JP2005274169A - X-ray ct apparatus and detection method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray CT apparatus capable of being enhanced in the quality of a photographed image while enhancing the measuring sensitivity of X-ray detection, and to provide a detection method due to X-ray CT apparatus. <P>SOLUTION: In the X-ray CT apparatus equipped with a means for emitting X-rays to an object to be examined, a plurality of X-ray sensors for detecting X-rays transmitted through the object to be examined and an X-ray sensor signal processing circuit for processing the output signals of a plurality of the X-ray sensors, the X-ray sensor of the X ray CT apparatus is used as a CdTe sensor and a DC component is removed from the output signal from the output signal of the sensor. Alternatively, the X-ray sensor of the X-ray CT apparatus is composed of a material having polarizing effect characteristics and an AC coupling current integration circuit for detecting a sensor output current is provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an X-ray CT apparatus and a detection method using the X-ray CT apparatus.

  A semiconductor-based X-ray detection apparatus is described in, for example, Japanese Patent Application Laid-Open No. 10-512398.

Japanese National Patent Publication No. 10-512398

  However, improvement in image quality during long-time imaging with an X-ray CT apparatus has not been considered while improving measurement sensitivity of X-ray detection.

  An object of the present invention is to provide an X-ray CT apparatus and a detection method using the X-ray CT apparatus that can improve the quality of a captured image by the X-ray CT apparatus while improving the measurement sensitivity of the X-ray detection.

  The X-ray sensor of the X-ray CT apparatus is a CdTe sensor, and a DC component is removed from the output signal of the sensor. Alternatively, the X-ray sensor of the X-ray CT apparatus is made of a material having polarization effect characteristics, and has an AC coupled current integration circuit for detecting the sensor output current.

  According to the present invention, it is possible to improve the sensitivity of the X-ray CT apparatus and improve the CT image quality.

The X-ray sensor of the X-ray CT apparatus is a CdTe sensor, and a DC component is removed from the output signal of the sensor, or the X-ray sensor of the X-ray CT apparatus is a material having polarization effect characteristics, and the sensor output current is By having an AC coupling current integration circuit for detection, it is possible to improve the sensitivity of the sensor of the X-ray CT apparatus and improve the CT image quality.

The industrial X-ray CT apparatus is a very useful nondestructive inspection apparatus for observing and measuring the internal shape of an object. For this reason, recently it has come to be used mainly by automobile companies for measuring the shape of developed products and measuring the distribution of casting nests. In order to take a tomographic image of a large cast product or the like, an X-ray CT apparatus using an accelerator that generates high-energy X-rays with high transmission power as an X-ray source has been developed. For example, “Reference: Hiroshi Uemura, Industrial high energy X-ray CT apparatus and application to digital engineering, Journal of the Institute of Electrical Engineers of Japan, Vol. 122, No. 2, 100-
103, 2002 "shows an industrial X-ray CT apparatus using an electron beam accelerator as an X-ray source and a strip-shaped silicon semiconductor sensor as an X-ray detector. This X-ray CT apparatus is a so-called third-generation CT apparatus that takes a tomographic image by rotating the subject once around an axis perpendicular to the X-ray fan beam.

  FIG. 9 shows the configuration of an industrial X-ray CT apparatus having the configuration of a third generation CT apparatus. The X-ray CT apparatus includes an electron beam accelerator 1 that outputs an X-ray fan beam 2, a scanner 3 on which a subject 14 is installed, and X-ray sensors 4-1 to 4 that detect X-rays that have passed through the subject 14. 512 and a signal processing for amplifying the output signal of the collimator 5 and the sensor, which serves to suppress the incidence of scattered X-rays to the X-ray sensor 4 in order to improve the S / N ratio of the X-ray sensor 4 and converting it into a digital signal Collects digital data from the device 10 and the signal processing device and displays the control device 6 for controlling the entire device, the image reconstruction device 7 for image reconstruction, the image created by the image reconstruction and other information The controller 8 controls the operation of the electron beam accelerator 1, the scanner 3, and the signal processing device 10 according to a control command from the display device 8 and the control device 6. The X-ray CT apparatus 13 in this figure shows a third-generation X-ray CT apparatus that rotates a subject and images one cross section. The scanner 3 has a rotation function and each height of the subject. It has a function to move up and down to perform cross-sectional photography.

