JPH11271456A - Flat detector - Google Patents

Abstract

[PROBLEMS] To properly control the temperature of an X-ray flat panel detector, and more specifically, to maintain the temperature within an operating temperature and a storage temperature. Provided is an X-ray flat panel detector capable of obtaining a uniform image without causing a problem such as deterioration of the X-ray plane. As a means for adjusting the temperature of an X-ray flat panel detector, a cooling mechanism (6) attached to a heat generation area (61) of a glass support (60) is provided. The cooling mechanism 6 includes a Peltier element 63,
It is composed of a radiation fin 65 and a forced air cooling fan 66. Silicon rubbers 62 and 64 as heat conductors are provided between the Peltier element 63 and the glass support 60 and between the radiation fin 66 and the Peltier element 63. The drive of the Peltier element 63 and the forced air cooling fan 66 is independently controlled. It is thus possible to operate each simultaneously or individually.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a flat panel detector used for an X-ray diagnostic apparatus, for example.

[0002]

2. Description of the Related Art As a conventional example of a flat panel detector used in an X-ray diagnostic apparatus, several X-ray solid flat panel detectors employing a direct conversion system or an indirect conversion system have been proposed. The former is described, for example, in U.S. Pat. No. 5,319,206, and the latter is described, for example, in U.S. Pat. No. 4,689,206.
487.

FIG. 1 is a diagram showing a schematic configuration of a direct conversion type X-ray solid flat panel detector, and FIG. 2 is a diagram showing a schematic configuration of an indirect conversion type X-ray solid flat panel detector. These flat detectors are provided with means for converting electromagnetic waves (X-rays) into electric charges. For example, in the direct conversion method shown in FIG.
X-rays incident on (selenium: photoconductor) contribute to charge generation and are accumulated in the capacitance of the pixel. Further, in the indirect conversion type flat detector shown in FIG. 2, X-rays are once converted into light through a chemical substance (a scintillation layer shown in FIG. 2) such as an intensifying screen or a CSI crystal. The light intensity is accumulated as a charge in the capacitance of the pixel.

Further, the conventional flat panel detector has means for converting the amount of charge into a voltage, selects the charge stored in the pixel by, for example, a switching function of a thin film transistor, and charges (reads) the selected charge. ) The voltage output of the amplifier is obtained by transferring it to the amplifier. In addition, there is provided means for converting a voltage output from the charge amplifier obtained as an analog into a digital value (for example, an ADC (A / D converter) for converting an analog value into a digital value). FIG. 3 shows a configuration for reading out a signal (charge) in such a flat panel detector. The plane detector has a conversion layer that generates charges according to the incident electromagnetic wave, pixel electrodes arranged in a two-dimensional matrix that collects the charges generated by the conversion layer, and stores the charges collected by the pixel electrodes. A charge storage element connected to each pixel electrode, and readout means for reading charge information stored in the charge storage element. The reading means electrically connects the switching elements (eg, thin film transistors) respectively connected to the charge storage elements and the TFT gates in the same row so that the charge information respectively connected to the charge storage elements can be read. A control signal line to be controlled, a switching element control means for controlling the switching elements On and Off in units of rows by supplying a control voltage to the control signal line, and an output of a TFT in the same column is electrically connected. An output signal line and a selection means for selecting and outputting the output of each output signal line are provided.
The above-described flat detector is not limited to X-rays, but can be considered as a flat detector for light.

[0005] The allowable temperature range of the above-described flat detector during operation and storage is not so large. Specifically, for example, 10 ° C. to avoid melting, alteration, and freezing (at low temperature) of Se (photoconductor).
Generally, it is set to 〜50 ° C.

[0006] Then, there is a problem that the temperature of the detector cannot be maintained in such a narrow temperature range depending on the heat generation of the detector itself or a change in the outside air temperature. by the way,
When a high voltage may be applied to the switching element of each reading unit, a mechanism for protecting the switching element (specifically, a thin film transistor or the like) is provided. When a current flows through the resistance portion in the detector, heat is generated, and there is a problem that Se (photoconductor), an additional film and the like are deteriorated and a uniform image cannot be obtained.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above circumstances, and has as its object to appropriately control the temperature of an X-ray flat panel detector, and more specifically, to operate the detector. Provided is an X-ray flat panel detector capable of maintaining a temperature within the storage temperature and without causing a problem such as deterioration of a photoconductor or the like of the X-ray flat panel detector and capable of obtaining a uniform image. That is.

