Calibration device, medical imaging system and calibration method

Abstract

To provide a calibration device, medical imaging system and calibration method that allow an operator to easily acquire calibration data for a photon-counting detector.SOLUTION: A calibration device used to acquire calibration data for a photon-counting detector that outputs an electric signal corresponding to photon energy of an incident radiation, includes: a holding unit which holds a first basis material and a second basis material having a larger attenuation coefficient for the radiation than that of the first basis material; and a moving mechanism that moves each of the first basis material and the second basis material between a position inside an irradiation field and a position outside the irradiation field by moving the holding unit in a body axis direction of a subject to which the radiation is applied.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a calibration device, a medical imaging system, and a calibration method. [Background technology]

[0002] Photon-counting computed tomography (PCCT) systems equipped with photon-counting detectors, which employ a photon-counting method, are known. Because photon-counting detectors can measure the photon energy of incident radiation photons, PCCT systems can obtain medical images in which materials with different compositions are differentiated, such as images in which iodine contrast agents used in angiography are differentiated from calcified plaques in blood vessels. To obtain medical images with differentiated materials, the detectors are calibrated. Therefore, for combinations of multiple base materials with known compositions and thicknesses, the relationship between the output and photon energy measured by the photon-counting detector is acquired in advance as calibration data for each detector element.

[0003] Patent Document 1 discloses that calibration data is obtained from each of a stepped phantom made of acrylic and aluminum. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-146480 Summary of the Invention [Problem to be solved by the invention]

[0005] When a stepped phantom such as that described in Patent Document 1 is applied to a large irradiation field of about 50 cm, the phantom becomes heavy and difficult to handle, and it takes time to obtain calibration data for the photon counting detector, making it difficult to obtain calibration data.

[0006] The present disclosure has been made in consideration of the above circumstances, and aims to provide a calibration device, a medical imaging system, and a calibration method that can easily obtain calibration data for a photon-counting detector. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, a calibration device of a first aspect of the present disclosure is a calibration device used to obtain calibration data of a photon counting detector that outputs an electrical signal corresponding to the photon energy of incident radiation, and includes a holding unit that holds a first basis material and a second basis material that has a larger attenuation coefficient for radiation than the first basis material, and a moving mechanism that moves each of the first basis material and the second basis 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 a subject to be irradiated with radiation.

[0008] The calibration device of the second aspect is the calibration device of the first aspect, in which the moving mechanism moves the holding portion in a linear motion to move each of the first base material and the second base material between a position within the irradiation field and a position outside the irradiation field.

[0009] A calibration device of a third aspect is the calibration device of the first aspect, wherein the holding section includes a first holding member that holds a first basis substance and a second holding member that holds a second basis substance.

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

[0011] A calibration device of the fifth aspect is the calibration device of the third aspect, in which the first basis material has multiple measurement areas with different thicknesses in the direction in which radiation passes, and the moving mechanism moves the first basis material to a position within the irradiation field for each measurement area.

[0012] A sixth aspect of the calibration device is the third aspect of the calibration device, wherein the second basis material has a plurality of measurement areas with different thicknesses in the direction in which radiation passes, and the moving mechanism moves the second basis 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 basis material and the second basis material each have a plurality of divided parts, and a moving mechanism moves the first basis material and the second basis material part by part to a position within the irradiation field.

[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 basis material and the second basis material to a position within the irradiation field using a movement mechanism depending on the combination of the first basis material and the second basis material.

[0015] In order to achieve the above object, a medical imaging system according to a ninth aspect of the present disclosure 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 a calibration device as described in the present disclosure.

