Radiation detection device, ct apparatus, and method for controlling ct apparatus

Abstract

A radiation detection device according to the present disclosure is divided into a plurality of sections, and each of the plurality of sections is provided with: a detector module that detects radiation; an intake port; an exhaust port; a temperature-measuring instrument that measures the temperature of air which is discharged from the exhaust port; and an exhaust fan for which the rotation speed is controlled on the basis of the temperature.

Description

Radiation Detection Apparatus, CT Apparatus, and Control Method for CT Apparatus

[0001] The technology of the present disclosure relates to a radiation detection apparatus, a CT apparatus, and a control method for a CT apparatus.

[0002] In a CT (Computed Tomography) apparatus, temperature control of a radiation detection apparatus that detects radiation emitted from a radiation source and transmitted through a subject is important for maintaining the performance and reliability of the apparatus. As temperature control for a radiation detection apparatus, an air cooling method using a fan is generally used. For example, methods are known in which heat is discharged from the radiation detection apparatus using an exhaust fan operating at a constant rotational speed, and methods in which the temperature of the radiation detection apparatus is maintained constant while using a heater in combination.

[0003] In particular, in a PCCT (Photon Counting Computed Tomography) apparatus, which is a type of CT apparatus, photon counting is performed in each of a plurality of detector modules constituting the radiation detection apparatus. Therefore, compared with conventional CT apparatuses, the amount of heat generated is larger, and temperature variation among detector modules is greater. This is because in a PCCT apparatus, incident photons are converted into electric charges in a semiconductor layer, and heat is generated in the process where the electric charges are counted by a photon counting circuit, and the amount of generated heat varies according to the counting rate. Therefore, it is difficult to maintain the radiation detection apparatus at an appropriate temperature with the above temperature control.

[0004] Accordingly, a technique for performing temperature control on a detector module basis in a PCCT apparatus has been proposed (see, for example, Japanese Patent Application Laid-Open No. 2024-037489). The apparatus described in Japanese Patent Application Laid-Open No. 2024-037489 includes an acquisition unit that acquires information related to the amount of heat generated by a detector module, air blowing units installed at an air intake port and an air exhaust port of a housing, an opening / closing mechanism disposed between the air intake port or the air exhaust port of the housing and the detector module, and an opening / closing control unit that controls the opening / closing mechanism based on the heat generation information. As described above, Japanese Patent Application Laid-Open No. 2024-037489 proposes a method for maintaining the temperature of the radiation detection apparatus constant by controlling the opening / closing mechanism based on heat generation information for each detector module to adjust the air flow rate.

[0005] The technology described in Japanese Patent Publication No. 2024-037489 has the following problems. Firstly, it is difficult to control the temperature of the detector module in response to changes in ambient temperature using only information on the amount of heat generated by the detector module.

[0006] Secondly, radiation detection devices have multiple built-in detector modules, and from the perspective of saving space in the device, it may be difficult to place an opening / closing mechanism between the air intake or exhaust port and the detector module. Furthermore, adding an opening / closing mechanism also has the disadvantage of increasing the cost of the device.

[0007] Thirdly, because the rear of the radiation detector has a rotating disc, frame, and slip rings, if part of the intake and exhaust structure is placed on the rear side of the radiation detector, there is a problem that the intake and exhaust volume will decrease, and the cooling efficiency will decline.

[0008] In recent years, cooling methods utilizing water cooling technology have also been proposed, but due to their high cost and complex structure, they have not yet been widely put into practical use.

[0009] Therefore, the technology disclosed herein provides a radiation detection device, a CT scanner, and a control method for a CT scanner that can control temperature with high precision while suppressing structural complexity.

[0010] The radiation detection device of this disclosure is a radiation detection device divided into a plurality of compartments, each of which comprises a detector module for detecting radiation, an air intake port, an exhaust port, a temperature measuring device for measuring the temperature of the air exhausted from the exhaust port, and an exhaust fan whose rotational speed is controlled based on the temperature.

[0011] The CT apparatus of this disclosure comprises a radiation source that emits radiation, a radiation detection device divided into a plurality of compartments, and a control board, and is configured to be rotatable about a central axis with the radiation source and the radiation detection device facing each other, and each of the plurality of compartments comprises a detector module for detecting radiation, an air intake port, an exhaust port, a temperature measuring device for measuring the temperature of the air exhausted from the exhaust port, and an exhaust fan whose rotation speed is controlled by the control board based on the temperature.

[0012] The temperature measuring device may be placed between the detector module and the exhaust fan.

[0013] The intake and exhaust ports may be located at different distances from the central axis.

[0014] The air intake may be positioned further from the central axis than the exhaust port.

[0015] Intake and exhaust ports may be formed in the front cover that constitutes the front side of each of the multiple compartments.

[0016] Within each of the multiple compartments, a separation plate may be provided between the intake port and the exhaust port to separate the intake and exhaust air.

[0017] Multiple sections may be separated by multiple partition plates.

[0018] Each of the multiple compartments may be provided with an intake cover that surrounds the intake port and an exhaust cover that surrounds the exhaust port, thereby separating the intake and exhaust outside the compartment.

[0019] The intake cover may have an opening on the side in the direction of rotation from which the radiation source and radiation detection device rotate.

[0020] Multiple intake covers may have their length in the central axis direction decreasing in stages toward the direction of rotation.

[0021] The exhaust cover may have an opening formed on the opposite side of the direction of rotation from which the radiation source and radiation detector rotate.

[0022] Multiple exhaust covers may have their length in the central axis direction gradually decreasing in the direction opposite to the direction of rotation.

[0023] The air intake may have a grid-like opening shape.

[0024] Each of the multiple compartments has multiple through-holes and a shielding plate to block radiation at its bottom, and the shielding plate may be placed in the area to which radiation that has passed through the detector module is irradiated.

[0025] A sound-absorbing sheet may be attached to at least one of the intake cover and the exhaust cover.

[0026] The detector module may have a heatsink attached.

[0027] The heat sink may have multiple fins that form grooves in a direction along the path of the exhaust air.

[0028] The control board may control the rotation speed of the exhaust fan based on the rotation speed of the radiation source and the radiation detector, in addition to the temperature.

[0029] The detector module has a circuit element that includes a photon counting circuit for counting the number of photons, and the temperature measuring device may be incorporated into the circuit element.

[0030] The detector module has multiple circuit elements, a temperature measuring device is incorporated into each of the multiple circuit elements, and the control board may control the rotation speed based on the average or median value of the multiple temperature measurements.

[0031] The control board may perform a first control process that determines the rotational speed of the exhaust fan in steps based on a predetermined rotational speed for each temperature range.

[0032] The control board may determine a target rotation speed and control time corresponding to the temperature range to which the measured temperature belongs, based on a control table that associates rotation speed and control time for each temperature range, and then execute a second control process to change the rotation speed from the current rotation speed to the target rotation speed over the control time.

