Calibration device, medical imaging system, and calibration method

Abstract

The invention provides a calibration device, a medical imaging system and a calibration method which can easily acquire calibration data of a photon counting detector. A calibration device for acquiring calibration data for a photon counting detector that outputs an electric signal corresponding to photon energy of incident radiation, the calibration device being provided with: a holding unit that holds a first substrate material and a second substrate material having a greater attenuation coefficient with respect to the radiation than the first substrate material; and a movement mechanism that moves the first substrate material and the second substrate material between a position within the irradiation field and a position outside the irradiation field by moving the holding unit in the body axis direction of the subject irradiated with the radiation.

Description

Technical Field

[0001] The present invention relates to a calibration device, a medical image photography system and a calibration method. Background Art

[0002] PCCT (Photon Counting Computed Tomography) devices are known that include detectors that utilize a photon counting method, namely photon counting detectors. Photon counting detectors can measure the energy of incident radiation photons, i.e., photon energy. Therefore, PCCT devices can produce medical images that distinguish between substances of different compositions, such as iodine contrast agents used in angiography and calcified plaques in blood vessels. Furthermore, to obtain medical images that distinguish between substances, detector calibration is performed. For this purpose, the relationship between the output and photon energy when measured using a photon counting detector is pre-obtained for each detector element, as calibration data, for a combination of multiple base materials with known compositions and thicknesses.

[0003] Patent Document 1 discloses acquiring calibration data from step-shaped phantoms made of acrylic and aluminum.

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-146480

[0005] When the stepped phantom described in Patent Document 1 is applied to a large irradiation field of about 50 cm, the phantom becomes heavy and difficult to handle, so obtaining calibration data for the photon counting detector takes time and effort. Summary of the Invention

[0006] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a calibration device, a medical imaging system, and a calibration method that can easily acquire calibration data of a photon counting detector.

[0007] In order to achieve the above-mentioned purpose, the calibration device of the first mode of the present invention is used to obtain calibration data of a photon counting detector that outputs an electrical signal corresponding to the photon energy of the incident radiation. The calibration device comprises: a holding portion that holds a first base material and a second base material whose attenuation coefficient for radiation is greater than that of the first base material; and a moving mechanism that moves the holding portion in the body axis direction of the subject irradiated with radiation, thereby moving the first base material and the second base material between a position within the irradiation field and a position outside the irradiation field, respectively.

[0008] The calibration device according to the second aspect is the calibration device according to the first aspect, wherein the moving mechanism linearly moves the holding portion to move the first and second base substances between positions within and outside the irradiation field, respectively.

[0009] A calibration device according to a third aspect is the calibration device according to the first aspect, wherein the holding portion includes a first holding member that holds the first base substance and a second holding member that holds the second base substance.

[0010] A calibration device according to a fourth aspect is the calibration device according to the third aspect, wherein the holding portion includes a plurality of first holding members and a plurality of second holding members.

[0011] A fifth aspect of the calibration device is the third aspect of the calibration device, wherein the first base material has a plurality of measurement regions having different thicknesses in the direction in which radiation is transmitted, and the moving mechanism moves the first base material to a position within the irradiation field for each measurement region.

[0012] The sixth aspect of the calibration device is the third aspect of the calibration device, wherein the second base material has a plurality of measurement areas having different thicknesses in the direction in which radiation is transmitted, and the moving mechanism moves the second base material to a position within the irradiation field for each measurement area.

[0013] A seventh aspect of the calibration device is the calibration device of the first aspect, wherein the first base material and the second base material each have a plurality of divided parts, and the moving mechanism moves the first base material and the second base material to a position within the irradiation field for each part.

[0014] The calibration device of the eighth aspect is the calibration device of the first aspect, further comprising: a control unit that controls the movement of the first and second base substances to positions within the irradiation field by the movement mechanism according to the combination of the first and second base substances.

[0015] In order to achieve the above-mentioned object, a medical imaging system according to a ninth aspect of the present invention comprises: a radiation source; a photon counting detector that outputs an electrical signal corresponding to the photon energy of radiation irradiated from the radiation source; and the calibration device described in the present invention.

