JP2004298617A - Inspection method of radiation photography system and medical image processing apparatus using it, and phantom used for inspection of radiation photography system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily make both of a quantitative evaluation and a visual evaluation of an image at a low cost in the inspection of the radiation photography system, and to provide a phantom and the like capable of raising the precision of invariance evaluation of the radiation photography system. <P>SOLUTION: This phantom is used for inspection of the radiation photography system by evaluating the radiation image obtained by photographing the phantom with the radiation photography system about at least one image quality evaluation item, and contains a substrate, the first member which is arranged on the substrate and formed with the first image quality evaluation pattern used for the visual evaluation of the predetermined image evaluation items, and the second member which is arranged on the substrate and formed with the second image quality evaluation pattern used for the quantitative evaluation of the predetermined image evaluation items. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a radiation imaging system inspection method for inspecting the quality of a radiation imaging system including an image reading device that reads image information from a sheet on which a radiation image is recorded, and a medical image processing apparatus using such an inspection method. The present invention also relates to a phantom used for image quality management of a radiographic image at the time of inspection of such a radiographic system.
In this application, the term “radiation” refers to broad radiation including particle beams such as electron beams and electromagnetic waves in addition to general radiation such as X-rays, α-rays, β-rays, γ-rays, and ultraviolet rays. .

  Conventionally, imaging methods using radiation (X-rays, α-rays, β-rays, γ-rays, electron beams, ultraviolet rays, etc.) have been used in various fields, and especially in the medical field, it is the most important for diagnosis. It has become one of the means. Since the first X-ray photography was realized, the X-ray photography method has been improved many times, and at present, a method combining a fluorescent screen and an X-ray film has become mainstream. On the other hand, in recent years, various digitized apparatuses such as X-ray CT, ultrasound, and MRI have been put into practical use, and the construction of diagnostic information processing systems and the like in hospitals is being promoted. Many studies for digitizing X-ray images have also been made, and a radiographic method using a stimulable phosphor has been established and has attracted attention as a replacement for conventional X-ray photography.

  A photostimulable phosphor (accumulative phosphor) accumulates a portion of its radiation energy when irradiated with radiation, and then accumulates when irradiated with excitation light such as visible light. It is a substance that emits photostimulative light according to its energy, and its existence has been conventionally known. The radiography method using this is as follows. That is, first, a radiographic image of a subject such as a human body is photographed and recorded on a sheet coated with a stimulable phosphor using an image photographing device. Next, using the image reader, the photostimulable phosphor sheet is scanned with excitation light such as laser light, and the resulting photostimulated light is used as a photomultiplier (photoelectronic amplifier tube) of the image reader. Read photoelectrically. Digital image data is obtained based on the analog image signal thus obtained. Furthermore, after this image data is appropriately processed using a medical image processing apparatus, it is output to a display such as a CRT or printed on a film by a laser printer or the like. Thereby, a radiation image in which the energy level of radiation transmitted through the subject is visualized by shading can be obtained.

  By the way, when using such a radiographic image for medical diagnosis or the like, it is necessary that the radiography system is highly reliable and, therefore, the performance of the radiography system must be measured and verified as needed. I must. If any of the radiographic systems including the photostimulable phosphor sheet or the image reading device deteriorates or becomes abnormal, a normal radiographic image cannot be obtained, and the reliability in analyzing the image is impaired. Because. In addition, since irradiation with a high level of radiation energy adversely affects the human body, verification of the performance of the radiation imaging system is also important in terms of safety.

  In Patent Document 1, even if the opening / closing member of the housing is opened, the photoelectric reading means is prevented from being adversely affected, and a maintenance worker is mistakenly irradiated with excitation light above a specified level during maintenance. In addition, a radiation image reading apparatus is disclosed in which a test such as checking a sheet conveyance state can be executed even when the opening / closing member is open.

  The radiation image reading apparatus described in Patent Document 1 prepares a test image signal in advance, and generates image data based on the test image signal. However, in this radiation image reading apparatus, it is not possible to perform a test in the process from the generation of the stimulated emission light to the generation of image data based on the image signal represented by the stimulated emission light.

  Patent Documents 2 to 5 disclose inspection methods for easily detecting abnormalities in a radiographic imaging apparatus. In the inspection method disclosed in Patent Document 2, the entire surface of the photostimulable phosphor detector (sheet) is uniformly irradiated with ultraviolet light, and the stimulable phosphor detector is irradiated with excitation light. Photo-amplification of photostimulable luminescent light has been performed. However, according to this inspection method, only limited items such as the S value indicating the density of the output image, the uniformity of the density, and the graininess can be inspected.

  Patent Document 3 discloses an inspection method that uses image data obtained when a subject is photographed, and therefore does not need to be photographed again for inspection. Further, in Patent Document 4, the stimulable phosphor detector (sheet) is irradiated with excitation light modulated so that the interval between the non-irradiated portions changes widely, and a read signal (image) from the stimulable phosphor detector is disclosed. An inspection method for numerically calculating how much the difference between the signal) and the modulation state of the excitation light is disclosed. However, according to these inspection methods, only limited items such as S value and resolution can be inspected.

  In the inspection method disclosed in Patent Document 5, blue light test light emitted from a light source provided at a position adjacent to a stimulable phosphor detector (sheet) is guided to a photomultiplier by a condensing unit. Photoelectric amplification is performed using a photomultiplier. However, according to this inspection method, only limited items such as the light collecting unit can be inspected.

Therefore, a method capable of efficiently inspecting a radiation imaging system including a radiation image reading apparatus is desired.
By the way, when inspecting a radiography system, a physical phantom or a body imitation phantom is used. For example, Patent Document 6 discloses an image quality test phantom and method for automatic monitoring and evaluation of image quality in digital fluoroscopy and imaging systems.

  A physical phantom (also referred to as a QC phantom) is a member in which various members manufactured using a material such as a metal or a resin having a known radiation absorption coefficient are arranged on a substrate. These members have a predetermined size, shape, density, composition, and the like, and are used as an image quality evaluation pattern. These image quality evaluation patterns are designed so that one or a plurality of image quality evaluation items related to the radiation imaging system can be measured.

  Radiation imaging is performed by irradiating such a QC phantom with radiation such as X-rays, and radiation image information of the QC phantom is recorded on a recording medium such as a stimulable phosphor sheet. By performing predetermined processing on this recording medium, a radiation image is generated and displayed on a CRT monitor or the like. By analyzing the radiographic image based on predetermined image evaluation items, the invariance of various performance parameters of the radiographic system is evaluated, and thereby the quality inspection of the radiographic system is performed.

  The evaluation of the invariance of the performance parameter is performed by quantitative evaluation or visual evaluation. Quantitative evaluation refers to a test that is quantitatively evaluated by processing including arithmetic processing of digital data. Further, the visual evaluation refers to an inspection performed by a method other than the above quantitative evaluation, for example, an inspection that is evaluated by an operator viewing a radiation image. Among these inspections, the visual evaluation can be performed relatively easily, but is less objective because it depends on the subjectivity of the operator. On the other hand, the quantitative evaluation can expect an objective evaluation, but requires a lot of work. In general, the visual evaluation is performed weekly, whereas the quantitative evaluation is performed about once every three months, and the visual evaluation is performed more frequently than the quantitative evaluation. Further, when the invariance evaluation is performed in a large-scale facility, since there are many cases where ten or more readers are installed, efficient work is required.

  However, a general QC phantom is not designed to perform both visual evaluation and quantitative evaluation for one image quality evaluation item. Therefore, for example, when an objective measurement result of the image quality parameter is required after the visual evaluation, a phantom dedicated for quantitative evaluation must be newly installed and the radiographing must be performed again. That is, since it is necessary to change to a dedicated phantom depending on whether visual evaluation or quantitative evaluation is performed, verification work of the radiation imaging system becomes complicated, and much labor and time are required.

  In addition, when visual evaluation and quantitative evaluation are performed using separate phantoms, it is difficult to compare and examine the measurement results of both, so it is possible to evaluate the visual evaluation results from a more objective viewpoint. Can not. For this reason, since an accurate invariance evaluation cannot be expected, there is a problem that the reliability of the evaluation cannot be ensured. Furthermore, since two phantoms for visual evaluation and quantitative evaluation are required, there is a problem that the cost becomes high and it is not economical.

Furthermore, in order to ensure the reliability of the inspection accuracy, a QC phantom is installed in the appropriate reference area in the radiographic image by installing a QC phantom at a position corresponding to the reference position of the recording medium and the inspection target area at the time of imaging. An image needs to be displayed. For this reason, when the QC phantom is installed at a position deviated from the appropriate position, the image of the QC phantom is not displayed in the appropriate reference area in the radiographic image. Therefore, the position of the QC phantom must be corrected and imaging must be performed again. As a result, the inspection work is interrupted and complicated, and there is a problem that the automation of the inspection work is significantly hindered.
JP 2000-275758 A (pages 6-8, FIG. 1) JP 2002-277792 A (pages 4-5, FIG. 3) Japanese Patent Laid-Open No. 2002-277993 (pages 3 to 4, FIG. 3) Japanese Patent Laid-Open No. 2002-277795 (pages 3 to 4, FIG. 4) JP 2002-278004 A (pages 4-5, FIG. 3) Japanese Patent Laid-Open No. 11-4822

  Therefore, in view of the above points, the first object of the present invention is to perform both quantitative evaluation and visual evaluation of radiographic images easily and at low cost, and to increase the accuracy of invariance evaluation of the radiographic system. . In addition, a second object of the present invention is to make it possible to inspect even detailed items using a radiographic image obtained by one imaging when inspecting a radiation imaging system. Furthermore, the third object of the present invention is to ensure the reliability of the inspection accuracy and to promote the automation of the inspection work without being affected by the installation position of the phantom when performing the inspection of the radiation imaging system. And

  In order to solve the above problems, the phantom according to the first aspect of the present invention evaluates a radiographic image obtained by imaging a phantom using a radiographic system with respect to at least one image quality evaluation item, A phantom used for inspecting a radiation imaging system, wherein a first image quality evaluation pattern that is disposed on the substrate and used for visual evaluation is formed on a predetermined image quality evaluation item. 1 member, and a second member which is arranged on the substrate and has a second image quality evaluation pattern used for quantitative evaluation for a predetermined image quality evaluation item.

  A phantom according to a second aspect of the present invention is for inspecting a radiographic system by evaluating a radiographic image obtained by imaging the phantom using the radiographic system with respect to at least one image quality evaluation item. A substrate, at least one member arranged on the substrate and having an image quality evaluation pattern used for a predetermined image quality evaluation item, and a plurality of different ones on the substrate A plurality of markers respectively arranged at positions, and a plurality of markers used for detecting the position of the image quality evaluation pattern in the radiation image.