[0033] The control board may calculate a target rotational speed by adding to the reference rotational speed a value obtained by multiplying the difference between the measured temperature and the lower limit temperature by the adjustment amount, based on the reference rotational speed corresponding to the lower limit temperature of the temperature range to which the measured temperature belongs and the adjustment amount set for that temperature range, and then execute a third control process to change the rotational speed of the exhaust fan based on the calculated target rotational speed.

[0034] The control method for a CT apparatus according to this disclosure comprises a radiation source that emits radiation, a radiation detection device divided into a plurality of compartments, and a control board, wherein the radiation source and the radiation detection device are configured to rotate around a central axis while facing each other, and each of the plurality of compartments is provided with a detector module for detecting radiation, an air intake port, an exhaust port, a temperature measuring device for measuring the temperature of the air exhausted from the exhaust port, and an exhaust fan, and the control board controls the rotation speed of the exhaust fan based on the temperature.

[0035] The technology disclosed herein provides a radiation detection device, a CT scanner, and a control method for a CT scanner that can control temperature with high precision while suppressing structural complexity.

[0036] This is a schematic diagram showing the configuration of a CT apparatus according to an embodiment. This is a schematic diagram showing the configuration of the gantry. This is a diagram showing the internal configuration of the X-ray detection device. This is a diagram showing the internal configuration of the X-ray detection device. This is a diagram showing the configuration of the detector module. This is a diagram showing the external appearance of the X-ray detection device. This is a diagram showing the configuration of the internal compartments of the X-ray detection device. This is a diagram showing the detailed configuration of the internal compartments of the X-ray detection device. This is a diagram showing the configuration of the air intake port. This is a diagram showing the bottom structure of the X-ray detection device. This is a flowchart showing the flow of temperature control by the control board. This is a diagram showing a modified exhaust cover. This is a diagram showing a modified intake cover. This is a diagram showing a modified intake cover with a changed length in the Z direction. This is a diagram showing a modified exhaust cover with a changed opening position. This is a diagram showing a modified exhaust cover with a changed length in the Z direction. This is a flowchart showing a modified temperature control. This is a flowchart showing the flow of the first control process. This is a diagram showing an example of a control table used in the first control process. This is a characteristic diagram showing the relationship between exhaust temperature and rotation speed in the first control process. This is a flowchart showing the flow of the second control process. This is a diagram showing an example of a control table used in the second control process. This is a characteristic diagram showing the relationship between exhaust temperature and rotation speed in the second control process. This is a flowchart showing the flow of the third control process. This is a diagram showing an example of a control table used in the third control process. This is a characteristic diagram showing the relationship between exhaust temperature and rotational speed in the third control process.

[0037] Embodiments relating to the technology of this disclosure will be described below with reference to the drawings. The CT apparatus of this disclosure is applicable to a PCCT type CT apparatus that detects radiation emitted from a radiation source and generates a radiation image based on an electrical signal corresponding to the number of photons of the radiation. In this embodiment, the case where the radiation is X-rays will be described as an example.

[0038] [Embodiment] Figure 1 schematically shows the configuration of a CT apparatus 2 according to an embodiment. The CT apparatus 2 includes an X-ray source 3, an X-ray detection device 4, a gantry 5, a patient bed 6, a control unit 7, and an image processing unit 8. A circular opening 5A is provided in the center of the gantry 5 for arranging the patient bed 6 on which the subject H is placed. The gantry 5 is also provided with a rotating plate 50 fixed in a position opposite the X-ray source 3 and the X-ray detection device 4, and a drive mechanism (not shown) for rotating the rotating plate 50 about a central axis A. The X-ray detection device 4 is also provided with a plurality of exhaust fans 60. The X-ray source 3 is an example of a "radiation source" according to the technology of this disclosure. The X-ray detection device 4 is an example of a "radiation detection device" according to the technology of this disclosure.

[0039] In the following, the mechanism that includes the X-ray source 3, the X-ray detection device 4, and the rotating plate 50, and performs imaging while rotating, may be referred to as a "scanner."

[0040] Hereinafter, in this disclosure, the circumferential direction of the opening 5A is defined as the X direction, the radial direction as the Y direction, and the direction parallel to the central axis A as the Z direction (see Figures 2 and 3). The Z direction is perpendicular to the X and Y directions and is generally the axis direction of the subject H. The direction in which the rotating plate 50 rotates around the central axis A is referred to as the "rotation direction C".

[0041] The X-ray source 3 includes an X-ray tube 31. An X-ray filter 32 and a bowtie filter 33 are provided on the output side of the X-ray source 3. The X-ray tube 31 generates X-rays and irradiates the subject H with the generated X-rays. The X-ray filter 32 adjusts the dose of X-rays irradiated from the X-ray tube 31. The bowtie filter 33 optimizes the exposure dose 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.

[0042] The control unit 7 is constituted by a processor such as a CPU (Central Processing Unit). The control unit 7 controls the operations of the X-ray source 3, the X-ray detection device 4, the gantry 5, and the bed 6. Specifically, the control unit 7 controls the irradiation of X-rays from the X-ray tube 31 of the X-ray source 3, X-ray detection by the X-ray detection device 4, rotation of the rotating plate 50 of the gantry 5, and movement of the bed 6. In addition, the control unit 7 acquires data output from the X-ray detection device 4.

[0043] The image processing unit 8 is an image processing processor that generates a tomographic image by performing reconstruction processing based on data acquired by the control unit 7 from the X-ray detection device 4. The image processing unit 8 may be configured as a part of the control unit 7.

[0044] In addition, an input device 9, a display device 10, a storage device 11, and a communication device 12 are connected to the control unit 7. The input device 9 is a device for an operator to input operation instructions, and is constituted by a keyboard, a mouse, and the like. The display device 10 is a display such as a liquid crystal display, and displays operation screens, tomographic images, and the like. The storage device 11 is a memory, a storage device, or the like, and stores tomographic images, programs, various types of information, and the like.

[0045] The communication device 12 is a communication interface for communicating with Radiology Information Systems (RIS), Picture Archiving and Communication Systems (PACS), and the like. The communication device 12 performs transmission control in accordance with a communication protocol based on a wired or wireless communication standard.

[0046] Figure 2 schematically shows the configuration of the gantry 5. The gantry 5 includes a rotating plate 50, a bearing 51, a frame 52, a slip ring 53, and a fixing portion 54. The bearing 51, the frame 52, the slip ring 53, and the fixing portion 54 are arranged in this order on the opposite side of the rotating plate 50 from the X-ray detection device 4.

[0047] The bearing 51 is provided between the rotating plate 50 and the frame 52, and smoothly rotates the rotating plate 50. The slip ring 53 is a member for transmitting electric power and signals between the rotating rotating plate 50 and the fixed portion 54, and its structure consists of concentrically arranged conductive rings and brushes. It is used for supplying electric power to the X-ray detector 4 and the X-ray tube 31, and transmitting data output from the X-ray detector 4 to the control unit 7.

[0048] The fixed portion 54 is a fixed structure that supports the frame 52 and the slip ring 53, and has a contact portion with which the conductive brush of the slip ring 53 comes into contact, whereby electric power and data are transmitted.