[0016] In order to achieve the above-mentioned object, a calibration method of a tenth aspect of the present disclosure is a method for calibrating a photon counting detector that outputs an electrical signal corresponding to the photon energy of incident radiation, wherein a holding unit holds a first basis material and a second basis material having a larger attenuation coefficient for radiation than the first basis material, and a moving mechanism moves the holding unit in the body axis direction of a subject to be irradiated with radiation, moving each of the first basis material and the second basis material between a position within the irradiation field and a position outside the irradiation field, and acquiring multiple calibration data obtained by varying the combination of the first basis material and the second basis material inserted into the irradiation field. [Effects of the Invention]

[0017] According to the present disclosure, calibration data for photon-based detectors can be easily obtained. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a configuration diagram illustrating an example of the overall configuration of a medical image capturing system according to an embodiment. [Figure 2] 10A and 10B are diagrams for explaining an example of a method for calibrating a detector panel that is a photon counting detector. [Figure 3] FIG. 1 is a configuration diagram illustrating an example of a configuration of a calibration device according to an embodiment. [Figure 4A] FIG. 2 is a diagram for explaining the movement of a first basis substance. [Figure 4B] FIG. 10 is a diagram for explaining the movement of a second basis substance. [Figure 5] FIG. 10 is a configuration diagram showing an example of the configuration of a calibration device according to a first modified example. [Figure 6A] 10 is a diagram showing an example of a first basis material provided in the calibration device of Modification 1. FIG. [Figure 6B] 10 is a diagram showing an example of a second basis material provided in the calibration device of Modification 1. FIG. [Figure 7] 10 is a diagram showing an example of a first basis substance and a second basis substance provided in a calibration device of Modification 2. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the embodiment.

[0020] First, an example of the overall configuration of a medical image capturing system according to this embodiment will be described. Fig. 1 shows a configuration diagram illustrating an example of the overall configuration of a medical image capturing system 10 according to this embodiment.

[0021] 1, a medical imaging system 10 of this embodiment includes a gantry 20, a bed 27, a console 30, and a calibration device 40. In the following description, the horizontal direction in FIG. 1 is defined as the X-axis, the vertical direction as the Y-axis, and the direction perpendicular to the XY plane as the Z-axis.

[0022] The gantry 20 has an opening 26, and the subject S to be imaged is placed on a bed 27 and placed in the opening 26. The gantry 20 and the bed 27 are capable of moving relatively in the Z-axis direction.

[0023] Inside the gantry 20, a radiation source 22 having a radiation tube 23 and a bowtie filter 24, and a detector panel 28 are arranged facing each other with the subject S in between. The radiation R emitted from the radiation tube 23 is shaped by the bowtie filter 24 into a beam shape appropriate for the size of the subject S, and is then irradiated onto the subject S. The detector panel 28 detects the 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 in this embodiment is a photon-counting detector in which a plurality of detection elements 28P that detect photon energy, which is the energy of photons of the incident radiation, are arranged in an arc shape centered on the focal point 23F of the radiation tube 23. The detector panel 28, which is a photon-counting detector, outputs projection data corresponding to the photon energy.

[0024] The radiation tube 23 and the detector panel 28 are rotated around the subject S by a rotation drive unit (not shown) of the gantry 20. The irradiation of radiation from the radiation tube 23 and the detection of radiation by the detector panel 28 are repeated as they rotate, thereby obtaining projection data at various projection angles. The multiple projection data obtained by the detector panel 28 are output to the console 30.

[0025] The dose of radiation emitted 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 the scan conditions input by a user such as a technician.

[0026] The console 30 of this embodiment controls the acquisition of projection data, the generation of medical images, and the calibration of the detector panel 28 by the calibration device 40, among other things.

[0027] 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), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. (all not shown). As an example, the console 30 of this embodiment is a server computer.

[0028] The ROM stores various programs in advance, including programs executed by the CPU for controlling the acquisition of projection data, generating medical images, and controlling the calibration of the detector panel 28 by the calibration device 40. The RAM temporarily stores various data.

[0029] Image data of medical images and various other information are stored in the storage unit 33. The storage unit 33 is realized by a storage medium such as an HDD (Hard Disk Drive), an SSD (Solid State Drive), or a flash memory.

