JP2007101556A - Nuclear medicine diagnosis system, positron emission tomography scanner, and detector unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nuclear medicine diagnosis system which improves temporal resolution and energy resolution, and also improves diagnostic accuracy by heightening moisture-proof and dust-proof effects of a radiation detector while efficiently cooling the radiation detector. <P>SOLUTION: Both a first region A for housing the radiation detector 21 via a heat insulating member 7, and a second region B for housing a signal processing device are provided for the inside of a housing member 5. The housing member 5 is provided with a ventilation hole 8, which is provided with a dust-proof filter 9, in such a way as to communicate with the first region A, and also provided with: a ventilation hole 34 to be an inlet of cooling air; and a unit fan 33 to be its outlet in such a way as to communicate with the second region B. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a nuclear medicine diagnostic apparatus using radiation, and in particular, X-ray CT, positron emission tomography (hereinafter referred to as “PET”), single photon emission tomography (Single Photon Emission Tomography). The present invention relates to a nuclear medicine diagnostic apparatus, a positron emission tomography apparatus, and a detector unit suitable for performing a plurality of types of radiation examination such as Computed Tomography (hereinafter referred to as “SPECT”).

  The inspection technique using radiation can inspect the inside of a subject nondestructively. In particular, radiation inspection techniques for the human body include X-ray CT, PET, SPECT and the like. Each of these techniques is a technique for measuring a physical quantity to be inspected as an integral value in the radiation flight direction, and calculating and imaging the physical quantity of each voxel in the subject by back projecting the integral value. With these technologies, it is necessary to process enormous amounts of data, and with the rapid development of computer technology in recent years, it has become possible to provide high-speed, high-detail images.

  PET and SPECT, which are nuclear medicine diagnostic apparatuses, are techniques capable of detecting functions and metabolism at the molecular biology level that cannot be detected by nuclear medicine diagnostic apparatuses such as X-ray CT, and can provide functional images of the body. Is possible.

PET is a technique in which a radiopharmaceutical labeled with positron-emitting nuclides such as ¹⁸ F, ¹⁵ O, and ¹¹ C is administered, and its distribution is measured and imaged. Fluorodeoxyglucose (2- [F-18] fluoro-2-deoxy-D-glucose, ¹⁸ FDG), etc., is used as the drug, which utilizes the fact that it is highly accumulated in the tumor tissue due to glucose metabolism. Used to identify the site. Radionuclides taken into the body decay and release positrons (β +). The emitted positron emits a pair of annihilation γ-rays (an annihilation γ-ray pair) having energy of 511 keV when annihilated by combining with electrons. Since this annihilation γ-ray pair is emitted in almost opposite directions (180 ° ± 0.6 °), the annihilation γ-ray pairs are simultaneously detected by a plurality of radiation detectors arranged so as to surround the subject, Projection data can be obtained by accumulating the radiation direction data. Back projection of projection data (using a filtered back projection method or the like) makes it possible to identify and image a radiation position (an accumulation position of radionuclides).

  SPECT is a technique in which a radiopharmaceutical labeled with a single photon emitting nuclide is administered and its distribution is measured and imaged. A single gamma ray having energy of about 100 keV is emitted from the drug, and this single gamma ray is measured by a radiation detector. In this single gamma ray measurement, since the flight direction cannot be identified, SPECT obtains projection data by inserting a collimator in front of the radiation detector and detecting only gamma rays from a specific direction. Similar to PET, image data is obtained by back projecting projection data using a filtered back projection method or the like. The difference from PET is that there is no need for simultaneous measurement due to the measurement of a single gamma ray, the number of radiation detectors can be reduced, and the apparatus configuration is simple.

  In the conventional nuclear medicine diagnosis apparatuses such as PET and SPECT described above, a scintillator is used as a radiation detector in order to obtain an image. This scintillator performs a process of once converting incident γ-rays into visible light and then converting it back to an electric signal by a photomultiplier tube (photomal). In addition, the scintillator has a problem that the number of photons generated at the time of visible light conversion is small and the two-step conversion process is required as described above, so that the energy resolution is low and the diagnostic accuracy cannot always be improved. It was. This decrease in energy resolution is the cause of the inability to perform quantitative evaluation particularly during 3D imaging of PET. This is because, since the energy resolution is low, the energy threshold of γ rays has to be lowered, and many in-vivo scatterings, which are noises that increase during 3D imaging, are detected.

  Thus, in recent years, semiconductor radiation detectors have attracted attention as radiation detectors for nuclear medicine diagnostic apparatuses. This semiconductor radiation detector directly converts incident γ-rays into electrical signals, and has a feature of high energy resolution because of the large number of generated electrons and hole pairs.

  The characteristics of these radiation detectors (scintillators and semiconductor radiation detectors) are generally temperature dependent. The characteristics mentioned here are time resolution and energy resolution. It is known that these properties are improved by using radiation detectors at lower temperature conditions.

Patent Document 1 below describes a cooling structure that efficiently cools the signal processing device and the radiation detector. By maintaining the radiation detector at a low temperature, the image quality and the quantification can be improved. Accurate diagnosis is possible.
JP 2005-128000 A (paragraphs 0058 to 0060)

  By the way, in the radiation detector, moisture resistance and dust resistance are important except for the temperature. In particular, in the case of a semiconductor detector, it is necessary to apply a high voltage bias to the detector, and if dust adheres to the detector or the high voltage application part on the substrate, the leakage current increases, and energy resolution and time resolution are reduced. descend. Further, when the humidity increases in addition to the adhesion of dust, the energy resolution and time resolution further decrease.

  In addition, the conventional technology has a structure in which the radiation detector is sealed in order to prevent adhesion of dust, but it is technically difficult to make the radiation detector completely sealed in consideration of maintainability. It was difficult to control the humidity of the vessel, and there was a problem that dust would get mixed in if the device was used for a long time.