[0049] FIGS. 3 and 4 show the internal configuration of the X-ray detector 4. The X-ray detector 4 includes a plurality of detector modules 40, a plurality of control boards 80, and a case 40A. The case 40A has an arc shape centered on the focal point of the X-ray tube 31, and holds the plurality of detector modules 40. The plurality of detector modules 40 are arranged in a channel direction that is a direction along the arc shape. For example, the number of detector modules 40 is about 30 to 50. The plurality of control boards 80 are arranged on the back side of the plurality of detector modules 40, and are connected to the plurality of detector modules 40 via cables not shown. Each control board 80 has a control circuit.

[0050] Each of the detector modules 40 includes a collimator 41, a semiconductor layer 42, and an ASIC (Application Specific Integrated Circuit) 43 (see FIG. 1).

[0051] The collimator 41 is arranged on the X-ray incident side of the semiconductor layer 42 and fixed to the frame 45 of the detector module 40. Note that the collimator 41 may be fixed to the case 40A of the X-ray detector 4 in some cases. The collimator 41 removes scattered radiation by restricting the incident direction of X-rays to the semiconductor layer 42. The semiconductor layer 42 is formed of cadmium zinc telluride (CZT), cadmium telluride (CdTe), or the like, and converts X-rays that have passed through the subject H and entered the semiconductor layer 42 into electric charges corresponding to photons and outputs the electric charges.

[0052] The ASIC 43 is located on the opposite side of the semiconductor layer 42 from the collimator 41. The ASIC 43 is an example of a circuit element that includes a photon counting circuit 44. The photon counting circuit 44 counts the number of charges output by the semiconductor layer 42 as the number of photons and outputs a counting signal. For example, the photon counting circuit 44 is composed of an amplifier circuit, a waveform shaping circuit, a comparator circuit, a counter circuit, etc. The photon counting circuit 44 may also include an A / D (Analog to Digital) converter.

[0053] Furthermore, electrodes for applying a high voltage to the semiconductor layer 42 are formed on the upper and lower surfaces of the semiconductor layer 42. By patterning the electrodes on the lower surface of the semiconductor layer 42, multiple pixels are formed in the semiconductor layer 42. The photon counting circuit 44 counts photons for each pixel and outputs a counting signal. This counting signal is output from the X-ray detection device 4 as the data described above via the circuit board 46, which will be described later.

[0054] Figure 5 shows the configuration of the detector module 40. The detector module 40 includes a plurality of semiconductor layers 42, a plurality of ASICs 43, a substrate 49, a frame 45, a circuit board 46, and a heat sink 47. The frame 45 extends in a column direction (corresponding to the Z direction) perpendicular to the channel direction. The frame 45 is made of a metal such as aluminum (Al) or copper (Cu). Both ends of the frame 45 in the column direction are fixed to the case 40A described above. The substrate 49 is made of ceramic, for example, and is provided on the frame 45.

[0055] Multiple ASICs 43 are arranged in a row on the upper surface of the substrate 49. In this embodiment, two ASICs 43 are arranged on the substrate 49. However, the number of ASICs 43 is not limited to this example. Alternatively, multiple ASICs 43 may be arranged in multiple rows on the frame 45. The semiconductor layer 42 is placed on each ASIC 43.

[0056] The circuit board 46 is connected to the board 49 via a cable (for example, a flexible cable) not shown. The counting signals output from each ASIC 43 are transmitted to the control unit 7 as the data described above via the board 49, the circuit board 46, and the control board 80.

[0057] The heat sink 47 is a component for efficiently dissipating heat generated in the ASIC 43 and is connected to the lower surface of the frame 45. The heat sink 47 is made of a metal such as aluminum (Al). In this embodiment, the heat sink 47 is a plate fin type heat sink composed of flat fins 47A arranged in parallel. In this embodiment, it is rectangular in shape and elongated in the Z direction.

[0058] Multiple fins 47A are arranged in the X direction at a constant (i.e., equal) or unequal pitch. Two adjacent fins 47A form a groove extending in the Z direction. In this embodiment, three fins 47A are arranged, but the number is not limited to this example.

[0059] Figure 6 shows the external appearance of the X-ray detection device 4. The multiple detector modules 40 described above are housed inside the housing 48. The housing 48 includes a front cover 48A, a rear block 48B, and a bottom cover 48C. The front cover 48A and the rear block 48B are opposite each other in the Z direction. One end of the bottom cover 48C in the Z direction is connected to the front cover 48A, and the other end is connected to the rear block 48B.

[0060] Furthermore, the interior of the housing 48 is divided into multiple compartments by partition plates 48D in the channel direction. One end of each partition plate 48D in the Z direction is connected to the front cover 48A, and the other end is connected to the rear block 48B. In this embodiment, the interior of the housing 48 includes three compartments S1 to S3. Hereinafter, when compartments S1 to S3 are not distinguished, they will simply be referred to as compartment S. The number of compartments S is not limited to three. The front cover 48A constitutes the front side of compartment S, and the rear block 48B constitutes the rear side of compartment S.

[0061] As shown in Figure 7, one compartment S contains multiple detector modules 40. The number of detector modules 40 included in a compartment S is not limited; it is sufficient that it contains at least one detector module 40. As will be explained in more detail later, a compartment S is a unit that performs intake and exhaust for heat dissipation. Multiple partition plates 48D separate the intake and exhaust for each compartment S.

[0062] Figure 8 shows the internal configuration of compartment S. Compartment S has at least one intake port 70 and at least one exhaust port 71. In this embodiment, compartment S has one intake port 70 and two exhaust ports 71. The intake port 70 and exhaust ports 71 are each formed in the front cover 48A. The intake port 70 and exhaust ports 71 are positioned at different distances from the central axis A of the rotating plate 50. Specifically, the intake port 70 is positioned further from the central axis A than the exhaust port 71. The distances from the central axis A of the two exhaust ports 71 are equal.

[0063] Furthermore, the front cover 48A is provided with an intake cover 61 that surrounds the intake port 70. The intake cover 61 has an opening 61A for drawing in air. The intake cover 61 is, for example, a rectangular parallelepiped with one side open. The opening 61A is formed on the opposite side from the exhaust port 71 (i.e., the side farther from the central axis A) so as not to draw in air exhausted from the exhaust port 71. The intake port 70 and the intake cover 61 extend in the X direction so as to span the two exhaust ports 71. Note that one intake port 70 may be provided for each exhaust port 71. That is, one intake cover 61 may be provided for each exhaust cover 62. The intake cover 61 and the exhaust cover 62 function as separation plates that separate intake and exhaust outside the compartment S.

[0064] An exhaust fan 60 is attached to the exhaust port 71. The exhaust fan 60 is mounted on the outside of the front cover 48A and discharges air through the exhaust port 71. The front cover 48A is also provided with an exhaust cover 62 that surrounds the exhaust port 71. The exhaust cover 62 also covers the exhaust fan 60. The shape of the exhaust cover 62 is not limited and may be cylindrical with respect to the rotation axis of the exhaust fan 60. An opening 62A for exhausting air is formed in the exhaust cover 62. The opening 62A only needs to allow air to pass through and may be covered with a mesh-like material or the like.

