JP3856511B2 - Gantry for positron CT system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gantry for a positron CT apparatus with improved cooling efficiency.
[0002]
[Prior art]
A positron CT device administers a radiopharmaceutical labeled with a positron emitting nuclide to a subject, and detects positron annihilation gamma rays emitted from within the subject with a detector arranged in a ring around the subject. This is an apparatus for imaging the distribution of the radiopharmaceutical in the subject.
[0003]
FIG. 7 is a perspective view showing the appearance of a general gantry of such a positron CT apparatus. In FIG. 7, 1 indicates the entire gantry and 1a indicates a gantry cover. Reference numeral 2 denotes a subject opening into which a subject (not shown) is inserted and positioned.
[0004]
8A and 8B are views for explaining the outline of the internal structure of the gantry 1 shown in FIG. 7, in which FIG. 8A is a front view, and FIG. 8B is a cross-sectional view taken along line AA ′ in FIG. 8A and 8B, reference numerals 1, 1a, and 2 denote a gantry, a gantry cover, and an opening for the subject, as in FIG. 3 is a detector unit in which a plurality of radiation detectors are arranged in a ring shape, 6 is a detector ring base to which this detector unit 3 is attached, and 7a to 7d are detector output processes from the detector unit 3. An electronic circuit device unit 8 including a plurality of electronic circuit devices for use in controlling each circuit or the like, 8 is a slice collimator, and these are incorporated in the gantry cover 1a. 5a to 5h are cooling fans for releasing heat generated inside the gantry 1 (inside the gantry cover 1a) to the outside, and 71 is external air for taking in low-temperature air outside the gantry 1 (outside the gantry cover 1a). It is an intake.
[0005]
FIG. 9 is a diagram showing the detector unit 3, the detector ring base 6, and the slice collimator 8 in FIG. In FIG. 9, reference numeral 18 denotes a detector constituting the detector unit 3, and the detectors 18 are closely arranged in a ring shape.
[0006]
Incidentally, in general, many electronic circuit devices (see electronic circuit device units 7a to 7d) are incorporated in the gantry 1 as shown in FIG. Typically, these electronic circuit devices are used in an environment where the integrated circuit chips and other electronic components that make them do not exceed their maximum allowable temperatures. This is important for ensuring the stable operation of the integrated circuit chip and electronic components and reducing the failure rate.
[0007]
In the case of a positron CT apparatus, it is further necessary to consider operating temperature conditions from another viewpoint. In particular, a detector element (germanic acid (bismuth) scintillator) used in a positron CT apparatus has a negative temperature characteristic, and the output peak value tends to decrease as the ambient temperature increases.
[0008]
For this reason, the system sensitivity depends on the ambient temperature, and the quantitativeness of the resulting image is impaired. Therefore, it is necessary to release the heat generated from the electronic circuit equipment including these detectors. This is because the internal high-temperature air is discharged to the outside by the cooling fans 5a to 5h attached to the cover of the gantry 1 or the like. On the other hand, the external low temperature air is taken into the inside through the external air intake 71. That is, in the conventional apparatus, the cooling of the electronic circuit device or the like is performed based on heat transfer by forced air cooling.
[0009]
There is also a gantry for a positron CT apparatus provided with a water cooling (liquid cooling) type cooling device using a liquid such as water as a heat transfer medium.
[0010]
[Problems to be solved by the invention]
In recent years, with the increase in performance of positron CT apparatuses, the number of detector electronic circuit devices has been increasing and the density has been increasing. Furthermore, along with the downsizing of the gantry 1, the electronic circuit devices and the like incorporated in the gantry 1 are becoming denser. For this reason, in the above-described conventional technique in which the heat generated in the gantry is released by the forced air cooling method, it is necessary to increase the number of cooling fans 5a to 5h to be used or increase the air volume of the cooling fans 5a to 5h. Therefore, noise increases. In the brain metabolism test method using the positron CT apparatus, ambient noise affects the subject, and there is a concern that the test result may be hindered. For this reason, with respect to this type of inspection method, it is required to suppress ambient noise as low as possible, but the increase in noise in the above-described prior art is contrary to this.
[0011]
Even if the cooling fans 5a to 5h are increased, various devices are intricately arranged inside the gantry as shown in FIGS. 8 and 9, so that a smooth air flow cannot be ensured. Becomes uneven. For this reason, in the conventional gantry 1 using the forced air cooling method, it is difficult to uniformly cool the detector unit 3, and the sensitivity varies depending on the position where the detector 18 is attached.
