JP2010246714A - Radiographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiographic apparatus acquiring a radiation transmission image suitable for diagnosis even when the behavior of a detecting element (undefined element) temporarily showing a defective property of the movement included in the radiographic apparatus is under an unstable condition. <P>SOLUTION: The X-ray imaging apparatus 1 prepares two maps used for removing a movement defective element reflected in the radiation transmission image. One of them is selected and the movement defective element reflected in the image is removed. A selecting section 16 selects either map for using. The selecting section 16 catches the radiation detecting element reduced over time which can not detect X-ray, and when the variation of increase and decrease is lowered to a predetermined level, the second map is selected as substitute for the first map. The result is that the defective movement detecting element reflected in the image is accurately removed, and regardless of the stability of FPD4, the radiation transmission image suitable for diagnosis can be always acquired. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a radiographic apparatus that irradiates a subject with radiation and generates a fluoroscopic image based on the radiation transmitted through the subject, and in particular, corrects a defective pixel of a radiation detector that detects radiation. It is related with the radiography apparatus which can do.

  A medical institution is provided with a radiation imaging apparatus that acquires a fluoroscopic image of a subject. A conventional configuration of such a radiation imaging apparatus will be described. A conventional radiographic apparatus includes a top plate on which a subject is placed, a radiation source provided on the top of the top, and radiation detection means (FPD) provided on the bottom of the top.

  In the FPD, radiation detection elements are two-dimensionally arranged, and a fluoroscopic image is reflected in the FPD when each of the radiation detection elements detects radiation. This perspective image is converted into image data in which pixel values are two-dimensionally arranged and output to a monitor or the like.

  However, not all of the radiation detection elements provided in the FPD function completely. That is, the radiation detection element provided in the FPD includes a malfunctioning element that cannot detect radiation. Such a malfunctioning element cannot sense radiation irradiation. The malfunctioning element appears as a bright spot or a dark spot on the image data, and deteriorates the visibility of the radioscopic image.

  Because of such inconvenience, in the conventional configuration, the arrangement of malfunctioning elements in the FPD is registered in a map, the pixel in which the malfunctioning element is reflected is specified in the image data, and the pixel value is changed. Thus, a configuration that removes the bright spots and dark spots described above is employed. Such a radiation imaging apparatus is described in Patent Document 1, for example.

Japanese Patent Laid-Open No. 2005-110981

However, the conventional radiographic apparatus has the following problems.
That is, according to the configuration as described above, when the detection element that temporarily shows defective operation, such as immediately after the radiation imaging apparatus is turned on, is in an unstable state, the radioscopy is sufficiently suitable for visual recognition. There is a problem that images cannot be provided. Among malfunctioning elements in the FPD, there are detection elements (indeterminate elements) that temporarily exhibit malfunctioning, that is, operations that repeat normal operations and malfunctions. Immediately after the power is turned on, many of the indefinite elements behave like malfunctions, but as time elapses after the power is turned on, the indefinite elements gradually start to operate normally.

  Some conventional radiographic apparatuses have a function of dynamically extracting malfunctioning elements from the FPD. That is, such a radiographic apparatus is configured to remove bright spots and dark spots that appear in an image based on a map that represents a position where a malfunctioning element appears in the image. However, the change in characteristics of the indefinite element as described above is relatively rapid, and it is almost impossible to predict the disposition of malfunctioning elements over time with the conventional function. In order to specify the arrangement of malfunctioning elements, it is necessary to refer to a plurality of pieces of image data while the behavior of the indefinite element is stable. Otherwise, the malfunctioning element is erroneously recognized and excessive image processing is performed, and the image is blurred. Further, the malfunctioning element is not recognized, and bright spots and dark spots remain in the radiographic image.

  In addition, even if you try to adopt a configuration that prepares multiple maps and switches according to changes in detectors, it is impossible to determine when to switch maps, so eventually the bright spots that appear in the image The dark spots cannot be removed sufficiently.

  The present invention has been made in view of such circumstances, and the purpose thereof is a state in which the behavior of a detection element (indefinite element) that temporarily includes defective operation included in a radiation detector is unstable. Even if it exists, it is providing the radiography apparatus which can acquire the radiographic image suitable for a diagnosis.

In order to solve the above-described problems, the present invention has the following configuration.
That is, the invention according to claim 1 is a radiation source that irradiates radiation, a radiation detection unit that detects radiation and includes a plurality of radiation detection elements, and a readout execution that executes readout of detection data to the radiation detection unit In the radiation imaging apparatus comprising the means and the image generation means for generating an image based on the detection data, among the radiation detection elements of the radiation detection means, the radiation detection elements that cannot detect radiation are temporarily defective elements Temporary defective elements are those that recover their ability to detect radiation over time, and those that do not recover their ability to detect other radiation are considered permanent defective elements. First map storage means for storing a first map indicating the position of the defective element in the radiation detection means, and radiation detection means for the permanent defective element A second map storage means for storing a second map indicating a position in the image; an image processing means for complementing pixels derived from a radiation detection element that cannot detect radiation reflected in the image using the map; Selection means for selecting which one of the map and the second map is used by the image processing means, (A) the selection means selects the first map, and (B) the read execution means is the intermittent The data is read out from the radiation detection means and the image generation means generates a monitoring reference image each time, and (D) the selection means detects the radiation reflected in each of the monitoring reference images. (E1) The selection means replaces the first map when the decrease is reduced to a predetermined level indicating when the recovery of the radiation detection capability of the recovery element is completed. It is characterized in that selects the second map.