[0065] Furthermore, a separation plate 72 is provided between the intake port 70 and the exhaust port 71 to separate the intake and exhaust air within the compartment S. In this embodiment, one end of the separation plate 72 is connected to the front cover 48A, and the other end extends toward the rear block 48B. The front cover 48A and the rear block 48B are separated and form a communication section R. The separation plate 72 separates the interior of the compartment S into a space K1 through which air flows in from the intake port 70 and a space K2 through which air flows out toward the exhaust port 71. Spaces K1 and K2 are connected by the communication section R.

[0066] The grooves extending in the Z direction, formed by two adjacent fins 47A of the heat sink 47, are formed to follow the flow path of intake or exhaust air.

[0067] Furthermore, the bottom cover 48C has a plurality of through holes 73 that communicate with the outside. The through holes 73 are additional air intakes that draw in additional air from outside the compartment S into the internal space K1. The through holes 73 are formed in the area of ​​the bottom cover 48C that is not irradiated by X-rays emitted from the X-ray source 3 and transmitted through the detector module 40. In the area of ​​the bottom cover 48C that is irradiated by X-rays, a shielding plate 74 containing lead is provided to shield the X-rays.

[0068] Inside compartment S, at least one temperature measuring device 75 is provided. The temperature measuring device 75 is, for example, a thermistor and is positioned between the exhaust fan 60 and the detector module 40, corresponding to each exhaust port 71. For example, the temperature measuring device 75 is positioned on a separator plate 72. The temperature measuring device 75 is connected to a control board 80 via signal lines (not shown). The temperature measuring device 75 measures the temperature of the air exhausted from the exhaust ports 71 by the exhaust fan 60 (hereinafter referred to as exhaust temperature) and transmits the measured value to the control board 80.

[0069] The exhaust fan 60 is connected to the control board 80 via signal lines (not shown). The control board 80 adjusts the rotational speed of the exhaust fan 60 based on the measured exhaust temperature. In this disclosure, rotational speed means the number of rotations per unit time.

[0070] Figure 9 shows the configuration of the air intake port 70. The air intake port 70 has a grid-like opening shape. This is for the purpose of countermeasures against electromagnetic interference (EMC). Specifically, it prevents unwanted electromagnetic waves from entering from the outside and suppresses the leakage of electromagnetic waves generated from the detector module 40 inside compartment S, thereby providing a shielding effect that reduces the impact on surrounding equipment.

[0071] Figure 10 shows the bottom of compartment S. Multiple through holes 73 are arranged on both sides in the Z direction of the area where the shielding plate 74 is provided in the bottom cover 48C. This makes it possible to ensure an appropriate ventilation path while maintaining the radiation shielding effect.

[0072] Next, the temperature control of the X-ray detection device 4 by the control board 80 will be described. The main factors causing the temperature rise of the X-ray detection device 4 include the heat generated by the ASIC 43 due to photon counting, the rise in the internal temperature of the scanner due to X-ray exposure, and changes in the heat distribution of the scanner.

[0073] Specifically, in the CT scanner 2, the computational load on the photon counting circuit 44 increases as each X-ray photon is counted individually, leading to increased heat generation. In particular, the power consumption of the ASIC 43 fluctuates depending on the X-ray attenuation of the subject H, resulting in different exhaust temperature distributions depending on the position in the X-direction. In addition to this temperature rise due to heat generation, the X-ray irradiation also increases the heat generated by the X-ray tube 31 itself, which in turn raises the temperature inside the scanner. This causes the intake air temperature to rise, and consequently, the temperature of the detector module 40 to rise. Furthermore, the heat distribution changes depending on the state of the scanner. When the scanner is stationary, the heat from the X-ray tube 31 mainly escapes from the top of the scanner to the outside, but when the scanner rotates, the heat diffuses throughout the entire interior of the scanner, affecting the intake air temperature. These temperature changes cause the temperatures of the multiple detector modules 40 to become non-uniform, making it necessary to perform efficient and highly accurate temperature control.

[0074] Figure 11 shows the flow of temperature control by the control board 80. For example, the control board 80 acquires measured values ​​of the exhaust temperature from each temperature measuring device 75 when preparing for scanning (step S10). Next, the control board 80 adjusts the rotation speed of each exhaust fan 60 based on the acquired measured values ​​(step S11). Specifically, the control board 80 increases the rotation speed of the exhaust fan 60 as the exhaust temperature increases. This is because a higher rotation speed of the exhaust fan 60 results in a larger exhaust volume and a higher cooling effect.

[0075] For example, the control board 80 constantly monitors the exhaust temperature and controls the rotation speed of the exhaust fan 60. In this case, the control board 80 repeatedly executes steps S10 and S11. Alternatively, the control board 80 may monitor the exhaust temperature before starting the scan and then control the rotation speed of the exhaust fan 60 to control the temperature. In this case, the control board 80 executes step S10 and then repeatedly executes step S11.

[0076] The symbol F in Figure 8 schematically represents the flow of intake and exhaust air. As the exhaust fan 60 rotates, air drawn in from the intake port 70 flows from space K1 into space K2 via the connecting part R. In space K2, the air flows toward the exhaust port 71. A portion of this airflow is cooled as heat is removed as it passes through the heat sink 47. After this, the air is exhausted to the outside through the exhaust port 71.

[0077] The technology disclosed herein allows for high-precision temperature control while minimizing structural complexity by using only an exhaust fan for cooling, without the need for an intake fan as in conventional designs, and by controlling the rotation speed of the exhaust fan based on the exhaust temperature.

[0078] Conventional technologies used a combination of intake fans, exhaust fans, and switching mechanisms for cooling. However, using an intake fan resulted in a tendency for cooling air to concentrate on a portion of the detector module, leading to temperature variations. The technology disclosed herein uses only an exhaust fan and draws in air naturally through negative pressure, creating a uniform airflow across the entire area where the detector module is located, thus preventing localized cooling deficiencies.

[0079] Furthermore, since the technology disclosed herein does not require an intake fan or an opening / closing mechanism, the structure of the device is simplified and the number of parts is reduced, thereby reducing costs and improving maintainability.

[0080] Furthermore, the technology disclosed herein adjusts the rotation speed of the exhaust fan based on the exhaust temperature, allowing for real-time monitoring of the actual thermal state of the detector module and appropriate temperature control. This enables immediate response to temperature fluctuations caused by multiple factors, such as heat generation fluctuations of the ASIC due to photon counting and temperature increases inside the scanner, and makes it possible to maintain a stable temperature for the detector module.

[0081] Furthermore, since exhaust temperature serves as an indicator that comprehensively reflects the cooling conditions within a compartment, it can prevent localized overcooling or overheating and suppress temperature variations.

[0082] The technology disclosed herein uses a plate-fin type heat sink to improve the cooling efficiency of the detector module.

