Phantom, calibration device, method, and program

Abstract

The phantom, calibration device, method, and program are designed to allow for the easy acquisition of multiple desired types of calibration data. [Solution] A phantom is provided for acquiring calibration data for a detector that outputs an electrical signal corresponding to the photon energy of incident radiation. The phantom includes a first base material and at least one second base material having a greater attenuation coefficient than the first base material. The thickness of the first base material changes in a direction perpendicular to the radiation field during imaging. The second base material is embedded in the first base material and changes in size and position in a direction perpendicular to the radiation field during imaging.

Description

Technical Field

[0001] The present disclosure relates to phantoms, calibration devices, methods and programs.

Background Art

[0002] A PCCT (Photon Counting Computed Tomography) device equipped with a photon counting detector, which is a detector adopting a photon counting method, is known. Since the photon counting detector can measure the photon energy, which is the energy of incident radiation photons, in the PCCT device, medical images in which substances with different compositions are discriminated, for example, a medical image in which an iodine contrast agent used for angiography and calcified plaques in blood vessels are discriminated can be obtained.

[0003] In addition, a Dual Energy (DE) CT device acquires X-ray energy information in the same manner as a PCCT device. In the DECT device, by reconstructing two projection data taken at two tube voltages at an arbitrary single energy level, it is possible to generate a virtual monochromatic X-ray image as if taken with X-rays at an arbitrary single energy level.

[0004] By the way, when performing imaging with a PCCT device and a DECT device (hereinafter represented by a PCCT device), the same substance should have the same value in the acquired image regardless of its position and size. However, in a PCCT device, the same substance may have different attenuation coefficients depending on the subject size and the position of the substance, or may have different values in an image using energy (substance discrimination image and virtual monochromatic image).

[0005] Therefore, in order to obtain a substance discrimination image or the like in a PCCT device, calibration of the detector is performed. In this case, for combinations of a plurality of base substances that are substances with known composition and thickness, the relationship between the output measured by the photon counting detector and the photon energy is acquired in advance for each detector element as calibration data.

[0006] For example, Patent Document 1 proposes a method for acquiring calibration data using a phantom that combines cylindrical, rectangular, and prism-shaped objects. Patent Document 1 also proposes a phantom whose size changes in a direction perpendicular to the direction of movement when it is installed in a PCCT device during configuration and imaging is performed. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Special Publication No. 2022-520241 [Overview of the project] [Problems that the invention aims to solve]

[0008] Calibration data, especially for the substance whose values ​​need to be matched, requires data of various sizes at various locations within the sample. However, acquiring calibration data by taking multiple images while changing the position of the substance in the phantom is time-consuming and laborious.

[0009] This disclosure is made in view of the above circumstances and aims to enable the easy acquisition of multiple types of calibration data as desired. [Means for solving the problem]

[0010] The phantom according to this disclosure is a phantom for acquiring calibration data for a detector that outputs an electrical signal corresponding to the photon energy of incident radiation, It comprises a first base material and at least one second base material having a greater attenuation coefficient than the first base material, The first base material changes in thickness in a direction perpendicular to the radiation field during imaging. The second base material is embedded in the first base material, and its size and position change in a direction perpendicular to the radiation field during imaging.

[0011] In the phantom according to this disclosure, the first base material occupies a larger proportion than the second base material.

[0012] In the phantom according to this disclosure, the first base material has a frustoconical shape with its central axis perpendicular to the radiation field at the time of imaging.

[0013] The calibration device according to this disclosure is a calibration device that acquires calibration data for a detector that outputs an electrical signal corresponding to the photon energy of incident radiation, Equipped with a processor, The aforementioned processor, The calibration data of the detector is obtained using the phantom provided in this disclosure.

[0014] The calibration method described herein is a calibration method in which a computer acquires calibration data for a detector that outputs an electrical signal corresponding to the photon energy of incident radiation, The calibration data of the detector is obtained using the phantom provided in this disclosure.

[0015] The calibration program provided in this disclosure is a calibration program that causes a computer to perform a procedure for acquiring calibration data for a detector that outputs an electrical signal corresponding to the photon energy of incident radiation, The computer is instructed to perform a procedure to acquire the calibration data of the detector using the phantom provided in this disclosure.