  The medical image processing apparatus according to the first aspect of the present invention records radiation image information on a recording medium by performing radiation imaging, generates image data by reading the radiation image information from the recording medium, and generates the image data. A medical image processing apparatus for examining a radiographic system by evaluating the image quality of a radiographic image obtained by using a radiographic system that displays or outputs a radiographic image by performing predetermined image processing on data. Image processing means for performing image processing on the input image data, and image data representing a radiographic image obtained by photographing a phantom in which a plurality of image quality evaluation patterns for predetermined image quality evaluation items are arranged are input Measurement means for measuring a predetermined image quality evaluation item with respect to the input image data , An input means used for inputting the inspection result obtained for a predetermined image quality evaluation item by visually observing the displayed or output radiation image, and an inspection input using the measurement result and the input means in the measuring means Determination means for determining the image quality of the radiation image based on the result.

  A medical image processing apparatus according to a second aspect of the present invention is a medical image processing apparatus that performs an examination of a radiographic system by evaluating the image quality of a radiographic image obtained by using the radiographic system. Radiation obtained by imaging a phantom in which an image quality evaluation pattern for one image quality evaluation item is arranged and a plurality of markers are respectively arranged at a plurality of different positions using a radiation imaging system When image data representing an image is input, position detection means for detecting the position of the phantom in the radiation image using a plurality of markers, the position of the phantom detected by the position detection means, and the position in the radiation image By comparing with the reference position of the phantom, the amount of deviation in the linear and rotational directions is calculated. Comparison calculation means, search area changing means for changing a search area, which is an area in a radiographic image measured for a predetermined image quality evaluation item, based on the amount of deviation calculated by the comparison calculation means, and the search area change A physical quantity calculating means for calculating a physical quantity representing the characteristics of the radiation image by measuring a predetermined image quality evaluation item in the search area changed by the means, and a determination used for determining the image quality of the radiation image The determination reference changing means for changing the reference based on the deviation amount calculated by the comparison calculating means, and the physical quantity calculated by the physical quantity calculating means based on the determination reference changed by the determination reference changing means. Determination means for determining the image quality of the radiation image.

  A medical image processing apparatus according to a third aspect of the present invention is a medical image processing apparatus that examines a radiographic system by evaluating the image quality of a radiographic image obtained by using the radiographic system. Obtained by photographing a phantom in which an image quality evaluation pattern for at least one image quality evaluation item is arranged and a plurality of markers are respectively arranged at a plurality of different positions using a radiation imaging system When image data representing a radiation image is input, position detection means for detecting the position of the phantom in the radiation image by using a plurality of markers, and the position of the phantom detected by the position detection means, By comparing with the reference position of the phantom in the radiation image, the linear direction and rotation Comparison calculating means for calculating the amount of deviation in the direction, image correcting means for correcting the position of the phantom in the radiographic image so as to reduce the amount of deviation calculated by the comparison calculating means, and position by the image correcting means Based on the physical quantity calculated by the physical quantity calculating means, the physical quantity calculating means for calculating the physical quantity representing the characteristics of the radiation image by measuring the predetermined image quality evaluation item for the phantom image corrected for Determining means for determining the image quality of the radiation image.

  An inspection method for a radiographic system according to a first aspect of the present invention is a method for inspecting a radiographic system by evaluating the image quality of a radiographic image obtained by using the radiographic system, (A) inputting image data representing a radiographic image obtained by radiographing a phantom in which a plurality of image quality evaluation patterns for image quality evaluation items including measurement of linearity, sharpness, and reduction ratio are arranged; (B) detecting the position of the phantom in the radiation image based on the image data input in step (a), and the phantom image based on the image data input in step (a). , At least for image quality evaluation items including measurement of linearity, sharpness and reduction ratio And step (c) performing, on the basis of the measured measurement result in step (c), it includes a determining the quality of the radiation image (d).

  The inspection method of the radiographic system according to the second aspect of the present invention records radiographic image information on a recording medium by performing radiography, generates image data by reading the radiographic image information from the recording medium, A method for inspecting a radiographic system by evaluating the image quality of a radiographic image obtained by using a radiographic system that displays or outputs a radiographic image by performing predetermined image processing on the image data. Inputting image data representing a radiographic image obtained by radiographing a phantom in which an image quality evaluation pattern used for visual evaluation and an image quality evaluation pattern used for quantitative evaluation are arranged for a predetermined image quality evaluation item With respect to the image data input in step (a) and step (a), a predetermined image Step (b) for quantitatively measuring the evaluation item, and displaying or outputting a radiation image based on the image data input in step (a), and visually observing the displayed or output radiation image The image quality of the radiation image is determined on the basis of the step (c) for inspecting a predetermined image quality evaluation item, the measurement result measured in step (b), and the inspection result inspected in step (c). Determining (d).

  An inspection method for a radiographic system according to a third aspect of the present invention is a method for inspecting a radiographic system by evaluating the image quality of a radiographic image obtained by using the radiographic system, comprising: Image data representing a radiographic image obtained by radiographing a phantom in which an image quality evaluation pattern for one image quality evaluation item is arranged and a plurality of markers are arranged at a plurality of different positions. Step (a), step (b) for detecting the position of the phantom in the radiographic image using a plurality of markers based on the image data input in step (a), and step (b) And the reference position of the phantom in the radiation image In step (c), the step (c) for calculating the amount of deviation in the linear direction and the rotational direction by comparison and the search region that is the region in the radiographic image measured for the predetermined image quality evaluation item were calculated. A step (d) that is changed based on the amount of deviation, and a step that calculates a physical quantity representing the characteristics of the radiation image by measuring the image quality evaluation item in the search area changed in step (d) ( e), a step (f) for changing the judgment standard used for judging the image quality of the radiation image based on the deviation amount calculated in the step (c), and a judgment standard changed in the step (f). And (g) determining the image quality of the radiation image using the physical quantity calculated in step (e) based on

  An inspection method for a radiographic system according to a fourth aspect of the present invention is a method for inspecting a radiographic system by evaluating the image quality of a radiographic image obtained by using the radiographic system, comprising: Image data representing a radiographic image obtained by radiographing a phantom in which an image quality evaluation pattern for one image quality evaluation item is arranged and a plurality of markers are arranged at a plurality of different positions. Step (a), step (b) for detecting the position of the phantom in the radiographic image using a plurality of markers based on the image data input in step (a), and step (b) And the reference position of the phantom in the radiation image Step (c) for calculating the deviation amount in the linear direction and the rotation direction by comparing, and the step for correcting the position of the phantom in the radiographic image so that the deviation amount calculated in Step (c) is reduced. (D) and (e) calculating a physical quantity representing the characteristics of the radiation image by measuring a predetermined image quality evaluation item for the image of the phantom whose position is corrected in step (d), And (f) determining the image quality of the radiation image based on the physical quantity calculated in step (e).

  According to the present invention, since a QC phantom having a plurality of members arranged on a substrate is used, it is possible to inspect up to a detailed item about the radiation imaging system by one imaging. In addition, by constructing an inspection system for a radiographic system using such a QC phantom, it is possible to efficiently perform an inspection in which reliability is ensured.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted. In the present application, quantitative evaluation refers to digital data representing a radiographic image such as an image quality management phantom (inspection structure) obtained by radiography, and performs quantitative measurement by performing processing including arithmetic processing, Based on the measurement result, it refers to an inspection for obtaining an inspection quantitative value, an inspection pass or failure determination, and the like. Further, in this application, visual evaluation refers to an inspection performed by an inspection other than the above quantitative evaluation on a radiation image such as the above phantom, specifically, a radiographic image displayed on a film or a screen is displayed by an operator. Means an inspection performed by visual inspection.

FIG. 1 is a block diagram showing a configuration of a radiation imaging system including a medical image processing apparatus according to the first embodiment of the present invention.
As shown in FIG. 1, the radiographic system is a radiographic apparatus 100 that records radiographic image information on a recording sheet 10 by performing radiographic imaging, and reads out radiographic image information recorded on the recording sheet 10 to obtain image data. And a medical image processing apparatus 300 that performs predetermined processing on image data input from the medical image reading apparatus 200. These radiation imaging apparatus 100, medical image reading apparatus 200, and medical image processing apparatus 300 are connected to each other via a network N1.
The network N1 includes a radiation information management system (RIS) 500 that is used to manage various tasks related to radiographic imaging, and a hospital information management that is used to manage the entire hospital. A communication control unit 540 for communicating with the maintenance center 530 via a system (hospital information system, HIS) 510 and the Internet 520 is also connected. Furthermore, an external device 550 such as a hospital database server, an ID card reader, or a terminal device is connected to the network N1 as necessary.

  The radiation imaging apparatus 100 is an apparatus that records radiation that has passed through a subject on the recording sheet 10 as radiation image information about the subject by irradiating the recording sheet 10 with radiation through the subject. The recording sheet 10 is a sheet coated with a stimulable phosphor material that accumulates energy of irradiated radiation (stimulable phosphor sheet), and is used as a recording medium for recording radiation image information.

  The radiation imaging apparatus 100 includes an imaging position raising / lowering mechanism 101 that adjusts the imaging position of the subject by moving the position of the recording sheet 10 up and down, an imaging table 102 that determines the position of the subject's legs, and a subject. A radiation generation unit 103 that generates radiation applied to the imaging unit, an imaging control unit 104 that controls the radiation generation unit 103 and the like according to a given imaging condition, and an input unit 105 that is used to input various commands and imaging conditions. Including. The shooting control unit 104 is connected to the network N1, and can set shooting conditions via the network N1.

  When examining the radiation imaging system, the phantom 20 is placed in the radiation imaging apparatus 100 as a subject. Then, radiation image information of the phantom 20 is recorded on the recording sheet 10 by performing radiation imaging under predetermined imaging conditions. After photographing, the recording sheet 10 is set at a predetermined position of the medical image reading apparatus 200. The phantom 20 will be described in detail later.

  The medical image reading apparatus 200 photoelectrically reads the radiation image information recorded on the recording sheet 10 and generates image data by converting the energy level of the radiation applied to the recording sheet 10 into data. Reading of radiation image information is performed as follows. That is, the surface of the recording sheet 10 is scanned by the light beam emitted from the laser light source 201 and passed through the light scanning unit 202. As a result, an amount of stimulated emission light corresponding to the accumulated radiation energy is generated from the region of the recording sheet 10 irradiated with the light beam. This stimulated emission light is guided by a light guide, photoelectrically detected by a photomultiplier (photomultiplier tube) 203, and output as an analog signal representing radiation image information. Further, this analog signal is amplified by an amplifier 204 and digitized by an A / D converter 205. The image data generated in this way is output to the medical image processing apparatus 300 via the network N1 together with the image supplementary information.

  Alternatively, another method as described below may be used as the method of the medical image reading apparatus. That is, a line light source in which LEDs or the like are arranged in the main scanning direction is used as a light source for exciting the stimulated emission light, and a CCD line or the like arranged in the main scanning direction as a detector for detecting the stimulated emission light. A read head having a sensor is used. The excitation light emitted from the line light source is incident on the stimulable phosphor sheet 10 while relatively moving the reading head and the stimulable phosphor sheet 10 in the sub-scanning direction orthogonal to the main scanning direction. The stimulated emission light generated from the photostimulable phosphor sheet 10 is read by a line sensor.