  The present invention can improve the moisture-proof and dust-proof effect of the radiation detector without impairing maintainability while efficiently cooling the radiation detector, improving the time resolution and energy resolution, and performing highly accurate diagnosis. It is an object of the present invention to provide a nuclear medicine diagnostic apparatus, a positron emission tomography apparatus, and a detector unit that can perform the above-mentioned.

  In order to solve the above-described problems, the present invention provides a nuclear medicine diagnostic apparatus in which a detector unit is arranged around a bed that holds a subject. The detector unit includes a plurality of radiation detectors that detect radiation and each of the radiation detectors. A plurality of unit substrates including a plurality of signal processing devices to which detection signals of the radiation detectors are separately input, and a first region in which the plurality of unit substrates are incorporated and the plurality of radiation detectors are arranged And a storage member partitioned into a second region in which the plurality of signal processing devices are disposed, and a coolant discharge for introducing and discharging a gas coolant for cooling the signal processing device to the second region A vent hole communicating with the first region and the outside of the storage member, and a dustproof filter is provided at the vent hole.

  In the nuclear medicine diagnosis apparatus of the present invention, the radiation detector and the signal processing apparatus are separated from each other, and a ventilation port with a dustproof filter is provided on the radiation detector side while air-cooling the signal processing apparatus side. By the coolant discharging means, the radiation detector suppresses the propagation of heat from the signal processing device that is a heating element, and suppresses the temperature rise of the radiation detector. Further, a vent hole through which air can flow is provided in a portion communicating with the first region where the radiation detector is provided, and the dust filter is provided in the vent hole to prevent the dust from flowing into the radiation detector. Yes. Furthermore, by providing a vent hole equipped with a dustproof filter, the humidity set immediately outside the apparatus is set immediately, and humidity control becomes easy.

  According to the present invention, the moisture-proof and dust-proof structure is made possible while holding the radiation detector at a low temperature, so that the time resolution and the energy resolution are remarkably improved, the quantitativeness is improved, and the diagnostic accuracy can be improved.

  Hereinafter, a nuclear medicine diagnostic apparatus which is a preferred embodiment of the present invention will be described with reference to FIGS. In this embodiment, PET will be described as an example of a nuclear medicine diagnostic apparatus. However, the present invention is not limited to a PET apparatus, but can be applied to other nuclear medicine diagnostic apparatuses such as SPECT.

  As shown in FIG. 1, a PET apparatus 1 (nuclear medicine diagnostic apparatus) includes an imaging apparatus 11, a data processing apparatus 12 that processes detection data obtained by imaging by the imaging apparatus 11 and converts the detection data into image data, A display device 13 for displaying the image data output from the data processing device 12 two-dimensionally or three-dimensionally, and a bed 14 on which a subject (subject) H (see FIG. 2) is placed so as to be able to advance and retract in the body axis direction. And.

  As shown in FIG. 2, the imaging device 11 includes a detector unit 2 having a number of semiconductor radiation detectors (hereinafter simply referred to as detectors, details will be described later) 21. The detector unit 2 is disposed in the casing 11A of the imaging device 11 and is circumferentially centered on the body axis Z of the subject H so as to surround the bed 14 inserted in the space S of the imaging device 11. Many are arranged.

The subject H, radiopharmaceuticals, for example, fluorodeoxyglucose the half-life containing ¹⁸ F of 110 minutes (FDG) is administered. This radiopharmaceutical accumulates, for example, in the affected area C of cancer. As shown in FIG. 2, a pair of γ rays (radiation) generated when the positrons emitted from the FDG are extinguished are simultaneously emitted from the body of the subject H in the direction of 180 ° ± 0.6 °. These γ rays are detected by the two detectors 21 positioned in the opposite directions of 180 °. Based on the detection signals output from the respective detectors 21, the position of the γ-ray generation source (radiopharmaceutical accumulation portion) in the body of the subject H is specified. The configuration of the detector unit 2 and its peripheral portion shown in FIG. 2 is schematically shown to explain the arrangement, and the detailed configuration will be described in detail later.

  Further, the imaging device 11 further includes a cooling device 50 (a part of the components are shown in FIG. 2). The cooling device 50 is for cooling each detector unit 2, and in the present embodiment, air is used as cooling air (gas coolant). Details of the cooling device 50 will be described later.

  As shown in FIG. 2, the data processing device 12 includes a simultaneous measurement device 12A and an image information creation device 12B. The data processing device 12 receives data (packet data to be described later) output from the integrated FPGA 28 (see FIG. 3 (b)) of the coupling substrate 22 (see FIG. 3 (b)) built in the detector unit 2 to be described later. take in. The simultaneous measuring device 12A specifies the position of the generation source from the pair of γ rays from the same generation source in the acquired data, and stores the position information in a storage device (not shown). Then, the image information creation device 12B creates PET image information (tomographic image information) on the subject H based on the specified position information, and displays it on the display device 13.

  Specifically, in the simultaneous measurement device 12A, the detection time data of a plurality of detection data is compared, and two data within the simultaneous measurement time window length, for example, within 10 ns, are determined as valid data pairs. Further, the image information creation device 12B accumulates flight direction data of γ-ray pairs from the IDs of the valid data pair detectors 21, and performs image reconstruction from the data to create a PET image. Then, the created PET image is output to the display device 13.

  As shown in FIGS. 3A and 3B, the detector unit 2 includes a storage member 5, a coolant discharge means 6, a heat insulating member (partition member) 7, and a unit substrate 20. . Incidentally, the imaging device 11 (see FIG. 2) is configured so that, for example, 60 to 70 detector units 2 are detachably arranged in the circumferential direction, and maintenance and inspection are facilitated.

  The unit substrate 20 has a detector substrate 20A as a first substrate and a plurality of detectors 21, and these detectors 21 are arranged in a matrix on both sides of the detector substrate 20A.