[0016] Furthermore, the technology disclosed herein may be applied to program products. [Effects of the Invention]

[0017] According to this disclosure, multiple types of desired calibration data can be easily obtained. [Brief explanation of the drawing]

[0018] [Figure 1] Front view and side view showing a phantom according to an embodiment of the present disclosure. [Figure 2] Perspective view showing the first substrate [Figure 3] Perspective view showing the second substrate [Figure 4] Schematic configuration diagram of a medical imaging system equipped with a calibration device according to the present embodiment [Figure 5] Diagram showing the hardware configuration of the calibration device according to the present embodiment [Figure 6] Functional configuration diagram of the calibration device according to the present embodiment [Figure 7] Diagram for explaining the calibration method [Figure 8] Flowchart showing the processes performed in the present embodiment

Mode for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. First, a phantom according to an embodiment of the present disclosure will be described. FIG. 1 is a front view and a side view showing the configuration of the phantom according to the present embodiment. As shown in FIG. 1, the phantom 10 according to the present embodiment has a frustum-of-a-cone shape. A frustum-of-a-cone is a frustum whose base is a circle. That is, it is a solid figure obtained by cutting a cone with a plane parallel to the base and removing the small cone part. The phantom 10 includes a first base material 11 and at least one second base material 12. The phantom 10 is imaged in a CT device described later and is used to obtain calibration data for a detector.

[0020] Figure 2 shows the first base material. The first base material 11 is made of a material having a radiation attenuation coefficient similar to that of the human body, for example. Examples of such materials include acrylic. The first base material 11 has a frustoconical shape, and several second base materials 12, which will be described later, are embedded within it. In order for the phantom 10 to resemble the human body, the first base material 11 occupies a larger proportion than the second base material 12. In the side view of Figure 1, the straight line connecting the center points of the left and right sides of the frustoconical shape (i.e., the center points of the top and bottom surfaces of the circular shape) is shown as the central axis C1 of the first base material 11. The central axis C1 of the first base material 11 coincides with the central axis C0 of the phantom 10 (see Figure 1).

[0021] When calibrating the CT apparatus using the phantom 10 according to this embodiment, as described later, the central axis C1 of the first base material 11 is positioned in the CT apparatus so as to be perpendicular to the radiation field. Therefore, the thickness of the first base material 11 changes in a direction perpendicular to the radiation field during imaging. In this embodiment, the direction perpendicular to the radiation field is the direction perpendicular to the optical axis of the radiation and coincides with the direction in which the imaging table moves in the CT apparatus, as described later. The first base material 11 is manufactured so that its maximum diameter fits within the maximum radiation field that the CT apparatus 2, described later, can set.

[0022] Figure 3 shows the second base material. The second base material 12 is made of a material with a larger attenuation coefficient than acrylic, which is the material of the first base material 11. Examples of such materials include aluminum, but other materials having an attenuation coefficient similar to that of contrast agents actually used, such as iodine, can be used. The second base material 12 has, for example, a frustoconical shape, and the size of the cross-section perpendicular to the central axis C2 changes in the direction along the central axis C2 connecting the center points of the upper and lower surfaces of the circular shape. In this embodiment, three types of second base materials 12A, 12B, and 12C are used, which differ in length and the way in which the cross-sectional size perpendicular to the central axis C2 changes. The end faces of the second base material 12 are processed to match the surface of the first base material 11 when embedded in the first base material 11, but in Figure 3, the second base materials 12A to 12C are shown as frustoconical shapes for illustrative purposes.

[0023] The second base material 12A-12C is embedded in the first base material 11 such that its central axis C2 is inclined with respect to the central axis C1 of the first base material 11. As a result, in the phantom 10, the size and position of the second base material 12A-12C change in a direction perpendicular to the radiation field during imaging.

[0024] Next, a calibration device according to an embodiment of the present disclosure will be described. Figure 4 is a schematic diagram of a medical imaging system equipped with the calibration device according to this embodiment. As shown in Figure 4, the medical imaging system 1 of this embodiment includes a CT scanner 2 and a console 3.

[0025] The CT scanner 2 includes a gantry 4 and a patient bed 8. In the following description, the horizontal direction in Figure 4 is referred to as the X-axis, the vertical direction as the Y-axis, and the direction perpendicular to the XY plane as the Z-axis.