[0016] In order to achieve the above-mentioned purpose, the calibration method of the 10th embodiment of the present invention is a calibration method for a photon counting detector that outputs an electrical signal corresponding to the photon energy of the incident radiation, and the calibration method includes the following steps: a holding portion holds a first base material and a second base material whose attenuation coefficient for radiation is greater than that of the first base material; a moving mechanism moves the holding portion in the body axis direction of the subject irradiated with radiation so that the first base material and the second base material move between a position within the irradiation field and a position outside the irradiation field, respectively; and a plurality of calibration data are obtained by obtaining different combinations of the first base material and the second base material inserted into the irradiation field.

[0017] Effects of the Invention

[0018] According to the present invention, calibration data of a photon counting detector can be easily acquired. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a configuration diagram showing an example of the overall configuration of a medical imaging system according to an embodiment.

[0020] Figure 2 This is a diagram for explaining an example of a calibration method for a detector panel as a photon counting detector.

[0021] Figure 3 This is a structural diagram showing an example of the structure of a calibration device according to an embodiment.

[0022] Figure 4A It is a diagram for explaining the movement of the first base substance.

[0023] Figure 4B It is a diagram for explaining the movement of the second base substance.

[0024] Figure 5 This is a structural diagram showing an example of the structure of a calibration device according to Modification 1.

[0025] Figure 6A This is a diagram showing an example of a first base material included in the calibration device according to Modification 1.

[0026] Figure 6B This is a diagram showing an example of a second base material included in the calibration device of Modification 1.

[0027] Figure 7 This is a diagram showing an example of a first base material and a second base material included in a calibration device according to Modification 2.

[0028] Explanation of symbols

[0029] 10-Medical imaging system, 20-Frame, 22-Radiation source, 23-Radiation tube, 23F-Focus, 24-Butterfly filter, 26-Opening, 27-Diagnostic bed, 28-Detector panel, 28P-Detection element, 28R-Reference detector, 30-Control console, 32, 42-Control unit, 33, 43-Storage unit, 34, 44-I / F unit, 36-Operation unit, 38-Display unit, 40-Calibration device, 50-Moving mechanism, 52-Holding unit, 521- 1st holding part, 522-second holding part, 531, 5311 to 5314-first base material, 531a-normal area, 531b-reference area, 532, 5321 to 5324-second base material, 532a-normal area, 532b-reference area, 54-combination, 55-calibration data, 58-trolley, 581-frame, 582-wheel, 601, 602-measured area, R-radiation, RF-irradiation field, S-subject, α-direction. DETAILED DESCRIPTION

[0030] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, these embodiments do not limit the present invention.

[0031] First, an example of the overall configuration of the medical imaging system according to this embodiment will be described. Figure 1 , a configuration diagram showing an example of the overall configuration of the medical imaging system 10 according to the present embodiment is shown.

[0032] like Figure 1 As shown in FIG. 1 , the medical imaging system 10 of this embodiment includes a gantry 20, a diagnostic bed 27, a console 30, and a calibration device 40. Figure 1 The horizontal direction in the figure is set as the X-axis, the vertical direction is set as the Y-axis, and the direction perpendicular to the XY plane is set as the Z-axis.

[0033] The gantry 20 has an opening 26, and a subject S to be imaged is placed on a diagnostic bed 27 and disposed in the opening 26. The gantry 20 and the diagnostic bed 27 are relatively movable in the Z-axis direction.

[0034] Inside the gantry 20, a radiation source 22 comprising a radiation tube 23 and a butterfly filter 24 and a detector panel 28 are arranged in a position facing each other with a subject S interposed therebetween. Radiation R emitted from the radiation tube 23 is shaped by the butterfly filter 24 into a beam suitable for the size of the subject S and then irradiated onto the subject S. The detector panel 28 detects radiation that has passed through the subject S and generates projection data corresponding to the dose of the detected radiation. As an example, the detector panel 28 of this embodiment is a photon counting detector, with multiple detection elements 28P arranged in an arc shape centered on the focal point 23F of the radiation tube 23, which detect the energy of incident radiation photons. The detector panel 28, as a photon counting detector, outputs projection data corresponding to the photon energy.