  The medical image processing apparatus 300 generates a radiographic image by performing image processing on the image data generated by the medical image reading apparatus 200, and performs measurement on a predetermined image quality evaluation item for such a radiographic image. To check the performance of the radiographic system and the invariance of parameters. The medical image processing apparatus 300 is configured using, for example, a personal computer. The medical image processing apparatus 300 includes an input unit 310 such as a keyboard and a mouse, a display unit 320 such as a CRT monitor that displays radiographic images, and the like, which are used for inputting various commands and examination results. And a printer 330 that prints a diagnostic image on a film or the like.

  FIG. 2 is a block diagram showing in detail the configuration of the medical image processing apparatus 300 shown in FIG. The medical image processing apparatus 300 includes a memory 301 that temporarily stores input image data and image supplementary information, a hard disk control unit 302, an interface 303, a network interface 304, a central processing unit (hereinafter referred to as a CPU) 400, And a hard disk 410 as a recording medium. The memory 301, the hard disk control unit 302, the network interface 304, and the CPU 400 are connected to each other via a bus line BL.

  The CPU 400 is connected to the input unit 310, the display unit 320, and the printer 330 via the interface 303. The CPU 400 is also connected to the radiation imaging apparatus 100, the medical image reading apparatus 200, the RIS 500, the HIS 510, and the communication control unit 540 illustrated in FIG. 1 via the network interface 304 and the network N1.

  The hard disk 410 is recorded with a basic program for operating the CPU 400, software including a program (QC program) used to inspect the radiation imaging system, information used for the processing, and the like. Yes. In FIG. 2, an image data recording unit 411 that records image data and image supplementary information, a parameter file recording unit 412 that records parameters used at the time of inspection, and history information of inspection results of the radiation imaging system are recorded. An inspection result recording unit 413 and a QC program recording unit 414 are shown. In addition to the built-in hard disk 410, an external hard disk, flexible disk, MO, MT, RAM, CD-ROM, DVD-ROM, or the like may be used as the recording medium.

  Next, the functional blocks 401 to 407 shown in FIG. 2 will be described. These functions are for inspecting the quality of the radiographic system shown in FIG. 1 by evaluating the image quality of a radiographic image obtained by radiographing a phantom described later. In the present embodiment, these functional blocks 401 to 407 are realized by the CPU 400 and software (program).

The image processing unit 401 performs predetermined image processing such as normalization, gradation processing, and logical reading processing on the image data input from the medical image reading apparatus 200.
The marker position detection unit 402 detects the position of the image representing the marker arranged on the phantom on the recording sheet 10 based on the image data subjected to the image processing in the image processing unit 401.

Based on the position of the detected marker image, the comparison calculation unit 403 calculates the amount of positional deviation of the image representing the phantom 20 in the parallel direction and the rotation direction with respect to the recording sheet 10.
The measurement region calculation unit 404 calculates a region on the radiographic image to be measured when performing an examination based on the calculated amount of positional deviation.

  The measurement unit 405 measures the image quality evaluation item quantitatively evaluated based on the calculated measurement area for the image data subjected to the image processing, and calculates a physical quantity necessary for the image quality evaluation. In addition, about the image quality evaluation item evaluated visually, an operator inspects the radiographic image displayed on the display part 320 visually. The inspection result by the operator is input to the medical image processing apparatus 300 using the input unit 310.

The determination unit 406 determines whether or not each image quality evaluation item is abnormal based on the measurement result input from the measurement unit 405 and the inspection result by the operator input via the input unit 310. Create the result.
The output unit 407 outputs the image data subjected to the image processing in the image processing unit 401, the determination result created by the determination unit 406, and the like to the display unit 320 or the printer 330 via the interface 303. The inspection results and determination results for each image quality evaluation item are also stored in the hard disk 410.

  Next, a phantom according to an embodiment of the present invention will be described with reference to FIGS. The phantom according to the present embodiment is an image quality management phantom used when inspecting the quality of the radiation imaging system shown in FIG. Hereinafter, the image quality management phantom used in the present embodiment is referred to as a QC (quality control) phantom.

  FIG. 3 is a plan view showing the configuration of the QC phantom according to the present embodiment. 4A to 4E respectively show cross sections of the QC phantom 20 taken along lines A-A 'to E-E' shown in FIG. As shown in FIG. 3, the QC phantom 20 is provided with various image quality measurement patterns 25 to 29 formed of members such as acrylic, copper, tungsten, lead, and mesh. These image quality measurement patterns correspond to a plurality of image quality evaluation items used when evaluating a radiation image. In the present embodiment, image quality measurement patterns are arranged so that both quantitative evaluation and visual evaluation can be executed for predetermined image quality evaluation items among the image quality evaluation items. The image quality evaluation items that can be measured in the present embodiment include image linearity, dynamic range, sharpness (resolution), contrast, S / N ratio, and reduction ratio.

  As shown in FIG. 4A, the QC phantom 20 is configured by arranging various members in a space surrounded by a white acrylic case 21 and a white or transparent acrylic lid 22. In FIG. 3, the acrylic lid 22 is not shown in order to explain the inside of the QC phantom 20.

  The acrylic case 21 includes a substrate 21a on which various members are arranged, and a side wall 21b surrounding the substrate 21a. The substrate 21a and the side wall 21b may be formed integrally, or may be formed by bonding separately formed substrates. A copper plate 23 is laid on the bottom surface inside the acrylic case 21.

  As shown in FIG. 3, three markers 24 a to 24 c are arranged on the QC phantom 20. The markers 24a to 24c obtain geometric positions of the QC phantom image (hereinafter referred to as phantom image) recorded on the recording sheet 10 on the recording sheet 10, and thereby images of the image quality measurement patterns 25 to 29 are obtained. This is used to detect the position (hereinafter referred to as a pattern image). The markers 24a to 24c preferably have different radiation transmittances from the other parts of the QC phantom 20 in order to easily and reliably detect a radiation image (marker image) of the marker. The image quality measurement patterns 25 to 29 are preferably formed in a different shape. As shown to (a) of FIG. 4, in this embodiment, these markers 24a-24c are formed by cutting out the copper plate 23, for example in the circle of diameter 5mm.

  By detecting the position of the pattern image using the marker, the accuracy of the quality inspection of the radiation imaging system can be improved, and the image processing and the processing of the image quality evaluation items can be easily automated. Note that the markers 24 a to 24 c may be used for alignment of the QC phantom 20.

  As shown in FIG. 3, the QC phantom 20 is provided with a copper step pattern 25 including a plurality of copper plates having different thicknesses arranged in a staircase pattern. The copper step pattern 25 is used for inspecting the linearity and dynamic range of the luminance of the image due to the difference in the radiation dose irradiated to the recording sheet by visual evaluation or quantitative evaluation by an operator. Since the intensity of the radiation transmitted through the copper plate is inversely proportional to its thickness, the use of copper plates having different thicknesses (including thickness 0) can provide an intensity level from the highest intensity to the lowest intensity. is there. As shown in FIG. 4B, in the present embodiment, the thicknesses of these patterns 25a to 25b, including the thickness of the copper plate 23, are 0 mm, 0.8 mm, 2.5 mm, and 5.mm, respectively. 5 mm. The pattern 25 a having a thickness of 0 mm is produced by cutting out the copper plate 23. Note that the number, size, and thickness of the copper plates included in the step pattern are not limited to this embodiment, and the step pattern may be configured using copper plates having various sizes and thicknesses.

  As shown in FIG. 3, the QC phantom 20 is provided with two edge detection patterns 26 in which sharp angular edge portions are formed. The edge detection pattern 26 is used to quantitatively evaluate the sharpness of the radiation image. Differentiating the image of the angle edge portion arranged in these edge detection patterns 26 to obtain a line spread function, and then performing Fourier transform, the MTF (modulation transfer function) in the X direction and the Y direction is measured. The In the present embodiment, the two edge detection patterns 26 are arranged so as to be shifted by 5 ° with respect to two orthogonal sides (two scanning directions) of the QC phantom 20. Further, as shown in FIG. 4C, each edge detection pattern 26 is arranged using a tungsten plate 26a so that the lead member 26b is floated from the substrate 21a.

  As shown in FIG. 3, the QC phantom 20 is provided with a berga phantom (contrast resolution pattern) 27 formed of an acrylic member. Burger phantom 27 is used to visually inspect low contrast resolution, thereby verifying the relative contrast and S / N ratio of the radiographic system. As shown in FIG. 3 or FIG. 4D, in the present embodiment, the acrylic member having a predetermined thickness in the line DD ′ direction changes in diameter to 1 mm, 2 mm, 3 mm, and 4 mm. Are arranged as follows. On the other hand, as shown in FIG. 4 (e), the acrylic member having a predetermined diameter is arranged so that the thickness changes to 1 mm, 1.5 mm, 2 mm, and 3 mm in the direction of the line EE ′. Yes.

  As shown in FIG. 3, the QC phantom 20 is provided with two copper scale patterns 28 formed of a copper member. The copper scale pattern 28 is used to quantitatively evaluate the reduction ratio in each scanning direction. In this embodiment, the size of these copper members is 100 mm in length, 10 mm in width, and 0.5 mm in thickness, and the long side of the copper member is relative to two sides (two scanning directions) perpendicular to the QC phantom 20. Are arranged in parallel to each other.

  Further, a wire mesh pattern 29 is arranged on the QC phantom 20. The wire mesh pattern 29 is used for visually evaluating the sharpness of the radiographic image and its non-uniformity. The wire meshes 29a to 29d are preferably made of steel mesh, and have different wire intervals. Sharpness non-uniformity is evaluated over a wide range from their entirety by comparing the non-uniformity of sharpness between the wire meshes 29a-29d. In this embodiment, the wire intervals of the wire meshes 29a to 29d are 300 μm, 250 μm, 180 μm, and 150 μm, respectively. In the present embodiment, four wire meshes are used, but five or more different sizes of mesh portions may be provided in order to improve the accuracy of the sharpness non-uniformity evaluation. Various values may be used for the size, thickness, and interval of these meshes.

  Next, an inspection method for the radiation imaging system according to the first embodiment of the present invention will be described with reference to FIGS. The inspection method for the radiation imaging system according to the present embodiment is performed using the QC phantom 20 shown in FIG. 3 in the radiation imaging system shown in FIGS. 1 and 2. FIG. 5 is a flowchart for explaining the inspection method of the radiation imaging system according to the present embodiment.