[0026] The gantry 4 has an opening 4A, and the subject to be photographed is placed inside the opening 4A while on the bed 8. In this embodiment, the phantom 10 is also placed inside the opening 4A while on the bed 8 during calibration. The gantry 4 and the bed 8 are movable relative to each other in the Z-axis direction. The phantom 10 is placed on the bed 8 so that the central axis C1 of the first base material 11 coincides with the Z-axis.

[0027] Inside the gantry 4, a radiation source 5 having a radiation tube 6 and a bowtie filter 7, and a detector 9 are arranged facing each other across the patient bed 8. The bowtie filter 7 optimizes the amount of radiation exposure to the subject by increasing the dose near the center and decreasing the dose around the periphery in order to reduce the exposure dose in the peripheral area. The radiation emitted from the radiation tube 6 is shaped by the bowtie filter 7 into a beam shape suitable for the size of the subject or the phantom 10 in this embodiment, and is irradiated onto the subject or the phantom 10.

[0028] The detector 9 detects radiation that has passed through the subject or phantom 10 placed on the bed 8 and generates projection data corresponding to the detected radiation dose. As an example, the detector 9 in this embodiment is a photon counting type detector in which a plurality of detection elements 9P that detect the photon energy, which is the energy of the photons of the incident radiation, are arranged in an arc shape centered on the focal point of the radiation tube 6.

[0029] In this embodiment, X-rays are used as an example of radiation, but the invention is not limited to this, and gamma rays or other types of radiation can also be used.

[0030] The radiation source 5 and the detector 9 are mounted on a rotating plate 4B inside the gantry 4 and are rotated around the patient bed 8 by a rotation drive unit (not shown). During imaging of the subject, radiation irradiation from the radiation source 5 and detection of radiation by the detector 9 are repeated as both rotate, so that raw data is acquired in multiple view units with different radiation projection angles onto the subject. The raw data acquired by the detector 9 is output to the console 3.

[0031] The radiation dose emitted from the radiation tube 6, the rotation speed of the gantry 4, and the relative movement speed between the gantry 4 and the patient bed 8 are all set by the console 3 based on the imaging conditions entered by the operator, such as a technician.

[0032] The console 3 of this embodiment performs tasks such as acquiring calibration data using the phantom 10 according to this embodiment, controlling the imaging of the subject, generating tomographic images from the data acquired by imaging, and setting data storage. Console 3 is an example of the calibration device of this disclosure.

[0033] Next, the calibration device according to this embodiment will be described. First, with reference to Figure 5, the hardware configuration of the calibration device according to this embodiment, which is contained within the console 3, will be described. As shown in Figure 5, the calibration device 20 contained within the console 3 is a computer such as a workstation, server computer, or personal computer, and is equipped with a CPU (Central Processing Unit) 21, non-volatile storage 23, and memory 26 as a temporary storage area.

[0034] The calibration device 20 also includes a display 24, an input device 25, and an I / F (Interface) 27. The CPU 21, storage 23, display 24, input device 25, memory 26, and I / F 27 are connected to the bus 28. The CPU 21 is an example of a processor in this disclosure.

[0035] The storage 23 is implemented using an HDD (Hard Disk Drive), SSD (Solid State Drive), flash memory, etc. The calibration program 22 installed in the calibration device 20 is stored in the storage 23 as a storage medium. The CPU 21 reads the calibration program 22 from the storage 23, expands it into memory 26, and executes the expanded calibration program 22.

[0036] The display 24 is a device that displays various types of screens, such as a liquid crystal display or an EL (Electro Luminescence) display.

[0037] The input device 25 is used by the operator to input instructions and various information regarding the shooting conditions when photographing a subject, image generation and display, etc. Examples of input devices 25 include various switches, buttons, touch panels, styluses, keyboards, and mice. The display 24 and the input device 25 may be integrated to form a touch panel display.

[0038] I / F27 communicates various types of information with the rotational drive unit (not shown) of the gantry 4, the radiation source 5, and the detector 9 via wired or wireless communication.

[0039] The calibration program 22 is stored in a memory device of a server computer connected to the network, or in network storage, in a state that allows external access, and is downloaded and installed on the computers comprising the calibration device 20 upon request. Alternatively, it is recorded on a recording medium such as a DVD (Digital Versatile Disc) or CD-ROM (Compact Disc Read Only Memory) and distributed, and then installed from that recording medium on the computers comprising the calibration device 20.