[0083] Generally, heat sinks come in various shapes, such as plate-fin and pin-type, and their cooling performance differs depending on the shape. Plate-fin heat sinks have a structure in which multiple parallel fins are arranged at regular intervals, and the airflow is easily straightened along the fins. This ensures a sufficient volume of air passing through the heat sink, enabling efficient heat dissipation. On the other hand, pin-type heat sinks have a structure in which multiple columnar pins are arranged, but the airflow tends to be turbulent, resulting in a reduced cooling effect.

[0084] The technology disclosed herein uses a plate-fin type heat sink, which efficiently utilizes the airflow generated by the exhaust fan to enable uniform cooling across the entire heat sink. This improves the uniformity of heat distribution in each part of the heat sink and suppresses localized temperature rises. Furthermore, to improve cooling efficiency, it is preferable to determine the fin arrangement pitch based on the balance between the airflow passing through the heat sink and the surface area.

[0085] Various modifications of the above embodiment are described below.

[0086] [First Modified Example] Figure 12 shows the exhaust cover 62 according to the first modified example. In this modified example, in order to reduce the noise generated from the exhaust fan 60, the opening 62A of the exhaust cover 62 is covered with a sound-absorbing cover 76.

[0087] When the exhaust fan 60 is in operation, noise is generated due to turbulence caused by the airflow and vibrations of the exhaust fan 60. In particular, the noise level increases when it rotates at high speed. By covering the opening 62A of the exhaust cover 62 with a sound-absorbing cover 76, noise radiated from the opening 62A can be effectively absorbed, and the propagation of sound to the outside can be suppressed. It is preferable to use porous materials, fibrous materials, etc., as the material for the sound-absorbing cover 76. In addition, to suppress noise radiated from the intake port 70, the opening 61A of the intake cover 61 may also be covered with a sound-absorbing cover.

[0088] [Second Modification] Figure 13 shows an X-ray detection device 4 according to the second modification. In this modification, an opening 61B is provided on the side of the intake cover 61 that is in the direction of rotation C of the scanner, in order to efficiently take in air from the intake port 70 into the interior of the X-ray detection device 4.

[0089] As the scanner rotates, external air flows along the direction of rotation. By providing an opening 61B on the rotation direction C side of the intake cover 61, natural intake using the rotational airflow can be promoted. This enables efficient intake by combining the negative pressure from the exhaust fan 60 with the rotational airflow of the scanner, without the need for an intake fan. The shape and size of the opening 61B are preferably determined to optimize the flow of the intake air.

[0090] [Third Modification] Figure 14 shows an X-ray detection device 4 according to the third modification. In this modification, in addition to the configuration of the second modification, the length of the multiple intake covers 61 in the Z direction is changed. Specifically, the length of the intake covers 61 in the Z direction is gradually shortened as you move toward the rotation direction C side of the scanner. Specifically, in this modification, if the length of the intake cover 61 in the Z direction of compartment S1 is LA1, the length of the intake cover 61 in the Z direction of compartment S2 is LA2, and the length of the intake cover 61 in the Z direction of compartment S3 is LA3, then the relationship LA1 < LA2 < LA3 is satisfied.

[0091] To efficiently draw in air using the airflow generated by the rotation of the scanner, it is important to regulate the airflow toward the intake port 70 and reduce elements that obstruct the airflow. In particular, the intake cover 61 located on the rotation direction C side may obstruct the airflow. In this modified example, the length of the multiple intake covers in the Z direction is gradually shortened as it moves toward the rotation direction C side, thereby regulating the airflow and enabling smooth intake.

[0092] [Fourth Modification] Figure 15 shows an X-ray detection device 4 according to the fourth modification. In this modification, an opening 62B is provided on the opposite side of the scanner's rotation direction C in the exhaust cover 62 in order to promote exhaust and improve cooling efficiency.

[0093] As the scanner rotates, the air inside the exhaust cover 62 also flows along the direction of rotation C. Therefore, by providing an opening 62B on the opposite side of the exhaust cover 62 from the direction of rotation C, the exhaust efficiency is improved. It is preferable that the shape and size of the opening 62B be determined to optimize the flow of the exhausted air.

[0094] Furthermore, this modified example may be applied to the X-ray detection device 4 according to the second or third modified example.

[0095] [Fifth Modification] Figure 16 shows the X-ray detection device 4 according to the fifth modification. In this modification, in addition to the configuration of the fourth modification, the length of the multiple exhaust covers 62 in the Z direction is changed. Specifically, the length of the exhaust cover 62 in the Z direction is gradually shortened as you move away from the direction of rotation C of the scanner. Specifically, in this modification, if the length of the exhaust cover 62 in the Z direction of compartment S1 is LB1, the length of the exhaust cover 62 in the Z direction of compartment S2 is LB2, and the length of the exhaust cover 62 in the Z direction of compartment S3 is LB3, then the relationship LB1 > LB2 > LB3 is satisfied.

[0096] In order to efficiently utilize the airflow generated as the scanner rotates for exhaust, it is important to regulate the airflow from the exhaust port and reduce elements that obstruct the airflow. In this modified example, the length of the multiple exhaust covers 62 in the Z direction is gradually shortened toward the opposite side of the rotation direction C, thereby regulating the airflow and enabling smooth exhaust.

[0097] In this modified example, the lengths of the two exhaust covers 62 in the Z-direction of one compartment S are equal, but the length of the exhaust cover 62 on the opposite side of the rotation direction C may be made shorter in the Z-direction. Furthermore, this modified example may be applied to the X-ray detection device 4 according to the second or third modified example.

[0098] [Sixth Modification] Figure 17 shows the temperature control flow according to the sixth modification. In this modification, the control board 80 acquires the scanner's rotation speed in step S20 after step S10. In this modification, the control board 80 adjusts the rotation speed of each exhaust fan 60 in step S11 after step S20, based on the acquired measured value and rotation speed. Specifically, the control board 80 increases the rotation speed of the exhaust fan 60 as the exhaust temperature increases, and decreases the rotation speed of the exhaust fan 60 as the scanner's rotation speed increases.

[0099] When the scanner is rotating at high speed, the airflow due to the rotation becomes stronger, so noise can be reduced by lowering the rotation speed of the exhaust fan 60. On the other hand, when the scanner is rotating slowly or stopped, there is insufficient exhaust, so proper heat dissipation can be maintained by increasing the rotation speed of the exhaust fan 60.

[0100] [Control of Exhaust Fan Rotation Speed] Next, a specific example of the rotation speed control of the exhaust fan 60 described in the above embodiment will be explained. In each of the following examples, the rotation speed of the exhaust fan 60 is expressed as a percentage, which is the ratio to the maximum rotation speed. The unit of measurement for exhaust temperature is 0.1°C. The control board 80 controls the rotation speed of the exhaust fan 60 by changing the duty cycle of the pulse signal input to the exhaust fan 60. In this disclosure, "continuous" includes a mode in which the rotation speed is updated at predetermined minimum control units.

[0101] [First Control Process] Figure 18 is a flowchart showing the flow of the first control process. In this process, the control board 80 performs control to determine the rotation speed of the exhaust fan 60 in steps based on the exhaust temperature. First, in step S30, the control board 80 obtains the measured value of the exhaust temperature from the temperature measuring device 75.

