches. (Half cut size) etc. are prepared.

  Thus, in this embodiment, since the radiation solid state detector 1 is formed in conformity with the JIS standard regarding the cassette for screens / films, a CR cassette formed in conformity with the JIS standard can be loaded. A radiation solid state detector 1 can be mounted on a bucky device 51 (see FIG. 1) for a CR cassette.

  The present invention is not limited to the case where the radiation solid detector 1 is formed in conformity with the JIS standard as described above, or the case where the bucky device 51 for CR cassette is used as the bucky device 51. However, if the bucky device 51 for CR cassette is used as the bucky device 51, the radiation solid image detector 1 as the FPD and the conventional CR cassette can be loaded into the bucky device 51 to perform radiographic imaging. It becomes.

  On the other hand, the radiation solid state detector 1 is not loaded in the bucky device 51, and can be used in a so-called single state. That is, the radiation solid state detector 1 is disposed in a single state, for example, on a support stand provided in the photographing room R1 or a bucky device 51B for lying position photographing, and a subject on the radiation incident surface R (see FIG. 1). The patient's hand or the like can be placed, or can be used, for example, inserted between the patient's waist or legs lying on the bed and the bed. In this case, for example, radiographic imaging is performed by irradiating the radiation solid state detector 1 with radiation from the portable radiation generator 52B or the like through the subject.

  The bucky device 51 is provided with a cassette holding unit 51a for holding the radiation solid detector 1 in a predetermined position, and the cassette unit 51a can be loaded with the radiation solid detector 1 and the CR cassette. Yes. Further, in the present embodiment, as the bucky device 51, there are provided a bucky device 51A for standing position shooting and a bucky device 51B for standing position shooting.

  The imaging room R1 includes at least one radiation generating device 52 including an X-ray tube that irradiates a subject with radiation and irradiates the radiation solid-state detector 1 and CR cassette loaded in the Bucky device 51 with radiation transmitted through the subject. One is provided. In the present embodiment, one radiation generating device 52A is shared by the bucky devices 51A and 51B for standing position shooting and lying position shooting. It should be noted that it is also possible to configure each of the bucky devices 51A and 51B in association with a separate radiation generating device.

  At the time of radiography, the radiation generator 52A applies an appropriate dose of radiation to, for example, the radiation solid detector 1 and the CR cassette based on an instruction from an operation console 56 described later. It is set up to change the power to be supplied, etc., is moved to a predetermined position by a moving means (not shown), and the direction is adjusted so that the radiation direction is directed to a predetermined direction.

  In the present embodiment, a portable radiation generation device 52B that is not associated with the standing-up imaging device 51A and the standing-up imaging device 51B is also provided. It can be carried to any place in the photographing room R1, and can be irradiated with radiation in any direction.

  In the present embodiment, the portable radiation generation device 52B is also set up based on an instruction from the console 56. In addition to this, for example, an operator can manually set up, It is also possible to set up by transmitting a radio signal from the radiation solid state detector 1 to the portable radiation generator 52B.

  A wireless access point provided with a radio antenna 53 that relays the communication between the radiation solid state detector 1 and the console 58, the switch means 55 of the console 56, etc., in a corner of the radiographing room R1. 54 is installed.

  FIG. 1 shows a case where the wireless access point 54 is provided near the entrance of the imaging room R1, but the present invention is not limited to this, and wireless communication with the antenna device 40 of the radiation solid state detector 1 is possible. It is installed at an appropriate position where possible. In the present embodiment, the wireless access point 54 is connected to each of the bucky devices 51A and 51B with a cable or the like, and communicates with the bucky devices 51A and 51B, the radiation solid state detector 1 loaded therein, the console 58, and the like. It can also be performed by a wired system.

  On the other hand, the front room R2 is provided with an operation console 56 provided with a switch means 55 for instructing the start of radiation irradiation from the radiation generator 52. The console 56 includes a computer having a general-purpose CPU (Central Processing Unit), a computer having a dedicated processor, or the like. In the present embodiment, the console 56 is connected to the switch means 55 and the radiation generator 52 and also to the console 58.

  As shown in FIG. 1, a stroke detecting means 60 for detecting that a button portion (not shown) of the switch means 55 is pressed by an operator such as a radiologist is attached. Radiation is started via the wireless access point 54 when the radio button is detected and the radiation generator 52 is instructed to start radiation irradiation and the radiation is stopped after the pressing is released. If such information is transmitted to the solid state detector 1, as described above, the radiation solid state detector 1 is provided with the radiation sensor 35 for detecting the start and end of radiation irradiation. It is not necessary to detect the start or end of radiation irradiation with the device 1 itself.