  [Operation / Effect] According to the present invention, it is possible to provide a radiation imaging apparatus capable of acquiring an image suitable for diagnosis by removing an element having a defective operation regardless of the state of the radiation detection means. That is, the radiation imaging apparatus according to the present invention includes a first map storage unit and a second map storage unit, and selects any one of the two maps to remove malfunctioning elements that appear in the image. It has become. Therefore, a map suitable for removing malfunctioning elements can be selected and used in accordance with the state of the radiation detection means.

  Moreover, according to the present invention, the selection means selects which map is used. Specifically, the selection means first selects the first map. This is a map suitable when the radiation detection means is in the initial state. Subsequently, the selection unit monitors the radiation detection unit and changes the map used for the removal process of the malfunctioning element to the second map at an appropriate timing. The second map is a map suitable for example when the change in the state of the radiation detection means is settled and is in a stable state.

  Switching between maps by the selection means is performed as follows. That is, the monitoring reference image is acquired intermittently. By comparing the reference images for monitoring, it is possible to know the decrease over time of the radiation detection elements that cannot detect radiation. The selection means selects the second map instead of the first map when the increase / decrease change has decreased to a predetermined level. Since the present invention is configured to change the map based on the monitoring reference image, the malfunction detecting element reflected in the image is accurately removed, and is always regardless of the stability of the radiation detecting means. A radioscopic image suitable for diagnosis can be acquired.

  The invention according to claim 2 is characterized in that, in the radiation imaging apparatus according to claim 1, the recovery element cannot detect radiation when the radiation imaging apparatus is turned on.

  According to the above-described configuration, the recovery element cannot detect radiation when the radiation imaging apparatus is turned on. When the power of the radiation imaging apparatus is turned on, the operation of the radiation detection element is unstable, so that there are many radiation detection elements that cannot detect radiation. A part of the radiation detection element suffered from such an initial failure recovers the radiation detection ability. The present invention can be applied to a radiation imaging apparatus that has the largest number of radiation detection elements that cannot detect radiation when the power is turned on, and that the number gradually decreases as time passes.

  The invention according to claim 3 is the radiographic apparatus according to claim 2, further comprising integrating means for integrating the reference images generated by the image generating means, and the second map has a decrease to a predetermined level. It is obtained by integrating a plurality of second map creation reference images acquired at the time

  [Operation / Effect] The above-described configuration shows a specific generation state of the second map. That is, the second map is generated by integrating a plurality of second map creation reference images. The second map creation reference image includes a radiation detection element (operation failure element) that cannot detect radiation, but does not faithfully specify the position of the operation failure element. In other words, the unevenness appearing in the second map creation reference image appears due to various factors other than the presence of the malfunctioning element. If the second map creation reference images are integrated, various uncertain factors are removed, and the position of the malfunctioning element is markedly shown. In this way, according to the above-described configuration, an image in which the reflection of the malfunctioning element is reliably canceled can be acquired.

  According to a fourth aspect of the present invention, in the radiation imaging apparatus according to any one of the first to third aspects, the radiation detection means includes a conversion means that converts radiation into electric charge, and an accumulation means that accumulates electric charge. The first map includes a plurality of first map creation reference images in a state in which the accumulation time, which is the time for accumulating the charges in the accumulation means, is longer than when the second map creation reference image is acquired. Is obtained by accumulating these and integrating them.

  [Operation / Effect] The above-described configuration shows a specific generation of the first map. Also in the first map, a plurality of first map creation reference images are integrated to generate a first map in which the positions of the detection elements that are acting poorly are marked. Furthermore, the first map creation reference image is acquired in a state where the accumulation time is longer than that when the second map creation reference image is acquired. Thereby, the malfunction of the detection element when the radiation detection means is in the initial state is reproduced, and the first map suitable for the case where the radiation detection means is in the initial state can be generated.

  The invention according to claim 5 is the radiographic apparatus according to any one of claims 1 to 4, wherein the first map is acquired after the examination of the subject. is there.

  [Operation / Effect] By configuring as described above, the first map can be reliably acquired before the start of the inspection. It is desirable that the first map is already prepared when the radiation imaging apparatus is turned on. According to the present invention, for example, the first map can be acquired after the examination of the subject is completed, and the first map of the previous day can be used when the radiation imaging apparatus is turned on the next day.

  According to a sixth aspect of the present invention, in the radiographic apparatus according to any one of the first to fourth aspects, the monitoring reference image is acquired in a state where no radiation image is reflected on the radiation detection means. It is characterized by this.

  [Operation / Effect] With this configuration, the monitoring reference image can be monitored without applying radiation to the radiation detecting means. When radiation is irradiated while the subject is set between the radiation detection means and the radiation source, a fluoroscopic image of the subject is reflected on the radiation detection means. By the way, the monitoring reference image needs to reflect the behavior of the detecting element that is operating as defective, and if an extra image other than this is reflected, it interferes with the monitoring performed by the selection means. This means that the monitoring reference image cannot be acquired when the subject is set. However, as in the configuration described above, if the reference image is acquired in a state in which no radiation image is reflected on the radiation detection means, the monitoring reference image can be monitored even when the subject is set. . In this way, the map can be exchanged with the subject set.