[0102] Next, in step S31, the control board 80 refers to a control table pre-stored in the storage device 11. The control table is a table that associates the temperature range of the exhaust temperature with the rotational speed of the exhaust fan 60, and a command value for the rotational speed corresponding to each exhaust temperature category is set. As shown in Figure 19, in the control table, the temperature range of the exhaust temperature T is divided into multiple categories. For example, the range of 24.0°C to 26.9°C is designated as category A, and a rotational speed of 20% is associated with category A. Similarly, the range of 27.0°C to 31.9°C is designated as Category B and associated with a rotation speed of 30%, the range of 32.0°C to 33.9°C is designated as Category C and associated with a rotation speed of 40%, the range of 34.0°C to 35.9°C is designated as Category D and associated with a rotation speed of 50%, the range of 36.0°C to 37.9°C is designated as Category E and associated with a rotation speed of 75%, and the range of 38.0°C to 39.0°C is designated as Category F and associated with a rotation speed of 100%.

[0103] Next, in step S32, the control board 80 determines the temperature category to which the acquired exhaust temperature belongs, and determines the rotational speed command value corresponding to that temperature category as the rotational speed of the exhaust fan 60. For example, if the exhaust temperature is 28.0°C, the exhaust temperature belongs to category B, so a rotational speed of 30% is determined. If the exhaust temperature is 36.5°C, the exhaust temperature belongs to category E, so a rotational speed of 75% is determined.

[0104] Next, in step S33, the control board 80 adjusts the rotational speed of the exhaust fan 60 based on the determined rotational speed command value. Specifically, the control board 80 controls the rotational speed of the exhaust fan 60 to the set value by outputting a drive signal corresponding to the rotational speed command value to the exhaust fan drive circuit.

[0105] The control board 80 repeatedly executes the processes from step S30 to step S33 at a predetermined control cycle. This allows the rotation speed of the exhaust fan 60 to be updated sequentially in response to changes in exhaust temperature, enabling continuous rotation speed control that follows the exhaust temperature.

[0106] Figure 20 is a characteristic diagram showing the relationship between exhaust temperature and rotational speed based on the control table shown in Figure 19. As shown in Figure 20, this process has a stepped characteristic in which the rotational speed of the exhaust fan 60 increases in stages in response to the rise in exhaust temperature. That is, the rotational speed of the exhaust fan 60 is kept constant within each temperature range, and when the exhaust temperature moves to the next temperature range, the rotational speed of the exhaust fan 60 switches to the value of the next stage.

[0107] Thus, according to the first control process, by referring to a control table using the exhaust temperature as an indicator, the rotation speed of the exhaust fan 60 can be appropriately controlled with a simple configuration in response to complex temperature fluctuations, including fluctuations in the amount of heat generated by each detector module 40, fluctuations in ambient temperature, and changes in the operating state of the scanner.

[0108] [Second Control Process] Next, the second control process will be explained based on Figures 21 to 23. The second control process is similar to the first control process in that it determines the rotational speed of the exhaust fan 60 according to the exhaust temperature, but it is characterized in that it changes the rotational speed over a predetermined control period of time when the temperature category is changed.

[0109] Figure 21 is a flowchart showing the flow of the second control process. In step S30, the control board 80 acquires the measured value of the exhaust temperature, and in step S31, it refers to the control table, which is the same as in the first control process. In step S32, the control board 80 determines the rotation speed corresponding to the temperature category to which the exhaust temperature belongs, as well as the control time associated with that temperature category. In other words, in this process, the rotation speed and control time are determined in combination.

[0110] Here, control time refers to the time set to change the rotational speed of the exhaust fan 60 from the current rotational speed to the target rotational speed when the current rotational speed is different from the temperature category corresponding to the target rotational speed, and is the period during which the rotational speed command value is gradually changed so that the target rotational speed is reached within that time.

[0111] Figure 22 shows an example of a control table used in the second control process. As shown in Figure 22, each temperature category is associated with a control time in addition to the rotation speed. For example, the control time is set to 10 seconds for categories A to D, and to 25 seconds for categories E and F. In this way, the control time is set to be longer when the amount of change in the rotation speed of the exhaust fan 60 is large.

[0112] In step S33, the control board 80 adjusts the rotational speed of the exhaust fan 60 using the control time determined in step S32. Specifically, if the current rotational speed is different from the temperature category corresponding to the target rotational speed, the control board 80 changes the rotational speed command value in steps or continuously so that the current rotational speed reaches the target rotational speed within the control time.

[0113] Figure 23 is a characteristic diagram showing the relationship between exhaust temperature and the rotational speed of the exhaust fan 60 based on the control table shown in Figure 22. As shown in Figure 23, when the exhaust temperature exceeds the boundary of each temperature zone, the rotational speed does not immediately switch to the value of the next stage, but rather gradually increases over a set control time. Therefore, the time change of the rotational speed results in a waveform with a slope.

[0114] Thus, according to the second control process, even when the temperature zone is switched, it is possible to suppress instantaneous changes in the rotational speed of the exhaust fan 60 and smooth out the time change in rotational speed.

[0115] The control board 80 may also store the elapsed time from the start of the previous transition in case the temperature zone changes again during the transition to the target rotation speed. If the temperature zone changes before the target rotation speed is reached, the control board 80 determines the control time to be used for the transition to the new target rotation speed based on the stored elapsed time. The control board 80 then gradually adjusts the rotation speed of the exhaust fan 60 toward the new target rotation speed.

[0116] [Third Control Process] Next, the third control process will be explained based on Figures 24 to 26. The third control process is similar to the first control process in that it determines the rotational speed of the exhaust fan 60 according to the exhaust temperature, but it is characterized by continuously changing the rotational speed within the temperature range.

[0117] Figure 24 is a flowchart showing the flow of the third control process. In step S30, the measured value of the exhaust temperature is acquired, and in step S31, the control table is referenced, which is the same as in the first control process. In step S32, the control board 80 determines the rotation speed range corresponding to the temperature category to which the exhaust temperature belongs and the adjustment amount set for that temperature category. Here, the adjustment amount is a coefficient that indicates the rate at which the rotation speed is increased or decreased per unit change in exhaust temperature.

[0118] Figure 25 shows an example of a control table used in the third control process. As shown in Figure 25, each temperature category is associated with a rotation speed range and an adjustment amount in addition to the temperature range. For example, in category B, when the exhaust temperature is in the range of 26.0°C to 27.9°C, the rotation speed range is set to 20% to 30%, and the adjustment amount is set to 5% per degree Celsius. In category D, when the exhaust temperature is in the range of 31.0°C to 34.9°C, the rotation speed range is set to 30% to 50%, and the adjustment amount is set to 5% per degree Celsius. Furthermore, in category E, when the exhaust temperature is in the range of 35.0°C to 38.9°C, the rotation speed range is set to 50% to 100%, and the adjustment amount is set to 12.5% ​​per degree Celsius.

[0119] In addition, in categories A and C, the adjustment amount is set to zero, so even if the exhaust temperature changes within that temperature category, the rotation speed is not adjusted and is maintained at a constant value.