[0008]

In order to solve the above-mentioned problems and achieve the object, a flat panel detector according to the present invention is configured as follows. The flat detector of the present invention is provided corresponding to a plurality of pixels arranged on the detection surface, a charge conversion means for converting incident X-rays into charges, and provided corresponding to the charge conversion means, In a flat detector provided with a detection unit including a storage unit that stores the charge converted by the charge conversion unit and a charge readout unit that reads out the charge stored in the charge storage unit, a predetermined amount near the charge conversion unit is provided. A temperature control means is provided in the heat generation area and controls the temperature of the area.

According to this configuration, the temperature of the predetermined heat generating region near the charge conversion means can be controlled, and thereby the temperature of the flat detector can be prevented from exceeding the allowable temperature range during operation and storage.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 4 is a view showing X according to a first embodiment of the present invention.
FIG. 3 is a perspective view illustrating a configuration of a cooling mechanism provided in the linear flat panel detector. In the figure, reference numeral 60 denotes a glass support of the X-ray flat panel detector, and the glass support 60 is provided on the side opposite to the X-ray detection surface. The present embodiment includes a cooling mechanism 6 attached to the heat generation region 61 of the glass support 60 as a means for adjusting the temperature of the X-ray flat panel detector. Note that X
Since the configuration of the line plane detector is the same as that of the above-described conventional one, a specific description is omitted here.

The cooling mechanism 6 is a Peltier element 6 here.
3. It is composed of a radiation fin 65 and a forced air cooling fan 66. Silicon rubbers 62 and 64 as heat conductors are provided between the Peltier element 63 and the glass support 60 and between the radiation fin 66 and the Peltier element 63.

Peltier element 63 and forced air cooling fan 66
Are independently driven and controlled. For this reason, each can be operated simultaneously or individually.
The operation of the present embodiment configured as described above will be described.

First, after the operation of the detector main body is started, the driving of the Peltier element 63 is started. The drive voltage at this time is not limited to a specific value. In addition, the forced air cooling fan 66 is driven and operated together with the driving of the Peltier element.

By operating the Peltier element 63,
The heat from the heat generating region 61 is conducted to the radiation fin 65 via the silicone rubbers 62 and 64. Since the silicon rubbers 62 and 64 are made of a heat conductor, the heat generation region 61
The heat conduction between the Peltier device 63 and the Peltier device 63 and between the Peltier device 63 and the radiation fins 65 are good. Further, according to the radiation fins 65, heat transmitted from the silicon rubber 64 is radiated. On the other hand, when the forced air cooling fan 66 operates, the space between the heat generation region 60 and the radiation fins 65 is forcibly cooled.

Peltier element 63 and forced air cooling fan 66
Is completed after the operation of the X-ray flat panel detector is completed. Note that it is desirable to control the driving of the Peltier element 63 or the forced air cooling fan 66 in order to prevent overcooling or prevent a phenomenon in which the Peltier element 63 itself becomes high temperature due to heat storage.

According to this embodiment described above, the temperature of the X-ray flat panel detector does not exceed the allowable temperature range during operation and storage. Therefore, the problem that the photoconductor of the X-ray flat panel detector is deteriorated by heat does not occur, and a uniform image can be obtained.

(Second Embodiment) In a second embodiment of the present invention, the temperature of the heat generation area is measured, and when the temperature falls outside the allowable temperature range during operation or storage, cooling or heating is forcibly performed. The present invention relates to an X-ray flat panel detector having a temperature control unit for performing the same. FIG. 5 is a circuit diagram showing a schematic configuration of the temperature adjusting means.

As shown in FIG. 1, a temperature measuring sensor 70 composed of, for example, a thermocouple is provided to take out the temperature of the X-ray flat panel detector as an electric signal. For example, the temperature measurement sensor is provided so as to be in contact with a portion of the X-ray flat panel detector other than the high voltage surface. X
The configuration of the line plane detector is the same as the above-described conventional one.

A comparator 71 for determining whether or not the current temperature of the X-ray flat panel detector is outside the allowable temperature range during operation and storage based on the electric signal obtained from the temperature measurement sensor. 72.