  A tag reader 57 for exchanging information with the radiation solid detector 1 is installed in the vicinity of the entrance of the front chamber R2 using the RFID technology described above. The tag reader 57 transmits predetermined instruction information on radio waves or the like via a built-in antenna (not shown), and detects the radiation solid detector 1 entering or leaving the front room R2 or the imaging room R1. Yes. The tag reader 57 reads the unique information stored in the detected RFID tag of the radiation solid detector 1 and transmits the read unique information to the console 58.

  The console 58 is composed of a computer in which a CPU, a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface and the like (not shown) are connected to the bus, and reads a predetermined program stored in the ROM. It expands in the work area of the RAM and executes various processes according to the program to control the entire radiographic imaging system 50 as described above.

  Although FIG. 1 shows a case where the console 58 is installed outside the photographing room R1 or the front room R2, for example, the console 58 can be configured to be installed in the front room R2 or the like. It is. It is also possible to configure a plurality of shooting rooms R1 and the like with one console 58.

  The console 58 is connected to the above-described console 56, tag reader 57, and the like, and is connected to the wireless access point 54 via the console 56 and the like. The console 58 is connected to a storage means 59 composed of an HDD (Hard Disk Drive) or the like. Further, the console 58 is provided with a display screen 58a made up 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 receives the unique information including the cassette ID of the radiation solid state detector 1 detected by the tag reader 57 as described above, the radiation existing in the imaging room R1 and the like registered in the storage unit 59 is transmitted to the console 58. A list of the solid state detector 1 is referred to. If the transmitted unique information is not registered in the storage unit 59, the console 58 detects that the radiation solid detector 1 has been newly brought into the imaging room R1 or the front room R2. The cassette ID of the device 1 is added to the above list and registered in the storage means 59.

  If the transmitted unique information is already registered in the storage means 59, it is assumed that the radiation solid detector 1 is taken out from the imaging room R1 or the front room R2. Delete the cassette ID etc. from the above list. In this way, the console 58 grasps the radiation solid detector 1 brought into or taken out of the photographing room R1 or the like and manages it on the storage means 59.

  The console 58 is a reading device that reads image data from a stimulable phosphor when a CR cassette containing a stimulable phosphor sheet or a stimulable phosphor plate is used for radiographic imaging. 61 is connected. As the reading device 61, for example, a known reading device as described in Patent Document 3 described above is used.

  The reading unit of the reading device 61 is configured, for example, as shown in FIG. 8, and when a CR cassette (not shown) used for radiographic imaging is loaded in the reading device 61, the stimulable phosphor sheet starts from the CR cassette. S and the like are taken out, and the photostimulable phosphor sheet S is driven on a flat platen (not shown) by a conveyance roller (not shown) and conveyed in a conveyance direction Y indicated by an arrow Y in the drawing. .

  Also, the excitation light L1 that is laser light emitted from the laser diode 62 is converted into parallel light by the collimator lens 63, and a small part of the parallel light is reflected by the beam splitter 64 and sent to the detector 65 for laser power monitoring. Feedback to the laser driver circuit 66, and the laser output from the laser diode 62 is adjusted. Further, the excitation light L1 is refracted by the imaging lens 67 made of a cylindrical lens, is imaged and reflected linearly on the mirror surface of the polygon mirror 68, passes through the fθ lens 69 and the cylindrical mirror 70, and then is a stimulable phosphor sheet. The reading surface of S is irradiated.

  At this time, the inclination of the mirror surface with respect to the excitation light L1 incident on the mirror surface of the polygon mirror 68 changes as the polygon mirror 68 itself rotates, so that the excitation light L1 incident on the photostimulable phosphor sheet S is read. The surface is moved in the main scanning direction X indicated by an arrow X in the figure, and the reading surface is scanned along the reading line Z.

  Note that the mirror surface that reflects the excitation light L1 is sequentially switched by the rotation of the polygon mirror 68, so that the excitation light L1 scanned from the right end to the left end of the reading line Z in FIG. Scan from the right end to the left end of the read line Z. In this way, the excitation light L1 repeats scanning in one direction on the main scanning direction X along the reading line Z on the reading surface of the photostimulable phosphor sheet S by the rotation of the polygon mirror 68. It has become.