  The detector substrate 20A is arranged in the storage member 5 in a state in which a plurality of detector substrates 20A are arranged in the body axis Z direction (longitudinal direction of the bed 14) of the subject H shown in FIG. In this embodiment, as shown in FIG. 3B, a total of 15 detector boards 20A are provided as an example.

  In FIG. 3A, as an example, 16 pieces are arranged in the circumferential direction of the imaging device 11 (the arrangement direction of the detector units 2) per one surface of the detector substrate 20 </ b> A, and the radial direction of the imaging device 11 (the detector unit 2 of the detector unit 2). A total of 64 detectors 21 are provided, four in the direction orthogonal to the arrangement direction. That is, in the present embodiment, the detectors 21 are arranged in the circumferential direction around the central axis of the imaging device 11 (substantially coaxial with the body axis Z of the subject H). In the present embodiment, the detector 21 is densely arranged by reducing the arrangement pitch of the detectors 21 so that the detectors 21 can be mounted on the detector substrate 20A at a high density. Therefore, the detection efficiency of γ rays in the detector substrate 20A can be improved, and the inspection time can be shortened.

  The detector 21 has a semiconductor member stacked between a cathode and an anode (not shown). This semiconductor member is made of any single crystal such as CdTe (cadmium telluride), TlBr (thallium bromide), GaAs (gallium arsenide), or the like. Any material such as Pt (platinum), Au (gold), In (indium), or the like is used for the anode and the cathode. By using the detector 21 having such a structure, the charge collection efficiency is increased, the amount of γ-rays passing through is reduced, and the interaction (count number) between the semiconductor member and γ-rays is increased. (Sensitivity can be increased). The detector 21 does not necessarily have such a laminated structure, and may be a single layer or an appropriate layered structure.

  Here, in the PET apparatus 1, as the number of detectors 21 to be installed increases, γ-rays are easily detected, and the positional accuracy at the time of γ-ray detection is increased. Therefore, the detectors 21 are preferably arranged densely as described above, and as shown in FIG. 5, the detector unit 2 includes the casing 11 </ b> A of the imaging device 11 (see FIGS. 2 and 5). It is preferable that they are arranged close to each other in the circumferential direction. By adopting such an arrangement structure, the position resolution of the obtained image can be increased.

  With this configuration, each detector 21 detects 511 keV γ-rays (radiation) used in the PET apparatus 1, and analog signals (γ that correspond to the energy of the γ-rays (energy that has interacted with the semiconductor member)). Line detection signal).

  As shown in FIG. 3B, the other end (upper end) of the signal processing board 20B is provided with a board connector C2, and the signal processing board is connected by a connecting line R1 connected through the board connector C2. 20B and the coupling substrate 22 are electrically connected.

  The signal processing board 20B is mounted with an integrated circuit (analog ASIC 24, ADC 25, digital ASIC 26) for processing the γ-ray detection signal output from each detector 21 described above. Note that the analog AISC 24 functions as the signal processing apparatus of this embodiment.

  One analog ASIC 24 includes 32 sets of analog signal processing circuits (analog signal processing devices) having a slow system and a fast system. An analog signal processing circuit is provided for each detector 21, and one analog signal processing circuit is connected to one detector 21. Here, the first system has a timing pick-off circuit that outputs a timing signal for specifying the detection time of γ rays. In the slow system, a polar amplifier (linear amplifier), a bandpass filter (waveform shaping device), and a peak hold circuit (peak value holding device) are connected in this order for the purpose of obtaining the detected γ-ray peak value. Has been provided. Incidentally, the slow system is named “slow” because it takes a certain amount of processing time to obtain the peak value. Incidentally, the γ-ray detection signal output from the detector 21 and passing through the capacitor and the resistor is amplified by a charge amplifier and a polarity amplifier. The amplified γ-ray detection signal is input to a peak hold circuit through a band pass filter. The peak hold circuit holds the maximum value of the detection signal, that is, the peak value of the γ-ray detection signal proportional to the detected γ-ray energy. One analog ASIC 24 is an LSI made up of 32 sets of analog signal processing circuits.

  These integrated circuits amplify the weak γ-ray detection signal output from the detector 21 and measure the energy and detection time of the detected γ-ray. Then, a detector ID set individually for each detector 21 in advance is added to the measured energy and detection time data, and is output as packet data (digital data).

  The signal processing board 20B is provided with a connector C1 at its end (lower end), and the signal processing board 20B is mechanically and electrically connected to the detector board 20A via the connector C1. Yes. In addition, in the overlap part of this detector board | substrate 20A and signal processing board | substrate 20B, you may mutually couple | bond together with a screw (not shown) so that attachment or detachment is possible. By using such an electrical connection structure between the detector board 20A and the signal processing board 20B, a signal can be transmitted from the detector board 20A to the signal processing board 20B with low loss. Incidentally, when the loss is reduced, for example, the energy resolution of the detector 21 is improved.

  As described above, the connection between the detector substrate 20A and the signal processing substrate 20B is performed by the connector C1, and thus the substrates can be easily attached and detached. Therefore, for example, when a problem occurs in the detector 21, the analog ASIC 24, etc., only the defective part, that is, only the detector board 20A or the signal processing board 20B may be replaced. Therefore, since there is a defect in part, waste such as replacing the entire substrate with a new one can be eliminated, and maintenance costs can be reduced.

  The coupling board 22 is an integrated FPGA (Field Programmable) that collects the packet data output through the high-voltage power supply 27 that is a booster for supplying a voltage to each unit board 20 and the board connector C2 of each signal processing board 20B. Gate Array) 28 and a data transfer device 29 for transmitting the aggregated packet data to the data processing device 12 (see FIG. 2). In the present embodiment, the combined substrates 22 are arranged in the same manner as the signal processing substrate 20B (unit substrate 20) and arranged on the rear side (right side in FIG. 3B) in the storage member 5 described later. The position of the coupling substrate 22 is not limited to this, and may be the front side of the storage member 5 or the like.