[0012]
If the water cooling method is adopted, the above noise problem can be solved, but the configuration becomes complicated due to the necessity of water supply facilities, etc., and the cost is increased including the low maintainability. It was.
[0013]
An object of the present invention is to enable effective and uniform forced air cooling without increasing the number of cooling fans and air flow, to reduce fan noise, to make the detector sensitivity characteristics uniform, and to thereby make the image quantitative. It is an object to provide a gantry for a positron CT apparatus capable of improving the above.
[0014]
[Means for Solving the Problems]
The object is to provide a detector unit in which a plurality of radiation detectors are arranged in a ring shape, a detector ring base to which the detector unit is attached, and a plurality of electronic circuit device units inside the gantry cover. In the gantry for a positron CT apparatus incorporated in the air, the air directly taken in from the outside of the gantry cover is caused to flow along the detector ring base and the detector unit part through the detector ring base. A plurality of ring-shaped detector unit air cooling means including an air flow guide for forming an air flow path to be discharged to the outside of the gantry cover after heat exchange and a fan for generating an air flow are provided. Is achieved. The number of divisions is set according to the amount of heat in the detector unit.
[0015]
The electronic circuit equipment unit air cooling means is provided thermally independently from each other in each of the electronic circuit equipment units 7, and after cooling each electronic circuit equipment unit with air directly taken from outside the gantry cover, the electronic circuit equipment unit outside the gantry cover. Direct release. In addition, the detector unit forced air cooling means is provided thermally independently from each of the electronic circuit device unit forced air cooling means, and after cooling the detector unit with air directly taken from the outside of the gantry cover, the detector unit forced air cooling means directly to the outside of the gantry cover. Release.
[0016]
That is, air cooling means for cooling objects (each electronic circuit device unit and detector unit) are provided thermally and separately from each other, and each cooling object is cooled in a one-to-one correspondence. Moreover, the low temperature air outside the gantry cover is directly taken in and cooled, and the high temperature air after cooling is directly discharged outside the gantry cover.
[0017]
Thereby, the cooling efficiency of each cooling object is significantly improved. In addition, the high-temperature air released from the cooling target with a large heat generation amount heats the cooling target with a relatively small heat generation amount, or the high-temperature air heated by cooling other cooling targets is recirculated for cooling. In addition, the individual objects to be cooled are always cooled by external cold air. For this reason, effective and uniform cooling can be achieved without increasing the number of cooling fans or increasing the air volume. The ability to uniformly cool the object to be cooled means that the detector sensitivity characteristic is made uniform, particularly for the detector unit, and the quantitativeness of the image is improved.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram showing the main part of an embodiment of a gantry for a positron CT apparatus according to the present invention, in which (a) is a front view and (b) is a sectional view taken along line AA ′ in FIG. .
In FIGS. 1A and 1B, 1, 1a, 2, 3, 7a to 7d and 8 are the same as those in FIG.
[0019]
Reference numeral 100 (100a to 100d) denotes an electronic circuit device unit forced air cooling means, and is provided thermally independent of each of the electronic circuit device units 7 (7a to 7d). This air cooling means 100 is an air flow path that directly discharges the air directly taken from the outside of the gantry cover 1a to the outside of the gantry cover 1a after exchanging heat with this part via the electronic circuit device unit 7 part. The air flow guide EG1 (hoods 9a and 9b) for forming the air flow and the fan 5 for forcibly generating the air flow are provided. In addition, 10 shows an external air intake port and 11 shows an internal air discharge port.
[0020]
Reference numeral 200 denotes a detector unit forced air cooling means, which is provided thermally independently from each of the electronic circuit device unit forced air cooling means 100 (100a to 100d). The air cooling means 200 allows air taken directly from the outside of the gantry cover 1 a to flow along the detector ring base 6 and exchanges heat with the detector unit 3 through the detector ring base 6. And an air flow guide EG2 (duct 12 and hood 13) that forms an air flow path that is directly discharged to the outside of the gantry cover 1a and a fan that forcibly generates an air flow (see 15 'in FIG. 3). Become. In addition, 15 shows an external air intake port and an arrow shows an air flow.
[0021]
Next, details of the electronic circuit device unit forced air cooling means 100 and the detector unit forced air cooling means 200 will be described below.