  The electron beam accelerator 1 is connected to a controller 9 by a control cable 16, and generation / stop of the X-ray fan beam is controlled by the controller. Similarly, the scanner 3 is connected to the controller 9 via a control cable 15 to adjust the rotation and vertical position of the scanner.

  The X-ray sensors 4 are arranged in a row so as to anticipate the generation point of the fan beam 2, and the imaging resolution improves as the number of sensors increases, but 512 in this conventional example are installed. The X-ray sensor detects X-rays that have passed through the subject every time an X-ray pulse is output from the electron beam accelerator 1 at a certain angle in synchronization with the rotation of the scanner. The signal corresponding to the X-ray dose output from the X-ray sensor 4 is amplified and converted into a digital signal, and then sent to the image reconstruction device 7 through the signal device 17 via the control device 6 and the CT image. Used for reconstruction.

  In an X-ray CT apparatus using an accelerator, X-rays are usually pulsed X-rays generated periodically due to the characteristics of the accelerator. As a general value, a powerful X-ray pulse (collection of X-ray photons) having a width of 5 μs is output in a period of 5 ms. In this conventional example, X-ray pulses are irradiated 1920 times during one rotation of the subject, and data is measured. That is, the X-ray dose is measured every 0.1875 degrees. Since there are 512 sensors, the data amount for reconstructing one slice is 512 × 1920 data amounts.

FIG. 10 shows the internal configuration of the signal processing apparatus 10. The preamplifiers 21-1 to 21-512 convert the output current of the sensor into a voltage and amplify it. The sample and hold amplifiers 22-1 to 22-512 hold the output of each connected preamplifier, and the AD converters 23-1 to 23-512 convert the output of the sample and hold amplifier into a digital value. The control circuit 24 controls these timings by signals from the controller 9.

  In the silicon semiconductor sensor, the detection efficiency of high energy X-rays is obtained about 20%. However, in order to improve the density resolution of tomographic images, the higher the detection efficiency (sensitivity) of the sensor, the better. Of course, the density is about twice as high as that of silicon, and the detection efficiency can be improved about twice. The use of CdTe semiconductor sensors, which are expected to be CdTe semiconductor sensors are already widely used for radiation wave height analysis, and in particular to analyze radionuclides at low dose rates, leakage current due to bias voltage is minimized and signal-to-noise ratio (SN ratio) is improved. It is desirable to do. A CdTe sensor using an In electrode as an anode and a Pt electrode as a cathode (hereinafter referred to as an In / CdTe / Pt sensor) can be considered. In this sensor, the leakage current is very small at 1 nA or less.

  If an In / CdTe / Pt sensor is used, detection efficiency about twice that of a silicon semiconductor sensor can be realized. When the In / CdTe / Pt sensor is applied to the third generation high-energy X-ray CT, the output of the sensor is about doubled, but the In / CdTe / Pt sensor is used for long-time tomographic image measurement. Fluctuated, and ring-shaped artifacts (false images) appeared in the image. In such a state, it is difficult to improve the accuracy of dimension measurement or the like from 3D bitmap data obtained by collecting tomographic images as described in the third generation technique described above.

  This is considered to be because the sensitivity changed during photographing due to the polarization effect peculiar to the CdTe sensor. The polarization effect is a phenomenon in which electrons are trapped in the vicinity of an electrode, the electric field in the sensor is reduced, and the sensitivity of the sensor is lowered. The influence varies depending on the dose rate and the bias voltage. At present, in ordinary radiation analysis applications, the polarization effect of the CdTe sensor is suppressed to a problem-free level by increasing the bias voltage. For radiation analysis applications, the dose rate is at most about 10,000 cps (counts per second).