  The high-voltage power supply 27 is connected to a low-voltage power supply (not shown) installed outside the imaging device 11, and a low-voltage voltage is boosted to 300 V by a DC-DC converter and supplied to each detector 21. . Further, since the high-voltage power supply 27 is mounted on the coupling substrate 22 and disposed in the storage member 5, it can be easily installed in the imaging device 11 by attaching the detector unit 2 to the unit support portion 40 (FIG. 2). In the present embodiment, in the imaging apparatus 11, each detector 21 is arranged so as to face the longitudinal direction (front-rear direction) of the bed 14. However, the present invention is not limited to this structure. You may arrange | position so that the circumferential direction of the apparatus 11 may be faced.

  Note that the unit substrate 20 is not limited to the above-described configuration, and for example, the unit substrate 20 may be configured by a single substrate to mount the detector 21 and various integrated circuits. By doing so, the cost is reduced by the absence of the connector C1, and the assembly of the apparatus is simplified. Further, the stray capacitance is reduced, and the characteristics of the detector 21 and thus the characteristics of the device can be improved.

  As shown in FIGS. 3A, 3 </ b> B, and 4, the storage member 5 is a square box type having a space inside, and is a ring-shaped unit support provided in the casing 11 </ b> A of the imaging device 11. 40 (see FIG. 4) is attached in the circumferential direction.

  In the present embodiment, as described above, the unit substrates 20 housed in the housing member 5 are arranged in 15 rows at predetermined intervals so as not to overlap in the depth direction (longitudinal direction of the bed 14). The coupling substrate 22 is arranged at a predetermined interval on the rear side (right side in FIG. 3B) of the storage member 5. The unit substrate 20 and the combined substrate 22 are arranged in the vicinity of the four corners of the signal processing substrate 20B by four substrate fixing bars 32 extending in the longitudinal direction of the storage member 5 (longitudinal direction of the bed 14) and spanning the storage member 5. Is supported by the storage member 5 by being penetrated and supported.

  Further, an exhaust unit fan 33 is provided above the storage member 5. This unit fan 33 incorporates a fan that is driven to rotate by a thin motor (not shown), and exhaust air 43 (see FIG. 2) provided in the housing member 5 above (outside) the air in the housing member 5. It has a function to discharge toward The unit fan 33 operates by receiving power from a low-voltage power source (not shown) supplied to the coupling substrate 22. Further, the unit fan 33 may be always operated, or may be configured to operate by detecting that the temperature in the storage member 5 has reached a predetermined temperature. With this configuration, power consumption can be suppressed.

  Further, in the storage member 5, a heat insulating member 7 is provided as a partition member that divides into a first region A in which the detector 21 is disposed and a second region B in which the signal processing device is disposed. Yes. As shown in FIG. 3B, the heat insulating member 7 is located between the unit substrates 20, between the unit substrates 20 and the coupling substrate 22, and between the unit substrate 20 and the housing member 5 at the position of the connector C <b> 1 of the unit substrate 20. 3b, between the coupling substrate 22 and the inner surface 5b of the storage member 5, and between each unit substrate 20 and the inner surfaces 5c, 5c of the storage member 5, as shown in FIG. In the meantime, the heat insulating member 7 is provided (sticked) with a predetermined thickness in a gap S1 formed between the coupling substrate 22 and the inner side surface (not shown) of the storage member 5. That is, with the heat insulating member 7 as a boundary, the space (first region A) inside the storage member 5 in which all the detectors 21 of the detector substrate 20A are positioned, the storage in which the signal processing substrate 20B and the coupling substrate 22 are positioned. It is partitioned into a space (second region B) inside the member 5. The presence of the heat insulating member 7 can prevent heat generated in the integrated circuit (such as the digital ASIC 26) in the second region B from being propagated to the first region A, so that the detector 21 is exposed to a high temperature. Can be prevented.

  As the heat insulating member 7, a material having a low thermal conductivity and an excellent filling property with respect to the gap S 1, for example, urethane can be used. Preferably, urethane may be wrapped with a member capable of shielding electromagnetic waves (electromagnetic wave shielding member), for example, a metal sheet. By using such a member capable of shielding electromagnetic waves, the detector 21 can be protected from electromagnetic waves generated from an integrated circuit (such as the digital ASIC 26). Thereby, the time resolution and energy resolution of the detector 21 can be increased. Further, the heat insulating member 7 is made of a member having elasticity, for example, a member having elasticity such as rubber, so that the work of scoring the gap S1 is further simplified. Even if vibration occurs in the substrate 20, it can be suitably suppressed.

  In the above example, the heat insulating member 7 is filled at the position of the connector C1 of the unit substrate 20. However, this is an example, and heat from the integrated circuit (digital ASIC 26 or the like) is transmitted to the detector 21 side. You may provide in the arbitrary positions which can be prevented, for example, the downward vicinity position etc. of the analog ASIC24.

  As shown in FIG. 3B, the coolant discharge means 6 is composed of a unit fan 33 and a large number of air holes 34. The unit fan 33 forcibly discharges the air in the storage member 5 to the outside. The unit fan 33 is on the opposite side (180 ° opposite side) of the detector 21 across the signal processing board 20B of the storage member 5, that is, FIG. It is provided in the upper part of the storage member 5 shown in FIG. The ventilation holes 34 are for introducing cooling air into the storage member 5 from the outside of the detector unit 2, and are formed on both side portions 5 a and 5 a in the width direction (circumferential direction in FIG. 2) of the storage member 5. The cooling air is introduced from the side with respect to the surface of the signal processing board 20B. In the present embodiment, four vent holes 34 are formed in each side portion 5a along the signal processing board 20B. Although not shown, the vent holes 34 in the arrangement shown in FIG. A plurality of sets (for example, the number of the signal processing substrates 20B and the coupling substrates 22) are formed along the arrangement direction of the processing substrates 20B (longitudinal direction of the bed 14). As a result, a predetermined amount of air is introduced into the storage member 5 substantially uniformly, and the signal processing board 20B and the coupling board 22 can be uniformly cooled.