  Then, the stimulable phosphor sheet S or the like is repeated by repeating the scanning in the main scanning direction X along the reading line Z of the excitation light L1 with respect to the stimulable phosphor sheet S or the like conveyed in the transport direction Y. The excitation light L1 is sequentially irradiated two-dimensionally over a predetermined range of the reading surface.

  When the reading surface of the photostimulable phosphor sheet S is irradiated with the excitation light L1, the radiation energy accumulated in the photostimulable phosphor layer in the photostimulable phosphor sheet S is stimulated emission light (fluorescence) L2. Is emitted as. Then, the stimulated emission light L2 is condensed on the condenser 72 via the light guide means 71 and guided to the photoelectric conversion means 73 such as a photomultiplier tube or a photodiode. Then, the photoelectric conversion means 73 reads and amplifies the condensed stimulated light L2 and outputs a current value or a voltage value proportional to the light amount of the stimulated light L2.

  As described above, since the excitation light L1 is scanned in the main scanning direction X with respect to a predetermined range of the reading surface such as the photostimulable phosphor sheet S conveyed in the conveyance direction Y, the photostimulable phosphor sheet S is scanned. A current value or a voltage value proportional to the amount of the stimulated emission light L2 is output for each pixel on the reading surface within a predetermined range.

  For example, as described in Patent Document 3 described above, in a normal reading device, as described above, in order to obtain the same gradation characteristic as that of a radiographic image obtained when an image is taken with an old screen / film system, as described above. The current value or voltage value proportional to the amount of the stimulated emission light L2 output from the photoelectric conversion means 73, that is, the output value proportional to the radiation dose is A / D converted, logarithmically converted, and the radiation dose. In many cases, the image data is converted into image data proportional to the logarithm of the image and output.

  Also in the reading device 61 according to the present embodiment, each of the photostimulated phosphors such as the photostimulable phosphor sheet S irradiated with the radiation transmitted through the subject at the time of radiographic imaging is read and amplified by the photoelectric conversion means 73. The output value for each pixel is an output value proportional to the amount of the stimulated emission light L2, but the output value is A / D converted by a conversion means (not shown) and logarithmically converted, and is proportional to the logarithm of the radiation dose. Image data, ie, second image data for each pixel is converted and output.

  When the reading device 61 converts the output value read from each pixel such as the photostimulable phosphor sheet S into the second image data as described above, the second image data for each pixel is converted into the console 58 (see FIG. 7). To be sent to.

  Hereinafter, the gradation processing for the second image data and the processing for the first image data in the console 58 will be described, and the operation of the radiation image capturing system 50 according to the present embodiment will be described.

  The console 58 functions as gradation processing means in the present invention, and the following is applied to the second image data read from the photostimulable phosphor such as the photostimulable phosphor sheet S by the reader 61. Such gradation processing is performed.

  As described above, the second image data is logarithmically transformed into image data proportional to the logarithm of the radiation dose. In addition, the gradation processing is configured to be similarly performed on the first image data that has been pre-processed and logarithmically converted as described later, and the second image data and the pre-processing are performed. The gradation processing is commonly performed on the first image data.

  In the gradation processing, when the above-described second image data for each pixel is transmitted from the reading device 61, the console 58 votes the pixels for each pixel as shown in FIG. 9A. The distribution of the signal value f of the second image data for each is obtained. When the console 58 specifies the maximum value H and the minimum value L of the distribution of the signal value f, as shown in FIG. 9B, the maximum value H and the minimum value L of the distribution of the signal value f are respectively radiation. Each signal value f is normalized so as to be the maximum reference value SH and the minimum reference value SL in the image.

In the process of converting each signal value f to each normalized signal value f ^* , each signal value f is normalized in accordance with a normalized LUT (Look Up Table) as shown in FIG. Although it is often converted linearly to f ^* , it is not always necessary to convert linearly, and the normalized LUT is appropriately set. Further, as will be described later, the normalization LUT used when the signal values are normalized with respect to the first image data that has been preprocessed and logarithmically converted is different from the normalization LUT used for the second image data. It may be an LUT and is prepared in advance as necessary.