Further, a heater 73 and a cooler 74 for controlling the temperature of the X-ray flat panel detector in accordance with the judgment results of the comparators 71 and 72 are provided. Here, the cooler 74 is a semiconductor element such as the Peltier described in the first embodiment, but is not limited thereto, and other means may be used. Specifically, any one of a heat sink, a forced air cooling unit, a water cooling unit, an oil cooling unit, a heat pipe, or a combination thereof may be used.

An A / D converter for converting an electric signal representing a temperature from an analog signal to a digital signal may be provided for facilitating the control. The operation of the present embodiment configured as described above will be described.

First, the temperature is measured by the temperature detecting sensor 70. An electric signal indicating the temperature as a measurement result of the sensor 70 is supplied to comparators 71 and 72, respectively. The comparator 71 outputs a true value when the detected temperature is lower than the allowable temperature range during operation or storage, and thereby the heater 73 is driven to heat the detector.

Thus, it is possible to avoid a problem at a low temperature of the detector that the photoconductor is separated from the glass support due to a difference between the expansion coefficient of the photoconductor (Se) and the expansion coefficient of the glass support.

On the other hand, if the detected temperature is higher than the allowable (guaranteed) temperature range during operation or storage, the comparator 72 outputs a true value, whereby the cooler 74 is output.
Is driven to forcibly cool the detector. The allowable temperature range during operation or storage is, specifically, 10 ° C. to 40 ° C. When the detector is heated, the heating effect may be enhanced by reversing the polarity of the current for driving the Peltier element.

According to this embodiment, the temperature of the X-ray flat panel detector can be maintained within the operating temperature and the storage temperature with higher accuracy than in the first embodiment. For this reason, the defect that the photoconductor of the X-ray flat panel detector is deteriorated does not occur, so that a uniform image can be obtained.

Here, a modification of the second embodiment will be described. (Modification 1) Modification 1 relates to an X-ray diagnostic apparatus including the X-ray flat panel detector according to the second embodiment. This apparatus includes means for stopping the X-ray irradiation from the X-ray tube and stopping the driving of the detector when the temperature of the X-ray flat panel detector becomes abnormal.

FIG. 6 is a block diagram for explaining the structure of the first modification. When an abnormal temperature rise (or drop) occurs during the operation of the detector and the temperature of the detector falls outside the allowable temperature range during operation or storage, the comparator 71, 72 shown in FIG. An OFF signal is issued, and the controller 8 controls the generation of X-rays.
0, and is supplied to the control unit 82 which controls the driving operation of the flat panel detector.

Thus, the controller 80 controls the X-ray tube 81 so as to stop the generation of X-rays. Further, the control unit 82 performs a control operation to stop driving of the detector.
When the generation of X-rays is stopped and the driving of the detector is stopped, the above-described temperature adjustment by the cooling and heating mechanism is performed.

According to the first modification, it is possible to avoid a problem caused by the detector continuing to operate at an abnormal temperature. (Modification 2) Modification 2 relates to a more specific configuration example in the case where the above-described temperature control mechanism is formed of a semiconductor element such as a Peltier element.

FIG. 7 is a sectional view of an X-ray flat panel detector according to a second modification of the present embodiment. As shown in the figure, a glass surface 90 is formed on the gate G side of a thin film transistor for signal readout including a gate G, a drain D, and a source S, and a surface of the glass surface 90 opposite to the detector. The Peltier device 91 is formed. The Peltier element 91 includes an n-type semiconductor, a p-type semiconductor, and a metal 92, and is connected to a DC power supply 94 for driving the element. Further outside the Peltier element 91, a heat sink 95 for improving the heat radiation effect (during cooling driving) is provided.

According to the second modification, it is possible to provide an X-ray flat panel detector in which a temperature adjusting mechanism is integrated. Less than,
A more specific effect of the first embodiment will be described.

FIG. 8 is a graph showing a temperature change during cooling in the X-ray flat panel detector according to the first embodiment. In the graph, the horizontal axis represents time, and the vertical axis represents temperature. Section A is a temperature change when the degree of adhesion between the X-ray flat panel detector and the cooling mechanism is reduced and the Peltier element 63 and the forced air cooling fan 66 are operated. Section B is a section between the X-ray flat panel detector and the cooling mechanism. The Peltier element 63 is turned off while keeping the adhesion of
Section C is a case where the forced air cooling fan 66 is operated, and section C is a case where the Peltier element 63 and the forced air cooling fan 66 are operated by increasing the degree of close contact between the X-ray flat panel detector and the cooling mechanism. This is a case where the Peltier element 63 is turned off and only the forced air cooling fan 66 is operated while keeping the degree of adhesion between the X-ray flat panel detector and the cooling mechanism high.