In contrast, in a high energy X-ray CT apparatus such as an accelerator as a means for emitting X-rays to the device under test, 10,000 or more X-rays are incident on the sensor in 5 μs. 2 × 10 ⁹
cps, which is a dose rate that is orders of magnitude greater than that of radiation analysis applications. Under such a high dose rate, the In / CdTe / Pt sensor causes a decrease in sensitivity. If the irradiation is performed for a certain period of time, the sensitivity becomes constant, and a tomographic image can be taken with twice the sensitivity of the Si sensor. However, in the X-ray CT apparatus, a large number (several hundreds) of tomographic images of the subject are continuously photographed. In this case, the dose rate of X-rays incident on the sensor (especially the sensor in the vicinity of the center) is maintained at a low state as compared with the case where there is no subject for a long time. When the dose rate of X-rays is lowered, the decrease in sensitivity due to the polarization effect is alleviated, and conversely, the sensitivity is restored. It is considered that such a sensitivity change of the sensor causes a ring artifact in the reconstructed tomographic image. In such a measurement environment, it was found that the In / CdTe / Pt sensor is greatly affected by the polarization effect, which is a very big problem in the high energy X-ray CT apparatus.

  For this reason, it is also considered that for each X-ray pulse, the bias voltage applied to the CdTe sensor is changed to recover the polarization effect, thereby preventing a change in sensitivity of the CdTe sensor. However, the bias voltage used for the CdTe sensor is about 100V or more, and a complicated control circuit is required to turn on / off in the order of ms, and the circuit itself becomes a noise source, reducing the measurement accuracy of the reconstructed image. There is a possibility to make it.

  Next, it demonstrates more concretely using one Example of this invention. FIG. 1 is a diagram showing the configuration of an embodiment of the present invention. The outline will be described with reference to FIG. The X-ray CT apparatus is a means for emitting X-rays to a test object, and is an X-ray generator that outputs an X-ray fan beam 102, that is, an electron beam accelerator 101, a scanner 103 on which a subject 114 is installed, a subject In order to improve the S / N ratio of the X-ray sensors 104-1 to 104-512 that detect X-rays that have passed through 114 and the X-ray sensor 4, the role of suppressing the incidence of scattered X-rays to the X-ray sensor 104. Collimator 105, a signal processor 110 that amplifies the output signal of the sensor and converts it into a digital signal, a controller 106 that collects digital data from the signal processor and controls the entire apparatus, and an image that performs image reconstruction Electron beam acceleration by a control command from the reconstruction device 107, a display device 108 for displaying an image created by image reconstruction and other information, and a control device 106 101, a controller 109 for controlling the operation of the scanner 103, and a signal processing device 110.

  The operation of the X-ray CT apparatus in the third generation CT technology has already been described with reference to FIG. However, in this embodiment, the X-ray sensors 104-1 to 104-512 use CdTe semiconductor sensors (Pt / CdTe / Pt sensors) using Pt electrodes for both the anode and cathode, and measure the output of the sensors. An AC-coupled current integrating amplifier is used for the sensor signal amplification unit of the signal processing apparatus.

  Hereinafter, a detailed description will be given with reference to FIG. FIG. 3 is an elevation view and a plan view showing the structure of the X-ray sensor used in this embodiment. Pt electrodes 201 and 202 are deposited on and under the CdTe crystal 200 to form a Pt / CdTe / Pt sensor. The Pt / CdTe / Pt sensor is bonded to the insulating substrate 203, the Pt electrode 202 on the insulating substrate 203 side is directly bonded to the printed wiring terminal 208 with a conductive adhesive, and the upper Pt electrode 201 is printed with the bonding wire 206. 207. The size of the CdTe crystal is 3 mm long × 40 mm wide × 0.5 mm high. As the insulating substrate 203, a flexible substrate is used. The heavy metal substrate 204 is made of a tungsten alloy and plays a role of shielding X-ray scattering and counter-electron incident on the adjacent sensor simultaneously with protecting the sensor.