Next, the console 58 sets the normalized signal value f ^* to the final image data F according to each gradation LUT as shown in FIG. 11, for example, set in advance for each imaging target part of the patient's body as a subject. It is supposed to convert to. As a subject to be imaged of the patient's body, which is the subject, for example, a specific part such as a patient's head, neck, chest, abdomen, arms, hands, legs, or mammography breast is set By performing such conversion, the region to be imaged in which information such as the lesion is imaged is appropriately displayed on the radiographic image, so that the doctor appropriately diagnoses Can be reduced.

  Prior to radiographic imaging, the console 58 can set radiographing order information that defines patient information, radiographic target sites, radiographing methods, and the like that are radiographic imaging targets. 1 and the reading device 61, when the first image data and the second image data for each pixel (each radiation detection element 7) are transmitted, the console 58 converts the first image data and the second image data, In some cases, the image data is stored in association with radiographing order information of radiographic imaging performed to obtain image data.

  In such a case, the console 58 uses information about whether the image data associated with the shooting order information is the first image data or the second image data, and the shooting device used for shooting the image data. Is preferably configured to store information such as whether it is a radiation solid state detector (FPD) 1 or a CR cassette in association with imaging order information.

  Further, the console 58 refers to the imaging order information associated with the second image data, identifies the imaging target part of the patient's body, which is the subject, and the gradation LUT set in advance for the imaging target part. The final image data F can be converted according to the above. Further, when not configured in this way, for example, it is possible to configure the operator to input and set the imaging target region on the console 58.

  On the other hand, when the first image data for each pixel (each radiation detection element 7) is transmitted from the radiation solid-state detector 1, the console 58 performs preprocessing for the first image data prior to the above gradation processing. Is supposed to do. That is, the console 58 functions as preprocessing means in the present invention.

  As described above, each first image data transmitted from the radiation solid detector 1 is proportional to the logarithm of the dose of radiation read from the stimulable phosphor such as the stimulable phosphor sheet S by the reader 61. Unlike the second image data, the radiation dose irradiated to each radiation detection element 7 (in this embodiment, the radiation incident from the radiation incident surface R of the radiation solid detector 1 is converted by the scintillator 3 and output. Image data proportional to the amount of electromagnetic waves).

  Therefore, a logarithmic conversion process for performing logarithmic conversion on each first image data is required as a pre-process for converting each first image data into a form suitable for the above gradation processing.

  However, the radiation detection element 7 used in the radiation solid-state detector 1 does not have a read efficiency of charges read from each radiation detection element 7 in one readout process, and as shown in FIG. The reading efficiency from the radiation detection element 7 has a characteristic that it changes depending on the dose of radiation irradiated directly on the radiation detection element 7 or indirectly through the scintillator 3. Therefore, it is necessary to perform a correction process for correcting the first image data based on the reading efficiency from the radiation detection element 7 corresponding to the dose of the irradiated radiation.

  As shown in FIG. 12, the reading efficiency from the radiation detecting element 7 has a characteristic that it converges to a constant value of about 90% when the radiation dose becomes 10 [mR] or more. In addition, the transmittance of the radiation that passes through the subject varies depending on the region to be imaged, such as the chest (front and side surfaces) and legs of the patient as the subject, and even if the patient is different, the region to be imaged is the same. For example, it is empirically known that the transmittance is almost the same.

  Therefore, in the correction processing in the present embodiment, the radiation transmittance is set in advance according to the region to be imaged, and the console 58 sets the radiation irradiation dose set for the radiation generator 52 (see FIG. 1). The radiation dose incident on the radiation incident surface R of the radiation solid detector 1 is calculated by multiplying the radiation transmittance according to the imaging target region of the patient specified by the imaging order information described above. Then, referring to the readout efficiency from the radiation detection element 7 as shown in FIG. 12, when the readout efficiency a corresponding to the calculated radiation dose does not reach the constant value A such as 90% described above. The first image data is corrected by A / a to correct the first image data.

  In the correction process, as described above, the first image data is not corrected only when the reading efficiency a does not reach the constant value A. For example, a predetermined reading efficiency B is set in advance. The reading efficiency from the radiation detection element 7 corresponding to the radiation dose calculated by multiplying the radiation dose of the radiation generator 52 by the radiation transmittance corresponding to the imaging target region as described above is b. In this case, the first image data can be corrected by multiplying the first image data by B / b.

  Then, the console 58 performs logarithmic conversion processing that performs logarithmic conversion on each corrected first image data. In this way, when the first image data is transmitted from the radiation solid detector 1 to the console 58, the console 58 corrects the first image data as described above, and performs a pre-processing for logarithmic conversion. Thereafter, the gradation processing is performed on the corrected and logarithmically converted first image data in the same manner as the gradation processing on the second data described above.