[0030] The I / F unit 34 communicates various types of information with a rotation drive unit (not shown) of the gantry 20, the radiation source 22, the detector panel 28, and the calibration device 40 via 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.

[0031] The operation unit 36 ​​is used by the user to input scan conditions for acquiring projection data, instructions and various information regarding image generation and display, etc. The operation unit 36 ​​is not particularly limited, and examples thereof include various switches, buttons, a touch panel, a touch pen, a keyboard, and a mouse. The display unit 38 displays various information, medical images, etc. The operation unit 36 ​​and the display unit 38 may be integrated into a touch panel display. Alternatively, for example, the operation unit 36 ​​may receive voice input from the user.

[0032] The console 30 acquires a plurality of projection data from the detector panel 28 via the I / F unit 34. The control unit 32 performs reconstruction processing on the acquired plurality of projection data to generate a tomographic image of the subject S. Note that, when the plurality of projection data is image data acquired while the bed 27 and the gantry 20 are moving relatively in the Z-axis direction, the control unit 32 generates a three-dimensional image of the subject S from the plurality of projection data. Note that, in this embodiment, the projection data acquired by the detector panel 28, as well as the tomographic image and three-dimensional image generated by the control unit 32, are collectively referred to as "medical images."

[0033] The calibration device 40 of this embodiment is a device for calibrating the entire medical imaging system 10, mainly the detector panel 28. The medical imaging system 10, which includes the detector panel 28, which is a photon-counting detector, can acquire a photon energy spectrum related to projection data of the subject S, thereby generating medical images in which materials with different compositions are differentiated and medical images separated into multiple energy components. To obtain such medical images in which materials with different compositions are differentiated, it is necessary to calibrate in advance for each detector element 28P the relationship between the output and photon energy when a combination of multiple basis materials, each of which has a known composition and thickness, is measured by the detector panel 28. The calibration device 40 is a device used for this calibration. Note that the arrangement and orientation of the calibration device 40 shown in FIG. 1 are for convenience of explanation and will differ from the arrangement and orientation of the calibration device 40 when the detector panel 28 is actually constructed.

[0034] Now, with reference to FIG. 2, an example of a method for calibrating the detector panel 28, which is a photon counting detector, will be described.

[0035] A plurality of basis materials with known compositions and thicknesses are used to calibrate the detector panel 28, which is a photon-counting detector. In the calibration example shown in Fig. 2, two types of basis materials, a first basis material 53_1 and a second basis material 53_2, are used. The first basis material 53_1 and the second basis material 53_2 have different attenuation coefficients for radiation, and in this embodiment, the second basis material 53_2 has a larger attenuation coefficient than the first basis material 53_1. For example, the first basis material 53_1 can be acrylic, and the second basis material 53_2 can be aluminum, which has a larger attenuation coefficient than acrylic.

[0036] 2, by combining two first basis materials 53_1 having the same thickness and two second basis materials 53_2 having the same thickness, calibration data 55 is obtained for each of a plurality of combinations 54 of the first basis materials 53_1 and the second basis materials 53_2 having different thicknesses in the transmission direction of the radiation R. For example, if the first basis materials 53_1 have J different thicknesses and the second basis materials 53_2 have K different thicknesses, J×K pieces of calibration data 55 are obtained by the combinations 54 of the J×K types of basis materials.

[0037] Specifically, in the example shown in FIG. 2, if the case where the first basis material 53_1 is not provided within the irradiation field RF is defined as a case where the thickness of the first basis material 53_1 is "0 (zero)", there are J = 3 types of thicknesses of the first basis material 53_1. Similarly, if the case where the second basis material 53_2 is not provided within the irradiation field RF is defined as a case where the thickness of the second basis material 53_2 is "0 (zero)", there are K = 3 types of thicknesses of the second basis material 53_2. Therefore, in this case, there are 3 × 3 = 9 types of combinations of basis materials. Note that "Air" in FIG. 2 corresponds to a case where neither the first basis material 53_1 nor the second basis material 53_2 is provided within the irradiation field RF, i.e., a case where the thicknesses of the first basis material 53_1 and the second basis material 53_2 are "0 (zero)".