  The vent hole 34 is formed so as to communicate with the second region B of the storage member 5, and is located farthest from the unit fan 33 at a position near the detector 21 (first region A). Formed in position. Thereby, as shown by the one-dot chain line in FIG. 5, the cooling air can be made to flow through the entire signal processing board 20B and the coupling board 22, so that the cooling efficiency can be improved.

  As shown in FIG. 3 (b), the storage member 5 is provided with a vent hole 8 at a position communicating with the first region A on the side portion 5 d on the rear side in the longitudinal direction. A dustproof filter 9 is provided so as to cover the whole. The air vent 8 provided with the dust filter 9 is not limited to the side portion 5d on the rear side in the longitudinal direction of the storage member 5, and may be another side portion or the lower portion 5e of the storage member 5. Good. Moreover, the vent hole 8 provided with the dustproof filter 9 may be provided at a plurality of locations instead of at one location.

  Examples of the dust filter 9 include a HEPA (High Efficiency Particulate Air) filter. The dustproof filter 9 is not limited to a single filter, and may be a combination of a plurality of types of filters. Moreover, it is not limited to a HEPA filter, Another kind of filter, such as paper and a nonwoven fabric, may be used. Providing such a dustproof filter 9 at the vent 8 of the storage member 5 prevents dust and the like from entering the first region A where a large number of detectors 21 are provided from the outside of the storage member 5. it can. Further, by providing the vent 8 provided with the dust filter 9 on the side not facing the adjacent detector unit 2, the detector units 2 can be arranged more densely in the circumferential direction, and the detection sensitivity is improved. Can be planned.

  As shown in FIG. 4, the detector unit 2 having the storage member 5 configured as described above is attached to a unit support portion 40 installed in the casing 11 </ b> A (see FIG. 2) of the imaging device 11. The unit support part 40 has a ring shape, and a plurality of openings 40a are provided on the outer peripheral surface of the unit support part 40 at predetermined intervals along the circumferential direction. The detector unit 2 is provided in each opening 40a, and the detector of the unit substrate 20 is provided. It is configured to be inserted from the substrate 20A side. The detector unit 2 is fixed to the unit support portion 40 by using a screw or the like (not shown). Thereby, since the detector unit 2 is configured to be detachable from the unit support portion 40, maintenance and the like are facilitated.

  In the present embodiment, as shown in FIG. 5, the storage members 5 of the adjacent detector units 2 are arranged close to each other at a minute angle, so that the amount of γ rays that pass through is minimized. As a result, the radiation detection sensitivity can be improved. Therefore, the inspection time can be shortened.

  As shown in FIG. 2, the cooling device 50 includes a blower 51, a duct 52 that introduces air from the blower 51 into the unit support 40, and an air guide path 42 provided in the unit support 40. An exhaust duct 43 provided so as to surround the outside of the air guide path 42 and an exhaust fan 44 provided in the exhaust duct 43 are mainly provided. As shown in FIG. 5, the air guide path 42 is formed between the storage members 5 by the opening edge 40 b, the side portion 5 a of the storage member 5, and the top plate 42 a spanning the storage members 5. ing.

  The blower 51 and the duct 52 are installed outside the casing 11A. The blower device 51 is disposed at a place where it does not interfere with the operation and maintenance of the image pickup device 11 such as the side and the rear of the image pickup device 11. The air is sucked and supplied to the air guide path 42 through the duct 52 through a flow path (not shown). An air purification filter (not shown) is attached to the air inlet side of the blower 51, and the air that has passed through the air purification filter is used as cooling air. As the air cleaning filter, a hepa (HEPA) filter having high dust collection performance, an electric dust collection filter, or the like can be used.

  The air guide path 42 communicates with the second region B in the storage member 5 through a vent 34 provided in the side portion 5 a of the storage member 5. In combination with driving of the unit fan 33 provided in the storage member 5, air from the air guide path 42 is introduced into the storage member 5. The exhaust duct 43 communicates with the inside of the storage member 5 via the unit fan 33, and the air inside the storage member 5 is discharged toward the exhaust duct 43 by driving the unit fan 33. The exhaust duct 43 is provided with a total of three exhaust ports 43a opened in the room in which the imaging device 11 is installed. The exhaust ducts 43 are provided through the exhaust fans 44 provided in the exhaust ports 43a. Air is discharged into the room.

  In the present embodiment, the air inside the room in which the imaging device 11 is installed is sucked and used as cooling air, and is discharged again after cooling into the examination room. However, the air is sucked from outside the examination room. The air after cooling may be configured to be discharged out of the examination room again.

  Next, the operation of the PET apparatus 1 of the present embodiment will be described. When power is supplied to the imaging device 11 by operating the power switch, the blower 51, the unit fan 33, and the exhaust fan 44 are operated in conjunction with the operation of the imaging device 11. Cooling air is sent from the blower 51 to the air guide path 42 of the unit support 40 via the duct 52, and the sent cooling air passes through the vent hole 34 provided in the side portion 5 a of the storage member 5. It is introduced into the second region B in the storage member 5. At this time, since the unit fan 33 is driven and the air in the second region B in the storage member 5 is forcibly discharged, the air flow in the second region B in the storage member 5 is as shown in FIG. As indicated by the alternate long and short dash line, the integrated circuit such as the analog ASIC 24 is cooled from the air hole 34 toward the unit fan 33, and the temperature rise in the second region B can be suppressed.