  The invention according to claim 7 is the radiation imaging apparatus according to any one of claims 1 to 6, further comprising irradiation permission means for permitting radiation irradiation to the radiation source. When irradiation is permitted and radiation is emitted from the radiation source, the readout execution unit executes readout of the radiation image reflected in the radiation detection unit, causes the image generation unit to generate a radiographic image, and It is characterized in that no readout relating to a monitoring reference image competing with readout is performed.

  [Operation / Effect] According to the above-described configuration, it is possible to acquire a radioscopic image while acquiring a reference image for monitoring. That is, when radiation is emitted toward the radiation detection means, a radiographic image reflected on the radiation detection means is read out, and a radiographic image in which the subject is reflected is acquired. During this time, readout related to the monitoring reference image is not performed. That is, when the acquisition of the fluoroscopic image and the acquisition of the monitoring reference image compete, acquisition of the fluoroscopic image has priority. Thereby, since a radiographic image can be reliably acquired at the timing instructed by the operator, a radiation imaging apparatus with excellent operability can be provided.

  The invention according to claim 8 is the radiation imaging apparatus according to any one of claims 1 to 7, wherein (D1) the selection means cannot detect the radiation reflected in the monitoring reference image. Among the element blocks, which are blocks in which the radiation detection elements are gathered, the reduction of the largest element block appearing in the monitoring reference image is sequentially monitored.

  The invention according to claim 9 is the radiation imaging apparatus according to any one of claims 1 to 7, wherein (D2) the selection means cannot detect the radiation reflected in the monitoring reference image. Among element blocks, which are blocks in which radiation detection elements are gathered, reduction of a plurality of element blocks appearing in the monitoring reference image is sequentially monitored.

  The invention according to claim 10 is the radiation imaging apparatus according to any one of claims 1 to 7, wherein (D3) the selection means cannot detect the radiation reflected in the monitoring reference image. Among the element blocks, which are a group of radiation detection elements, select a plurality of element blocks in descending order of the size shown in the reference image for monitoring, and sequentially decrease the average value of the selected element blocks. It is characterized by monitoring.

  [Operation / Effect] The above-described configuration represents a specific configuration capable of more easily monitoring the monitoring reference image performed by the selection unit. That is, the selection means recognizes the element block reflected in the monitoring reference image as the target area and observes the change thereof. Then, the selection means switches the map when the change in the size of the target area decreases to a predetermined level. That is, it is not necessary for the selection means to monitor the entire area of the monitoring reference image, and it is sufficient to monitor a limited area of the monitoring reference image. With this configuration, the calculation load on the selection unit is reduced, and a radiation imaging apparatus with a simpler mechanical configuration can be provided.

  Various aspects can be considered for observing the element block of the selection means. For example, the selection unit may be configured to monitor a change in the size of the largest element block reflected in the monitoring reference image, or may be configured to monitor the reduction of a plurality of element blocks. Alternatively, among the element blocks reflected in the monitoring reference image by the selection means, a plurality of element blocks are selected in descending order of the size appearing in the monitoring reference image, and the average size of the selected element blocks is reduced. May be monitored.

  The invention according to claim 11 includes a radiation source for irradiating radiation, radiation detecting means for detecting radiation and having a plurality of radiation detecting elements, and image generating means for generating an image based on the detection data. In the radiation imaging apparatus, among the radiation detection elements included in the radiation detection means, the radiation detection element that cannot detect radiation is regarded as a temporary defective element, and among the temporary defective elements, the ability to detect radiation over time When a recovery element is a recovery element and a non-recoverable element capable of detecting radiation is a permanently defective element, a first map that stores the position of the temporary defect element in the radiation detection means is stored. Using a map storage means, a second map storage means for storing a second map indicating the position of the permanently defective element in the radiation detection means, and a map An image processing unit that complements a pixel derived from a radiation detection element that cannot detect radiation reflected in the image, and a selection between the first map and the second map to be used by the image processing unit. (A) the selection means selects the first map, and (E2) the selection means indicates the time from the selection of the first map until the recovery of the radiation detection ability of the recovery element is completed. The second map is selected when a predetermined waiting time has elapsed.

  [Operation / Effect] According to the present invention, the configuration of the selection means is simplified. Specifically, the selection means first selects the first map. This is a map suitable when the radiation detection means is in the initial state. Thereafter, the selection means selects the second map when a predetermined waiting time has elapsed. The second map is a map suitable for example when the change in the state of the radiation detection means is settled and is in a stable state.

  ADVANTAGE OF THE INVENTION According to this invention, the radiation imaging device which can acquire the image suitable for a diagnosis by removing the radiation detection element (malfunction element) which cannot detect a radiation irrespective of the state of a radiation detection means can be provided. . That is, the radiographic apparatus according to the present invention provides at least two maps used for deleting malfunctioning elements reflected in a radioscopic image. The two maps are a first map that is suitable when the radiation detection unit is in an initial state and a second map that is suitable when a change in the state of the radiation detection unit is in a stable state. One of these is selected to remove malfunctioning elements that appear in the image. The selection means selects which map to use. The selection means knows the increase / decrease of the radiation detecting element which is behaving as defective in operation, and selects the second map instead of the first map when the increase / decrease change has decreased to a predetermined level. Since the present invention is configured to change the map with reference to the monitoring reference image, the malfunction detecting element reflected in the image is accurately removed regardless of the stability of the radiation detection means, A radioscopic image suitable for diagnosis can always be acquired.