[0038] Each of the nine combinations 54 is inserted into the irradiation field RF of radiation R, and radiation R is irradiated from the radiation source 22. The radiation R that has passed through the combination 54 is detected by the detector panel 28, thereby obtaining a photon energy spectrum for each combination 54 as calibration data 55. The nine types of calibration data 55 obtained in this manner are output to the console 30, stored in the memory unit 33 of the console 30, and used to calibrate the projection data of the subject S.

[0039] The configuration of a calibration device 40 of this embodiment used for such calibration will be described with reference to Figures 1 and 3. The calibration device 40 of this embodiment is configured as a cart 58 having a housing 58_1 and a plurality of wheels 58_2, and includes a control unit 42, a storage unit 43, and an I / F unit 44 within the housing 58_1.

[0040] The control unit 42 includes a CPU, a ROM, a RAM, etc. (all not shown). The ROM stores various programs in advance, including a program executed by the CPU for controlling the acquisition of the calibration data 55. The RAM temporarily stores various data. The storage unit 43 stores various information, etc. The storage unit 43 is realized by a storage medium such as an HDD, an SSD, or a 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 acquiring the calibration data 55 from the console 30.

[0041] The calibration device 40 further includes a holding unit 52 and a moving mechanism 50. As shown in FIG. 3, the holding unit 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 basis materials 53_1 (53_11 to 53_14), and each of the first holding members 52_1 holds one of the first basis materials 53_11 to 53_14. As an example, in this embodiment, as shown in FIG. 4A, each of the pair of first holding members 52_1 holds a pair of opposing sides extending in the Z-axis direction of the first basis material 53_1, which has a rectangular shape and whose plane intersecting the irradiation direction of the radiation R (the XZ plane in FIG. 4A). The calibration device 40 also includes four second basis materials 53_2 (53_21 to 53_24), and each second holding member 52_2 holds one of the second basis materials 53_21 to 53_24. As an example, in this embodiment, as shown in FIG. 4B, each of the pair of second holding members 52_2 holds a pair of opposing sides extending in the Z-axis direction of the second basis material 53_2, which has a rectangular shape and whose plane intersecting the irradiation direction of the radiation R (the XZ plane in FIG. 4B) is a rectangular shape. As shown in FIGS. 4A and 4B, one ends of the first holding member 52_1 and the second holding member 52_2 are connected to a moving mechanism 50 provided in a housing 58_1 of a dolly 58.

[0042] The moving mechanism 50 moves each of the first basis material 53_1 and the second basis material 53_2 between a position within the irradiation field RF and a position outside the irradiation field RF by moving the holding member 52 in the body axis direction of the subject S to be irradiated with the radiation R under the control of the control unit 42. In the present embodiment, as shown in Figures 3, 4A and 4B, the moving mechanism 50 moves each of the first holding member 52_1 and the second holding member 52_2 linearly in the α direction along the Z axis, thereby moving each of the first basis material 53_1 and the second basis material 53_2 between a position within the irradiation field RF and a position outside the irradiation field RF. In addition, Figure 3 shows a state in which the first basis materials 53_13, 53_14 and the second basis materials 53_21, 53_22 are arranged at positions within the irradiation field RF, and the first basis materials 53_11, 53_12 and the second basis materials 53_23, 53_24 are arranged at positions outside the irradiation field RF.

[0043] As the movement mechanism 50 capable of linearly moving the first holding member 52_1 and the second holding member 52_2 in the α direction in this manner, for example, a linear actuator or the like can be used.

[0044] 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 in a state where the gantry 20 is not rotated.

[0045] First, the person performing the calibration moves the cart 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 moving mechanism 50 moves the holder 52, thereby allowing the first basis material 53_1 and the second basis material 53_2 to be moved between positions inside and outside the irradiation field RF of the radiation R.