[0035] The radiation tube 23 and detector panel 28 are rotated around the subject S by a rotation drive unit (not shown) of the gantry 20. As the radiation tube 23 irradiates the radiation and the detector panel 28 detects the radiation, projection data at various projection angles is acquired. The plurality of projection data acquired by the detector panel 28 is output to the console 30.

[0036] The dose of radiation irradiated from the radiation tube 23 , the rotation speed of the gantry 20 , and the relative movement speed between the gantry 20 and the bed 27 are set by the console 30 based on scan conditions input by a user such as an engineer.

[0037] The console 30 of the present embodiment performs control related to acquisition of projection data, generation of medical images, control related to calibration of the detector panel 28 by the calibration device 40 , and the like.

[0038] The console 30 includes a control unit 32, a storage unit 33, an I / F (Interface) unit 34, an operation unit 36, and a display unit 38. The control unit 32 includes a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory) (all not shown). As an example, the console 30 of this embodiment is a server computer.

[0039] The ROM stores various programs in advance, including programs for performing control related to acquisition of projection data, generation of medical images, and calibration of the detector panel 28 by the calibration device 40, which are executed by the CPU. The RAM temporarily stores various data.

[0040] Image data of medical images and other various information are stored in the storage unit 33. The storage unit 33 is implemented by a storage medium such as a HDD (Hard Disk Drive), an SSD (Solid State Drive), or a flash memory.

[0041] The I / F unit 34 communicates various information with the rotation drive unit (not shown) of the gantry 20, the radiation source 22, the detector panel 28, and the calibration device 40 through wired or wireless communication. The console 30 of this embodiment receives projection data and calibration data 55 from the detector panel 28 via the I / F unit 34.

[0042] The operating unit 36 ​​allows the user to input scanning conditions for acquiring projection data, instructions related to image generation and display, and various information. The operating unit 36 ​​is not particularly limited; examples include various switches, buttons, a touch panel, a stylus, a keyboard, and a mouse. The display unit 38 displays various information, medical images, and the like. Alternatively, the operating unit 36 ​​and display unit 38 may be integrated into a touch panel display. Furthermore, for example, the operating unit 36 ​​may accept voice input from the user.

[0043] The console 30 acquires multiple projection data from the detector panel 28 via the I / F unit 34. The control unit 32 reconstructs the acquired multiple projection data to generate a tomographic image of the subject S. Furthermore, if the multiple projection data are image data acquired while the bed 27 and gantry 20 are moving relative to each other in the Z-axis direction, the control unit 32 generates a three-dimensional image of the subject S from the multiple projection data. In this embodiment, in addition to the projection data acquired by the detector panel 28, the tomographic images and three-dimensional images generated by the control unit 32 are collectively referred to as "medical images."

[0044] The calibration device 40 of this embodiment is a device for calibrating the entire medical imaging system 10, mainly the detector panel 28. In the medical imaging system 10 having the detector panel 28 as a photon counting detector, the photon energy spectrum related to the projection data of the subject S can be obtained, so that a medical image that identifies substances with different compositions or a medical image divided into multiple energy components can be generated. In order to obtain medical images that identify substances with different compositions, etc., it is necessary to pre-calibrate each detection element 28P by measuring the relationship between the output and the photon energy when the detector panel 28 measures a substance with a known composition or thickness, that is, a combination of multiple base substances. The calibration device 40 is a device used for this calibration. In addition, Figure 1 The arrangement and orientation of the calibration device 40 shown are set for convenience of explanation and are different from the arrangement and orientation of the calibration device 40 when the detector panel 28 is actually constructed.

[0045] Here, reference Figure 2 An example of a calibration method for the detector panel 28 as a photon counting detector will be described.

[0046] In the calibration of the detector panel 28 as a photon counting type detector, a plurality of substrate materials with known compositions or thicknesses are used. Figure 2 In the illustrated calibration example, two base materials are used: a first base material 53_1 and a second base material 53_2. The first base material 53_1 and the second base material 53_2 have different attenuation coefficients for radiation. In this embodiment, the attenuation coefficient of the second base material 53_2 is greater than that of the first base material 53_1. For example, acrylic acid can be used as the first base material 53_1, and aluminum, which has a greater attenuation coefficient than acrylic acid, can be used as the second base material 53_2.

