JPH119586A - X-ray ct scanner apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray CT scanner apparatus which forms a better image by blocking the transfer of heat in a detector to a rotary plate to stabilize the temperature in the detector and a measuring system. SOLUTION: This X-ray CT scanner apparatus is provided with an opening part in which an object 18 to be inspected is arranged at the central part of a disc-shaped rotary plate 2 arranged in a scanner cover 1. An X-ray tube 3 and an X-ray detector 7 are arranged facing each other sandwiching the opening part while an amplification circuit device 9 is arranged to amplify an electrical signal from the X-ray detector. Moreover, a rotating mechanism is provided containing a belt 12 for relatively drive the rotary plate 2 and a motor 13 for driving. In this case, a temperature adjustor is provided in the X-ray detector 7 for keeping temperature constant while the X-ray detector 7 is so arranged to be fixed on the rotary plate 2 by a mounting device 8. The mounting device 8 for fixing the X-ray detector 7 on the rotary plate 2 is made up of a plate-shaped member mechanically film and low in heat conductivity, for example, made of stainless steel or acrylate. The temperature in the X-ray detector 7 is blocked from affecting the rotary plate 2 thereby stabilizing the temperature in the detector.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray CT scanner, and more particularly, to a method for reducing a temperature change in a detector by preventing heat in the detector from flowing toward a rotating plate. The present invention relates to the manufacture of an X-ray CT scanner device that can operate stably and obtain good images.

[0002]

2. Description of the Related Art In a scanner unit of an X-ray CT scanner, an opening for arranging a subject is provided in the center,
Further, a rotating plate that rotates around the subject is provided. An X-ray tube device containing an X-ray tube for emitting X-rays for measurement, a heat radiation device for efficiently radiating heat generated by the X-ray tube, and an X-ray A collimator that narrows the X-rays from the tube to a predetermined width, a detector that receives the X-rays that have passed through the subject and outputs an electric signal corresponding to the X-ray intensity, and amplifies the signal from the detector to an appropriate level An amplifier circuit device that converts digital data to perform an image reconstruction operation, a control device that controls the movement of a rotating plate motor, an interface device that exchanges data between a scanner unit and a console or an image processing device, Further, a power supply and the like for operating the above devices are mounted. The rotating plate is connected by a belt or the like, is placed in the scanner unit, and is rotated by a motor.

In recent CT scanners, data can be obtained at high speed (for example, about one second per rotation) by continuous rotation. And since the rotating plate rotates at a high speed in this way, the detectors mounted on it need to be firmly fixed on the rotating plate so that they do not come off or move due to the high-speed rotation. There is. Therefore, a strong metal material is used for the mounting brackets such as these detectors.

As an X-ray detector, for example, an ionization chamber detector or a solid state detector is currently used in a CT apparatus. This name means that in the former ionization chamber detector, the conversion of the X-ray-electric signal is mainly performed by gas, whereas in the latter solid-state detector, the conversion is mainly performed by using a solid scintillator. So called. Regarding the structure and the principle of detection, in the ionization chamber detector, an electrode plate is arranged in a container filled with gas, and incident X-rays are generated by ionizing the gas between the electrode plates. An electric signal is obtained by collecting electrons or ions on the electrode plate. On the other hand, the solid-state detector is configured by combining a scintillator that emits light in accordance with the incident X-ray intensity and a photoelectric conversion element such as a photodiode that receives the light and outputs an electric signal.

[0005] In either of the above detectors, X
In order to obtain a good image as a line CT scanner,
Elements having a channel width of about 1 mm need to be accurately arranged for less than 1000 channels. In practice, it is difficult to arrange these elements one by one. Therefore, usually, these elements are divided into several parts to assemble a module having a plurality of channels, and these modules are arranged inside the container. The whole detector is assembled by this method.

In the ionization chamber detector, as a material constituting such a module, a material obtained by processing a ceramic material or the like is used because electrical insulation and dimensional accuracy are important.
On the other hand, a solid state detector uses a scintillator material, a silicon material (photodiode substrate), and the like. On the other hand, as a material for the container, a metal material is used because it has a size of about 1 meter as a whole and high-precision machining is required.

As described above, since the material constituting the module and the material of the container for fixing the module are different, if a temperature change occurs in the container containing the module, the difference in thermal expansion between the modules causes the difference between the modules. The distance changes, so that the measurement error of the specific channel increases. In particular, in a solid-state detector, since the photodiode used is a semiconductor, its characteristics are sensitive to temperature changes, which also causes an increase in measurement error.