  The cooling air supplied into the storage member 5 is forcibly exhausted to the exhaust duct 43 by the unit fan 33. The cooled air exhausted from the exhaust duct 43 is exhausted from the exhaust port 43a into the room by an exhaust fan 44 provided at the exhaust port 43a. As described above, cooling using the cooling air by the cooling device 50 is performed.

  By the way, the cooling device 50 is provided with a filter (not shown) on the inlet side to the unit support portion 40, but the filter here introduces dust having a relatively large particle diameter into the imaging device 11. Is preventing. This is because, if an attempt is made to remove dust having a particle size smaller than necessary, the aperture ratio decreases, the air flow becomes worse, and the cooling capacity decreases. For this reason, fine dust having a particle diameter that cannot be removed by the filter provided on the cooling device 50 side flows through the detector unit 2. As a result, dust accumulates in the second region B in the detector unit 2 after a long operation. The storage member 5 is divided into a first region A in which the detector 21 is disposed and a second region B in which an integrated circuit such as an analog ASIC 24 (signal processing device) is accommodated. The first region A and the second region B are completely shielded, in other words, the air flow cannot be completely blocked, and between the heat insulating member 7 and the unit substrate 20, the heat insulating member 7 and Minute gaps may be formed between the bonding substrate 22, between the heat insulating member 7 and the inner side surfaces 5 b and 5 b of the storage member 5, between the heat insulating member 7 and the corners in the storage member 5, and the like. Alternatively, the minute gap as described above may be formed due to deterioration of the heat insulating member 7 or the like. If the storage member 5 is not provided with the vent hole 8 (see FIG. 3) of the present embodiment, the air generated in the second region B as shown in FIG. Due to the flow (updraft), the air in the second region B is sucked through the aforementioned gap, and the second region B has a negative pressure. Thereafter, when the unit fan 33 stops, air instantaneously flows from the second region B into the first region A. Therefore, the dust that has accumulated in the second region B flows in simultaneously with the inflow of air into the first region A. As a result, there is a problem that dust adheres to the detector 21 or the like and the characteristics of the detector 21 are impaired.

  In addition, while the PET apparatus 1 is moving, the entire examination room in which the PET apparatus 1 is placed is set so that low-humidity air is taken into the detector unit 2 by the air conditioning equipment. When the first region A is in a halfway sealed state due to the presence of the minute gap, the humidity of the first region A provided with the detector 21 is not provided. Immediately, the humidity set by the air conditioner does not reach the humidity, making humidity control difficult. Even if the humidity can be controlled, it takes a long time to reach the set humidity.

  Therefore, in the present embodiment, it is possible to prevent the first region A from becoming negative pressure by providing the vent hole 8 at a position communicating with the first region A of the storage member 5. Accordingly, when the unit fan 33 is stopped, the inflow of air from the second region B to the first region A through the minute gap is prevented, and the dust accumulated in the second region B is prevented from flowing into the first region A. Can be prevented from entering. Therefore, the inconvenience that the performance of the radiation detector 21 is impaired can be prevented.

  Moreover, in this embodiment, since the dustproof filter 9 is provided in the whole opening of the vent hole 8 described above, intrusion of dust from the vent hole 8 can be prevented. Further, with respect to the humidity, the first region A is almost equal to the open state by the installation of the dust filter 9, so that the first region A can be immediately set to the humidity set by the air conditioning equipment. Therefore, the humidity control of the first area A is facilitated.

  In this embodiment, the semiconductor radiation detector is used as the radiation detector. However, the present invention is not limited to this, and for example, a scintillator may be used. A signal processing device when a scintillator is used as the radiation detector can be configured by a photomultiplier, a position calculation device, and the like. Also in this case, it is possible to obtain a dustproof and moistureproof effect by providing a vent hole provided with a dustproof filter in the housing member that covers the scintillator.

  In addition, the detector 21 using CdTe as a semiconductor material used in the present embodiment generates charges in response to light, so that light from the outside does not enter and the detector 21 is shielded from light. Is preferably applied. Specifically, the storage member 5 and the unit support portion 40 shown in FIG. 4 are made of a light-shielding material such as aluminum or an aluminum alloy, and eliminate a gap through which light enters, including a portion where both fit together. It is configured as follows.

  With respect to light entering from the direction of the space S, the cylindrical plate 40c is disposed so that the outer peripheral surface thereof is positioned in the vicinity of the lower end of the storage member 5, thereby reliably preventing light from reaching the detector 21. can do. Moreover, the light shielding property can be improved by forming the cylindrical plate 40c from an aluminum alloy (or aluminum). Furthermore, as another method for preventing light entering from the direction of the space S, the housing member 5 may be covered with a light shielding cover (not shown), or a light shielding film may be used instead of the light shielding cover. A light shielding material may be applied to the detector 21 so as to be formed.

Next, another embodiment of the cooling device will be described with reference to FIGS. 6 and 7. The cooling device 50 </ b> A includes an introduction member 60 and a discharge member 70.
As shown in FIG. 6, the introduction member 60 is provided on the rear surface side (back surface side) of the PET apparatus 1 and has an annular shape covering the entire rear surface side (back surface side) of the unit support portion 40. The introduction member 61 includes a ring-shaped inner tube portion 61a, a ring-shaped outer tube portion 61b, a shielding portion 61c that joins the inner tube portion 61a and the outer tube portion 61b, a plurality of intake fans 62, And a filter 63. The inner tube portion 61a and the outer tube portion 61b are formed with a predetermined length in the front-rear direction, and are formed with the same length. The shielding part 61c is joined to the inner pipe part 61a and the outer pipe part 61b at an intermediate position in the front-rear direction (see FIG. 7). Each intake fan 62 is provided along the circumferential direction with respect to the shielding portion 61c. The filter 63 is for preventing the intrusion of dust contained in the air from the outside of the PET apparatus 1, and has an inner tube portion 61 a and an outer tube portion 61 b on the rear surface side (back surface side) of the shielding portion 63. It is arrange | positioned so that the whole cyclic | annular area | region pinched | interposed by may be covered. Thereby, the cooling air from which the dust with a large particle diameter taken in from the outside of the PET apparatus 1 is removed is introduced into the introducing portion 71a. Further, by providing a plurality of intake fans 62 in the direction in which the detector units 2 are arranged, the cooling air can be supplied to each air guide path 42 with a uniform air volume, and each detector unit 2 can be uniformly cooled.