[0047] exist Figure 2 In the illustrated example, by combining two first base materials 53_1 having the same thickness and two second base materials 53_2 having the same thickness, calibration data 55 is obtained for each of a plurality of combinations 54 of first base materials 53_1 and second base materials 53_2 having different thicknesses in the transmission direction of the radiation R. For example, if there are J types of thicknesses of the first base material 53_1 and K types of thicknesses of the second base material 53_2, then J×K calibration data 55 can be obtained from J×K base material combinations 54.

[0048] Specifically, in Figure 2 In the example shown, when the thickness of the first base material 53_1 is "0 (zero)" when the first base material 53_1 is not set in the irradiation field RF, there are J = 3 types of thicknesses of the first base material 53_1. Similarly, when the thickness of the second base material 53_2 is "0 (zero)" when the second base material 53_2 is not set in the irradiation field RF, there are K = 3 types of thicknesses of the second base material 53_2. Therefore, in this case, there are 3 × 3 = 9 types of combinations of base materials. In addition, Figure 2 In FIG. 1 , “air” corresponds to a case where neither the first base material 53_1 nor the second base material 53_2 is provided in the irradiation field RF, that is, a case where the thicknesses of the first base material 53_1 and the second base material 53_2 are “0 (zero)”, respectively.

[0049] Each of the nine combinations 54 is inserted into the irradiation field RF of the radiation R, the radiation R is irradiated from the radiation source 22, and the detector panel 28 detects the radiation R that has passed through the combination 54. Thus, a photon energy spectrum is acquired as calibration data 55 for each combination 54. The nine types of calibration data 55 acquired in this manner are output to the console 30 and stored in the storage unit 33 of the console 30, and are used for calibration of the projection data of the subject S.

[0050] refer to Figure 1 and Figure 3 The structure of the calibration device 40 of this embodiment used for such calibration will be described. The calibration device 40 of this embodiment is configured as a carriage 58 having a frame 58_1 and a plurality of wheels 58_2. The frame 58_1 includes a control unit 42, a storage unit 43, and an I / F unit 44.

[0051] The control unit 42 includes a CPU, ROM, and RAM (all not shown). Various programs are pre-stored in the ROM, including programs for executing, for example, the control related to obtaining the calibration data 55 executed by the CPU. The RAM temporarily stores various data. Various information is stored in the storage unit 43. The storage unit 43 is implemented, for example, by a storage medium such as an HDD, SSD, or flash memory. The I / F unit 44 communicates various information with the console 30 via wired or wireless communication. Specifically, the I / F unit 44 receives information related to the control for obtaining the calibration data 55 from the console 30.

[0052] Furthermore, the calibration device 40 includes a holding portion 52 and a moving mechanism 50. Figure 3 As shown, the holding portion 52 includes a plurality of first holding members 52_1 and a plurality of second holding members 52_2. The calibration device 40 includes four first base materials 53_1 (53_11 to 53_14), and each first holding member 52_1 holds the first base materials 53_11 to 53_14. As an example, in this embodiment, Figure 4A As shown, each of the pair of first holding members 52_1 holds the surface intersecting the irradiation direction of the radiation R (in Figure 4A In the XZ plane, each of the opposite sides of the rectangular first base material 53_1 extending in the Z-axis direction. In addition, the calibration device 40 includes four second base materials 53_2 (53_21 to 53_24), and each second holding member 52_2 holds the second base materials 53_21 to 53_24 respectively. As an example, in this embodiment, as Figure 4B As shown, each of a pair of second holding members 52_2 holds a surface intersecting the irradiation direction of the radiation R (in Figure 4BIn the XZ plane, the second rectangular substrate 53_2 is a pair of opposite sides extending in the Z-axis direction. Figure 4A 、 4B As shown, one end of the first holding member 52_1 and the second holding member 52_2 is connected to the moving mechanism 50 provided in the frame 58_1 of the carriage 58 .