  First, in step S <b> 1, the radiation imaging apparatus 100 performs radiation imaging using the QC phantom 20 as a subject, and records radiation image information on the recording sheet 10. Next, in step S <b> 2, the medical image reading apparatus 200 reads the radiation image information recorded on the recording sheet 10 and generates image data. In step S <b> 3, the medical image processing apparatus 300 performs first image processing including normalization, gradation processing, logical reading processing, and the like on the image data input from the medical image reading apparatus 200 in the image processing unit 401. . In step S <b> 4, the image data subjected to the first image processing is recorded in the image data recording unit 411 of the hard disk 410. When image supplementary information is input along with image data, the image supplementary information is also recorded on the hard disk 410.

In steps S5 to S7, the CPU 400 reads a predetermined program from the QC program recording unit 414 and executes it.
First, in step S5, the marker position detection unit 402 detects the positions of the marker images representing the three markers 24a to 24c based on the image data subjected to the image processing, and then the comparison calculation unit 403 By comparing the positions of the detected marker images with the reference position of the marker image in the phantom image recorded in advance in the parameter file 412, the deviation from the reference position of the phantom image in the radiation image (position shift) Calculate the amount.

  Here, when radiography is performed, the QC phantom 20 may be displaced from an appropriate position. When radiation imaging is performed in such a state, the phantom image is displaced in the parallel direction and the rotation direction within a predetermined range with respect to the reference position on the recording sheet. Alternatively, the QC phantom 20 may be installed upside down or upside down during radiography. Even in such a case, it is possible to know the arrangement of the QC phantom 20 at the time of photographing by detecting the positions of the three marker images. A method for detecting the position of the marker image and a method for calculating the amount of positional deviation in the parallel direction and the rotation direction will be described in detail later.

  In step S <b> 6, the measurement area calculation unit 404 calculates a position (hereinafter referred to as a measurement area) on the recording sheet 10 of an image (pattern image) of an image quality measurement pattern used for quantitative evaluation. In the present embodiment, the patterns used for quantitative evaluation include the copper step pattern 25, the edge detection pattern 26, and the copper scale pattern 28 shown in FIG. Information regarding the positions of these patterns (hereinafter referred to as reference areas) when no positional deviation has occurred, that is, the coordinates of the start and end points of the pixels corresponding to the reference areas are recorded in advance in the parameter file recording unit 412. . Therefore, the measurement region calculation unit 404 calculates the measurement region in the actually obtained radiographic image based on the positional deviation of the phantom image calculated in step S5 and the information on the reference region. A method for calculating the measurement region will be described later.

  In step S7, the measurement unit 405 recognizes the pattern image for the image quality evaluation item based on the measurement region calculated in step S6, and for the image data subjected to image processing, the linearity of the luminance of the image and the scan Measures the physical quantity necessary for evaluating the precision, sharpness, reduction ratio, etc.

  On the other hand, in step S8, the display unit 320 displays a radiation image of the QC phantom 20 based on the image data that has been subjected to image processing. In step S9, the operator visually inspects the image quality evaluation items with low contrast resolution and sharpness based on the radiation image displayed on the display unit 320, and uses the input unit 310 in FIG. Input to the image processing apparatus 300. For example, the low contrast resolution is inspected by measuring, for each diameter, the number of members that the operator can visually recognize among the plurality of members included in the berga phantom 27. Further, the visual sharpness is inspected by measuring the number of wire meshes that the operator can visually recognize. Note that the operator may perform a visual inspection using the radiation image of the QC phantom 20 output from the printer 330.

  In step S10, the determination unit 406 determines whether there is an abnormality in the inspection result. This determination is performed by, for example, setting a basic value in advance based on an average of one or a plurality of inspection results in the inspection result history information recorded in the inspection result recording unit 411, This is done depending on whether the maximum value or the minimum value calculated from the basic value is within an allowable range.

  As a result of the determination, if an abnormality is found in the inspection result, the process proceeds to step S11, and the CPU 400 notifies the maintenance center 530 of the abnormality. The notification to the maintenance center 530 may be performed via the central management unit of the RIS 500 or the HIS 510.

  On the other hand, if no abnormality is found as a result of the determination in step S10, the process proceeds to step S12, and the inspection result and the determination result are recorded in the inspection result recording unit 411 of the hard disk 410. In step S13, these inspection results and determination results are output to the display unit 320 and displayed on the screen. Further, in step S14, these inspection results and determination results are also output to the printer 330 and printed together with the radiation image of the QC phantom 20 if necessary.

Next, a method for detecting the position of the marker image in the radiographic image performed in step S5 in FIG. 5 will be described with reference to FIGS.
First, prior to detecting the position of a marker image, a range for searching for a marker is determined. 6A and 6B show the positional relationship between the recording sheet and the phantom image recorded there. FIG. 7 is a diagram for explaining a range for searching for a marker.

  As a premise for determining the marker search range, as shown in FIG. 6A, when the position where the center of the recording sheet 10 coincides with the center of the phantom image 30 is used as a reference, the phantom for the recording sheet 10 is used. The positional deviation in the parallel direction of the image 30 is assumed to be within a range of ± 10 mm vertically and horizontally. Further, as shown in FIG. 6B, when the reference angle is a state in which the long side of the recording sheet 10 and the long side of the phantom image 30 are parallel, the rotation direction of the phantom image 30 with respect to the recording sheet 10 Is assumed to be within a range of ± 5 °.

  Accordingly, as shown in FIG. 7A, the range in which the marker image 31 at the upper left of the phantom image 30 can exist is within the region abcd by translation, and within the region efghij by further rotational movement. It becomes. For this reason, when detecting the marker image 31, it is desirable to perform a search limited to the area efghij. However, in order to simplify the processing, a region ABCD that is a circumscribed rectangle of the region efghij is set as a search region. In FIG. 7A, the marker image 31 is represented by dots. However, when searching, it is necessary to consider the size of the marker image 31.

  As shown in FIG. 7B, the coordinates of each point and the size of each part are defined as follows. FIG. 7B shows a phantom image 30 in a state in which no positional deviation occurs with respect to the recording sheet 10. The X axis and the Y axis are parallel to two orthogonal sides of the recording sheet 10, respectively, and the x axis and the y axis are parallel to two orthogonal sides of the phantom image 30, respectively. In the following, unless otherwise specified, when the center point O of the recording sheet 10 is the origin, the right direction in FIG. 7B is the positive direction of X, and the upward direction is the positive direction of Y. And

I _X ... Horizontal size of recording sheet 10 I _Y ... Vertical size of recording sheet 10 F _X ... Horizontal size of phantom image 30 F _Y ... Vertical size of phantom image 30 M _X ... Marker from upper left of phantom image 30 the marker image position in the absence misalignment in the y direction a distance D R _... phantom image 30 from the upper left of the x-direction distance M Y _... phantom image 30 to the center of the marker image 31 to the center of the image 31 as a reference , The maximum parallel movement distance (X _S , Y _S ) of the marker image 31 on the x-axis and the y-axis ... the coordinates of the point A when the upper left corner of the recording sheet 10 is the origin (X _E , Y _E ) ... the recording sheet 10 The coordinates of the point C when the upper left of the recording sheet 10 is the origin. Here, when the upper left of the recording sheet 10 is the origin, the right direction in FIG. Direction is assumed to be the positive direction of the Y.

a (a _X , a _Y )... coordinates of point a with the center point O of the recording sheet 10 as the origin b (b _X , b _Y )... coordinates of point b with the center point O of the recording sheet 10 as the origin c ( c _X , c _Y )... coordinates of the point c with the center point O of the recording sheet 10 as the origin d (d _X , d _Y )... coordinates of the point d with the center point O of the recording sheet 10 as the origin A (C _X , B _Y ) ... Coordinates of point A with the center point O of the recording sheet 10 as the origin C (A _X , D _Y ) ... Coordinates of point C with the center point O of the recording sheet 10 as the origin

Moreover, the radius of the marker image 31 and _{M R.} Further, on the basis of the case where the long side of the recording sheet 10 and the long side of the phantom image 30 are parallel, the maximum rotation angle in the positive direction of the phantom image 30 is α and the maximum rotation angle in the negative direction is β. _{Let the} movement distance be DR. The maximum rotation angle is defined in the direction in which the angle increases (counterclockwise). In the cases shown in FIGS. 6A and 6B, α = 0.5 °, β = 0.5 °, and D _R = 10 mm.

By using the values defined in this way, the marker image search area ABCD shown in FIG. 7A has two points (X _S , Y _S ) represented by the following equations (1) and (2). And (X _E , Y _E ) (these origins are at the upper left of the recording sheet 10) and are determined by a rectangle having a diagonal line. As shown in FIG. 7B, two orthogonal sides of the rectangle are parallel to the X axis and the Y axis, respectively.

(X _S , Y _S ) = (I _X / 2 + C _X , I _Y / 2−B _Y ) (1)
(X _E , Y _E ) = (I _X / 2 + A _X , I _Y / 2−D _Y ) (2)
_{Here, C X, D Y, A} X and _{B Y} is expressed by the following equation (3) to (6).
C _X = a _X · cos (−α) + a _Y · sin (−α) (3)
D _Y = −b _X · sin (−α) + b _Y · cos (−α) (4)
A _X = d _X · cos (−β) + d _Y · sin (−β) (5)
B _Y = −a _X · sin (−β) + a _Y · cos (−β) (6)

Further, (a _X , a _Y ), (b _X , b _Y ) and (d _X , d _Y ) are expressed by the following formulas (7) to (9).
(A _X , a _Y ) = (− F _X / 2 + M _X −D _R −M _R ,
F _Y / 2-M _Y + D _R + M _R ) (7)
(B _X , b _Y ) = (− F _X / 2 + M _X −D _R −M _R ,
_{F Y / 2-M Y -D} R -M R) ... (8)
(D _X , d _Y ) = (− F _X / 2 + M _X + D _R + M _R ,
F _Y / 2-M _Y + D _R + M _R ) (9)

8 and 9 are flowcharts showing the operation of the medical image processing apparatus 300 (FIG. 2) for detecting the marker image and calculating the positional deviation of the phantom image using the marker image.
In the present embodiment, the marker image 31 is detected using the brightness and shape of the marker image 31. The reason is that, in addition to the marker image, the radiographic image obtained by photographing the QC phantom 20 includes a background outside the QC phantom 20, images inside the QC phantom including various patterns and bases, This is because there is a possibility that such an image may exist in the search region defined by the above formulas (1) and (2) because the QC phantom habit, aperture, and the like are included. .

First, in steps S <b> 21 to S <b> 24 of FIG. 8, the marker position detection unit 402 of the medical image processing apparatus 300 detects the presence or absence of the marker image 31 in the search region by detecting the luminance of the image in the search region. judge.
That is, in step S21, a histogram indicating the density distribution (specific luminance appearance frequency) of the image in the search area is created. FIG. 10 is a histogram showing the light and shade distribution of the image in the search area. The QL value indicated on the horizontal axis is an amount that increases as the luminance of the image decreases (approaches black), and the frequency indicated on the vertical axis is an amount corresponding to the number of pixels that indicate the QL value.