  The exhaust member 70 includes a frame 71 that covers each detector unit 2 and a plurality of exhaust fans 72. The frame 71 has a shape that covers the outside of each detector unit 2 protruding from the unit support 40, extends from the opening edge 40 b (see FIG. 7) of the unit support 40, and is a unit fan of the detector unit 2. A space serving as an air flow path is formed outside 33 (upper part of FIG. 7). In addition, the frame 71 is formed with an introduction portion 71 a that communicates with each of the air guide paths 42 on the rear surface side (back surface side). As shown in FIG. 6, the exhaust fan 72 is arranged on the outer surface of the frame 71 with an interval in the arrangement direction of the detector units 2. As described above, by providing the plurality of exhaust fans 72, the exhaust from each detector unit 2 can be efficiently discharged to the outside of the PET apparatus 1.

The effect by this embodiment is described below.
(1) According to this embodiment, since the vent hole 8 with the dust filter 9 attached is provided in the storage member 5 communicating with the first region A in which the detector 21 is stored, the detector (semiconductor radiation detection) The dust can be prevented from adhering to the device 21 and the characteristics of the detector 21 can be prevented from deteriorating. Therefore, it is possible to suppress changes in the device characteristics over time, and to greatly reduce the frequency of device maintenance.
(2) According to this embodiment, since the vent hole 8 with the dustproof filter 9 attached is provided in the storage member 5 communicating with the first region A in which the detector 21 is stored, humidity control for the detector 21 is performed. The characteristics of the detector 21, that is, the apparatus characteristics are stabilized, and the diagnostic accuracy can be improved.
(4) According to this embodiment, an integrated circuit (analog ASIC 24, ADC 25, digital ASIC 26) having a high possibility of failure is mounted on the signal processing board 20B, and the detector 21 is mounted on the detector board 20A. Since the substrate 22 is structured to be detachable from the storage member 5 of the detector unit 2, the maintainability such as substrate replacement and maintenance is very good.
(5) According to the present embodiment, the dustproof filters used for the cooling air inlet side to the imaging device 11 by the cooling device 50 and the first region A side are filters having different dust collection performance, that is, the inlet air. The filter can be used without reducing the cooling capacity of the detector unit 2 by selectively using a coarse filter with low dust collection performance on the side and a fine filter with high dust collection performance on the first region A side. It becomes possible to appropriately protect the element and the detector 21 from dust. In addition, by using a coarse filter on the inlet side, pressure loss is reduced, and the number of unit fans 33 and exhaust fans 44 provided in the imaging device 11 and the number of rotations can be reduced. As well as the operating noise of the device is greatly reduced.
(6) According to the present embodiment, the signal processing device that is the heat generating portion and the detector 21 that does not generate heat but wants to be kept at a lower temperature can be insulated to suppress the temperature rise of the detector 21 portion. it can. Therefore, the time resolution and energy resolution of the detector 21 are improved, the image quality and quantitativeness of the image obtained from the PET apparatus 1 are improved, and the diagnostic accuracy can be improved.
(7) According to the present embodiment, since the detector substrate 20A and the signal processing substrate 20B are connected to each other by the connector C1 as separate substrates, heat conduction from the signal processing system to the detector 21 is suppressed, and detection is performed. The temperature rise of the vessel 21 can be suppressed low. Therefore, the image quality and quantitativeness of the image obtained from the PET apparatus 1 are further improved, and the diagnostic accuracy can be improved.
(8) According to the present embodiment, since the temperature rise of the detector 21 can be suppressed, the characteristics of the detector 21 are stabilized (reduction in change over time, reduction in failure rate), and the reliability of the PET apparatus 1 is improved. As a result, the running cost can be reduced.

  In the present embodiment, the first region A that accommodates the detector 21 and the second region B that accommodates the signal processing device in the detector unit 2 are partitioned by the heat insulating member 7, but the present invention is not limited thereto. The sponge-like material is inserted between the unit substrates 20, between the unit substrate 20 and the coupling substrate 22, between the unit substrate 20 and the accommodating member 5, and between the coupling substrate 22 and the accommodating member 5, respectively. The first area A and the second area B may be partitioned.

  In the present embodiment, the storage member itself may be integrally formed in the first region A and the second region B, instead of another member such as the heat insulating member 7. Thereby, the number of parts can be reduced.

  In the present embodiment, the heat insulating member 7 is described as an example of the member that divides the first region A and the second region B. However, the present invention is not limited to this. By using the material having the property, it is possible to prevent the electromagnetic wave emitted from the signal processing device from propagating to the detector 21.

It is a perspective view which shows the structure of the nuclear medicine diagnostic apparatus concerning this embodiment. It is the figure which showed typically the cross section of the circumferential direction of the imaging device of FIG. (A) is sectional drawing when the detector unit used for the nuclear-medical-diagnosis apparatus concerning this embodiment is seen from the front side, (b) is side sectional drawing similarly. It is a perspective view which shows the aspect with which a detector unit is mounted | worn with the unit support part of an imaging device. It is sectional drawing which shows the state in which the detector unit was attached to the unit support part. It is a disassembled perspective view which shows the modification of a cooling device. It is sectional drawing of the modification of a cooling device.