[0053] The moving mechanism 50 moves the holding portion 52 in the body axis direction of the subject S irradiated with radiation R under the control of the control portion 42, thereby moving the first base material 53_1 and the second base material 53_2 between a position within the irradiation field RF and a position outside the irradiation field RF, respectively. Figure 3 、 Figure 4A 、 Figure 4B As shown, the moving mechanism 50 moves the first holding member 52_1 and the second holding member 52_2 linearly in the Z-axis α direction, thereby moving the first base material 53_1 and the second base material 53_2 between positions within the irradiation field RF and positions outside the irradiation field RF. Figure 3 , the following state is shown: the first base material 53_11, 53_12 and the second base material 53_23, 53_24 are arranged at positions within the irradiation field RF, and the first base material 53_13, 53_14 and the second base material 53_21, 53_22 are arranged at positions outside the irradiation field RF.

[0054] As described above, as the moving mechanism 50 capable of linearly moving the first holding member 52_1 and the second holding member 52_2 in the α direction, for example, a linear actuator or the like can be used.

[0055] Next, a method for calibrating the detector panel 28 using the moving mechanism 50 of this embodiment will be described. Note that the calibration described here is performed without rotating the gantry 20.

[0056] First, the person in charge of calibration moves the carriage 58 and places the calibration device 40 at a predetermined position in front of the gantry 20. The predetermined position is a position where the first base material 53_1 and the second base material 53_2 can be moved between positions within the irradiation field RF of the radiation R and outside the irradiation field RF by moving the holding portion 52 by the moving mechanism 50.

[0057] After calibration device 40 is installed, the person in charge instructs calibration via operation unit 36 ​​of console 30. Upon receiving the instruction, control unit 32 of console 30 instructs calibration device 40 via I / F unit 34 to acquire calibration data 55.

[0058] When the calibration device 40 receives an instruction to acquire the calibration data 55 from the console 30 via the I / F unit 44 , the control unit 42 instructs the moving mechanism 50 to move the first base substance 53_1 and the second base substance 53_2 .

[0059] As described above, the calibration device of this embodiment includes four first base materials 53_1 (53_11 to 53_14) and four second base materials 53_2 (53_21 to 53_24). Therefore, including the case where the thickness of the first base material 53_1 and the second base material 53_2 are both "0 (zero)", there are 5×5=25 combinations 54 of the first base material 53_1 and the second base material 53_2.

[0060] The control unit 42 sequentially controls the moving mechanism 50 based on the 25 combinations 54 to position the first substrate 53_1 and the second substrate 53_2 within the irradiation field RF. Under the control of the control unit 42, the moving mechanism 50 moves at least one of the first holding member 52_1 and the second holding member 52_2 in the α direction, thereby moving the first substrate 53_1 and the second substrate 53_2 to positions within the irradiation field RF of the opening 26 of the gantry 20.

[0061] When the first base material 53_1 and the second base material 53_2 are moved to a state corresponding to any of the 25 combinations 54, the control unit 42 transmits placement completion information to the console 30 via the I / F unit 44, indicating that the placement of the first base material 53_1 and the second base material 53_2 is complete. Upon receiving the placement completion information from the calibration device 40 via the I / F unit 34, the console 30 instructs the radiation source 22 to irradiate radiation R for acquiring calibration data 55. In response to the irradiation instruction, the radiation source control unit (not shown) of the radiation source 22 irradiates radiation R from the radiation tube 23 toward the combination 54 disposed in the opening 26 of the gantry 20. The radiation R that has passed through the combination 54 is detected by the detector panel 28, and calibration data 55 is acquired and output to the console 30.

[0062] The console 30 associates the calibration data 55 acquired from the detector panel 28 with the type of the combination 54 used to acquire the calibration data 55 and stores the associated data in the storage unit 33 .

[0063] In the medical imaging system 10 of this embodiment, 25 types of calibration data 55 are obtained by repeating the movement of the first base material 53_1 and the second base material 53_2 by the movement mechanism 50 of the calibration device 40, the irradiation of the radiation R by the radiation tube 23, and the detection of the radiation R by the detector panel 28. The control unit 32 uses the 25 types of calibration data 55 to calibrate the detector panel 28. The method for calibrating the detector panel 28 based on the calibration data 55 is not limited, and a known method can be applied.

[0064] Thus, according to the medical imaging system 10 of this embodiment, the detector panel 28 can be calibrated by using the calibration device 40. The technology of the present invention is not limited to the above-described embodiment, and may be, for example, modified examples 1 and 2 described below.