[0022]
FIG. 2 is a view showing the electronic circuit device unit forced air cooling means 100 (here, 100a) in FIG. 1, taken out from the side view (a) is a side view (the same side as FIG. 1 (a)), (b). These are front views (the figure seen from the right side of figure (a)). In FIG. 2, the same reference numerals as those in FIG. 1 denote the same or corresponding parts. The PCB is a plurality of printed circuit boards (heat generation sources) that constitute the electronic circuit device unit 7, for example, a large number of integrated circuit chips and other electronic components. Reference numerals 5k, 5l and 5m denote cooling fans for forcibly generating an air flow (see arrows) in the air cooling means 100.
[0023]
Here, the electronic circuit device unit 7 (7a to 7d) is attached to the inside of the gantry cover 1a (gantry 1) as shown in FIG. 1, so that air can be easily taken from the outside of the gantry cover 1a, and the gantry cover 1a. It is installed outside the gantry cover 1a as much as possible so that air can be easily released to the outside.
[0024]
In such an electronic circuit device unit forced air cooling means 100, the low-temperature air outside the gantry cover 1a is directly taken in from the external air intake port 10 and passes through the hood 9a as shown by the arrow in the figure, and the electronic circuit device unit 7 ( Here, 7a), that is, they are sent to a plurality of printed circuit board PCB portions which are heat sources to cool them. As a result, the air heated to high temperature is directly discharged from the internal air discharge port 11 to the outside through the hood 9b as shown by an arrow in the figure.
[0025]
Each electronic circuit device unit forced air cooling means 100 is provided thermally independent from each other in each electronic circuit device unit 7 so that it does not interfere thermally, and air is directly taken in from the outside, and Since it is directly discharged to the outside, effective and uniform forced air cooling can be performed without increasing the number of cooling fans 5 and the increase in air volume, and fan noise can be reduced.
[0026]
3A and 3B are diagrams showing the detector unit forced air cooling means 200 in FIG. 1 taken out, wherein FIG. 3A is a front view (viewed from the back side of FIG. 1A), and FIG. BB 'sectional drawing in the inside, (c) is a right view of (a) figure. 3, the same reference numerals as those in FIG. 1 denote the same or corresponding parts. Reference numeral 15 ′ denotes a cooling fan for forcibly generating an air flow (see arrow) in the air cooling means 200, which is attached to the external air intake port 15 here. 16 is an internal air discharge port, and 17 is a partition plate of the duct 12. The external air intake port 15 and the internal air discharge port 16 are formed at the end portions (back surface of the gantry cover 1a) of the hoods 13 and 13 protruding from the duct 12.
[0027]
Here, as shown in FIG. 3 (b), a plurality of cooling fins 14 are arranged on the surface of the duct 12 on the detector ring base 6 side in the direction along the air flow indicated by the arrows in FIG. 3 (a). Is formed.
[0028]
In such a detector unit forced air cooling means 200, the low-temperature air outside the gantry cover 1a is directly taken in from the external air intake port 15 and sent into the duct 12 through the hood 13 as shown by the arrows in the figure. The detector unit 3 is cooled via the detector ring base 6. As a result, the air heated to a high temperature is discharged directly from the internal air discharge port 16 to the outside through the hood 13 as indicated by an arrow in the figure.
[0029]
The detector unit forced air cooling means 200 is provided in each electronic circuit device unit forced air cooling means 100 thermally independent from each other so that they do not interfere with each other, and air is directly taken in from the outside, and Since it is directly discharged to the outside, it can be effectively and uniformly forced air-cooled without increasing the number of cooling fans 15 'or increasing the air volume, and fan noise can be reduced.
[0030]
In addition, if the cooling fin 14 is provided as shown in the figure, the heat radiation area increases, and the cooling efficiency can be further increased. The cross-sectional dimensions of the duct 12 and the height, thickness, spacing, etc. of the cooling fins 14 are based on the heat radiation to be set, the heat transfer rate, the ambient temperature, the temperature and mass of the detector ring base 6, the air flow rate, etc. Is set as appropriate. Further, if a bellows, for example, is used as the hood 13, it can be easily incorporated into the gantry cover 1a while avoiding obstacles (each component) in the gantry cover 1a.
[0031]
4A and 4B are diagrams showing another example of the detector unit forced air cooling means 200, where FIG. 4A is a front view and FIG. 4B is a right side view of FIG. 4, the same reference numerals as those in FIG. 1 denote the same or corresponding parts. As can be seen from the figure, here, the detector unit forced air cooling means 200 has a four-part configuration.