[0046] After placing the calibration device 40, the person in charge issues an instruction to perform calibration using the operation unit 36 ​​of the console 30. Upon receiving the instruction, the control unit 32 of the console 30 instructs the calibration device 40 to acquire calibration data 55 via the I / F unit 34.

[0047] When the calibration device 40 receives an instruction to acquire calibration data 55 from the console 30 via the I / F unit 44, the control unit 42 instructs the movement mechanism 50 to move the first basis material 53_1 and the second basis material 53_2.

[0048] As described above, the calibration device of this embodiment is provided with four first basis materials 53_1 (53_11 to 53_14) and four second basis materials 53_2 (53_21 to 53_24). Therefore, including the case where the thickness of each of the first basis materials 53_1 and the second basis materials 53_2 is "0 (zero)", 5 × 5 = 25 combinations 54 of the first basis materials 53_1 and the second basis materials 53_2 are obtained.

[0049] The control unit 42 controls the moving mechanism 50 sequentially in accordance with the 25 types of combinations 54 so that the first basis material 53_1 and the second basis material 53_2 are within the irradiation field RF. 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 in accordance with the control of the control unit 42, thereby moving the first basis material 53_1 and the second basis material 53_2 to positions within the irradiation field RF of the opening 26 of the gantry 20.

[0050] When the first basis material 53_1 and the second basis material 53_2 are moved to a state corresponding to one of the 25 combinations 54, the control unit 42 transmits arrangement completion information indicating that the arrangement of the first basis material 53_1 and the second basis material 53_2 has been completed to the console 30 via the I / F unit 44. When the console 30 receives the arrangement completion information from the calibration device 40 via the I / F unit 34, it instructs the radiation source 22 to irradiate radiation R to obtain calibration data 55. In response to the irradiation instruction, a radiation source control unit (not shown) of the radiation source 22 causes the radiation tube 23 to irradiate radiation R toward the combination 54 arranged at 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 obtained and output to the console 30.

[0051] The console 30 stores the calibration data 55 acquired from the detector panel 28 in the storage unit 33 in association with the type of combination 54 used to acquire the calibration data 55.

[0052] In the medical image capturing system 10 of this embodiment, 25 types of calibration data 55 are obtained by repeating the following steps: moving the first basis material 53_1 and the second basis material 53_2 using the movement mechanism 50 of the calibration device 40; irradiating the radiation R from the radiation tube 23; and detecting the radiation R using the detector panel 28. The control unit 32 calibrates the detector panel 28 using the 25 types of calibration data 55. Note that the method for calibrating the detector panel 28 using the calibration data 55 is not limited, and any known method can be applied.

[0053] As described above, according to the medical imaging system 10 of this embodiment, the detector panel 28 can be calibrated by using the calibration device 40. Note that the technology of the present disclosure is not limited to the above-described embodiment, and may be modified as in Modifications 1 and 2 described below, for example.

[0054] (Variation 1) In the above embodiment, the calibration device 40 is described as including four first basis materials 53_1 and four second basis materials 53_2 in order to make the thickness of each of the first basis materials 53_1 and the second basis materials 53_2 different in the transmission direction of the radiation R. However, the numbers of the first basis materials 53_1 and the second basis materials 53_2 included in the calibration device 40 are not limited to those in the above embodiment.

[0055] 5 shows a configuration diagram of the calibration device 40 of this modified example. The calibration device 40 of this modified example differs from the calibration device 40 of the above embodiment (see FIG. 3) in that the calibration device 40 of this modified example includes one first basis material 53_1 and one second basis material 53_2.

[0056] 6A, the first basis material 53_1 of this modified example has five measurement regions 60_1 having different thicknesses in the direction of transmission of the radiation R. The moving mechanism 50 of this modified example moves the first holding member 52_1 in the α direction, thereby moving the first basis material 53_1 to a position within the irradiation field RF for each of the measurement regions 60_1.