1 is a functional block diagram illustrating a configuration of an X-ray imaging apparatus according to Embodiment 1. FIG. 1 is a cross-sectional view illustrating a configuration of an FPD according to Example 1. FIG. 1 is a plan view illustrating a configuration of an FPD according to Embodiment 1. FIG. 3 is a flowchart according to a series of operations started by turning on the power of the X-ray imaging apparatus according to the first embodiment. 5 is a schematic diagram illustrating a first map according to Embodiment 1. FIG. 6 is a schematic diagram for explaining a monitoring reference image according to Embodiment 1. FIG. It is a schematic diagram explaining the 2nd map which concerns on Example 1. FIG. 6 is a timing chart for explaining reading of the FPD according to the first embodiment.

  Embodiments of the radiation imaging apparatus according to the present invention will be described below. The X-ray in Example 1 is an example of the radiation of the present invention.

<Overall configuration>
First, the configuration of the X-ray imaging apparatus 1 according to the first embodiment will be described. FIG. 1 is a functional block diagram illustrating the configuration of the X-ray imaging apparatus according to the first embodiment. As shown in FIG. 1, the X-ray imaging apparatus 1 according to the first embodiment is provided with a top plate 2 on which a subject M is placed and an upper part of the top plate 2, and irradiates a pulsed X-ray beam. X-ray tube 3 that is provided, a flat panel detector (FPD) 4 that is provided below the top plate 2 and detects X-rays transmitted through the subject M, and X-rays that remove scattered X-rays incident on the FPD 4 A grid 5 is provided. In addition, the configuration of the first embodiment includes an X-ray tube control unit 6 that controls the tube voltage, tube current, and X-ray beam irradiation time of the X-ray tube 3. In addition, the configuration of the first embodiment includes a read control unit 8 that controls reading of the detection signal to the FPD 4. Further, the configuration of the first embodiment receives the detection signal output from the FPD 4 and receives the X-ray fluoroscopic image and the image generation unit 11 that generates the X-ray fluoroscopic image in which the fluoroscopic image of the subject is reflected. And an image editing unit 12 that performs brightness processing and the like to make the X-ray fluoroscopic image more suitable for visual recognition. The image editing unit 12 also executes image processing for eliminating defective pixels reflected in a later-described X-ray fluoroscopic image by complementation. This image processing is performed with reference to either the first map M1 or the second map M2. Each of the X-ray tube 3, the FPD 4, and the X-ray tube control unit 6 corresponds to a radiation source, a radiation detection unit, and an irradiation permission unit of the present invention. The read control unit corresponds to the read execution unit of the present invention, the image generation unit corresponds to the image generation unit of the present invention, and the image editing unit corresponds to the image processing unit of the present invention.

  Further, the X-ray imaging apparatus 1 includes a first map storage unit 17 that stores the first map M1 and a second map storage unit 18 that stores the second map M2, and also integrates the generation of both maps M1 and M2. And a selection unit 16 that selects which of the maps M1 and M2 is sent to the image editing unit 12. The X-ray imaging apparatus 1 further includes an operation console 23 that receives an operator's instruction, and a display unit 24 that displays an X-ray fluoroscopic image or a moving image. The selection unit corresponds to selection means of the present invention. The first map storage unit corresponds to the first map storage unit of the present invention, and the second map storage unit corresponds to the second map storage unit of the present invention. The integrating unit corresponds to the integrating means of the present invention.

  Furthermore, the X-ray imaging apparatus 1 includes an X-ray tube control unit 6, a readout control unit 8, an image generation unit 11, an image editing unit 12, an integration unit 15, and a main control unit 22 that comprehensively controls the selection unit 16. It has. The main control unit 22 is constituted by a CPU, and realizes each unit by executing various programs. Further, each of the above-described units may be divided and executed by an arithmetic device that takes charge of them.

  Next, the configuration of the FPD 4 according to the first embodiment will be described. The FPD 4 has a configuration as shown in FIG. The amorphous selenium layer 53 corresponds to the conversion means of the present invention. The capacitor 55 corresponds to the storage means of the present invention.

  As shown in FIG. 2, the FPD 4 includes a surface electrode layer 52, an amorphous selenium layer 53, a support layer 54, and a capacitor 55. The surface electrode layer 52, the amorphous selenium layer 53, and the support layer 54 are laminated in this order. The surface electrode layer 52 is electrically connected to the bias voltage supply terminal 52a. A collection electrode 54 a is embedded in the support layer 54. In the FPD 4, a plurality of collection electrodes 54 a are provided, and the collection electrodes 54 a are two-dimensionally arranged along the plane in which each layer 52, 53, 54 extends.

  The collection electrode 54 a is in contact with the amorphous selenium layer 53 and is electrically connected to the capacitor 55. The capacitors 55 are arranged two-dimensionally. One of the capacitors 55, the amorphous selenium layer 53, and the surface electrode layer 52 laminated thereon form a single X-ray detection element. In other words, the FPD 4 can be regarded as a two-dimensional array of X-ray detection elements following the arrangement of the capacitors 55.