[0120] The control board 80 calculates the target rotational speed by multiplying the difference between the acquired exhaust temperature measurement value and the lower limit temperature of the temperature category by an adjustment amount, and adding the result to the reference rotational speed corresponding to the lower limit of the temperature category. For example, if the measured exhaust temperature is 27.3°C and belongs to category B, the control board 80 determines 26.5% as the target rotational speed by adding the difference between 27.3°C and 26.0°C (1.3°C) multiplied by an adjustment amount of 5% / °C to the reference rotational speed of 20% corresponding to the lower limit temperature of category B, which is 26.0°C.

[0121] Then, in step S33, the control board 80 adjusts the rotation speed of the exhaust fan 60 to achieve the calculated target rotation speed.

[0122] Figure 26 is a characteristic diagram showing the relationship between exhaust temperature and the rotational speed of the exhaust fan 60 based on the control table shown in Figure 25. As shown in Figure 26, the third control process has the characteristic that the rotational speed changes linearly within the temperature zone. That is, unlike the first control process, which changes stepwise at the boundaries of temperature zones, the rotational speed increases continuously within each temperature zone in accordance with the rise in exhaust temperature.

[0123] Thus, the third control process allows the rotation speed to precisely track even minute changes in exhaust temperature, making it possible to control the temperature of each detector module 40 more smoothly.

[0124] Furthermore, the rotational speed of the exhaust fan 60 may be configured to change in a curve-like manner according to the exhaust temperature. That is, the relationship between exhaust temperature and rotational speed may be set not only on a linear function, but also on a quadratic function, exponential function, or other nonlinear function, thereby setting the response characteristics of the rotational speed to changes in exhaust temperature to be nonlinear.

[0125] In the above embodiment, the technology of this disclosure is explained using a PCCT type CT device as an example, but it is not limited to this and can also be applied to conventional energy-integrating type CT devices.

[0126] Even in energy-integrating CT scanners, heat is generated from the X-ray tube during X-ray irradiation. Therefore, temperature control of the X-ray detector is a crucial issue, just as in PCCT scanners. This disclosure demonstrates that high-precision temperature control can be achieved even in energy-integrating CT scanners by combining cooling technologies such as exhaust fan rotation speed control based on exhaust temperature, dynamic exhaust adjustment considering scanner rotation speed, optimization of heat sink fin structure, and optimization of intake and exhaust cover configurations.

[0127] Furthermore, in the above embodiment, the temperature measuring device 75 is provided on the separation plate 72, but it may also be incorporated into each ASIC 43. In this case, the control board 80 adjusts the rotation speed of the exhaust fan 60 based on the temperature measured by the temperature measuring device 75 incorporated into each ASIC 43 included in the compartment S. For example, the control board 80 adjusts the rotation speed of the exhaust fan 60 based on the average value, median value, etc., of multiple temperature measured by multiple temperature measuring devices 75 in the compartment S.

[0128] Furthermore, although X-rays were used as an example of radiation in the above embodiments, gamma rays may also be used as radiation.

[0129] Furthermore, in the above embodiment, various processors shown below can be used as the control configuration for the control board 80. These various processors include a CPU, which is a general-purpose processor that executes software (programs) and functions as various processing units, as well as a PLD (Programmable Logic Device) such as an FPGA (Field-Programmable Gate Array) whose circuit configuration can be changed after manufacturing, and a dedicated electrical circuit, which is a processor with a circuit configuration specifically designed to execute a particular process, such as an ASIC.

[0130] Furthermore, the above various processes may be executed on one of these various processors, or on a combination of two or more processors of the same or different types (for example, multiple FPGAs, and a combination of a CPU and an FPGA). Alternatively, multiple processing units may be configured on a single processor. An example of configuring multiple processing units on a single processor is the use of a processor that realizes the functions of the entire system, including multiple processing units, on a single IC (Integrated Circuit) chip, such as a SoC (System on a Chip).

[0131] From the above description, the technology described in the following supplementary information can be understood.

[0132] [Note 1] A radiation detection device divided into a plurality of compartments, wherein each of the plurality of compartments comprises: a detector module for detecting radiation; an air intake port; an exhaust port; a temperature measuring device for measuring the temperature of the air exhausted from the exhaust port; and an exhaust fan whose rotational speed is controlled based on the temperature. [Note 2] A CT device comprising a radiation source that emits radiation, a radiation detection device divided into a plurality of compartments, and a control board, wherein the radiation source and the radiation detection device are configured to rotate around a central axis with the two facing each other, wherein each of the plurality of compartments comprises: a detector module for detecting radiation; an air intake port; an exhaust port; a temperature measuring device for measuring the temperature of the air exhausted from the exhaust port; and an exhaust fan whose rotational speed is controlled by the control board based on the temperature. [Note 3] The CT device according to Note 2, wherein the temperature measuring device is located between the detector module and the exhaust fan. [Note 4] The CT apparatus according to Note 2 or Note 3, wherein the intake port and the exhaust port are arranged at different distances from the central axis. [Note 5] The CT apparatus according to Note 4, wherein the intake port is located further from the central axis than the exhaust port. [Note 6] The CT apparatus according to any one of Note 2 to Note 5, wherein the intake port and the exhaust port are formed on the front cover that constitutes the front side of each of the plurality of compartments. [Note 7] The CT apparatus according to any one of Note 2 to Note 6, wherein a separation plate is provided inside each of the plurality of compartments between the intake port and the exhaust port to separate intake and exhaust. [Note 8] The CT apparatus according to any one of Note 2 to Note 7, wherein the plurality of compartments are separated by a plurality of partition plates. [Addendum 9] The CT apparatus according to any one of Addendum 2 to Addendum 8, wherein each of the plurality of compartments is provided with an intake cover that covers the periphery of the intake port and an exhaust cover that covers the periphery of the exhaust port, and the intake and exhaust are separated outside the compartment by the intake cover and the exhaust cover.[Note 10] The CT apparatus according to Note 9, wherein the intake cover has an opening formed on the side in the direction of rotation in which the radiation source and the radiation detection device rotate. [Note 11] The CT apparatus according to Note 10, wherein the length of the intake covers in the central axis direction decreases in stages toward the direction of rotation. [Note 12] The CT apparatus according to any one of Notes 9 to 11, wherein the exhaust cover has an opening formed on the side opposite to the direction of rotation in which the radiation source and the radiation detection device rotate. [Note 13] The CT apparatus according to Note 12, wherein the length of the exhaust covers in the central axis direction decreases in stages toward the side opposite to the direction of rotation. [Note 14] The CT apparatus according to any one of Notes 2 to 13, wherein the intake port has a grid-like opening shape. [Note 15] The CT apparatus according to any one of Notes 2 to 14, wherein each of the plurality of compartments is provided with a plurality of through holes and a shielding plate for shielding the radiation, and the shielding plate is positioned in the region to which the radiation that has passed through the detector module is irradiated. [Note 16] The CT apparatus according to any one of Notes 9 to 13, wherein a sound-absorbing sheet is attached to at least one of the intake cover and the exhaust cover. [Note 17] The CT apparatus according to any one of Notes 2 to 16, wherein a heat sink is attached to the detector module. [Note 18] The CT apparatus according to Note 17, wherein the heat sink comprises a plurality of fins that form grooves in the direction along the flow path of the exhausted air. [Note 19] The CT apparatus according to any one of Note 2 to Note 18, wherein the control board controls the rotation speed of the exhaust fan based on the rotation speed of the radiation source and the radiation detection device in addition to the temperature. [Note 20] The CT apparatus according to any one of Note 2 to Note 19, wherein the detector module has a circuit element including a photon counting circuit for counting the number of photons, and the temperature measuring device is incorporated into the circuit element.[Addendum 21] The CT apparatus according to Addendum 20, wherein the detector module has a plurality of circuit elements, the temperature measuring device is incorporated into each of the plurality of circuit elements, and the control board controls the rotation speed based on the average or median value of a plurality of temperature measurements. [Addendum 22] The CT apparatus according to any one of Addendum 2 to 21, wherein the control board performs a first control process to determine the rotation speed of the exhaust fan in steps based on a rotation speed preset for each temperature range of the temperature. [Addendum 23] The CT apparatus according to any one of Addendum 2 to 21, wherein the control board determines a target rotation speed and control time corresponding to the temperature range to which the temperature measurement value belongs, based on a control table to which rotation speed and control time are associated for each temperature range of the temperature, and performs a second control process to change the rotation speed from the current rotation speed to the target rotation speed over the control time. [Addendum 24] The CT apparatus according to any one of Addendum 2 to 21, wherein the control board calculates a target rotational speed by adding to the reference rotational speed a value obtained by multiplying the difference between the measured value and the lower limit temperature by the adjustment amount, based on the reference rotational speed corresponding to the lower limit temperature of the temperature range to which the measured temperature value belongs and the adjustment amount set for that temperature range, and performs a third control process to change the rotational speed of the exhaust fan based on the calculated target rotational speed.