Next, in step S22, a histogram is searched from the maximum QL value toward the minimum QL value. The reason is that when the background image outside the QC phantom is included in the search area, the marker image 31 is the next highest density area after the background image, and when the background image is not included, This is because the marker image 31 is the highest density region. Then, after the frequency value exceeds the maximum value of the QL value generated by the marker image 31 and the background image outside the QC phantom, the QL value when the frequency first falls below the threshold value Thd is obtained. _MAX 1 is assumed. Here, the threshold value Thd is a value determined by spatial resolution and bit resolution.

In step S23, the histogram is continuously searched from S _MAX 1 toward the lowest QL value, and it is determined whether or not the frequency value again exceeds the threshold value Thd. When it exceeds again, the QL value at that time is set to S _MAX 2, and the process proceeds to step S24. In this case, it is determined that there is a possibility that the marker image 31 exists in the search area, and S _MAX 1 is set as the threshold value Th1 for the QL value in step S24. On the other hand, when the frequency value does not again exceed the threshold value Thd, that is, when S _MAX 2 cannot be obtained, the search area is a uniform image, and therefore the marker image 31 is present in the search area. The detection of the marker image is considered to be absent.

  Incidentally, FIG. 10 shows a histogram when the density of the background image and the marker image 31 is close. In this case, the frequency peaks of the background image and the marker image 31 are connected. However, when the densities of the background image and the marker image 31 are not close, the frequency peaks of the background image and the marker image 31 are separated. Therefore, the threshold value Th1 set in step S24 is the threshold value of the background image that is the highest density region when the density of the background image and the marker image 31 is not close. When the density is close, it becomes a threshold value for the background image and the marker image.

  Therefore, in steps S25 to S29, the marker position detection unit 402 determines the shape of the region where the QL value is equal to or greater than the threshold value Th1. That is, in step S25, the search area is divided into two areas, that is, an area where the QL value is greater than or equal to the threshold value Th1 and an area where the QL value is less than the threshold value Th1. Next, in step S26, the pixels included in the region whose QL value is equal to or greater than the threshold value Th1 are labeled. Further, in step S27, regions where the labeled pixels are in contact with each other are collected, and this is set as a marker image candidate region.

Next, in step S28, it is determined whether or not there is a marker image candidate region having an area within a predetermined range. This determination is made according to whether or not the following equation (10) is satisfied.
0.5πM _R ² <area of marker image candidate region <1.5πM _R ² (10)
As a result of the determination based on Expression (10), if there is a marker image candidate region having an area within a predetermined range, the process proceeds to step S29. On the other hand, when there is no marker image candidate region having an area within a predetermined range, it is considered that the marker image 31 does not exist in the region where the QL value is equal to or greater than the threshold Th1, and the processing is shown in FIG. The process proceeds to step S31 shown.

In step S29, a determination is made as to whether or not the circularity of the marker image candidate region is greater than or equal to a predetermined value. The determination method is as follows. First, it is assumed that a circle having the same area as the marker image candidate region exists at the center of gravity of the marker image candidate region. Assuming that the area of the marker image candidate region is S, the assumed radius R of the circle is R = (S / π) ^1/2 .

Next, the area of a common area between the marker image candidate area and the assumed circle area is U, and the circularity of the marker image candidate area is U / S. And it is determined whether circularity U / S satisfy | fills following Formula (11).
U / S ≧ 0.8 (11)
As a result of the determination based on Expression (11), when the circularity of the marker image candidate region is equal to or greater than a predetermined value, the process proceeds to step S30. On the other hand, when the circularity of the marker image candidate region is less than the predetermined value, it is considered that the marker image 31 does not exist in the region where the QL value is equal to or greater than the threshold value Th1, and the process is shown in FIG. The process proceeds to S31.

In step S <b> 30, the comparison calculation unit 403 of the medical image processing apparatus calculates the positional deviation of the phantom image in the parallel direction and the rotation direction using the coordinates of the center of gravity of the marker image candidate region with the upper left of the recording sheet 10 as the origin. Then, the result is output to the measuring unit 405.
On the other hand, as a result of the determination in step S28 or S29 in FIG. 8, if it is determined that the marker image 31 does not exist in the region where the QL value is equal to or greater than the threshold value Th1, the threshold is set as shown in FIG. A determination is made as to whether or not the marker image 31 exists in an area that is less than the value Th1.

First, in steps S31 to S33, the marker position detection unit 402 determines the possibility of the presence or absence of the marker image 31 in the search area. That is, in step S31, in the histogram shown in FIG. 10, a search is performed from the threshold value Th1 to the lowest QL value for the QL value, and the QL value when the value falls below the threshold Thd is obtained. The value is set to S _MAX 3. Next, in step S32, a search is continuously performed from S _MAX 3 toward the lowest QL value, and it is determined whether or not the frequency value again exceeds the threshold value Thd. If the frequency value again exceeds the threshold value Thd, the QL value at that time is set to S _MAX 4, and the process proceeds to step S33. In this case, it is determined that there is a possibility that the marker image 31 exists in the search area, and in step S33, S _MAX 3 is set as the threshold value Th2 for the QL value. On the other hand, if the frequency value does not again exceed the threshold value Thd, that is, if S _MAX 4 cannot be obtained, the image other than the background image in the search area is a uniform image, It is considered that the marker image 31 does not exist, and the detection of the marker image ends.

  Next, in steps S34 to S38, the marker position detection unit 402 determines the shape of the region where the QL value is greater than or equal to the threshold value Th2 and less than Th1. That is, in step S34, the search area is divided into two areas: an area where the QL value is greater than or equal to the threshold Th2 and less than Th1, and the other areas. Next, in step S35, pixels included in a region where the QL value is greater than or equal to the threshold value Th2 and less than Th1 are labeled. Further, in step S36, regions where the labeled pixels are in contact with each other are collected, and this is set as a marker image candidate region.

  Next, in step S37, the marker position detection unit 402 determines whether there is a marker image candidate region having an area within a predetermined range, similarly to the processing in step S28. As a result, when there is a marker image candidate region having an area within a predetermined range, the process proceeds to step S38. On the other hand, when there is no marker image candidate area having an area within a predetermined range, it is considered that the marker image 31 does not exist in the search area, and the marker detection process is terminated.

  In step S38, as in the process in step S29, a determination is made as to whether or not the circularity of the marker image candidate region is greater than or equal to a predetermined value. As a result, when the circularity of the marker image candidate region is greater than or equal to a predetermined value, the process proceeds to step S39. On the other hand, when the circularity of the marker image candidate area is less than the predetermined value, it is considered that the marker image 31 does not exist in the search area, and the marker detection process ends. Further, in step S39, as in the process in step S30, the comparison operation unit 403 calculates the positional deviation of the phantom image, and outputs the calculated positional deviation amount to the measuring unit 405.

  The marker position detection unit 402 performs the marker detection process as described above also on the upper right and lower right marker images of the phantom image 30. In addition, the marker position detection unit 402 performs marker detection processing on the four corners of the phantom image 30 and detects three marker images, thereby determining whether or not the QC phantom 20 is photographed in an inverted state or upside down. It may be determined. In that case, the medical image processing apparatus 300 may perform image processing on the image data so that the obtained radiographic image is inverted vertically or horizontally or rotated 180 °.

  Next, a method for calculating a measurement area to be measured when quantitative evaluation is performed in step S6 in FIG. 5 will be described. In the present embodiment, the measurement region is calculated using the radiation images of the two markers 24a and 24b shown in the upper part of FIG.

  FIG. 11 shows a phantom image 30 recorded on the recording sheet 10. FIG. 11A shows a case where the phantom image 30 is appropriately recorded at the reference position of the recording sheet 10. That is, in FIG. 11A, the upper left position of the recording sheet and the upper left position of the phantom image coincide with each other, and the long side of the recording sheet and the long side of the phantom image are parallel to each other. FIG. 11B shows a case where the phantom image is shifted from the case of FIG. 11A and 11B, only the upper left marker image 31a, upper right marker image 31b, reference region 32, and measurement region 33 of the phantom image 30 are shown in order to simplify the description. It is shown.

  In FIG. 11A, with the upper left corner of the recording sheet 10 as the origin, the coordinates of the marker image 31a are (Mol, Sol), the coordinates of the marker image 31b are (Mor, Sor), and the coordinates of the starting point of the reference area 32 are ( Mss, Sss) and the coordinates of the end point are (Mse, Sse). 11B, the coordinates of the marker image 31a are (Mdl, Sdl), the coordinates of the marker image 31b are (Mdr, Sdr), the coordinates of the start point of the measurement region 33 are (Mds, Sds), and the end point. The coordinates are (Mde, Sde).

Using these values, the tilt angle θ and the offset values (ΔX, ΔY) of the phantom image 30 are expressed by the following equations (12) to (14).
θ = arctan {(Sdl−Sdr) / (Mdl−Mdr)} (12)
ΔX = Mdl−Mol (13)
ΔY = Sdl−Sol (14)

即ち、検査を行う際には、上記の２点を対角点とし、直交する２辺が記録シート１０の各辺にそれぞれ平行な長方形を計測対象とすれば良い。 Therefore, when the coordinate value of the reference area 32 recorded in advance in the parameter file is used, the coordinate of the measurement area 33 is obtained by the following expressions (15) and (16).

That is, when the inspection is performed, the above two points are diagonal points, and a rectangular object whose two orthogonal sides are parallel to the respective sides of the recording sheet 10 may be measured.

  As described above, according to the first embodiment of the present invention, it is possible to measure at least linearity, sharpness, and reduction ratio with respect to an image read by an image reading apparatus, including a material that attenuates or shields radiation. In order to perform the inspection, the image reader is inspected based on the image data generated by reading the radiation image using a QC phantom having a plurality of members arranged on the substrate. It is possible to inspect even the most important items.

  Further, according to the present embodiment, the position of the phantom image can be easily and reliably detected by using at least two markers arranged on the QC phantom. Therefore, by constructing an inspection system for a radiography system using such a QC phantom, it becomes possible to automate while maintaining the accuracy and certainty of the inspection operation, thereby interrupting and complicating the inspection operation. In addition, the reliability of the inspection can be ensured.

  In the present embodiment, when detecting the position of the marker image, a search area is set in advance, and the search is performed within the area. Thereby, it is possible to shorten the processing time as compared with the case of searching the entire region of the radiographic image, or it is possible to improve the detection accuracy within the same processing time. For example, the search area may be set by searching only the upper quarter of the radiation image.

  FIG. 12 shows a modification of the QC phantom according to one embodiment of the present invention. The QC phantom 40 includes a substrate 41 and a plurality of image quality measurement patterns 42 to 49 configured by a plurality of members disposed on the substrate 41. The substrate 41 is formed of, for example, a rectangular copper plate, imparts mechanical stability to the QC phantom 40, and provides X-ray beam quality appropriate for image analysis. In the present embodiment, the substrate 41 may be housed in an acrylic case as in the QC phantom 20 shown in FIG.