  As shown in FIG. 3, the detection data of the FPD 4 according to the first embodiment is read for each column C of the capacitor array. Specifically, a transistor is provided for each capacitor, a transistor matrix is generated, and a gate drive is provided for each column of the transistor matrix. When one of the gate drives is turned on, the transistors belonging to one column of the transistor matrix corresponding to the gate drive are turned on all at once, and the accumulated charges are read out simultaneously in the capacitors arranged in the row. Thereafter, all the gate drives of the FPD 4 are sequentially turned on. In this way, the detection signal is read out in each column of the capacitors, and the signal reading out for the entire area of the FPD 4 is completed.

<Operation of X-ray imaging apparatus>
Next, the operation of the X-ray imaging apparatus having such a configuration will be described. When performing general imaging, the power of the X-ray imaging apparatus is turned on in advance before imaging and the FPD 4 is sufficiently stabilized. This is because immediately after the X-ray imaging apparatus is turned on, the FPD 4 is in an unstable operation and is not suitable for X-ray imaging.

  However, there may be a case where an X-ray imaging apparatus has to be started immediately after starting an X-ray imaging apparatus that is turned off due to a sudden illness in a medical institution. According to the configuration of the first embodiment, there is an advantage that a radiographic image suitable for diagnosis can be acquired even when the FPD 4 is in an unstable state when the power is turned on. For the purpose of emphasizing this point, in the following description, the operation in such a case will be described. FIG. 4 is a flowchart relating to the description of a series of operations started by turning on the power of the X-ray imaging apparatus 1, and shows the overall description of the following operations.

  The operation will be described in order. First, it is assumed that it is necessary to immediately perform X-ray imaging. First, the X-ray imaging apparatus 1 is turned on, and the subject M is set on the top 2 (step S1). Then, the selection part 16 reads the 1st map M1 memorize | stored in the 1st map memory | storage part 17, and sends this to the image edit part 12 (step 2). The first map M1 stores where in the FPD 4 a detection element that cannot detect X-rays in an unstable state immediately after power-on (hereinafter referred to as an initial defective element for simplicity) is located. Specifically, the two-dimensional data is configured as shown in FIG. L1 shown in FIG. 5 is a lump of elements in the FPD 4 in which initial defective elements are gathered into a lump. The initial defective element cannot detect X-rays immediately after the power is turned on. However, the initial defective element deviated from the center of the element block L1 operates normally as the FPD 4 becomes stable. The initial defective element corresponds to the temporary defective element of the present invention. Among the initial defective elements, the detection element that can operate normally as the FDP 4 stabilizes corresponds to the recovery element of the present invention. Further, among the initial defective elements, a detection element that cannot detect X-rays regardless of the stability of the FPD 4 corresponds to the permanent defective element of the present invention.

  The reason why such a phenomenon occurs will be described. In the central portion of the element block L1, there is a so-called permanently defective element that can no longer operate normally due to a failure or the like. Elements in the vicinity of the permanently defective element should normally operate normally. However, when the FPD 4 is in an unstable state, such as when the power is turned on, the elements in the vicinity of the permanently defective elements are affected by the permanently defective elements, and the normal operation is hindered. It will behave. Nonetheless, as the FPD 4 stabilizes over time, nearby elements can operate normally. Therefore, as the time elapses after the power is turned on, the element block becomes smaller.

  Assume that radiography is performed immediately after power-on. A large element lump L1 is reflected in the radiographic image acquired at this time. The image editing unit 12 recognizes the shape, size, and position of the element block L1 with reference to the first map M1 in order to remove it from the radiographic image. Then, the image editing unit 12 refers to the pixel value of the pixel in the vicinity of the pixel block (hereinafter referred to as the missing pixel block) in which the element block L1 is reflected in the radiographic image, and the pixel value of the missing pixel block To change. As a specific example of this change, pixel values located in a region near the missing pixel block are averaged, and the average value is used as the pixel value of the missing pixel block to complement the pixel value. The pixel area to be referred to may be changed depending on the position of the missing pixel block.

  Next, the read interval instructs the FPD 4 to read data based on a predetermined sampling frequency (step S3). Reading at this time is performed in a state where the FPD 4 is not irradiated with X-rays, and a monitoring reference image R is generated based on the extracted data. Therefore, nothing should be captured in the monitoring reference image R including the fluoroscopic image of the subject M. However, when observed in detail, a certain amount of unevenness is reflected in the monitoring reference image R. This unevenness serves as an index for knowing the defective operation of the radiation detection element. Such reading is called dark reading, and the read data is called dark data. In addition, the image generation unit 11 generates the monitoring reference image R.

  As shown in FIG. 6, unevenness such as regions La and Lb appears in the monitoring reference image R. Although this unevenness has a shape substantially corresponding to the element block L1 in FIG. 5, it is not exactly the same, and is slightly different from the shape of the element block L1. In addition, a portion unrelated to the element block L1 as in the region Lb in FIG. 6 may appear as unevenness. That is, the unevenness in the monitoring reference image R appears as a result of entanglement of a plurality of factors, and does not faithfully represent the defective operation of the radiation detection element. Therefore, as apparent from a comparison between FIG. 5 and FIG. 6, the monitoring reference image R cannot be sent to the image editing unit 12 instead of the first map M1.