The X-ray sensor 104 is installed in the apparatus so that X-rays enter from the direction of the arrow in the figure.
Since CdTe is used, the density is about twice that of Si, so the sensitivity to incident X-rays, that is, the detection efficiency is about twice. CdTe material can improve sensitivity and detection efficiency. Here, a tungsten target is attached to the tip of the accelerator as a target, and X-rays are generated by irradiation with an electron beam. When an electron beam accelerator of 6 MeV is used as the electron beam accelerator 101, X-rays having a maximum energy of 6 MeV are generated. When the detection efficiency of each sensor is calculated by the Monte Carlo method under this condition, the Si sensor is approximately 20%, and the CdTe sensor. Then, it is about 40%.

  The X-ray sensor desirably has high sensitivity and no leakage current. The In / CdTe / Pt sensor used for X-ray wave height analysis with a highly sensitive CdTe sensor is ideal because it has a leak current of 1 nA or less. A Schottky barrier is formed by using the In electrode, thereby reducing the leakage current. For this reason, it has been found that the sensitivity change due to the polarization effect is large under the high dose rate environment of the X-ray CT apparatus although the sensitivity is high and the leakage current is small.

  Therefore, in this embodiment, a CdTe sensor (Pt / CdTe / Pt sensor) using Pt electrodes for both the anode and the cathode is used. The Pt / CdTe / Pt sensor is less affected by the polarization effect than the In / CdTe / Pt sensor in the application field of X-ray wave height analysis (the dose rate is very small as described above). It is known that there are many influential leak currents.

  When a Pt electrode is deposited on a CdTe crystal, it becomes an ohmic electrode, and the resistance of the sensor is determined by the resistance value of the crystal. Therefore, the leakage current when a bias voltage is applied is as large as 10 nA to 1 μA. However, when used as a sensor of an X-ray CT apparatus using an accelerator, the number of incident X-ray photons is very large, and even if the leakage current is large compared to the example of measuring the energy of one photon, the leakage current As long as the direct current component can be removed, the influence of the fluctuation of the leakage current is small.

  Ohmic electrodes can also be realized with Au. Other materials may be used as long as they can realize ohmic electrodes for both the anode and cathode of the CdTe sensor. By using an ohmic electrode, the sensitivity change due to the polarization effect can be reduced even in a high dose rate environment of a high energy X-ray CT apparatus.

FIG. 2 is a diagram illustrating a configuration of the signal processing device 110. The signal processing device 110 includes a bias power supply 127 for supplying a bias voltage to all the X-ray sensors 104-1 to 104-512, preamplifiers 121-1 to 121-512 for amplifying output current from each X-ray sensor, S / H amplifiers 122-1 to 122-512 that are sampling and hold amplifiers that hold the output of the preamplifier 121 for AD conversion, AD converters 123-1 to 123-512 that AD-convert the held signals, and each AD From the controller 126 that reads the digital data output from the converter via the bus 125 and transfers the data to the control device 106, the output hold of the S / H amplifier 122, and the timing controller 124 that controls the AD conversion start timing of the AD converter 123. Become.

  FIG. 4 is a diagram showing the configuration of the preamplifier 121. The X-ray sensor 104 has an anode connected to the bias power supply 127 and a cathode connected to the input of the preamplifier 121. The input of the preamplifier 121 is connected to the ground by a resistor 130, and is connected to the inverting input of the OP amplifier 136 via a capacitor 131 and an input resistor 132. The inverting input is coupled with the output of the OP amplifier, the feedback resistor 134 and the feedback capacitor 133. As is apparent from this configuration, the leak current (which is a DC current) of the X-ray sensor 104 due to application of a bias voltage is cut off by the capacitor 131 and flows through the resistor 130. For this reason, it is amplified by the preamplifier 121 and does not appear in the output. The sensor output pulse current due to the X-ray pulse generated by the electron beam accelerator 1 passes through the capacitor 131 and is amplified by the preamplifier.