  In the present embodiment, as described above, the case where the logarithmic conversion process is performed after the correction process is performed on the first image data generated and transmitted by the radiation solid detector 1 has been described. After the logarithmic conversion process is performed on the first image data, the reading efficiency from the radiation detection element 7 as shown in FIG. With reference, it is also possible to perform a correction process in which correction is performed based on the reading efficiency from each of the radiation detection elements in accordance with the dose of irradiated radiation. Which of the correction process and the logarithmic conversion process is performed first is determined as appropriate.

  As described above, according to the radiographic imaging system 50 according to the present embodiment, when the imaging apparatus used for radiographic imaging is the radiation solid detector 1, the first image data is received from the radiation detection element 7. A gradation process is performed in the same manner as the second image data obtained using the CR cassette after performing a pre-process for performing a correction process for correcting based on the reading efficiency and a logarithmic conversion process for logarithmic conversion. By configuring, it is possible for an operator such as a radiographer to perform the same image processing operation and obtain final image data regardless of whether the radiation solid state detector 1 or the CR cassette is used.

  As mentioned above, CR imaging devices are still often used for radiographic imaging, and there are many radiographers who are accustomed to operating CR imaging devices. Since the first image data imaged by the radiation solid detector 1 can be image-processed by the same operation, the radiographic image capturing system 50 according to the present embodiment is also convenient for such a radiographer. It will be a thing.

  Further, when the imaging device used for radiographic imaging is the radiation solid state detector 1, preprocessing for correcting the first image data based on the reading efficiency from the radiation detection element 7 and logarithmically converting it is performed. In addition, gradation processing that is performed in common for the first image data and the second image data is performed for each photographing target portion that is a subject.

  Therefore, even when a radiation solid state detector (FPD) is added to a CR cassette operating facility, the gradation characteristics determined to match the diagnostic resolution established in the conventional screen / film system are maintained. . At the same time, since it is possible to perform image processing accurately so that the imaging target site where the information such as the lesion is imaged is appropriately displayed on the radiographic image, the diagnostic ability cultivated by doctors ( The detection of a lesion part based on contrast in each part is maintained, and an appropriate diagnosis can be made without causing a misdiagnosis by overlooking the lesion part taken in the radiographic image.

  In the above embodiment, the case where the first image data generated and transmitted by the radiation solid state detector 1 is preprocessed by the console 58 and gradation processing is performed has been described. However, the radiation image detector 1 may be configured to perform preprocessing, that is, correction processing and logarithmic conversion processing on the first image data.

  That is, after the first image data is generated by the radiation solid detector 1, as preprocessing, correction processing and logarithmic conversion processing based on reading efficiency from the radiation detection element 7 are performed on the generated first image data, The preprocessed first image data may be transmitted to the console 58, and the console 58 may be configured to perform gradation processing on the transmitted preprocessed first image data. At this time, as pre-processing, it is appropriately determined which of correction processing and logarithmic conversion processing for the first image data is performed first.

  In addition, after the first image data is generated by the radiation solid detector 1, the radiation solid detector 1 performs a correction process based on the reading efficiency from the radiation detection element 7 among the preprocessing for the generated first image data. The corrected first image data is transmitted to the console 58, and the console 58 is configured to perform a gradation process after performing a logarithmic conversion process for logarithmically converting the received corrected first image data. It is also possible.

  Further, after the first image data is generated by the radiation solid state detector 1, a logarithmic conversion process for logarithmically converting the first image data among the preprocessing for the generated first image data is performed by the radiation image detector 1, and the logarithm After the converted first image data is transmitted to the console 58, the console 58 performs correction processing based on the read efficiency from the radiation detection element 7 on the log-converted first image data transmitted. It is also possible to configure to perform gradation processing.

  In any of the above-described modifications, it is possible to obtain the same effect as that of the radiographic image capturing system 50 according to the above-described embodiment.

  Needless to say, the present invention is not limited to the above-described embodiments and modifications, and can be changed as appropriate. For example, in the radiation solid-state detector, when output characteristics of each radiation detection element are not uniform or when temperature fluctuation occurs, so-called offset correction, gain correction, defect correction, etc. are performed on the read image data. However, also in the above embodiment, correction based on the readout efficiency may be performed after performing correction specific to the radiation solid state detector such as offset correction and gain correction in the preprocessing stage.