  Such an instruction to read dark data to the FPD 4 is intermittently performed, and a monitoring reference image R is generated each time. Each of the monitoring reference images R is sent to the selection unit 16. The selection unit 16 recognizes the largest unevenness in the monitoring reference image R as a target area, and monitors how the target area changes in the monitoring reference image R. The target area gradually becomes smaller as the FPD 4 is stabilized. This is because the radiation detection element (recovery element) that behaves like a failure under the influence of the defective element in the FPD 4 operates normally.

  In addition to the above, the observation of the element block of the selection unit 16 may be configured such that, for example, a plurality of element blocks appearing in the monitoring reference image R are selected as target regions and the reduction of these is monitored. If comprised in this way, the selection part 16 can monitor the radiation detection element which cannot detect an X-ray more correctly. Further, for example, among the element blocks reflected in the monitoring reference image R by the selection unit 16, a plurality of element blocks are selected as a target region in descending order of the size appearing in the monitoring reference image R, and the selected element blocks You may monitor the reduction | decrease in the average value of a magnitude | size.

  The selection unit 16 recognizes the size of a plurality of element blocks, orders the element blocks in order of size, calculates an average value of the element blocks, and performs operations related to element block monitoring. To do everything.

  When the FPD 4 is stabilized, the target area will not become smaller. When the change in the size of the target area falls within a predetermined range, the selection unit 16 recognizes that the FPD 4 is stable (step S4), and stores the second map M2 suitable for this state in the second map. The data is read from the unit 18 and sent to the image editing unit 12 (step S5). The image editing unit 12 discards the first map M1 and performs image processing to fill in the missing pixel block using the second map M2. The second map M2 is two-dimensional data that stores where the permanently defective elements are located in the FPD 4 when the FPD 4 is stable. That is, the second map M2 is two-dimensional data in which a small element block L2 is mapped as shown in FIG.

<Interruption of X-ray irradiation>
In parallel with the operation as described above, the X-ray imaging apparatus 1 receives an instruction to capture an X-ray fluoroscopic image through the console 23. X-ray fluoroscopic imaging is performed by irradiating X-rays from the X-ray tube 3. On the other hand, dark reading is performed in a state where X-rays are not irradiated. Therefore, if the above-described dark reading is performed continuously, an opportunity to irradiate X-rays from the X-ray tube 3 cannot be found, and X-ray fluoroscopic imaging cannot be performed. Therefore, the X-ray imaging apparatus 1 is configured to give priority to X-ray imaging when dark readout and X-ray imaging compete. That is, the readout control unit 8 stops the next dark readout at the time when the photographing of the fluoroscopic image is instructed. X-rays are irradiated from the X-ray tube 3, and a fluoroscopic image of the subject M is reflected in the FPD 4. The read control unit 8 instructs the FPD 4 to read detection data for the purpose of taking it out from the FPD 4. The image generation unit 11 assembles the output detection data and generates an X-ray fluoroscopic image. This is displayed on the display unit 24 after image processing is performed in the image editing unit 12. Thereafter, the X-ray imaging apparatus 1 resumes dark reading and prepares for the next X-ray fluoroscopic imaging.

<Acquisition Method of First Map M1 and Second Map M2>
Next, a method for acquiring each map will be described. The second map M2 is acquired when the X-ray imaging apparatus 1 is in an idle state, and is generated when the FPD 4 is stable. That is, the X-ray imaging apparatus 1 performs dark reading several times to obtain a plurality of second map creation reference images R2. The image generation unit 11 actually generates the second map creation reference image R2. The integrating unit 15 integrates the second map creation reference image R2 to generate the second map M2.

  The method for generating the first map M1 is different from that for the second map M2. FIG. 8 is a timing chart illustrating reading of the FPD according to the first embodiment. As shown in FIG. 8A, in the second map M2, data is read during the read time T3 after an accumulation time T2 that is a time for the capacitor 55 (see FIG. 3) to accumulate electric charge has elapsed. On the other hand, when acquiring the first map M1, as shown in FIG. 8B, the accumulation time T1 is longer than the accumulation time in the second map M2. By doing so, it is possible to reproduce an unstable state of the FPD 4 immediately after the power is turned on. Therefore, the first map M1 is suitable for use immediately after the power is turned on. In such a state, dark reading is performed several times, and a plurality of first map creation reference images R1 are acquired. The image generation unit 11 actually generates the first map creation reference image R1. The integrating unit 15 integrates these to generate the first map M1.

  Note that the first map M1 and the second map M2 need to be prepared before the X-ray imaging apparatus 1 is turned on. Therefore, the X-ray imaging apparatus 1 generates the maps M1 and M2 when it was operating last time. One day, the examination of the subject using the X-ray imaging apparatus 1 is completed, and the operator gives an instruction to turn off the power of the X-ray imaging apparatus 1 through the console 23. Then, the X-ray imaging apparatus 1 is configured such that the power is turned off after the maps M1 and M2 are generated. Thus, the X-ray imaging apparatus 1 is configured such that the maps M1 and M2 are prepared in advance before the power is turned off, and radiation imaging can be performed immediately after the next power-on.

  As described above, according to the configuration of the first embodiment, it is possible to provide the X-ray imaging apparatus 1 capable of acquiring an image suitable for diagnosis by removing malfunctioning elements regardless of the state of the FPD 4. That is, the X-ray imaging apparatus 1 according to the configuration of the first embodiment includes the first map storage unit 17 and the second map storage unit 18, and selects one of the two maps to be reflected in the image. The configuration is such that defective elements are removed. Therefore, a map suitable for removing malfunctioning elements can be selected and used in accordance with the state of the FPD 4.