[0040] Next, the functional configuration of the calibration device according to this embodiment will be described. Figure 6 is a diagram showing the functional configuration of the calibration device according to this embodiment. As shown in Figure 6, the calibration device 20 includes an image capture control unit 31 and an acquisition unit 32. The CPU 21 functions as the image capture control unit 31 and the acquisition unit 32 by executing the calibration program 22.

[0041] The calibration device 20 in this embodiment is a device for calibrating the entire medical imaging system 1, mainly the detector 9. In the medical imaging system 1 equipped with a detector 9, which is a photon counting type detector, the photon energy spectrum related to the projection data of the subject can be acquired, so it is possible to generate medical images in which substances of different compositions are discriminated and medical images separated into multiple energy components. In order to obtain medical images in which substances of different compositions are discriminated in this way, it is necessary to pre-calibrate the relationship between the output and photon energy when measuring a combination of multiple base materials, which are substances of known composition and thickness, with the detector 9, for each detection element 9P. The calibration device 20 is a device used for this calibration.

[0042] In this embodiment, the calibration device 20 uses the phantom 10 according to this embodiment for calibration of the detector 9. In Figure 4, the phantom 10 is located within the radiation field RF, and is fixed to the bed 8 by a fixing device (not shown) such that the central axis C0 of the phantom 10 coincides with the Z axis. Below, an example of a calibration method for the detector 9, which is a photon counting type detector, will be described. Figure 7 is a diagram illustrating the calibration method.

[0043] In this embodiment, the phantom 10, fixed to the bed 8, is moved in the Z-axis direction while the radiation source 5 and detector 9 are not rotated, and calibration data is acquired. Alternatively, calibration data is acquired while repeatedly moving in the Z-axis direction, stopping, and taking images. In this embodiment, the phantom 10 is assumed to acquire calibration data while repeatedly moving in the Z-axis direction, stopping, and taking images.

[0044] In this embodiment, the first base material 11 constituting the phantom 10 changes thickness in a direction perpendicular to the radiation field during imaging. The second base materials 12A to 12C are embedded in the first base material 11, and their size and position change in a direction perpendicular to the radiation field during imaging. Therefore, when the phantom 10 fixed to the bed 8 moves in the Z-axis direction, the transmission path of the radiation through the phantom 10 changes at each of the moved positions. For example, as shown in the side view of Figure 7, when the phantom 10 moves in the Z-axis direction, the transmission path of the radiation through the phantom 10 changes as shown in P1 to P5, for example, and as a result, the transmission path length also changes. In each transmission path P1 to P5, the distance from the central axis C0 of the second base materials 12A to 12C and the transmission path length also change.

[0045] Furthermore, at one of the phantom 10's moving positions, radiation passes through the phantom 10 in a fan shape, as shown in the front view of Figure 7. For example, if the radiation transmission paths are set discretely at nine locations P11 to P19, as shown in the front view of Figure 7, the radiation transmission path length in the phantom 10 will differ at each of the transmission paths P11 to P19, and furthermore, the distance from the central axis C0 of the second base material 12A to 12C and the transmission path length will also differ.

[0046] In this embodiment, the transmission path length in the radiation phantom 10 and the transmission path length in the second base material 12A to 12C are measured for each of the multiple transmission paths at each moving position of the bed 8. The transmission path length in the first base material 11 of the radiation is derived by subtracting the transmission path length of the second base material 12A to 12C from the transmission path length of the phantom 10. The transmission path length in the first base material 11 of the radiation is the thickness of the first base material 11 in the radiation transmission path, and the transmission path length in the second base material 12A to 12C of the radiation is the thickness of the second base material 12A to 12C in the radiation transmission path.

[0047] Therefore, in this embodiment, the phantom 10 fixed to the bed 8 is inserted into the radiation field RF, and the bed 8 is moved by the imaging control unit 31 of the calibration device 20, while radiation is irradiated from the radiation source 5 at each moving position. The detector 9 detects the radiation that has passed through each transmission path of the phantom 10, and the acquisition unit 32 acquires the photon energy spectrum in each transmission path at each moving position as calibration data K0. For example, if there are n types of moving positions of the phantom 10 in the Z direction and m types of transmission paths at each moving position, then calibration data K0 for n × m types of thicknesses of the first base material 11 and the second base materials 12A to 12C is acquired.

[0048] The n × m types of calibration data K0 obtained in this way are output to console 3, stored in console 3's storage 23, and used to calibrate the subject's projection data.