As can be seen from the graph, a high cooling effect can be obtained by increasing the degree of close contact between the X-ray flat panel detector and the cooling mechanism and operating the Peltier element 63 and the forced air cooling fan 66.

As described above, according to the present invention, the temperature of the X-ray flat panel detector can be maintained within the operating temperature and the storage temperature. Does not occur, and a uniform image can be obtained. The present invention is not limited to the above-described embodiment, and can be implemented with various modifications.

[0035]

As described above, according to the present invention, X
The temperature of the X-ray flat panel detector can be appropriately controlled, and more specifically, can be maintained within the operating temperature and the storage temperature. As a result, a defect such as deterioration of the photoconductor of the X-ray flat panel detector may occur. And an X-ray flat panel detector capable of obtaining a uniform image can be provided. Can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a direct conversion type solid-state flat panel detector according to a conventional example.

FIG. 2 is a diagram showing a schematic configuration of an indirect conversion type X-ray solid state detector according to a conventional example.

FIG. 3 shows a signal (charge) in a flat detector according to a conventional example.
FIG. 3 is a diagram showing a configuration for reading.

FIG. 4 is a perspective view showing a configuration of a cooling mechanism provided in the X-ray flat panel detector according to the first embodiment of the present invention.

FIG. 5 is a circuit diagram illustrating a schematic configuration of a temperature adjusting unit provided in an X-ray flat panel detector according to a second embodiment of the present invention.

FIG. 6 is a block diagram for explaining a configuration of a first modification of the second embodiment.

FIG. 7 is a sectional view of an X-ray flat panel detector according to Modification 2 of the second embodiment.

FIG. 8 is a graph showing a specific effect of the first embodiment.

[Explanation of symbols]

 Reference Signs List 60: Glass support 61: Heat generation area 62, 64: Silicon rubber 65: Radiation fin 66: Forced air cooling fan 70: Thermocouple 71, 72 ... Comparator 73: Heater 74: Cooler 80: Controller 81: X-ray tube 82 ... Control unit 90 ... Glass support 91 ... Peltier element 92 ... Metal 93 ... Semiconductor (n-type, p-type) 94 ... DC power supply for driving Peltier element 95 ... Heat sink

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Akira Tsukamoto 1385-1 Shimoishigami, Otawara-shi, Tochigi Pref.

Claims (9)

[Claims] 1. A charge conversion means provided corresponding to a plurality of pixels arranged on a detection surface and converting incident X-rays into charges; and a charge conversion means provided corresponding to the charge conversion means. Accumulating means for accumulating the charges converted by
A flat detector provided with a detection unit including a charge reading unit that reads out the charge stored in the charge storage unit; provided in a predetermined heat generation region near the charge conversion unit;
A flat panel detector comprising temperature control means for controlling the temperature of the area. 2. The apparatus according to claim 1, further comprising a measuring unit for measuring a temperature, wherein the temperature control unit cools or heats the heat generation area based on a measurement result of the measuring unit. A flat panel detector according to claim 1. 3. The temperature control means comprises a heat sink, forced air cooling means, water cooling means, oil cooling means, a semiconductor element such as a Peltier element, a heat pipe, a heater, or a combination thereof. Item 3. The flat panel detector according to item 1 or 2. 4. A flat detector according to claim 1, wherein said temperature control means is formed separately from said detection means. 5. A flat detector according to claim 1, wherein said temperature control means is integrally formed with said detection means. 6. The flat panel detector according to claim 5, wherein said temperature control means is constituted by using a semiconductor substance constituting said detection means. 7. The apparatus according to claim 5, wherein said temperature control means is formed on a support member provided in said detector means.
Or the flat panel detector according to 6. 8. The temperature control unit according to claim 1, wherein the temperature control unit controls the temperature so that the temperature of the detection unit is within an allowable temperature range during operation or storage. Plane detector. 9. X-rays for irradiating X-rays to a subject
An X-ray diagnostic apparatus comprising: a X-ray tube; and a flat detector for detecting X-rays emitted from the X-ray tube; a measuring unit for measuring a temperature of the flat detector; and a measurement result of the measuring unit. X from the X-ray tube based on
An X-ray diagnostic apparatus, comprising: means for stopping irradiation of the X-ray and stopping driving of the flat panel detector.