  In addition, according to the configuration of the first embodiment, the selection unit 16 selects which map is used. Specifically, the selection unit 16 first selects the first map M1. This is a map suitable when the FPD 4 is in the initial state. Subsequently, the selection unit 16 monitors the FPD 4 through the monitoring reference map R, and changes the map used for the removal process of the malfunctioning element to the second map M2 at an appropriate timing. The second map M2 is a map suitable when, for example, the change in the state of the FPD 4 is settled and is in a stable state.

  Switching of the map by the selection unit 16 is performed as follows. That is, the monitoring reference image R is acquired intermittently. By comparing the monitoring reference images R, it is possible to know a decrease with time of the radiation detection elements that cannot detect X-rays. When the decrease is reduced to a predetermined level, the selection unit 16 selects the second map M2 instead of the first map M1. Since the configuration of the first embodiment is configured to change the map based on the monitoring reference image R, the malfunction detecting element reflected in the image is accurately removed regardless of the stability of the FPD 4. Therefore, it is possible to always obtain a radioscopic image suitable for diagnosis.

  The specific generation of the second map M2 is as follows. That is, the second map M2 is generated by integrating a plurality of second map creation reference images R2. The second map creation reference image R2 includes the malfunctioning element, but does not faithfully specify the position of the malfunctioning element. That is, when unevenness appears in the second map creation reference image R2, various factors other than the presence of malfunctioning elements are intertwined. If the second map creation reference image R2 is integrated, various uncertain factors are removed, and the position of the malfunctioning element is markedly shown.

  The specific generation of the first map M1 is as follows. Also in the first map M1, a plurality of first map creation reference images R1 are integrated to generate a first map M1 in which the positions of detection elements that cannot detect X-rays are markedly shown. Furthermore, the first map creation reference image R1 is acquired in a state in which the accumulation time is longer than when the second map creation reference image R2 is acquired. Thereby, the malfunction of the detection element when the FPD 4 is in the initial state is reproduced, and the first map M1 suitable for the case where the FPD 4 is in the initial state can be generated.

  The configuration of the first embodiment can generate the monitoring reference image R without applying radiation to the FPD 4. When radiation is irradiated while the subject is set between the FPD 4 and the X-ray tube 3, a fluoroscopic image of the subject is reflected on the FPD 4. By the way, the monitoring reference image R needs to reflect the behavior of the detection element that cannot detect X-rays. If an extra image other than this is reflected, the selection unit 16 obstructs the monitoring. It becomes. This means that the monitoring reference image R cannot be acquired when the subject is set. However, as in the configuration described above, if the monitoring reference image R is acquired in a state where no radiation image is reflected in the FPD 4, the monitoring reference image R can be monitored even when the subject is set. It becomes. In this way, the map can be exchanged with the subject set.

  In addition, the configuration of the first embodiment can acquire a radioscopic image while acquiring the monitoring reference image R. That is, when radiation is irradiated toward the FPD 4, a radiographic image reflected on the FPD 4 is read out, and a radiographic image including the subject M is acquired. During this time, readout relating to the monitoring reference image R is not performed. That is, when the acquisition of the fluoroscopic image and the acquisition of the monitoring reference image R compete, acquisition of the radioscopic image has priority. Thereby, since a radioscopic image can be acquired reliably at the timing instructed by the operator, the X-ray imaging apparatus 1 having excellent operability can be provided.

  Further, the configuration of the first embodiment is configured such that the monitoring reference image R performed by the selection unit 16 can be monitored more easily. That is, the selection unit 16 recognizes the largest element block reflected in the monitoring reference image R as the target region and observes the change thereof. Then, the selection unit 16 switches the map when the change in the size of the target area is reduced to a predetermined level. That is, it is not necessary for the selection unit 16 to monitor the entire area of the monitoring reference image R, and it is sufficient to monitor a limited area of the monitoring reference image R. With this configuration, the calculation load on the selection unit 16 is reduced, and the X-ray imaging apparatus 1 with a simpler mechanical configuration can be provided.

  Next, the configuration of the second embodiment will be described. The second embodiment is almost the same as the configuration of the first embodiment. However, the operation of the selection unit 16 that has finished the above-described step S2 is different from that of the first embodiment. The selection unit 16 that has finished step S2 waits for a predetermined waiting time indicating the time until the recovery of the radiation detection ability of the detection element (recovery element) that can operate normally, and this After the elapse of time, the second map M2 is selected and sent to the image editing unit 12. In this way, the selection unit 16 can instruct switching of the map at a suitable timing without monitoring the element block.

  The present invention is not limited to the above-described configuration, and can be modified as follows.

  (1) Although each embodiment described above is a medical device, the present invention can also be applied to industrial and nuclear devices.

  (2) The X-ray referred to in each of the above-described embodiments is an example of radiation in the present invention. Therefore, the present invention can be applied to radiation other than X-rays.