As described above, since it is inevitable that a measurement error occurs when the temperature of the detector changes, the temperature of the entire detector is controlled in order to perform the measurement with high accuracy. This temperature control can be achieved, for example, by sensing the temperature of the detector and cooling or heating it so that the detector temperature becomes a set value. However, for the reason that cooling requires a large-scale apparatus, a method of keeping the detector temperature constant by heating is usually adopted. Specifically, the target value (r) of the temperature control of the detector is set to a temperature higher than the ambient temperature, and if the detector temperature is lower than the target value, the heater is energized and heated. When the temperature of the detector becomes higher than the target value, the detector is cooled down by stopping the power supply to the heater and radiating heat to the surroundings, whereby the detector temperature can be kept constant.

[0009]

By the way, actually,
Normally, the temperature control of the detector is continuous and always performed because the heat capacity of the detector container is large and it takes time from when the temperature control is started until the temperature becomes constant. However, if the target value of the temperature control is high, a large-capacity heater is required to maintain the target temperature even when there is almost no heat generation in the scanner unit at night or the like. In addition, by raising the temperature of the detector, the resin used inside the detector,
Degradation of adhesives, rubber, etc. is promoted, or
In the solid-state detector, it is pointed out that the dark current of the photodiode to be used increases with the temperature rise, so that the measurement accuracy decreases. In consideration of the above, the set temperature of the temperature control of the detector should be set as low as possible within a temperature controllable range.

However, as described above, since the detector must be firmly fixed to the rotating plate, a strong metal material is used for the detector mounting bracket, which is a metal material having a high thermal conductivity. In this case, the heat of the detector is transmitted to the rotating plate through the detector mounting bracket, and is carried out. Therefore, the ON / OFF operation of the temperature control device becomes frequent, and the temperature in the detector becomes unstable, and the measurement error increases.

In the conventional X-ray CT scanner described above, the detector is fixed to a rotating plate. In particular, continuous high-speed rotation in recent CT scanners (about one second per rotation).
The detector needs to be firmly fixed to the rotating plate so that data can be acquired at a high speed, that is, to withstand continuous rotation at high speed. Therefore, as the detector mounting bracket,
Usually, a strong metal material is used. However, if this is a metal material having a high thermal conductivity,
The heat of the detector propagates through the detector mounting bracket and flows toward the rotating plate, so that the temperature inside the detector becomes unstable. Therefore, the ON / OFF operation of the temperature control device becomes frequent, which further causes the temperature in the detector to become unstable, thereby increasing the measurement error.

Therefore, in the present invention, in view of the above-mentioned problems in the prior art, the temperature inside the detector is stabilized, so that stable calibration data and measurement data are obtained, thereby obtaining a good image. It is an object of the present invention to provide an improved structure of an X-ray CT scanner device which can be used.

[0013]

According to the present invention, in order to achieve the above object, an opening for arranging a subject is provided at a center portion of a disk shape, and an X-ray tube is sandwiched between the openings. A rotating plate in which an X-ray detector is arranged to face and an amplifier circuit device for amplifying an electric signal from the X-ray detector is arranged; and a mechanism for rotatingly driving the rotating plate is provided. A temperature controller for constant temperature is provided inside the line detector, and
An X-ray CT scanner having a structure in which the X-ray detector is fixed on the rotary plate by a fixture,
Provided is an X-ray CT scanner device in which a fixture for fixing a line detector on the rotating plate has a structure with low thermal conductivity to prevent the temperature in the X-ray detector from flowing to the rotating plate. Have been.

That is, the present invention has been made based on the inventor's knowledge that the above-mentioned problem in the prior art arises because a metal material having a high thermal conductivity is used for the detector fixture. The X-ray CT scanner device described above stabilizes the temperature inside the X-ray detector, thereby enabling stable acquisition of calibration data and measurement data.

[0015]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. First, FIG.
FIGS. 1 and 12 show the internal configuration of an X-ray CT scanner configured according to the present invention. In particular, FIG. 11 shows the arrangement of each device inside the scanner unit. That is, in the center of the inside of the scanner unit cover 1 shown in the figure, a rotating plate 2 having an opening at the center thereof is rotatably arranged.
X-ray tube device 3, X-ray tube cooling device 5 connected to X-ray tube device 3 by oil feed hose 4, X radiated from X-ray tube device 3
An X-ray collimator device 6 for narrowing a line to a desired width, an X-ray detector 7 for receiving an X-ray radiated from the X-ray tube device 3 through the X-ray collimator device 6 and converting the X-ray into an electric signal. A detector fixture 8 for fixing the X-ray detector to the rotating plate 2, an amplifying circuit device 9 for amplifying an electric signal output from the X-ray detector 7 and converting it into digital data, A transformer 10 for supplying a voltage, a power supply device 11 for operating each device on the rotating plate 2, and the like are arranged.