[0049] Next, the process performed in this embodiment will be described. Figure 8 is a flowchart of the process performed in this embodiment. The phantom 10 is assumed to be fixed to the bed 8. First, the imaging control unit 31 moves the bed 8 to move the phantom 10 in the Z-axis direction of the CT device 2 (step ST1), and the acquisition unit 32 acquires calibration data on multiple radiation transmission paths at the new position of the phantom 10 (step ST2). The imaging control unit 31 then determines whether or not calibration data has been acquired at all new positions (step ST3). If step ST3 is negative, the phantom 10 is moved to the next imaging position (step ST4), and the process returns to step ST2. If step ST3 is positive, the process ends.

[0050] Thus, the phantom 10 according to this embodiment includes a first base material 11 and at least one second base material 12A to 12C having a larger attenuation coefficient than the first base material 11. The thickness of the first base material 11 changes in a direction perpendicular to the radiation field during imaging, and the second base materials 12A to 12C are embedded in the first base material 11 and change in size and position in a direction perpendicular to the radiation field during imaging. Therefore, calibration data K0 can be obtained for the first base material 11 of different thicknesses, and for the second base materials 12A to 12C of different thicknesses and positions, using only one phantom 10. Consequently, when obtaining calibration data K0, it is not necessary to perform multiple imaging while changing the size and position of the material in the phantom, and as a result, multiple types of desired calibration data K0 can be easily obtained.

[0051] In the above embodiment, three types of second base materials 12A to 12C are used, but the invention is not limited to these. One, two, or four or more types of second base materials 12 may be used. Furthermore, when multiple second base materials 12 are used, each second base material 12 may be composed of materials having different attenuation coefficients. For example, in addition to iodine, the second base material 12 may be composed of materials having attenuation coefficients such as gold, which is used as a contrast agent.

[0052] Furthermore, in the above embodiment, the phantom 10 and calibration device 20 according to this embodiment are applied to acquire calibration data in a CT apparatus 2 equipped with a photon counting type detector 9, but the embodiment is not limited to this. The phantom 10 and calibration device 20 according to this embodiment can also be applied to acquire calibration data in a DECT apparatus.

[0053] Furthermore, although the first base material 11 is frustoconical in the above embodiment, it is not limited to this. Any other shape other than a frustoconical can be used as long as the thickness changes in the direction perpendicular to the radiation field during imaging. Similarly, the shapes of the second base materials 12A to 12C can also be any other shape other than a frustoconical.

[0054] In this embodiment, each process of the calibration device 20 is performed on any computer. Alternatively, any computer may perform these processes using a processor as hardware, a program as software, or a combination thereof. In that case, the processor is configured to work in cooperation with the program to perform the various processes in the calibration device 20 of this embodiment, and can function as a unit or means in this embodiment. Furthermore, the execution order of the processes by the processor is not limited to the order described and may be changed as appropriate. Any computer may be a general-purpose computer, a computer designed for a specific application, a workstation, or any other system capable of performing each process.

[0055] A processor may consist of one or more hardware components, and the type of hardware is not limited. For example, a processor may consist of a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a programmable logic device such as an FPGA (Field Programmable Gate Array), a dedicated circuit for executing a specific process such as an ASIC (Application Specific Integrated Circuit), a GPU (Graphic Processing Unit), or an NPU (Neural Processing Unit). Furthermore, the type of hardware may be a combination of different types of hardware. When multiple hardware components are configured to execute one or more processes of a processor, these components may reside in physically separate devices or in the same device. Also, in any embodiment, the order of each process performed by the processor is not limited to the order described above and may be changed as appropriate. Hardware is composed of electrical circuits (circuitry) that combine circuit elements such as semiconductor elements.

[0056] Furthermore, the program may be firmware or software such as microcode. Alternatively, the program may be, for example, a set of program modules, each function of which may be implemented by a processor configured to perform its respective function. The program may be program code or multiple code segments stored on one or more non-temporary computer-readable media (e.g., storage media or other storage). The program may be divided and stored on multiple non-temporary computer-readable media located in physically separate devices. Program code or code segments may represent any combination of procedures, functions, subprograms, routines, subroutines, modules, software packages, classes, or instructions, data structures, or program statements. Program code or code segments may be connected to other code segments or hardware circuits by sending and receiving information, data, arguments, parameters, or memory contents.