  As shown in FIG. 12, the QC phantom 40 quantitatively evaluates the image sharpness of the image as a burger phantom (contrast resolution pattern) 42 to 44 for visually evaluating the low contrast resolution of the image as an image quality evaluation pattern. An edge detection pattern 45, a wire mesh pattern 46 for visually evaluating the sharpness of the image, a step pattern 47 for visually evaluating and quantitatively evaluating the linearity and dynamic range of the image, and an image reduction ratio. A scale pattern 48 for quantitative evaluation is arranged. In the QC phantom 40, markers 49a and 49b used to detect the positions of these patterns are arranged in areas other than the empty areas 41a and 41b. The empty areas 41a and 41b may be used for quantitative evaluation of the S / N ratio of the radiation image signal.

  FIG. 13 is a perspective view showing the burger phantoms 42 to 44. The burger phantoms 42 to 44 include, for example, 12 step portions 42 a to 42 d, 43 a to 43 d, 44 a to 44 d made of acrylic resin. These step portions 42a to 42d, 43a to 43d, and 44a to 44d are arranged in a matrix so as to have different thicknesses in the X direction and different sizes (diameters) in the Y direction. In addition, as a member used for the burger phantom, a metal material may be used in addition to a resin material such as acrylic.

  The edge detection pattern 45 is a pattern used as a reference for geometric measurement, and includes sharp angular edge portions 45a and 45b for MTF measurement in the X direction and the Y direction. These angular edge portions 45a and 45b are formed of a tungsten plate, and a lead plate 50 is disposed on the outside thereof. Thereby, in the area | region around the angle edge parts 45a and 45b, most irradiated radiation is shielded, Therefore The influence of the periphery can be suppressed and sharpness can be evaluated more correctly. Here, the MTF is obtained by differentiating the radiation image of the edge detection pattern 45 to obtain a line spread function, and then performing a Fourier transform.

  In addition, as an image quality evaluation pattern for quantitatively evaluating the sharpness of an image, a pattern including at least one of an edge detection pattern, a slit pattern, and a rectangular wave pattern may be used instead of the edge detection pattern 45. Thereby, both quantitative evaluation and visual evaluation about sharpness can be performed.

FIG. 14 is a perspective view showing the step pattern 47. The step pattern 47 includes four rectangular copper plates 47a to 47d having different thicknesses. Thus, unlike the step pattern 25 shown in FIG. 3, all members included in the step pattern may be formed of a copper plate.
In this modification, the wire mesh pattern 46 is used as an image quality evaluation pattern for visually evaluating the sharpness of an image. In addition to this, at least one of a wire mesh pattern, a bar pattern, and a radial pattern is used. You may use what contains one.

Furthermore, in this modification, the arrangement of the wire mesh pattern 46 and the step pattern 47 is different from the arrangement in the QC phantom 20 shown in FIG. As described above, the arrangement of the image quality measurement patterns on the QC phantom can be variously changed.
In this modification, two markers 49 a and 49 b are arranged on the substrate 41. If there is no possibility that the QC phantom 40 is placed upside down or upside down during radiography, at least two markers 49a and 49b for detecting the position of the phantom image are sufficient.

  In the QC phantom and its modification according to one embodiment of the present invention described above, the marker is formed by hollowing out the copper plate. On the contrary, for example, the marker is formed using lead having a predetermined thickness or more. Thus, the radiation transmitted through the marker may have an energy level equal to or lower than a specified value under any imaging condition. In this case, the marker position detection unit 402 shown in FIG. 2 only needs to detect a region where the radiation dose is equal to or less than a specified value, and thus it is possible to stably detect the marker with a simple algorithm. The specified value may be determined or changed using a result obtained by monitoring the radiation dose.

  Further, the marker shape may be any shape such as a dot shape, a line shape, or a planar shape as long as the coordinates of at least two points are specified in the radiographic image. Furthermore, when it is assumed that the positional deviation of the phantom image is large, an appropriate allowable range is provided on the monitor screen on which the phantom image is displayed, and when the phantom image is displayed outside the allowable range, A message may be displayed to the operator to prompt the QC phantom 20 to re-shoot.

Next, a medical image processing apparatus according to the second embodiment of the present invention will be described. FIG. 15 is a block diagram showing a part of a radiation imaging system including a medical image processing apparatus according to this embodiment.
The radiographic system shown in FIG. 15 has a medical image processing apparatus 340 shown in FIG. 15 instead of the medical image processing apparatus 300 shown in FIG. 15 has a CPU 420 and a hard disk 430 instead of the CPU 400 and the hard disk 410 shown in FIG. Other configurations are the same as those of the radiation imaging system and the medical image processing apparatus shown in FIGS.

  The CPU 420 includes a QC calculation unit 421 that performs calculation for quantitative evaluation of the obtained radiation image, and an additional information output unit 422 that outputs additional information related to the image. In the present embodiment, the QC calculation unit 421 is incorporated in the CPU 420, but is not limited to such a form. For example, a QC calculation unit may be incorporated in a host computer that manages the entire system, or a personal computer equipped with only a QC calculation unit may be used.

  The hard disk 430 stores a basic program for operating the CPU 440, a program (QC tool) for inspecting the radiation imaging system, information used for the processing, and the like. FIG. 15 shows a tool recording unit 431 and an additional information recording unit 432. These pieces of information are read by the CPU 440 to the memory 301 as necessary and used for various processes.

In the QC tool recording unit 431, a quantitative evaluation program (software) corresponding to a plurality of image quality evaluation patterns of the QC phantom 20 is recorded. The software for quantitative evaluation has various signal processing algorithms, and when these algorithms are applied to image data representing the radiation image of the image quality evaluation pattern of the QC phantom 20, the quality of the radiographic system is improved. It includes all the logical means necessary to calculate the physical quantity to represent.
The additional information recording unit 432 includes radiographing conditions such as an X-ray tube voltage and a source-to-subject distance in the radiographic apparatus 100, image reading conditions in the medical image reading apparatus 200, and an image processing unit 401. Image processing conditions, image display conditions such as the number of pixels, the number of gradations, and the presence or absence of image processing in the display unit 320 are recorded. The additional information is read from the hard disk as necessary and used in the QC calculation unit 421 or output via the additional information output unit 422.

Next, the operation of the medical image processing apparatus 340 shown in FIG. 15 will be described.
In this embodiment, as shown in FIG. 3 or FIG. 12, the radiographic imaging system is inspected using a QC phantom in which an image quality measurement pattern for visual evaluation and quantitative evaluation corresponding to one image quality measurement item is formed. Is done.

When image data representing the radiation image of the QC phantom 10 shown in FIG. 3 is input from the medical image reading apparatus 200 (FIG. 1) to the medical image processing apparatus 340 via the network N1, the image processing unit 401 is input. The image data is subjected to predetermined image processing such as gradation processing.
Next, the CPU 420 sequentially reads and executes the quantitative evaluation program from the QC tool recording unit 431. That is, the QC calculation unit 421 performs quantitative evaluation on various image quality evaluation items corresponding to the image quality evaluation pattern based on the image data representing the radiation image of the QC phantom 20 processed by the image processing unit 401. At that time, the QC calculation unit 421 reads additional information from the additional information recording unit 432 and uses it when performing QC calculation as necessary.

  The output unit 407 outputs data representing the quantitative evaluation result obtained by the QC calculation unit 421 to the display unit 320 or the printer 330. At that time, the additional information output unit 422 outputs additional information such as image display conditions, image processing conditions, image reading conditions, and radiographing conditions recorded in the additional information recording unit 432. Thus, the information may be displayed or printed on a display screen or film together with the pattern image and the result of quantitative evaluation. As a result, the evaluation conditions of the image can be easily and reliably confirmed, and more accurate verification is possible.

  On the other hand, the medical image processing apparatus 340 outputs image data of a pattern image for a predetermined image quality evaluation item for which visual evaluation is performed, and causes the display unit 320 or the printer 330 to display or print the image data. The operator performs a visual evaluation on the displayed pattern image. In this manner, quantitative evaluation and visual evaluation are performed on the radiographic images of various image quality evaluation patterns included in the QC phantom 20 to verify the performance and invariance of the radiographic system.

  Here, the medical image processing apparatus 340 displays the pattern image for visual evaluation and the result of the quantitative evaluation on the screen or on the film for the image quality evaluation items for which both the visual evaluation and the quantitative evaluation are performed. Or output the data for printing. As a result, the operator can easily add quantitativeness to the image quality evaluation items for both visual evaluation and quantitative evaluation based on the results of quantitative evaluation displayed or printed on the screen or film. The visual evaluation can be performed while improving the accuracy of the evaluation.

  Such pattern images, results of quantitative evaluation, and display of additional information on the display unit 320 and printing on a film may be performed based on an operator's operation, and are automatically performed under the control of the CPU 420. May be. In the present embodiment as well, as in the first embodiment of the present invention, when an abnormality is found in the result of the inspection, the fact is notified to the maintenance center 530 shown in FIG. good.

  As described above, according to the second embodiment of the present invention, visual evaluation and objective evaluation of various image quality parameters such as contrast resolution, S / N ratio, sharpness, linearity, dynamic range, and reduction ratio are achieved. Quantitative evaluation can be performed using one QC phantom. Therefore, it is possible to easily verify the performance and invariance of the radiation imaging system, and it is possible to reduce labor, time and cost. Moreover, since it is possible to perform visual evaluation and quantitative evaluation using a single QC phantom for a predetermined image quality evaluation item, both measurement results can be easily compared, and the quantitative property of quantitative evaluation can be added to the visual evaluation. Can do. Therefore, a more objective evaluation can be performed and the accuracy of the invariance evaluation can be improved. Furthermore, since the evaluation result of the quantitative evaluation is displayed together with the radiation image of the image quality evaluation pattern, the visual evaluation taking into account the quantitative property of the quantitative evaluation can be easily performed, so that the accuracy of the evaluation is further improved. Also, by displaying additional information such as image display conditions, image processing conditions, imaging conditions, and quantitative evaluation results together with the radiation image of the image quality evaluation pattern, the image evaluation conditions can be easily confirmed, so that more accurate Evaluation can be performed.

  In the present embodiment, when one image quality evaluation pattern for one image quality evaluation item is used for both visual evaluation and quantitative evaluation, and for image quality evaluation pattern for visual evaluation for one image quality evaluation item. The image quality evaluation pattern for quantitative evaluation may be used for visual evaluation and quantitative evaluation, respectively, and the former and the latter image quality evaluation pattern may be included at the same time.