As is clear from the drawing, the rotating plate 2 is connected to a driving motor 13 by a belt 12. Thus, by rotating the driving motor 13, the rotating plate 2 rotates with the above-described devices mounted thereon. Inside the scanner unit, a part of the scanner cover 1 is cut out, and an intake fan 14 for sending outside air into the scanner and an exhaust fan 15 for sending air inside the scanner to the outside are installed. ing. That is,
The heat generated in the scanner unit is conveyed to the outside of the scanner unit by the flow of air by the intake fan 14 and the exhaust fan 15, thereby suppressing a rise in the temperature inside the scanner unit. Although not shown, the X-ray detector 7 is provided with a temperature controller for keeping the inside of the X-ray detector 7 at a constant temperature, thereby keeping the inside temperature constant.

In the scanner unit, a scanner control device 16 for generating a signal for appropriately operating each of the above-described devices is arranged. Although not shown, the scanner control device 16 is electrically connected to each device in the scanner unit. It is connected. In addition,
The scanner control device 16 and each device arranged on the rotary plate 2 are also electrically connected via a slip ring or the like (not shown). It can supply and exchange signals.

A subject 18 such as a patient, for example, placed on a top plate 17 of a so-called table unit, has an opening formed in the center of the rotating plate 2 in the direction of its length. 2 so as to be orthogonal to the surface.

FIG. 12 is a cross-sectional view of the X-ray CT scanner shown in FIG. 11 as viewed from the lateral direction. This FIG.
As is clear from FIG.
Can be moved in the horizontal direction and the vertical direction in the figure, and the top plate 17 on which the subject 18 is mounted can be moved in the horizontal direction and the vertical direction in the drawing. Can be aligned with

FIG. 13 is a view showing the structure of the whole unit of the X-ray CT scanner. The scanner unit 21 having the above-described internal structure and the table also having the above-described internal structure have been described. Unit 22
Is connected to the console unit 23 by a signal cable 24, and the scanner unit 21 and the table unit 22 operate together in accordance with an instruction from the console unit 23, thereby measuring the intensity distribution of X-rays transmitted through the subject 18. Is performed via the X-ray detector 7, and the measurement data is sent to the console unit 23 via the signal cable 24, and is imaged as a tomographic image by the image processing device of the console unit 23 and displayed to the operator.

Next, in the X-ray CT scanner device whose schematic configuration has been described above, measurement of the intensity distribution of X-rays
The line detector 7 is provided on the rotating plate 2 with the detector mounting member 8.
And, as mentioned above, a recent C
In the T-scanner, the X-ray detector 7 is firmly fixed to the rotating plate 2 so as to withstand continuous high-speed rotation in order to enable continuous high-speed rotation (about one second per rotation). There is a need.

FIG. 1 shows a detector fixture 8 for firmly fixing an X-ray detector 7 to the rotating plate 2 in the X-ray CT scanner according to the present invention. In this embodiment, the detector mounting member 8 can be provided with a heat insulating effect by using a material that is mechanically strong and has low thermal conductivity. . In addition, as a specific material, dimensional accuracy by processing can be secured to some extent, and machine processing is possible, for example,
A plate-like member such as stainless steel or acrylic is conceivable. Reference numeral 31 in the drawing denotes a mounting hole on the rotating plate 2 side, and reference numeral 32 denotes a mounting hole on the X-ray detector 7 side.

FIG. 2 shows a modified example of the detector mounting member 8. As is apparent from the drawing, in this embodiment, a material having mechanical strength necessary for the mounting member and a heat conductive material are used. The material having a low rate is a single or multiple sandwich structure 33. Such a sandwich structure 3
According to 3, there is also obtained an effect that the strength can be increased as compared with the case where the detector mounting member 8 is formed only of a single material having low thermal conductivity. Note that reference numeral 31 in FIG.
And 32 are a mounting hole on the rotating plate 2 side and a mounting hole on the X-ray detector 7 side.

Next, as still another modification of the detector mounting member 8, there is a structure shown in FIG. In this structure, FIG.
As shown in (a), by replacing the periphery of the mounting hole 31 on the rotating plate 2 side with a material 34 having a low thermal conductivity, a structure for obtaining a heat insulating effect for preventing heat transfer to the rotating plate 2 side can be obtained. . Furthermore, as shown in FIG. 3B, if only the mounting portion on the rotating plate 2 side is raised and the contact portion 35 is reduced,
A further heat insulating effect can be obtained.

Further, as still another modification of the detector mounting member 8, there is a structure shown in FIG. In the structure shown in FIG. 4, as is apparent from the drawing, contrary to the structure shown in FIG. 3, the mounting portion of the X-ray detector 7 of the detector mounting tool 8, that is, the X-ray detector The portion near the mounting hole 32 on the seventh side is replaced with a material 34 having low thermal conductivity. Even with such a structure of the detector mounting member 8, heat is hardly transmitted from the X-ray detector 7 to the detector mounting member 7, so that a heat insulating effect can be obtained.