[0057] Furthermore, although the above embodiment describes a configuration in which the calibration program 22 is pre-stored (installed) in the storage 23, the invention is not limited to this configuration. The calibration program 22 may be provided in the form of a recording medium such as a CD-ROM (Compact Disc Read Only Memory), DVD-ROM (Digital Versatile Disc Read Only Memory), or USB (Universal Serial Bus) memory. Alternatively, the calibration program 22 may be provided in the form of a download from an external device via a network.

[0058] The technology disclosed herein extends to all program products. Program products include all forms of products for providing programs. For example, program products include programs provided via networks such as the Internet, and non-temporary computer-readable recording media such as CD-ROMs, DVDs, and USB memory sticks on which programs are stored.

[0059] The following are additional notes to this disclosure. (Additional note 1) A phantom for acquiring calibration data for a detector that outputs an electrical signal corresponding to the photon energy of incident radiation, It comprises a first base material and at least one second base material having a greater attenuation coefficient than the first base material, The first base material changes in thickness in a direction perpendicular to the radiation field during imaging. The second base material is embedded in the first base material, and the phantom changes in size and position in a direction perpendicular to the radiation field during imaging. (Additional note 2) The first base material is a phantom as described in Appendix 1, with a larger occupancy ratio than the second base material. (Additional note 3) The first base material is a phantom according to appendix 1 or 2, having a frustoconical shape with its central axis perpendicular to the radiation field at the time of imaging. (Additional note 4) A calibration device for acquiring calibration data for a detector that outputs an electrical signal corresponding to the photon energy of incident radiation, Equipped with a processor, The aforementioned processor, A calibration device that acquires the calibration data of the detector using the phantom described in any one of the appendices 1 to 3. (Additional note 5) A calibration method in which a computer acquires calibration data for a detector that outputs an electrical signal corresponding to the photon energy of incident radiation, A calibration method for acquiring the calibration data of the detector using the phantom described in any one of the appendices 1 to 3. (Additional note 6) A calibration program that causes a computer to perform a procedure to acquire calibration data for a detector that outputs an electrical signal corresponding to the photon energy of incident radiation, A calibration program that causes a computer to perform a procedure for acquiring the calibration data of the detector using the phantom described in any one of the appendices 1 to 3. [Explanation of symbols]

[0060] 1. Medical imaging system 2 CT device 3 Console 4 Gantry 4A opening 4B Rotating Plate 5 Radiation source 6 Radiation tubes 7 Bowtie Filter 8 berths 9 Detectors 9P detection element 10 Phantom 11 First fundamental substance 12A~12C 2nd base material 20 Calibration device 21 CPU 22 Calibration Program 23 Storage 24 displays 25 Input Devices 26 memory 27 I / F 28 buses 31. Image capture control unit 32 Acquisition Department C0,C1,C2 Center axis P1-P5, P11-P19 Radiation transmission paths

Claims

1. A phantom for acquiring calibration data for a detector that outputs an electrical signal corresponding to the photon energy of incident radiation, It comprises a first base material and at least one second base material having a greater attenuation coefficient than the first base material, The first base material changes in thickness in a direction perpendicular to the radiation field during imaging. The second base material is embedded in the first base material, and the phantom changes in size and position in a direction perpendicular to the radiation field during imaging.

2. The phantom according to claim 1, wherein the first base material has a larger occupancy ratio than the second base material.

3. The phantom according to claim 1, wherein the first base material has a frustoconical shape with a central axis perpendicular to the radiation field at the time of imaging.

4. A calibration device for acquiring calibration data for a detector that outputs an electrical signal corresponding to the photon energy of incident radiation, Equipped with a processor, The aforementioned processor, A calibration device for acquiring the calibration data of the detector using the phantom described in any one of claims 1 to 3.

5. A calibration method in which a computer acquires calibration data for a detector that outputs an electrical signal corresponding to the photon energy of incident radiation, A calibration method for acquiring the calibration data of the detector using the phantom described in any one of claims 1 to 3.

6. A calibration program that causes a computer to perform a procedure to acquire calibration data for a detector that outputs an electrical signal corresponding to the photon energy of incident radiation, A calibration program that causes a computer to perform a procedure for acquiring the calibration data of the detector using the phantom described in any one of claims 1 to 3.

Images