Next, a medical image processing apparatus according to the third embodiment of the present invention will be described. FIG. 16 is a block diagram showing a part of a radiation imaging system including a medical image processing apparatus according to this embodiment.
The radiation imaging system according to the present embodiment includes a medical image processing apparatus 350 shown in FIG. 16 instead of the medical image processing apparatus 300 shown in FIG. A medical image processing apparatus 350 illustrated in FIG. 16 includes a CPU 440 and a hard disk 450 instead of the CPU 400 and the hard disk 410 illustrated in FIG. About another structure, it is the same as that of the radiography system shown in FIG.1 and FIG.2.

  The CPU 440, based on the positional deviation amount of the phantom image, based on the determination reference changing unit 441 that changes the reference for determining the pattern image, the physical quantity calculated for the pattern image, and the changed determination reference, A determination unit 442 that determines whether each image quality evaluation item has an abnormality and also determines whether the image quality of the phantom image is superior or inferior. Other functions of the CPU 440 are the same as those described with reference to FIG.

  The hard disk 450 stores a basic program for causing the CPU 440 to operate, a program for inspecting the radiation imaging system, information used for the processing, and the like. FIG. 16 shows an image data recording unit 411, a parameter file recording unit 412 storing information on the reference position of the phantom image, an inspection result recording unit 413, a QC program recording unit 414, and a phantom image Determination criterion correction program recording unit 451 that stores a program for changing a determination criterion for determining image quality based on the amount of positional deviation, and a determination criterion recording unit that stores determination criteria for image quality evaluation items 452. These pieces of information are read by the CPU 440 to the memory 301 as necessary and used for various processes.

Next, an inspection method for the radiation imaging system according to the third embodiment of the present invention will be described with reference to FIGS. 16 and 17. FIG. 17 is a flowchart showing the inspection method of the radiation imaging system according to the present embodiment.
First, in steps S1 to S7, as described in the first embodiment of the present invention with reference to FIG. 5, a phantom is used by using image data representing a radiographic image of the QC phantom 20 obtained by radiography. A positional deviation amount of the image is calculated, and a measurement region obtained based on the image positional displacement amount is inspected, and a physical quantity required for image quality evaluation is calculated. The generated radiographic image is displayed on the display unit 320.

  Next, in step S41, the CPU 440 reads out and executes the correction program from the determination reference correction program recording unit 451. That is, the determination criterion changing unit 441 reads the determination criterion of the pattern image from the determination criterion recording unit 452, and determines the pattern image based on the positional deviation amount (see FIG. 11) in the parallel direction and the rotation direction of the phantom image. Change the criteria. Further, in step S42, the determination unit 442 determines the physical quantity related to the pattern image calculated by the measurement unit 405 based on the changed determination criterion. The determination result obtained in this way is output to the display unit 320 or the like via the output unit 407. In the present embodiment, similarly to step S11 in FIG. 5, when an abnormality is found in the determination result, the CPU 440 may notify the maintenance center 530 of the abnormality.

  As described above, according to the third embodiment of the present invention, since the determination criterion of the image quality evaluation item is changed according to the positional deviation amount of the phantom image, the automation of the inspection work is promoted and the inspection is performed. It is possible to further increase the accuracy of the.

Next, a medical image processing apparatus according to the fourth embodiment of the present invention will be described. FIG. 18 is a block diagram illustrating a part of a radiation imaging system including the medical image processing apparatus according to the present embodiment.
The radiographic system according to the present embodiment includes a medical image processing apparatus 360 shown in FIG. 18 instead of the medical image processing apparatus 300 shown in FIG. A medical image processing apparatus 360 illustrated in FIG. 18 includes a CPU 460 and a hard disk 470 instead of the CPU 400 and the hard disk 410 illustrated in FIG. About another structure, it is the same as that of the radiography system shown in FIG.1 and FIG.2.

  The CPU 460 includes an image correction unit 461 that corrects the generated radiation image to an ideal position based on the positional deviation amount of the phantom image. Other functions of the CPU 460 are the same as those described with reference to FIG.

  The hard disk 470 stores a basic program for causing the CPU 460 to operate, a program for inspecting the radiation imaging system, information used for the processing, and the like. FIG. 18 shows an image data recording unit 411, a parameter file recording unit 412 that stores information on the reference position of the phantom image, an inspection result recording unit 413, a QC program recording 414, and a position of the phantom image. An image correction program recording unit 471 that stores a correction program for correcting the image to an ideal position and a determination criterion recording unit 472 that stores determination criteria for image quality evaluation items are shown. These pieces of information are read into the memory 301 by the CPU 460 as necessary and used for various processes.

Next, an inspection method for a radiation imaging system according to the fourth embodiment of the present invention will be described with reference to FIGS. FIG. 19 is a flowchart showing an inspection method of the radiation imaging system according to the present embodiment.
First, in steps S1 to S5, as described in the first embodiment of the present invention with reference to FIG. 5, a phantom is used by using image data representing a radiographic image of the QC phantom 20 obtained by radiography. The amount of image misregistration is calculated. The generated radiographic image is displayed on the display unit 320.

  Next, in step S51, the CPU 460 reads the correction program from the image correction program recording unit 472 and executes it. That is, the image correction unit 464 generates a phantom image in a direction opposite to the direction of the position shift based on the shift amount (see FIG. 11) in the parallel direction and the rotation direction of the phantom image obtained in step S5 in FIG. By performing image processing for translation and rotation, the positional deviation of the phantom image including the pattern image is corrected.

  Next, in step S52, the measurement unit 405 calculates a physical quantity for the image quality evaluation item for the corrected pattern image. Next, in step S53, the determination unit 406 reads the determination criterion for each pattern image from the determination criterion recording unit 473, and determines the physical quantity related to the calculated pattern image based on the determination criterion. The determination result obtained in this way is output to the display unit 320 or the like via the output unit 407. In the present embodiment as well, similarly to step S11 in FIG. 5, when an abnormality is found in the determination result, the CPU 460 may notify the maintenance center 530 of the abnormality.

  As described above, according to the fourth embodiment of the present invention, the inspection work can be automated, and the measurement region and the pattern image determination standard are not changed, so that the inspection process can be easily performed. become.

  The radiation imaging system inspection method, the medical image processing apparatus using the radiation imaging system according to the first to fourth embodiments of the present invention, and the QC phantom used for the inspection of the radiation imaging system have been described above. The present invention is not limited to the above-described embodiment, and various changes in design can be made without departing from the spirit of the invention described in the claims of the present invention. For example, as a recording medium for recording the transmission radiation of the QC phantom, a flat panel device that converts the transmission radiation level into an electrical signal may be used in addition to the stimulable phosphor sheet 10.

  The present invention can be used in a system for inspecting the quality of a radiation imaging system including an image reading apparatus that reads image information from a sheet on which a radiation image is recorded.

1 is a block diagram illustrating a configuration of a radiation imaging system including a medical image processing apparatus according to a first embodiment of the present invention. It is a block diagram which shows the structure of the medical image processing apparatus shown in FIG. It is a top view which shows the structure of the phantom which concerns on one Embodiment of this invention. 4A to 4E are views respectively showing cross sections of the phantom taken along lines A-A ′ to E-E ′ shown in FIG. 3. It is a flowchart for demonstrating the inspection method of the radiography system which concerns on the 1st Embodiment of this invention. FIG. 6 is a diagram illustrating a range in which the position of a phantom image is shifted with respect to a recording sheet. It is a figure which shows the presence range of a marker image. It is a flowchart (first half) for detecting a marker image and calculating a shift due to parallel and rotational movement. It is a flowchart (second half) for detecting a marker image and calculating a shift due to parallel and rotational movement. It is a histogram which shows the shading distribution of the image in a search area | region. It is a figure which shows the phantom image recorded on a recording sheet. It is a top view which shows the modification of the phantom which concerns on one Embodiment of this invention. FIG. 13 is a perspective view showing a Burger phantom (contrast resolution pattern) included in the phantom shown in FIG. 12. It is a perspective view which shows the step pattern contained in the phantom shown in FIG. It is a block diagram which shows a part of radiography system containing the medical image processing apparatus which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows a part of radiography system containing the medical image processing apparatus which concerns on the 3rd Embodiment of this invention. It is a flowchart which shows the inspection method of the radiography system which concerns on the 3rd Embodiment of this invention. It is a block diagram which shows a part of radiography system containing the medical image processing apparatus which concerns on the 4th Embodiment of this invention. It is a flowchart which shows the inspection method of the radiography system which concerns on the 4th Embodiment of this invention.

Explanation of symbols

10 Recording sheets 20, 40 Phantom (QC phantom)
21 Acrylic case 22 Acrylic lid 23, 50 Copper plates 24a-24c, 49a, 40b Marker 25, 47 Step pattern 26, 45 Edge detection pattern 27, 42-44 Burger phantom (contrast resolution pattern)
28, 48 Scale pattern 29, 46 Wire mesh pattern 30 Phantom image 31, 31a, 31b Marker image 32 Reference area 33 Measurement area 41 Substrate 41a, 41b Unoccupied area 100 Radiography apparatus 101 Imaging position elevating mechanism 102 Imaging platform 103 Radiation generator 104 Imaging control unit 105 Input unit 200 Medical image reading device 201 Laser light source 202 Optical scanning unit 203 Photomultiplier 204 Amplifier 205 A / D converter 300 Medical image processing device 301 Memory 302 Hard disk control unit 303 Interface 304 Network interface 310 Input unit 320 Display 330 Printer 400, 420, 440, 460 CPU (Central Processing Unit)
401 Image processing unit 402 Marker position detection unit 403 Comparison calculation unit 404 Measurement area calculation unit 405 Measurement unit 406, 442 Determination unit 407 Output unit 410, 430, 450, 470 Hard disk 411 Image data recording unit 412 Parameter file recording unit 413 Inspection result Recording unit 414 QC program recording unit 421 QC calculation unit 422 Additional information output unit 431 QC tool recording unit 432 Additional information recording unit 441 Judgment reference changing units 451 and 471 Judgment reference correcting program recording units 452 and 472 Judgment standard recording unit 461 Image correction unit 500 RIS
510 HIS
520 Internet 530 Maintenance Center 540 Communication Control Unit 550 External Device

Claims (31)