In addition, FIG. 5 shows still another modified example of the detector mounting member 8. As is apparent from FIG. Between the mounting hole portion 31 to the detector 7 and the mounting hole portion 32 to the detector 7 side.
This is a structure in which a material 34 having low thermal conductivity is inserted. According to the detector mounting member 8 having such a structure, heat is hardly transmitted from the mounting hole portion 32 on the detector 7 side to the mounting hole portion 31 on the rotating plate 2 side, so that the heat insulating effect is also obtained.

Subsequently, the detector fixture 8 described variously above is used.
Hereinafter, a fixing structure for fixing the X-ray detector 7 to the rotating plate 2 will be described. First, in FIG. 6, in the case of the plate-like detector mounting member 8, the mounting hole portion 31 is attached to the wall surface 36 of the rotating plate 2, while the mounting hole portion 32 is attached to the detector 7.

Further, instead of the fixing structure described above, as shown in FIG. 7, the detector mounting member 8 may be a cantilever structure. When the detector mounting member 8 has a cantilever structure as described above, the contact area of the detector mounting member 8 with the scanner rotating plate 2 side is reduced, so that a further heat insulating effect is obtained. Is obtained.

Further, instead of the above-mentioned cantilever structure, FIG.
As shown in (1), it is possible to form the detector mounting member 8 in a bridge structure. In this case, an effect of increasing the strength can be obtained.

In addition, in the detector mounting fixture 8 having the cantilever structure or the bridge structure shown in FIGS.
There is a gap between the detector mounting member 8 and the wall surface 36 of the rotating plate 2 of the scanner. Therefore, as shown in FIG. 9 or FIG. 10, it is also possible to insert a material 34 having a low thermal conductivity into the gap between the detector mounting member 8 and the wall surface 36 in the same manner as described above. As described above, by inserting the material 34 having low thermal conductivity into the gap between the detector mounting member 8 and the wall surface 36, the strength is further increased while preventing heat conduction to the rotating plate 2. The effect that it becomes possible is also obtained.

[0031]

As is apparent from the above detailed description, according to the structure of the X-ray CT scanner according to the present invention, particularly the detector mounting fixture, the temperature inside the detector is stabilized, Accompanying this, accurate and stable data measurement becomes possible, and CT with good diagnostic performance without artifacts
Images can be provided. In addition, since the heat in and out of the detector is reduced and the heat retention effect is obtained, the operation of the temperature control device can be reduced, so that the power consumption related to the operation of the temperature control device can be reduced. can get.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the structure of a detector mounting tool which is a feature of the structure of an X-ray CT scanner according to an embodiment of the present invention.

FIG. 2 is a perspective view showing another structure of the detector mounting member.

FIG. 3 is a front and side sectional view showing still another structure of the detector mounting member.

FIG. 4 is a side sectional view showing still another structure of the detector mounting tool.

FIG. 5 is a perspective view showing still another structure of the detector mounting tool.

FIG. 6 is a side sectional view showing a detector mounting structure using the detector mounting tool.

FIG. 7 is a side sectional view showing another mounting structure of the detector by the detector mounting tool.

FIG. 8 is a side sectional view showing still another mounting structure of the detector using the detector mounting tool.

FIG. 9 is a side sectional view showing a modification of another mounting structure of the detector using the detector mounting tool.

FIG. 10 is a side sectional view showing a modification of another mounting structure of the detector using the detector mounting tool.

FIG. 11 is a front sectional view showing the inside of a scanner unit of the X-ray CT scanner according to the embodiment of the present invention.

FIG. 12 is a side sectional view showing the inside of a scanner unit of the X-ray CT scanner according to the embodiment of the present invention.

FIG. 13 is a system configuration diagram of the X-ray CT scanner according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Scanner cover 2 Rotating plate 3 X-ray tube device 7 X-ray detector 8 Detector mounting fixture 9 Amplifying circuit device 12 Belt 13 Driving motor 31 Rotating plate side mounting hole 32 Detector side mounting hole 33 Sandwich structure 34 Heat Low-conductivity material 35 Contact part of rotating plate 36 Wall surface of rotating plate

Claims (1)

[Claims] An opening for arranging a subject is provided in a center portion of a disk, an X-ray tube and an X-ray detector are arranged to face each other across the opening, and the X-ray detection is performed. A rotating plate in which an amplifier circuit device for amplifying an electric signal from the detector is provided, and a mechanism for driving the rotating plate to rotate is provided, and a temperature controller for keeping the temperature constant is provided inside the X-ray detector, And the X
In an X-ray CT scanner having a structure in which a line detector is fixed on the rotary plate by a fixture, the fixture for fixing the X-ray detector on the rotary plate has a structure having a low thermal conductivity. An X-ray CT scanner device, wherein the temperature in the X-ray detector is prevented from flowing to the rotating plate.