Explanation of symbols

1 PET equipment (nuclear medicine diagnostic equipment)
2 detector unit 5 housing member 6 coolant discharge means 7 heat insulating member 8 vent 9 dustproof filter 20 unit substrate 20A detector substrate (first substrate)
20B Signal processing board (second board)
21 Detector (semiconductor radiation detector)
22 Bonding board 24 Analog ASIC (Signal processing device)
33 Unit fan 34 Ventilation hole 40 Unit support part A 1st area | region B 2nd area | region H Subject (subject)

Claims (19)

In a nuclear medicine diagnostic apparatus in which a detector unit is arranged around a bed holding a subject,
The detector unit includes a plurality of unit substrates including a plurality of radiation detectors for detecting radiation and a plurality of signal processing devices to which detection signals of the respective radiation detectors are separately input;
A housing member that incorporates the plurality of unit substrates and divides into a first region in which the plurality of radiation detectors are disposed and a second region in which the plurality of signal processing devices are disposed;
A coolant discharge means for introducing a gas coolant for cooling the signal processing device into the second region and discharging it from the second region;
The nuclear medicine diagnosis apparatus, wherein the storage member is formed with a vent hole communicating with the first region and the outside of the storage member, and a dustproof filter is provided in the vent hole. In a nuclear medicine diagnostic apparatus in which a detector unit is arranged around a bed holding a subject,
The detector unit includes a plurality of unit substrates including a plurality of radiation detectors for detecting radiation and a plurality of signal processing devices to which detection signals of the respective radiation detectors are separately input;
A housing member containing the plurality of unit substrates;
A partition member partitioning into a first region where the plurality of radiation detectors are disposed and a second region where the signal processing device is disposed;
A coolant discharge means for introducing a gas coolant for cooling the signal processing device into the second region and discharging it from the second region;
The nuclear medicine diagnosis apparatus, wherein the storage member is formed with a vent hole communicating with the first region and the outside of the storage member, and a dustproof filter is provided in the vent hole.   The nuclear medicine diagnosis apparatus according to claim 2, wherein the partition member is a heat insulating member.   The nuclear medicine diagnosis apparatus according to claim 2, wherein the partition member is an electromagnetic wave shielding member.   The nuclear medicine diagnosis apparatus according to any one of claims 1 to 4, wherein the air vent provided with the dustproof filter is provided on a side not facing an adjacent detector unit.   A vent hole for introducing the gas coolant into the second region is formed in the storage member, the vent hole is provided closer to the radiation detector, and the coolant discharge means sandwiches the signal processing device with the signal processing device interposed therebetween. The nuclear medicine diagnosis apparatus according to any one of claims 1 to 5, wherein the nuclear medicine diagnosis apparatus is provided on a side opposite to the radiation detector.   The nuclear medicine diagnosis apparatus according to any one of claims 1 to 6, wherein the radiation detector and the signal processing apparatus are provided on a single substrate. The radiation detector is provided on a first substrate;
The nuclear medicine according to any one of claims 1 to 6, wherein the signal processing device is provided on a second substrate coupled to the first substrate via a connector. Diagnostic device.   The nuclear medicine diagnosis apparatus according to claim 8, wherein the vent hole is configured such that the gas coolant is introduced from a side with respect to a surface of the second substrate.   The nuclear medicine diagnostic apparatus according to any one of claims 1 to 9, wherein the radiation detector is a semiconductor radiation detector.   The nuclear medicine diagnosis apparatus according to any one of claims 1 to 10, wherein the storage member has a light shielding property. In the positron emission tomography apparatus in which the detector unit is arranged around the bed holding the subject,
The detector unit includes a plurality of unit substrates including a plurality of radiation detectors for detecting radiation and a plurality of signal processing devices to which detection signals of the respective radiation detectors are separately input;
A housing member containing the plurality of unit substrates;
A partition member partitioning into a first region where the plurality of radiation detectors are disposed and a second region where the signal processing device is disposed;
A coolant discharge means for introducing a gas coolant for cooling the signal processing device into the second region and discharging it from the second region;
The positron emission tomography apparatus, wherein the storage member is formed with a vent hole communicating with the first region and the outside of the storage member, and a dustproof filter is provided in the vent hole.   A plurality of unit substrates including a plurality of radiation detectors for detecting radiation and a plurality of signal processing devices to which detection signals of the respective radiation detectors are separately input, and the plurality of unit substrates including the plurality of unit substrates A housing member that divides the first region in which the radiation detector is disposed and a second region in which the plurality of signal processing devices are disposed, and a gas coolant that cools the signal processing device is provided in the second region. A cooling medium discharging means for introducing into and discharging from the region, and the storage member is formed with a vent hole communicating with the first region and the outside of the storage member, and a dustproof filter is provided in the vent port. A detector unit provided.   A plurality of unit substrates including a plurality of radiation detectors for detecting radiation and a plurality of signal processing devices to which detection signals of the respective radiation detectors are separately input; and a housing member incorporating the plurality of unit substrates; A partition member that divides the first region in which the radiation detector is disposed and a second region in which the signal processing device is disposed; and a gas coolant that cools the signal processing device in the second region. A cooling medium discharging means that is introduced into and discharged from the storage member, wherein the storage member is formed with a vent hole that communicates with the first region and the outside of the storage member, and a dustproof filter is provided in the vent hole. A detector unit provided.   The detector unit according to claim 14, wherein the partition member has a heat insulating property.   The detector unit according to claim 14, wherein the partition member is made of a material that shields electromagnetic waves.   A vent hole for introducing the gas coolant into the second region is formed in the storage member, the vent hole is provided closer to the radiation detector, and the coolant discharge means sandwiches the signal processing device with the signal processing device interposed therebetween. The detector unit according to any one of claims 13 to 16, wherein the detector unit is provided on a side opposite to the radiation detector.   The detector unit according to claim 13, wherein the radiation detector and the signal processing device are provided on a single substrate. The radiation detector is provided on a first substrate;
The detector according to any one of claims 13 to 17, wherein the signal processing device is provided on a second substrate coupled to the first substrate via a connector. unit.

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