[0065] (Variation 1)

[0066] In the above embodiment, the calibration device 40 is described as including four first base materials 53_1 and four second base materials 53_2 in order to vary the thickness of each of the first base materials 53_1 and the second base materials 53_2 in the transmission direction of the radiation R. However, the number of first base materials 53_1 and second base materials 53_2 included in the calibration device 40 is not limited to the above embodiment.

[0067] exist Figure 5 The configuration diagram of the calibration device 40 of this modification is shown in FIG. The calibration device 40 of this modification is different from the calibration device 40 of the above embodiment (see FIG. 4 ) in that it includes one first base material 53_1 and one second base material 53_2. Figure 3 )different.

[0068] like Figure 6A As shown, the first base material 53_1 of this modification has five measurement regions 60_1 having different thicknesses in the direction of transmission of radiation R. The moving mechanism 50 of this modification moves the first base material 53_1 to a position within the irradiation field RF for each measurement region 60_1 by moving the first holding member 52_1 in the α direction.

[0069] And, as Figure 6B As shown, the second base material 53_2 of this modification has five measurement regions 60_2 having different thicknesses in the direction of transmission of radiation R. The moving mechanism 50 of this modification moves the second base material 53_2 to a position within the irradiation field RF for each measurement region 60_2 by moving the second holding member 52_2 in the α direction.

[0070] Thus, in the calibration device 40 of this modified example, the first base material 53_1 has five measurement regions 60_1 having different thicknesses in the transmission direction of the radiation R, and the second base material 53_2 has five measurement regions 60_2 having different thicknesses in the transmission direction of the radiation R. Thus, the calibration device 40 of this modified example is different from the calibration device 40 of the above embodiment (see FIG. Figure 3 ) Similarly, 25 types of calibration data 55 can be obtained.

[0071] Therefore, according to the calibration device 40 of this modification, the number of first holding members 52_1 and second holding members 52_2 can be reduced, thereby miniaturizing the moving mechanism 50. For example, when a linear actuator is provided for each first holding member 52_1 and second holding member 52_2, the number of linear actuators included in the moving mechanism 50 can be reduced.

[0072] (Variation 2)

[0073] The first base material 53_1 and the second base material 53_2 included in the calibration device 40 may each have a plurality of divided parts. Figure 7 In the example shown, the first base material 53_1 has two divided parts, namely, a normal area 53_1a and a reference area 53_1b. Furthermore, the second base material 53_2 has two divided parts, namely, a normal area 53_2a and a reference area 53_2b. The moving mechanism 50 moves the first base material 53_1 and the second base material 53_2 to positions within the irradiation field RF for each part. Figure 7 , one first base material 53_1 and one second base material 53_2 are shown. However, as in the above-described embodiment, a plurality of first base materials 53_1 and second base materials 53_2 may be provided.

[0074] Reference regions 53_1b and 53_2b correspond to the irradiation field RF of the radiation R irradiating the reference detector 28R. In this variation, a predetermined number of detection elements 28P at one end of the detector panel 28 serve as reference detectors 28R. Reference detectors 28R detect radiation R that does not transmit the subject S and output the detection results as reference data. The control unit 32 of the console 30 calibrates the radiation intensity levels detected by the other detection elements 28P using the radiation intensity obtained from the reference data as a reference, and generates tomographic images using the calibrated signals.

[0075] In the calibration device 40 of this modified example, the normal region 53_1a and the reference region 53_1b can be moved between a position within the irradiation field RF and a position outside the irradiation field RF by the moving mechanism 50. For example, a first holding member 52_1 different from the first holding member 52_1 holding the normal region 53_1a can be used to hold the reference region 53_1b, and the moving mechanism 50 can be used to linearly move each first holding member 52_1. Similarly, a second holding member 52_2 different from the second holding member 52_2 holding the normal region 53_2a can be used to hold the reference region 53_2b, and the moving mechanism 50 can be used to linearly move each second holding member 52_2.