A phantom used for inspecting the radiation imaging system by evaluating a radiation image obtained by imaging the phantom using the radiation imaging system with respect to at least one image quality evaluation item,
A substrate,
A first member disposed on the substrate and having a first image quality evaluation pattern used for visual evaluation for a predetermined image quality evaluation item;
A second member arranged on the substrate and having a second image quality evaluation pattern used for quantitative evaluation for the predetermined image quality evaluation item;
Phantom equipped with. When the predetermined image quality evaluation item is the sharpness of the radiation image, the first image quality evaluation pattern includes a wire mesh pattern formed by a plurality of types of wire mesh having different wire intervals, and a bar pattern. And at least one of a radial pattern,
When the predetermined image quality evaluation item is the sharpness of the radiation image, the second image quality evaluation pattern includes at least one of an edge pattern, a slit pattern, and a rectangular wave pattern.
The phantom according to claim 1.   In the case where the predetermined image quality evaluation item is the contrast resolution of the radiation image, the first image quality evaluation pattern is a burger phantom configured by a plurality of members having at least one of a size and a thickness different from each other. The phantom according to claim 1, comprising:   The phantom according to claim 1, wherein an empty area used for quantitative evaluation of the S / N ratio of the radiation image is formed on the substrate.   2. The phantom according to claim 1, wherein when the predetermined image quality evaluation item is a reduction ratio of the radiation image, the second image quality evaluation pattern includes a scale pattern.   When the predetermined image quality evaluation item is the linearity or dynamic range of the radiation image, the first and second image quality evaluation patterns are formed by a plurality of metal plates having different thicknesses. The phantom according to claim 1, comprising:   The phantom according to claim 1, further comprising a lid that forms a part of a case in which the substrate stores the first and second members, and covers the case. A phantom used for inspecting the radiation imaging system by evaluating a radiation image obtained by imaging the phantom using the radiation imaging system with respect to at least one image quality evaluation item,
A substrate,
At least one member disposed on the substrate and having an image quality evaluation pattern used for a predetermined image quality evaluation item;
A plurality of markers respectively arranged at a plurality of different positions on the substrate, the plurality of markers used for detecting the position of the image quality evaluation pattern in the radiation image;
Phantom equipped with.   The phantom according to claim 8, wherein the plurality of markers have radiation transmittances different from other regions of the phantom.   The phantom according to claim 8 or 9, wherein the plurality of markers have a shape different from the image quality evaluation pattern.   The phantom according to claim 8, wherein the plurality of markers include at least three markers. Radiation image information is recorded on a recording medium by performing radiography, image data is generated by reading the radiation image information from the recording medium, and a radiographic image is displayed by performing predetermined image processing on the image data. A medical image processing apparatus for inspecting the radiation imaging system by evaluating the image quality of the radiation image obtained by using the radiation imaging system to output,
Image processing means for performing image processing on the input image data;
When image data representing a radiation image obtained by photographing a phantom in which a plurality of image quality evaluation patterns for a predetermined image quality evaluation item are captured is input, the predetermined image quality is related to the input image data. A measuring means for measuring an evaluation item;
Input means used for inputting the inspection result obtained for the predetermined image quality evaluation item by visually observing the displayed or output radiographic image;
A determination unit that determines an image quality of the radiation image based on a measurement result in the measurement unit and an inspection result input using the input unit;
A medical image processing apparatus comprising:   The medical image processing apparatus according to claim 12, further comprising a position detection unit configured to detect a position of the phantom in the radiation image based on input image data.   The medical image processing apparatus according to claim 13, wherein the position detection unit detects the positions of the phantoms in the radiation image by detecting images of a plurality of markers respectively arranged at different positions of the phantom.   The medical image processing apparatus according to claim 14, wherein the plurality of markers include at least three markers.   Image data representing a radiographic image obtained by radiographing a phantom in which an image quality evaluation pattern used for visual evaluation and an image quality evaluation pattern used for quantitative evaluation are arranged for a predetermined image quality evaluation item is input. The medical device according to any one of claims 12 to 15, further comprising a control unit that controls to display a determination result based on the quantitative evaluation of the predetermined image quality evaluation item together with the radiation image. Image processing device.   Imaging conditions when the radiographic image is captured, image reading conditions when the radiographic image information is read from the recording medium, and input image data being subjected to image processing by the image processing means The control means which controls so that at least one of the image processing conditions and the display conditions when the radiographic image is displayed may be displayed together with the radiographic image. The medical image processing apparatus according to any one of the above.   18. The medical image processing apparatus according to claim 12, further comprising a recording unit configured to record a measurement result in the measurement unit and an examination result input using the input unit. A medical image processing apparatus for examining the radiation imaging system by evaluating the image quality of the radiation image obtained by using the radiation imaging system,
An image quality evaluation pattern for at least one image quality evaluation item is arranged, and a phantom in which a plurality of markers are arranged at a plurality of different positions from each other is obtained by imaging using the radiation imaging system. Position detection means for detecting the position of the phantom in the radiographic image using the plurality of markers when image data representing a radiographic image is input;
Comparison operation means for calculating the amount of deviation in the linear direction and the rotation direction by comparing the position of the phantom detected by the position detection means and the reference position of the phantom in the radiation image;
Search area changing means for changing a search area, which is an area in the radiographic image measured for a predetermined image quality evaluation item, based on the amount of deviation calculated by the comparison calculation means;
A physical quantity calculating means for calculating a physical quantity representing the characteristics of the radiation image by measuring the predetermined image quality evaluation item in the search area changed by the search area changing means;
A determination criterion changing means for changing a determination criterion used for determining the image quality of the radiation image based on a deviation amount calculated by the comparison calculation means;
A determination unit that determines an image quality of the radiation image using the physical quantity calculated by the physical quantity calculation unit based on the determination criterion changed by the determination reference change unit;
A medical image processing apparatus comprising: A medical image processing apparatus for examining the radiation imaging system by evaluating the image quality of the radiation image obtained by using the radiation imaging system,
An image quality evaluation pattern for at least one image quality evaluation item is arranged, and a phantom in which a plurality of markers are arranged at a plurality of different positions from each other is obtained by imaging using the radiation imaging system. Position detection means for detecting the position of the phantom in the radiographic image by using the plurality of markers when image data representing the radiographic image is input;
Comparison operation means for calculating a deviation amount in the linear direction and the rotation direction by comparing the position of the phantom detected by the position detection means with a reference position of the phantom in the radiation image;
Image correcting means for correcting the position of the phantom in the radiation image so that the amount of deviation calculated by the comparison calculating means is reduced;
With respect to the image of the phantom whose position has been corrected by the image correcting unit, a physical quantity calculating unit that calculates a physical quantity representing the characteristics of the radiation image by measuring a predetermined image quality evaluation item;
Determination means for determining image quality of the radiation image based on the physical quantity calculated by the physical quantity calculation means;
A medical image processing apparatus comprising:   21. The control unit according to claim 12, further comprising a control unit that controls to notify the maintenance center when the determination unit determines that there is an abnormality in image quality in the radiation image. Medical image processing apparatus. A method for inspecting the radiation imaging system by evaluating the image quality of a radiation image obtained by using the radiation imaging system,
Step (a) of inputting image data representing a radiographic image obtained by radiographing a phantom in which a plurality of image quality evaluation patterns for image quality evaluation items including at least measurement of linearity, sharpness, and reduction ratio are arranged When,
Detecting the position of the phantom in the radiation image based on the image data input in step (a) (b);
(C) performing measurement on image quality evaluation items including measurement of at least linearity, sharpness, and reduction ratio for the phantom image based on the image data input in step (a);
Step (d) of determining the image quality of the radiation image based on the measurement result measured in step (c);
An inspection method for a radiation imaging system comprising:   The radiographic imaging system inspection method according to claim 22, wherein step (d) includes determining the image quality by comparing the measurement result in step (c) with a past measurement result. Radiation image information is recorded on a recording medium by performing radiography, image data is generated by reading the radiation image information from the recording medium, and a radiographic image is displayed by performing predetermined image processing on the image data. Or a method for inspecting the radiation imaging system by evaluating the image quality of the radiation image obtained by using the radiation imaging system to output,
A step of inputting image data representing a radiographic image obtained by radiographing a phantom in which an image quality evaluation pattern used for visual evaluation and an image quality evaluation pattern used for quantitative evaluation are arranged for a predetermined image quality evaluation item (A) and
(B) performing quantitative measurement on the predetermined image quality evaluation item for the image data input in step (a);
A step (c) of displaying or outputting a radiographic image based on the image data input in step (a) and examining the predetermined image quality evaluation item by visually observing the displayed or output radiographic image When,
A step (d) of determining the image quality of the radiation image based on the measurement result measured in step (b) and the inspection result inspected in step (c);
An inspection method for a radiation imaging system comprising:   The radiographic imaging system inspection method according to claim 24, wherein step (c) includes displaying the result of quantitative evaluation based on the measurement result measured in step (b) together with the radiographic image.   Imaging conditions when radiation imaging is performed, image reading conditions when radiation image information is read from the recording medium, image processing conditions when image processing is performed on input image data, 26. The inspection method for a radiation imaging system according to claim 24, further comprising a step of displaying at least one of display conditions when the radiation image is displayed together with the radiation image.   27. The inspection of the radiographic system according to any one of claims 22 to 26, further comprising a step of notifying the maintenance center of the fact when it is determined in step (d) that there is an abnormality in image quality in the radiation image. Method. A method for inspecting the radiation imaging system by evaluating the image quality of a radiation image obtained by using the radiation imaging system,
An image representing a radiographic image obtained by radiographing a phantom in which an image quality evaluation pattern for at least one image quality evaluation item is arranged and a plurality of markers are arranged at a plurality of different positions. Inputting data (a);
(B) detecting the position of the phantom in the radiation image using the plurality of markers based on the image data input in step (a);
Calculating the amount of deviation in the linear and rotational directions by comparing the position of the phantom detected in step (b) with the reference position of the phantom in the radiation image;
A step (d) of changing a search region, which is a region in the radiographic image measured for a predetermined image quality evaluation item, based on the amount of deviation calculated in step (c);
(E) calculating a physical quantity representing characteristics of the radiation image by measuring the image quality evaluation item in the search region changed in step (d);
A step (f) of changing a criterion used to determine the image quality of the radiation image based on the amount of deviation calculated in step (c);
A step (g) of determining an image quality of the radiation image using the physical quantity calculated in the step (e) based on the determination criterion changed in the step (f);
An inspection method for a radiation imaging system comprising:   29. The inspection method for a radiation imaging system according to claim 28, further comprising a step of notifying the maintenance center of the fact when it is determined in step (g) that there is an abnormality in image quality in the radiation image. A method for inspecting the radiation imaging system by evaluating the image quality of a radiation image obtained by using the radiation imaging system,
An image representing a radiographic image obtained by radiographing a phantom in which an image quality evaluation pattern for at least one image quality evaluation item is arranged and a plurality of markers are arranged at a plurality of different positions. Inputting data (a);
(B) detecting the position of the phantom in the radiation image using the plurality of markers based on the image data input in step (a);
Calculating the amount of deviation in the linear and rotational directions by comparing the position of the phantom detected in step (b) with the reference position of the phantom in the radiation image;
Correcting the position of the phantom in the radiation image so that the amount of deviation calculated in step (c) is reduced;
(E) calculating a physical quantity representing the characteristics of the radiation image by measuring a predetermined image quality evaluation item for the image of the phantom whose position is corrected in step (d);
A step (f) of determining an image quality of the radiation image based on the physical quantity calculated in the step (e);
An inspection method for a radiation imaging system comprising:   The radiation imaging system inspection method according to claim 30, further comprising a step of notifying the maintenance center of the fact that it is determined in step (f) that there is an abnormality in image quality in the radiation image.

Images