R Reference image for monitoring R1 Reference image for creating a first map R2 Reference image for creating a second map 1 X-ray imaging apparatus (radiation imaging apparatus)
3 X-ray tube (radiation source)
4 FPD (radiation detection means)
6 X-ray tube controller (irradiation permission means)
8 Read controller (read execution means)
11 Image generation unit (image generation means)
12 Image editing unit (image processing means)
15 Integration unit (integration means)
16 Selection part (selection means)
17 1st map memory | storage part (1st map memory | storage means)
18 Second map storage unit (second map storage means)

Claims (11)

Based on a radiation source for irradiating radiation, a radiation detection means for detecting radiation and having a plurality of radiation detection elements, a read execution means for reading out detection data from the radiation detection means, and the detection data In a radiation imaging apparatus comprising an image generation means for generating an image,
Among the radiation detection elements of the radiation detection means, a radiation detection element that cannot detect radiation is a temporarily defective element,
Among the temporary defective elements, those that recover the ability to detect radiation over time are recovery elements, and those that do not recover the ability to detect other radiation are permanent defective elements,
First map storage means for storing a first map indicating a position of the temporary defective element in the radiation detection means;
Second map storage means for storing a second map indicating the position of the constantly defective element in the radiation detection means;
Image processing means for complementing pixels derived from a radiation detection element that cannot detect radiation reflected in the image using the map;
Selecting means for selecting which of the first map and the second map is to be used by the image processing means;
(A) The selection means selects the first map,
(B) The readout execution unit intermittently reads out data from the radiation detection unit, and causes the image generation unit to generate a monitoring reference image each time,
(D) The selection means sequentially monitors a decrease in radiation detection elements that cannot detect radiation reflected in each of the monitoring reference images,
(E1) The selection means selects the second map instead of the first map when the decrease is reduced to a predetermined level indicating the time when the recovery of the radiation detection ability of the recovery element is completed. A characteristic radiographic apparatus. The radiographic apparatus according to claim 1,
The radiographic apparatus, wherein the recovery element cannot detect radiation when the radiographic apparatus is turned on. The radiographic apparatus according to claim 1 or 2,
An accumulator for accumulating reference images generated by the image generator;
2. The radiographic apparatus according to claim 1, wherein the second map is obtained by integrating a plurality of second map creation reference images acquired when the decrease has decreased to a predetermined level. The radiographic apparatus according to any one of claims 1 to 3,
The radiation detection means includes
Conversion means for converting the radiation into electric charge;
Storing means for storing the charge,
The first map includes a plurality of first map creation reference images in a state in which an accumulation time, which is a time for accumulating charges in the accumulation means, is longer than that for acquiring a second map creation reference image. A radiographic apparatus characterized by being obtained by integrating and accumulating these. The radiation imaging apparatus according to any one of claims 1 to 4,
The radiographic apparatus according to claim 1, wherein the first map is acquired after the examination of the subject is completed. The radiation imaging apparatus according to any one of claims 1 to 4,
The radiographic apparatus according to claim 1, wherein the monitoring reference image is acquired in a state in which no radiation image is reflected in the radiation detection means. The radiographic apparatus according to any one of claims 1 to 6,
An irradiation permission means for permitting irradiation of the radiation to the radiation source,
(C) When radiation irradiation is permitted and radiation has been emitted from the radiation source, the readout execution unit performs readout of the radiation image reflected on the radiation detection unit and performs radiation on the image generation unit. A radiographic apparatus that generates a fluoroscopic image and does not perform readout related to the monitoring reference image that competes with readout of the radiographic image. The radiographic apparatus according to any one of claims 1 to 7,
(D1) The selection means is the largest of the element masses that are the masses of the radiation detection elements that cannot detect the radiation reflected in the monitoring reference image, and that appear in the monitoring reference image. A radiation imaging apparatus characterized by sequentially monitoring the reduction of an element block. The radiographic apparatus according to any one of claims 1 to 7,
(D2) The selection means includes a plurality of elements appearing in the reference image for monitoring, out of an element mass that is a mass of radiation detection elements that cannot detect radiation reflected in the reference image for monitoring. A radiation imaging apparatus characterized by sequentially monitoring the reduction of an element block. The radiographic apparatus according to any one of claims 1 to 7,
(D3) The selection means has a size that appears in the monitoring reference image out of an element block that is a group of radiation detection elements that cannot detect radiation reflected in the monitoring reference image. A radiation imaging apparatus, wherein a plurality of element clusters are selected in descending order, and a decrease in the average value of the selected element clusters is sequentially monitored. In a radiation imaging apparatus, comprising: a radiation source that irradiates radiation; a radiation detection unit that detects radiation and includes a plurality of radiation detection elements; and an image generation unit that generates an image based on the detection data.
Among the radiation detection elements of the radiation detection means, a radiation detection element that cannot detect radiation is a temporarily defective element,
Among the temporary defective elements, those that recover the ability to detect radiation over time are recovery elements, and those that do not recover the ability to detect other radiation are permanent defective elements,
First map storage means for storing a first map indicating a position of the temporary defective element in the radiation detection means;
Second map storage means for storing a second map indicating the position of the constantly defective element in the radiation detection means;
Image processing means for complementing pixels derived from a radiation detection element that cannot detect radiation reflected in the image using the map;
Selecting means for selecting which of the first map and the second map is to be used by the image processing means;
(A) The selection means selects the first map,
(E2) The selection means selects the second map when a predetermined waiting time has elapsed from the selection of the first map until the recovery of the radiation detection ability of the recovery element is completed. A radiographic apparatus characterized by.

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