[0032]
According to such a four-divided configuration, loss due to the ventilation resistance of the duct 12 is suppressed, and a fan with a small air volume, in other words, a low-noise fan can be used as the fan 15 ′. Further, by increasing the number of divisions in this way, the difference between the air temperature at the duct inlet and the air temperature at the outlet (air temperature difference between the intake port 15 and the discharge port 16) can be reduced, and the detector ring The temperature distribution of the base 6 and thus the detector unit 3 can be made more uniform.
[0033]
FIG. 5 is a view showing still another example of the detector unit forced air cooling means 200, in which (a) is a front view and (b) is a right side view of FIG. 5, the same reference numerals as those in FIGS. 1 and 4 denote the same or corresponding parts. As can be seen from the figure, here the detector unit forced air cooling means 200 has a three-part configuration. The number of divisions may be appropriately determined according to the amount of heat generated in the detector unit 3 portion.
[0034]
6A and 6B are configuration diagrams showing an embodiment of a gantry for a positron CT apparatus that performs cooling by a water cooling method, in which FIG. 6A is an internal configuration diagram shown from the side, and FIG. 6B is an internal configuration diagram shown from the back surface. . 6 (a) and 6 (b), 1, 1a, 2, 3 and 8 are the same as those in FIG. Reference numeral 20 denotes a water-cooling heat exchanger, whereby cold water is circulated through the pipe 19.
[0035]
Here, the pipe 19 is disposed in close contact with the detector ring base 6. However, in order to make the contact area as large as possible, the pipe 19 is embedded in the detector ring base 6 or the shape of the pipe 19 is flattened. For example, the heat transfer rate (cooling efficiency) may be improved. Further, the pipe 19 may be attached to the detector ring base 6 through an adhesive having a high thermal conductivity. Furthermore, a plurality of rows of pipes 19 may be arranged on the detector ring base 6 surface to improve heat transfer characteristics.
[0036]
For example, an AC power supply control circuit, a DC power supply circuit, and the like may be cooled by fans 5a to 5h (see FIG. 8) attached to the gantry cover 1a and the like, as in the past.
[0037]
【The invention's effect】
As described above, according to the present invention, effective and uniform forced air cooling can be performed without increasing the number of cooling fans or increasing the air volume, fan noise can be reduced, and detector sensitivity characteristics can be made uniform. This has the effect of improving the quantitativeness of the image. In particular, the reduction in fan noise is effective for precise metabolic examination of the brain and has the effect of improving examination accuracy.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a main part of an embodiment of a gantry according to the present invention.
FIG. 2 is a diagram showing an electronic circuit device unit forced air cooling means in FIG.
FIG. 3 is a diagram showing the detector unit forced air cooling means in FIG.
FIG. 4 is a diagram showing another example of the detector unit forced air cooling means.
FIG. 5 is a diagram showing another example of the detector unit forced air cooling means.
FIG. 6 is a configuration diagram showing an embodiment of a gantry for a positron CT apparatus that performs cooling by a water cooling method.
FIG. 7 is a perspective view showing an external appearance of a general gantry of a positron CT apparatus.
8 is a view for explaining an outline of the internal structure of the gantry shown in FIG. 7;
9 is a view showing a detector unit, a detector ring base, and a slice collimator portion extracted from FIG. 8. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Gantry 1a Gantry cover 2 Subject opening part 3 Detector unit 5, 5a-5h, 15 'Cooling fan 6 Detector ring base 7, 7a-7d Electronic circuit unit 8 Slice collimator 9a, 9b, 13 Hood 10, 15, 71 External air intake port 11 Internal air discharge port 12 Ducts 100, 100a to 100d Electronic circuit device unit forced air cooling means 200 Detector unit forced air cooling means EG1, EG2 Air flow guide

Claims (3)

A detector unit in which a plurality of radiation detectors are arranged in a ring shape, a detector ring base to which the detector unit is attached, and a plurality of electronic circuit device units are incorporated in the gantry cover. In the gantry for the positron CT apparatus, air directly taken from the outside of the gantry cover is caused to flow along the detector ring base to exchange heat with the detector unit portion via the detector ring base. And a ring-shaped detector unit air cooling means including an air flow guide that forms an air flow path that is discharged to the outside of the gantry cover and a fan that generates an air flow, and is divided into a plurality of parts. Gantry for positron CT equipment. 2. The gantry for a positron CT apparatus according to claim 1, wherein the detector unit air cooling means is provided independently of the electronic circuit equipment air cooling means for cooling the electronic circuit equipment unit. 2. The gantry for a positron CT apparatus according to claim 1, wherein the number of divisions is set according to the amount of heat in the detector unit.

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