In order for the pulse current to flow into the feedback capacitor 133 and the feedback resistor 134, the value of the resistor 130 needs to be the value of the resistor 132. In this example, the resistor 130 has 1 MΩ and the resistor 132 has almost 0. Used. The capacitor 131 is 100 pF, the capacitor 133 is 20 pF, and the resistor 134 is 10 MΩ. When such a constant is used, when an X-ray pulse having a width of 5 μs is incident on the X-ray sensor 104, the sensor current flows into the capacitor 133 and is integrated, and the output voltage is proportional to the incident X-ray dose (number of photons). Is output to the output terminal 137 of the preamplifier 121.

  FIG. 5 is a diagram showing the time change of the X-ray pulse incident on the X-ray sensor, the output current of the sensor, the preamplifier output voltage, and the output voltage of the S / H amplifier in the next stage. As described above, the X-ray pulse width Tp (= t1-t0) is 5 μS. Further, the generation interval (t3-t0) of the X-ray pulse is controlled by the controller 9 and is constant, and is 5 ms in this embodiment. Regardless of the presence or absence of an X-ray pulse, a constant leak current flows through the sensor, and the output current resulting from the X-ray increases only while the X-ray is incident on the sensor. In the preamplifier described with reference to FIG. 4, only the sensor output current due to X-rays is integrated into the capacitor 133 to become a preamplifier output voltage.

  Therefore, when a Pt / CdTe / Pt sensor is used for the X-ray sensor, not only an increase in the preamplifier output due to the high sensitivity of the CdTe sensor can be obtained, but also the disadvantage that the leakage current of the Pt / CdTe / Pt sensor is large can be eliminated. .

  As shown in this figure, the preamplifier output voltage is 0 V before the X-ray pulse is generated, and increases while integrating the current (X is negative because it is an inverting circuit) while the X-ray pulse is incident on the X-ray sensor (time t0 to t1). When the X-ray generation disappears, it attenuates with a constant time constant and returns to zero. Since the S / H amplifier holds the output at time t1 under the control of the timing controller 124, it can be converted into a digital value by the AD converter during the hold period (time t1 to t2).

  Of course, the values of the capacitors and resistors in the above-described embodiments are not limited to these values.

  As described above, by using a Pt / CdTe / Pt sensor as an X-ray sensor and combining it with an AC coupling current / voltage conversion preamplifier, an increase in preamplifier output due to the high sensitivity of the CdTe sensor can be obtained. In addition, the effects of large leakage currents of Pt / CdTe / Pt sensors can be removed, sensitivity changes when using In / CdTe / Pt sensors with low leakage currents can be avoided, and X-ray CT measurement sensitivity can be improved. It is possible to provide an industrial X-ray CT apparatus that improves the quality of the reconstructed image even during long-time imaging. In addition, the X-ray sensor is made of a material having polarization effect characteristics to improve sensitivity, and the influence of leakage current is reduced by an AC coupling current integration circuit for detecting the sensor output current, thereby improving measurement sensitivity and imaging quality. Improvement can be achieved.

  FIG. 6 shows another embodiment of the X-ray sensor 104 and the preamplifier. In this embodiment, the bias power source is set to a negative voltage, and a signal is taken out from the cathode side of the X-ray sensor 104. In this case as well, the same effect as in the first embodiment can be obtained, but since the bias voltage is applied to the capacitor 131 as it is, the withstand voltage of the capacitor needs to be high. Needless to say, a signal can be extracted from the anode side of the X-ray sensor.