[0076] The specific method for acquiring the calibration data 55 and reference data at this time is not limited, and for example, the following method can be used. First, the control unit 42 of the calibration device 40 uses the moving mechanism 50 to position both the normal area 53_1a and the reference area 53_1b within the irradiation field RF. With both the normal area 53_1a and the reference area 53_1b within the irradiation field RF, the calibration data 55 is acquired. Next, the control unit 42 uses the moving mechanism 50 to move the normal area 53_1a to a position outside the irradiation field RF. With only the reference area 53_1b within the irradiation field RF, the reference data is acquired. This series of processes for acquiring the calibration data 55 and reference data is performed for each combination 54.

[0077] As described above, according to this modification, reference data can also be easily acquired by the calibration device 40 .

[0078] In addition, in this embodiment, one end portion ( Figure 7 In the embodiment of the present invention, the right end portion of the detector panel 28 is used as the reference detector 28R, but the present invention is not limited to this embodiment. For example, both ends of the detector panel 28 may be used as the reference detector 28R. In this case, the first base material 53_1 has three divided portions, namely, one normal region 53_1a and two reference regions 53_1b. Furthermore, the second base material 53_2 has three divided portions, namely, one normal region 53_2a and two reference regions 53_2b.

[0079] As described above, the calibration device 40 of the above-described embodiment and various variations is used to obtain calibration data 55 for the photon-counting detector panel 28, which outputs an electrical signal corresponding to the photon energy of incident radiation R. The calibration device 40 includes a holding portion 52 that holds a first base substance 53_1 and a second base substance 53_2 having a greater attenuation coefficient for radiation R than the first base substance 53_1. Furthermore, the calibration device 40 includes a moving mechanism 50 that moves the holding portion 52 in the body axis direction of a subject S irradiated with radiation R, thereby moving the first base substance 53_1 and the second base substance 53_2 between positions within and outside the irradiation field RF.

[0080] For example, unlike the calibration device 40 of the above-described embodiment and its variations, when a calibration device using a stepped phantom, such as that described in Patent Document 1, increases the number of steps depending on the number of required base material combinations, resulting in an overall increase in size and weight of the calibration device. In contrast, in the calibration device 40 of the above-described embodiment and its variations, the moving mechanism 50 moves the first base material 53_1 and the second base material 53_2 as described above, thereby enabling the overall miniaturization of the calibration device 40. Therefore, the calibration device 40 of the above-described embodiment and its variations can easily acquire calibration data for a photon-counting detector.

[0081] Furthermore, the configurations and operations of the medical imaging system 10, console 30, and calibration device 40 described in the above-described embodiment and various modifications are merely examples and can, of course, be modified as appropriate without departing from the spirit of the present invention. Furthermore, the above-described embodiments can also be appropriately combined.

[0082] Regarding the above-mentioned embodiment, the following supplementary notes are further disclosed.

[0083] (Note 1)

[0084] A calibration device for acquiring calibration data for a photon counting detector that outputs an electrical signal corresponding to the energy of photons of incident radiation, the calibration device comprising:

[0085] a holding portion that holds a first base material and a second base material having an attenuation coefficient for the radiation greater than that of the first base material; and

[0086] The moving mechanism moves the holding portion in a body axis direction of a subject irradiated with the radiation, thereby moving the first base substance and the second base substance between a position within an irradiation field and a position outside the irradiation field.

[0087] (Note 2)

[0088] The calibration device according to Supplementary Note 1, wherein:

[0089] The moving mechanism linearly moves the holding portion to move the first base substance and the second base substance between a position within the irradiation field and a position outside the irradiation field, respectively.

[0090] (Note 3)

[0091] The calibration device according to Supplement 1 or Supplement 2, wherein:

[0092] The holding portion includes a first holding member that holds the first base material and a second holding member that holds the second base material.

[0093] (Note 4)

[0094] The calibration device according to Supplementary Note 3, wherein:

[0095] The holding portion includes a plurality of the first holding members and a plurality of the second holding members.

[0096] (Note 5)

[0097] The calibration device according to any one of Supplementary Notes 1 to 4, wherein:

[0098] The first base material has a plurality of measurement areas having different thicknesses in the direction in which the radiation is transmitted.

[0099] The moving mechanism moves the first base substance to a position within the irradiation field for each of the measurement areas.