Claims

1. A radiation detection device divided into multiple compartments, wherein each of the multiple compartments comprises: a detector module for detecting radiation; an air intake port; an exhaust port; a temperature measuring device for measuring the temperature of the air exhausted from the exhaust port; and an exhaust fan whose rotational speed is controlled based on the temperature.

2. A CT apparatus comprising a radiation source that emits radiation, a radiation detection device divided into a plurality of compartments, and a control board, wherein the radiation source and the radiation detection device are configured to rotate around a central axis with the two compartments facing each other, and each of the plurality of compartments comprises: a detector module for detecting the radiation, an air intake port, an exhaust port, a temperature measuring device for measuring the temperature of the air exhausted from the exhaust port, and an exhaust fan whose rotation speed is controlled by the control board based on the temperature.

3. The CT apparatus according to claim 2, wherein the temperature measuring device is arranged between the detector module and the exhaust fan.

4. The CT apparatus according to claim 2, wherein the intake port and the exhaust port are arranged at different distances from the central axis.

5. The CT apparatus according to claim 4, wherein the intake port is positioned further from the central axis than the exhaust port.

6. The CT apparatus according to claim 2, wherein the intake port and the exhaust port are formed in the front cover that constitutes the front side of each of the plurality of compartments.

7. The CT apparatus according to claim 2, wherein a separation plate is provided inside each of the plurality of compartments between the intake port and the exhaust port to separate the intake and exhaust air.

8. The CT apparatus according to claim 2, wherein the plurality of compartments are separated by a plurality of partition plates.

9. The CT apparatus according to claim 2, wherein each of the plurality of compartments is provided with an intake cover that covers the periphery of the intake port and an exhaust cover that covers the periphery of the exhaust port, and the intake and exhaust are separated outside the compartment by the intake cover and the exhaust cover.

10. The CT apparatus according to claim 9, wherein the intake cover has an opening formed on the side in the direction of rotation from which the radiation source and the radiation detection device rotate.

11. The CT apparatus according to claim 10, wherein the length of the multiple intake covers in the central axis direction decreases in stages toward the rotation direction.

12. The CT apparatus according to claim 9, wherein the exhaust cover has an opening formed on the side opposite to the direction of rotation in which the radiation source and the radiation detection device rotate.

13. The CT apparatus according to claim 12, wherein the length of the multiple exhaust covers in the central axis direction is progressively shorter toward the opposite direction of rotation.

14. The CT apparatus according to claim 2, wherein the air intake port has a grid-like opening shape.

15. The CT apparatus according to claim 2, wherein each of the plurality of compartments is provided with a plurality of through holes and a shielding plate for shielding the radiation, and the shielding plate is positioned in the region to which the radiation that has passed through the detector module is irradiated.

16. The CT apparatus according to claim 9, wherein a sound-absorbing sheet is attached to at least one of the intake cover and the exhaust cover.

17. The CT apparatus according to claim 2, wherein a heat sink is attached to the detector module.

18. The CT apparatus according to claim 17, wherein the heat sink comprises a plurality of fins that form grooves in a direction along the airflow path for exhaust.

19. The CT apparatus according to claim 2, wherein the control board controls the rotational speed of the exhaust fan based on the rotational speed of the radiation source and the radiation detection device, in addition to the temperature.

20. The CT apparatus according to claim 2, wherein the detector module has a circuit element including a photon counting circuit for counting the number of photons, and the temperature measuring device is incorporated into the circuit element.

21. The CT apparatus according to claim 20, wherein the detector module has a plurality of circuit elements, the temperature measuring device is incorporated into each of the plurality of circuit elements, and the control board controls the rotation speed based on the average or median value of a plurality of temperature measurements.

22. The CT apparatus according to claim 2, wherein the control board performs a first control process that determines the rotational speed of the exhaust fan in steps based on a rotational speed predetermined for each temperature range of the temperature.

23. The CT apparatus according to claim 2, wherein the control board determines a target rotation speed and control time corresponding to the temperature range to which the measured temperature belongs, based on a control table in which rotation speed and control time are associated for each temperature range, and performs a second control process to change the rotation speed from the current rotation speed to the target rotation speed by the control time.

24. The CT apparatus according to claim 2, wherein the control board calculates a target rotational speed by adding to the reference rotational speed a value obtained by multiplying the difference between the measured value and the lower limit temperature by the adjustment amount, based on the reference rotational speed corresponding to the lower limit temperature of the temperature range to which the measured temperature value belongs and the adjustment amount set for that temperature range, and then performs a third control process to change the rotational speed of the exhaust fan based on the calculated target rotational speed.

25. A control method for a CT apparatus comprising a radiation source that emits radiation, a radiation detection device divided into a plurality of compartments, and a control board, wherein the radiation source and the radiation detection device are configured to rotate around a central axis while facing each other, wherein each of the plurality of compartments is provided with a detector module for detecting the radiation, an air intake port, an exhaust port, a temperature measuring device for measuring the temperature of the air exhausted from the exhaust port, and an exhaust fan, and the control board controls the rotation speed of the exhaust fan based on the temperature.

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