DESCRIPTION OF SYMBOLS 1 Radiation solid state detector 7 Radiation detection element 50 Radiation imaging system 52 Radiation generator 58 Console (preprocessing means, gradation processing means)
61 Reader S Stimulable phosphor sheet (stimulable phosphor)

Claims (6)

A radiation generator for irradiating the subject with radiation;
A radiation solid state detector in which a plurality of radiation detection elements are arranged in a two-dimensional manner, and radiation that has passed through a subject is detected by each of the radiation detection elements to generate first image data proportional to the radiation dose,
A reading device for reading second image data proportional to the logarithm of the radiation dose from a stimulable phosphor irradiated with radiation transmitted through a subject;
A console capable of image processing both the transmitted first image data and the second image data;
With
The console is
When the transmitted image data is the first image data, a correction process for correcting the first image data based on the reading efficiency from each of the radiation detection elements according to the dose of irradiated radiation; Preprocessing means for performing logarithmic conversion processing for logarithmically converting the first image data;
For the transmitted second image data and the first image data corrected by the preprocessing means and logarithmically converted, a gradation process predetermined for each imaging target part that is a subject is commonly performed. Gradation processing means to perform;
A radiographic imaging system comprising: A radiation generator for irradiating the subject with radiation;
A radiation solid state detector in which a plurality of radiation detection elements are arranged in a two-dimensional manner, and radiation that has passed through a subject is detected by each of the radiation detection elements to generate first image data proportional to the radiation dose,
A reading device for reading second image data proportional to the logarithm of the radiation dose from a stimulable phosphor irradiated with radiation transmitted through a subject;
A console capable of image processing both the transmitted first image data and the second image data;
With
The radiation solid detector is configured to correct the generated first image data based on a reading efficiency from each radiation detection element according to a dose of irradiated radiation, and logarithmically the first image data. Logarithmic conversion processing to convert,
The console is
A gradation processing means for performing gradation processing predetermined for each part that is a subject in common with the transmitted second image data and the corrected and logarithmically converted first image data. A radiographic imaging system comprising:   The logarithmic conversion process is performed after the correction process, and the first image data corrected by the correction process is logarithmically converted in the logarithmic conversion process. The radiographic imaging system described.   The correction process is performed after the logarithmic conversion process. In the correction process, the first image data logarithmically converted by the logarithmic conversion process is obtained from each radiation detection element corresponding to the dose of irradiated radiation. The radiation image capturing system according to claim 1, wherein the radiation image capturing system is corrected on the basis of the reading efficiency. A radiation generator for irradiating the subject with radiation;
A radiation solid state detector in which a plurality of radiation detection elements are arranged in a two-dimensional manner, and radiation that has passed through a subject is detected by each of the radiation detection elements to generate first image data proportional to the radiation dose,
A reading device for reading second image data proportional to the logarithm of the radiation dose from a stimulable phosphor irradiated with radiation transmitted through a subject;
A console capable of image processing both the transmitted first image data and the second image data;
With
The radiation solid detector performs a correction process for correcting the generated first image data based on a readout efficiency from each radiation detection element according to a dose of irradiated radiation,
The console is
Pre-processing means for performing logarithmic conversion processing for logarithmically converting the corrected first image data when the transmitted image data is the corrected first image data;
For the transmitted second image data and the corrected first image data logarithmically converted by the preprocessing means, a predetermined gradation process is performed for each part that is a subject. Gradation processing means;
A radiographic imaging system comprising: A radiation generator for irradiating the subject with radiation;
A radiation solid state detector in which a plurality of radiation detection elements are arranged in a two-dimensional manner, and radiation that has passed through a subject is detected by each of the radiation detection elements to generate first image data proportional to the radiation dose,
A reading device for reading second image data proportional to the logarithm of the radiation dose from a stimulable phosphor irradiated with radiation transmitted through a subject;
A console capable of image processing both the transmitted first image data and the second image data;
With
The radiation solid detector performs a logarithmic conversion process for logarithmically converting the generated first image data,
The console is
When the transmitted image data is the logarithmically converted first image data, the logarithmically converted first image data is read from each of the radiation detection elements in accordance with the dose of the irradiated radiation. Preprocessing means for performing correction processing based on
For the transmitted second image data and the corrected first image data logarithmically converted by the preprocessing means, a predetermined gradation process is performed for each part that is a subject. Gradation processing means;
A radiographic imaging system comprising:

Images