[0100] (Note 6)

[0101] The calibration device according to any one of Supplementary Notes 1 to 4, wherein:

[0102] The second base material has a plurality of measurement areas having different thicknesses in the direction in which the radiation is transmitted.

[0103] The moving mechanism moves the second base substance to a position within the irradiation field for each of the measurement areas.

[0104] (Note 7)

[0105] The calibration device according to any one of Supplementary Notes 1 to 6, wherein:

[0106] The first base material and the second base material each have a plurality of divided parts.

[0107] The moving mechanism moves the first base material and the second base material to positions within the irradiation field for each of the portions.

[0108] (Note 8)

[0109] The calibration device according to any one of Supplementary Notes 1 to 7, further comprising:

[0110] The control unit controls the movement of the first and second base substances to positions within the irradiation field using the movement mechanism based on the combination of the first and second base substances.

[0111] (Note 9)

[0112] A medical imaging system comprising:

[0113] Radiation sources;

[0114] a photon counting detector that outputs an electrical signal corresponding to the photon energy of radiation irradiated from the radiation source; and

[0115] The calibration device according to any one of Supplementary Notes 1 to 8.

[0116] (Note 10)

[0117] A calibration method for a photon counting detector that outputs an electrical signal corresponding to the photon energy of incident radiation, the calibration method comprising the following steps:

[0118] The holding portion holds a first base material and a second base material having a greater attenuation coefficient for the radiation than the first base material;

[0119] a moving mechanism that moves the holding portion in a body axis direction of a subject irradiated with the radiation so as to move the first base substance and the second base substance between a position within an irradiation field and a position outside the irradiation field, respectively; and

[0120] A plurality of calibration data are acquired by varying the combination of the first base material and the second base material inserted into the irradiation field.

Claims

1. A calibration device for acquiring calibration data for a photon counting detector that outputs an electrical signal corresponding to the energy of photons of incident radiation, the calibration device comprising: a holding portion that holds a first base material and a second base material having an attenuation coefficient for the radiation greater than that of the first base material; and The moving mechanism moves the holding portion in a body axis direction of a subject irradiated with the radiation, thereby moving the first base substance and the second base substance between a position within an irradiation field and a position outside the irradiation field.

2. The calibration device according to claim 1, wherein: The moving mechanism linearly moves the holding portion to move the first base substance and the second base substance between a position within the irradiation field and a position outside the irradiation field, respectively.

3. The calibration device according to claim 1, wherein: The holding portion includes a first holding member that holds the first base material and a second holding member that holds the second base material.

4. The calibration device according to claim 3, wherein: The holding portion includes a plurality of the first holding members and a plurality of the second holding members.

5. The calibration device according to claim 3, wherein: The first base material has a plurality of measurement areas having different thicknesses in the direction in which the radiation is transmitted. The moving mechanism moves the first base substance to a position within the irradiation field for each of the measurement areas.

6. The calibration device according to claim 3, wherein: The second base material has a plurality of measurement areas having different thicknesses in the direction in which the radiation is transmitted. The moving mechanism moves the second base substance to a position within the irradiation field for each of the measurement areas.

7. The calibration device according to claim 1, wherein: The first base material and the second base material each have a plurality of divided parts. The moving mechanism moves the first base material and the second base material to positions within the irradiation field for each of the portions.

8. The calibration device according to claim 1, further comprising: The control unit controls the movement of the first and second base substances to positions within the irradiation field using the movement mechanism based on the combination of the first and second base substances.

9. A medical imaging system comprising: Radiation sources; a photon counting detector that outputs an electrical signal corresponding to the photon energy of radiation irradiated from the radiation source; and A calibration device according to any one of claims 1 to 8.

10. A calibration method for a photon counting detector that outputs an electrical signal corresponding to the energy of incident radiation photons, the calibration method comprising the following steps: The holding portion holds a first base material and a second base material having a greater attenuation coefficient for the radiation than the first base material; a moving mechanism that moves the holding portion in a body axis direction of a subject irradiated with the radiation so as to move the first base substance and the second base substance between a position within an irradiation field and a position outside the irradiation field, respectively; and A plurality of calibration data are acquired by varying the combination of the first base material and the second base material inserted into the irradiation field.

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