[0057] 6B, the second basis material 53_2 of this modification has five measurement regions 60_2 having different thicknesses in the direction of transmission of the radiation R. The moving mechanism 50 of this modification moves the second holding member 52_2 in the α direction, thereby moving the second basis material 53_2 to a position within the irradiation field RF for each measurement region 60_2.

[0058] As described above, in the calibration device 40 of this modified example, the first basis material 53_1 has five measurement regions 60_1 each having a different thickness in the transmission direction of the radiation R, and the second basis material 53_2 has five measurement regions 60_2 each having a different thickness in the transmission direction of the radiation R. As a result, the calibration device 40 of this modified example can acquire 25 types of calibration data 55, similar to the calibration device 40 of the above embodiment (see FIG. 3).

[0059] Therefore, according to the calibration device 40 of this modified example, it is possible to reduce the number of first holding members 52_1 and second holding members 52_2, thereby reducing the size of the movement mechanism 50. For example, when a linear actuator is provided for each of the first holding member 52_1 and the second holding member 52_2, the number of linear actuators provided in the movement mechanism 50 can be reduced.

[0060] (Variation 2) Each of the first basis material 53_1 and the second basis material 53_2 included in the calibration device 40 may have a plurality of divided portions. In the example shown in FIG. 7, the first basis material 53_1 has two divided portions, a normal region 53_1a and a reference region 53_1b. The second basis material 53_2 has two divided portions, a normal region 53_2a and a reference region 53_2b. The moving mechanism 50 moves the first basis material 53_1 and the second basis material 53_2 to positions within the irradiation field RF on a portion-by-portion basis. Note that, although FIG. 7 illustrates one each of the first basis material 53_1 and the second basis material 53_2, a plurality of first basis materials 53_1 and second basis materials 53_2 may be provided as in the above embodiment.

[0061] The reference regions 53_1b and 53_2b are regions corresponding to the irradiation field RF of the radiation R irradiated onto the reference detector 28R. In this modification, a predetermined number of detecting elements 28P at one end of the detector panel 28 are used as the reference detector 28R. The reference detector 28R detects the radiation R that does not pass through the subject S, and outputs the detection result as reference data. The control unit 32 of the console 30 calibrates the intensity levels of the radiation obtained by the other detecting elements 28P using the intensity of the radiation obtained from the reference data as a reference, and generates a tomographic image using the calibrated signal.

[0062] 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, the reference region 53_1b may be held by a first holding member 52_1 different from the first holding member 52_1 that holds the normal region 53_1a, and each of the first holding members 52_1 may be linearly moved by the moving mechanism 50. Similarly, the reference region 53_2b may be held by a second holding member 52_2 different from the second holding member 52_2 that holds the normal region 53_2a, and each of the second holding members 52_2 may be linearly moved by the moving mechanism 50.

[0063] Furthermore, the specific method for acquiring the calibration data 55 and the reference data in this case is not limited, but may be, for example, the following method. First, the control unit 42 of the calibration device 40 uses the movement mechanism 50 to position both the normal region 53_1a and the reference region 53_1b within the irradiation field RF. With both the normal region 53_1a and the reference region 53_1b positioned within the irradiation field RF, the control unit 42 acquires the calibration data 55. Next, the control unit 42 uses the movement mechanism 50 to move the normal region 53_1a to a position outside the irradiation field RF. With only the reference region 53_1b positioned within the irradiation field RF, the control unit 42 acquires the reference data. This series of processes for acquiring the calibration data 55 and the reference data is performed for each combination 54.

[0064] In this way, according to this modification, the calibration device 40 can also easily obtain reference data.

[0065] In this embodiment, one end of the detector panel 28 (the right end in FIG. 7) 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 basis material 53_1 has three divided parts: one normal region 53_1a and two reference regions 53_1b. Furthermore, the second basis material 53_2 has three divided parts: one normal region 53_2a and two reference regions 53_2b.

[0066] As described above, the calibration device 40 of the above embodiment and each modified example is a calibration device used to acquire calibration data 55 of a photon-counting detector panel 28 that outputs an electrical signal corresponding to the photon energy of incident radiation R. The calibration device 40 includes a holder 52 that holds a first basis material 53_1 and a second basis material 53_2 that has a larger attenuation coefficient for radiation R than the first basis material 53_1. The calibration device 40 also includes a movement mechanism 50 that moves each of the first basis material 53_1 and the second basis material 53_2 between a position within the irradiation field RF and a position outside the irradiation field RF by moving the holder 52 in the body axis direction of the subject S to be irradiated with radiation R.

[0067] For example, unlike the calibration device 40 of the above embodiment and each modified example, in the case of a calibration device using a stepped phantom as described in Patent Document 1, the number of steps increases depending on the number of combinations of required basis materials, which results in the overall size and weight of the calibration device. In contrast, in the calibration device 40 of the above embodiment and each modified example, the movement mechanism 50 moves the first basis material 53_1 and the second basis material 53_2 as described above, so the overall size of the calibration device 40 can be reduced. Therefore, according to the calibration device 40 of the above embodiment and each modified example, calibration data for a photon-counting detector can be easily obtained.

[0068] It should be noted that the configurations and operations of the medical image capturing system 10, console 30, calibration device 40, etc. described in the above embodiment and each modified example are merely examples, and can be modified according to the circumstances without departing from the spirit of the present invention. It should also be noted that the above embodiments can be combined as appropriate.

[0069] The following additional notes are provided regarding the above-described embodiment. (Appendix 1) A calibration device used to obtain calibration data for a photon-counting detector that outputs an electrical signal corresponding to the photon energy of incident radiation, comprising: a holder that holds a first basis material and a second basis material having a larger attenuation coefficient for the radiation than the first basis material; a movement mechanism that moves the holding unit in a body axis direction of the subject to be irradiated with the radiation, thereby moving each of the first basis material and the second basis material between a position within the irradiation field and a position outside the irradiation field; A calibration device comprising:

[0070] (Appendix 2) The moving mechanism moves the holding unit linearly to move each of the first basis material and the second basis material between a position within the irradiation field and a position outside the irradiation field. 10. The calibration device of claim 1.

[0071] (Appendix 3) The holding unit includes a first holding member that holds the first basis material and a second holding member that holds the second basis material. 10. The calibration device of claim 1 or 2.

[0072] (Appendix 4) The holding portion includes a plurality of the first holding members and a plurality of the second holding members. 10. A calibration device as described in Appendix 3.

[0073] (Appendix 5) the first basis material has a plurality of measurement regions having different thicknesses in the direction in which the radiation passes; The moving mechanism moves the first basis material to a position within the irradiation field for each of the measurement regions. 5. The calibration device of any one of claims 1 to 4.

[0074] (Appendix 6) the second basis material has a plurality of measurement regions having different thicknesses in the direction in which the radiation passes; The moving mechanism moves the second basis material to a position within the irradiation field for each of the measurement regions. 5. The calibration device of any one of claims 1 to 4.

[0075] (Appendix 7) each of the first basis material and the second basis material has a plurality of divided portions; The moving mechanism moves the first basis material and the second basis material to positions within the irradiation field for each of the portions. 7. The calibration device of any one of claims 1 to 6.

[0076] (Appendix 8) The apparatus further includes a control unit that controls the movement of the first basis material and the second basis material to positions within the irradiation field by the movement mechanism in accordance with the combination of the first basis material and the second basis material. 8. The calibration device of any one of claims 1 to 7.

[0077] (Appendix 9) A radiation source; a photon-counting detector that outputs an electrical signal corresponding to the photon energy of the radiation emitted from the radiation source; A calibration device according to any one of claims 1 to 8; and Equipped with Medical imaging system.

[0078] (Appendix 10) 1. A method for calibrating a photon-counting detector that outputs an electrical signal corresponding to the photon energy of incident radiation, comprising: a holder holds a first basis material and a second basis material having a larger attenuation coefficient for the radiation than the first basis material; a moving mechanism moving the holding unit in a body axis direction of the subject to be irradiated with the radiation, thereby moving each of the first basis material and the second basis material between a position within the irradiation field and a position outside the irradiation field; A plurality of calibration data sets are obtained by inserting different combinations of the first basis material and the second basis material into the irradiation field. Calibration methods. [Explanation of symbols]

[0079] 10 Medical imaging system 20 Gantry 22 Radiation source 23 radiation tube, 23F focus 24 Bowtie Filter 26 Opening 27 berths 28 detector panel, 28P detector element, 28R reference detector 30 Console 32, 42 Control section 33, 43 Storage section 34, 44 I / F section 36 Control section 38 Display section 40 Calibration Device 50 Moving mechanism 52 holding portion, 52_1 first holding member, 52_2 second holding member 53_1, 53_11-53_14 First base material, 53_1a Normal region, 53_1b Reference region, 53_2, 53_21-53_24 Second base material, 53_2a Normal region, 53_2b Reference region 54 combinations 55 Calibration Data 58 Cart, 58_1 Housing, 58_2 Wheels 60_1, 60_2 Measured area R radiation, RF field S subject α direction

Claims

1. A calibration device used to obtain calibration data for a photon-counting detector that outputs an electrical signal corresponding to the photon energy of incident radiation, comprising: a holder that holds a first basis material and a second basis material having a larger attenuation coefficient for the radiation than the first basis material; a movement mechanism that moves the holding unit in a body axis direction of the subject to be irradiated with the radiation, thereby moving each of the first basis material and the second basis material between a position within the irradiation field and a position outside the irradiation field; A calibration device comprising:

2. The moving mechanism moves the holding unit linearly to move each of the first basis material and the second basis material between a position within the irradiation field and a position outside the irradiation field. The calibration device of claim 1 .

3. The holding unit includes a first holding member that holds the first basis material and a second holding member that holds the second basis material. The calibration device of claim 1 .

4. The holding portion includes a plurality of the first holding members and a plurality of the second holding members.

4. The calibration device of claim 3.

5. the first basis material has a plurality of measurement regions having different thicknesses in the direction in which the radiation passes; The moving mechanism moves the first basis material to a position within the irradiation field for each of the measurement regions.

4. The calibration device of claim 3.

6. the second basis material has a plurality of measurement regions having different thicknesses in the direction in which the radiation passes; The moving mechanism moves the second basis material to a position within the irradiation field for each of the measurement regions.

4. The calibration device of claim 3.

7. each of the first basis material and the second basis material has a plurality of divided portions; The moving mechanism moves the first basis material and the second basis material to positions within the irradiation field for each of the portions. The calibration device of claim 1 .

8. a control unit that controls the movement mechanism to move the first basis material and the second basis material to positions within the irradiation field according to a combination of the first basis material and the second basis material. The calibration device of claim 1 .

9. A radiation source; a photon-counting detector that outputs an electrical signal corresponding to the photon energy of the radiation emitted from the radiation source; A calibration device according to any one of claims 1 to 8; Equipped with Medical imaging system.

10. 1. A method for calibrating a photon-counting detector that outputs an electrical signal corresponding to the photon energy of incident radiation, comprising: a holder holds a first basis material and a second basis material having a larger attenuation coefficient for the radiation than the first basis material; a moving mechanism moving the holding unit in a body axis direction of the subject to be irradiated with the radiation, thereby moving each of the first basis material and the second basis material between a position within the irradiation field and a position outside the irradiation field; acquiring a plurality of calibration data obtained by varying the combination of the first basis material and the second basis material inserted into the irradiation field; Calibration methods.

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