  FIG. 7 shows the configuration of an X-ray sensor and a preamplifier in still another embodiment. In this embodiment, the preamplifier 140 has a sensor current integration function and an S / H amplifier hold function simultaneously. The resistor 142 plays the role of causing a leakage current to flow to the ground, like the resistor 130 in the first embodiment (FIG. 4). The capacitor 143 is for AC coupling so that a leak current does not flow into the input of the OP amplifier 145. The switches S1 and S2 are controlled by the controller 141, and the circuit implements the function of a current integration / hold circuit by the operation of the switches S1 and S2.

  FIG. 8 shows the operation of the circuit of FIG. The switches S1 and S2 are closed before the X-ray pulse is output. Since the switches S1 and S2 are semiconductor switches, the resistance is not 0 but has a value of about 1 kΩ. Therefore, in this state, the output of the preamplifier 140 is 0 if the offset voltage of the amplifier is ignored. At the same time as the X-ray pulse output (time t0) (or immediately before), the controller 141 outputs a switch S2 closing signal, and the switch S2 is opened. Since the switch S1 is kept closed, the output current pulse of the sensor is integrated into the capacitor 144 and the amplifier output voltage is increased. At the same time (or immediately after) the X-ray pulse stops (time t1), the controller 141 outputs a switch S1 opening signal, and the switch S1 is opened. When both the switches S1 and S2 are opened, the output of the OP amplifier is held (time t1 to t2). In this state, the subsequent AD converter digitally converts the voltage value. After the digital conversion is completed, the controller 141 outputs an S2 closing signal (time t2), the switch S2 is closed, the electric charge (integrated value of the pulse current) accumulated in the capacitor 144 is discharged, and the output of the amplifier returns to zero. . The S1 close signal is output from the controller 141 a little later (or simultaneously), the switch S1 is closed, and the X-ray pulse measurement returns to the initial state.

Even in such a configuration, by using a Pt / CdTe / Pt sensor as an X-ray sensor and combining with an AC coupling (AC coupling) current integration / hold preamplifier, the preamplifier output is increased due to the high sensitivity of the CdTe sensor. Not only can it be obtained, but the influence of the large leakage current of the Pt / CdTe / Pt sensor can be removed, and the sensitivity change when using an In / CdTe / Pt sensor with a small leakage current can be avoided. In addition, it is possible to provide an industrial X-ray CT apparatus in which the quality of a reconstructed image does not deteriorate even during long-time imaging.

  The present embodiment can also be applied to an X-ray CT apparatus using a Si sensor. That is, if the apparatus originally employs an AC coupled preamplifier, the bias power supply is changed to a high voltage one, and the breakdown voltage of the AC coupled capacitor is confirmed, so that the polarity of the Si sensor is matched to that of Pt / CdTe / Pt. An X-ray CT apparatus having double the sensitivity can be realized simply by exchanging the sensor. The bias power supply is several tens of volts for the Si sensor, but a CdTe sensor requires 100 to several hundred volts.

  Needless to say, the X-ray source is not limited to an accelerator as long as the X-ray source generates pulsed X-rays. Further, in the above-described embodiment, the pulse current is converted into voltage and integrated by the preamplifier that is AC-coupled with the X-ray sensor. However, it is also possible to perform only the current-voltage conversion and provide the integration function in the subsequent circuit. Of course. Furthermore, in order to improve the signal-to-noise ratio of the measurement signal, it is possible to shape the waveform with a band-pass filter after the integrating circuit.

  As described above, according to the present embodiment, a CdTe sensor using ohmic electrodes for both the positive and negative electrodes is used as the sensor of the X-ray CT apparatus, and an AC coupled current integrating circuit is used to detect the sensor output current. By providing and removing the leakage current that causes problems with the sensor, not only can the preamplifier output be increased due to the high sensitivity of the CdTe sensor, but also the influence of the large leakage current of the Pt / CdTe / Pt sensor can be eliminated. In addition, it is possible to avoid sensitivity changes due to the polarization effect, increase the X-ray CT measurement sensitivity, and provide an industrial X-ray CT apparatus that does not deteriorate the quality of the reconstructed image even during long-time imaging. In other words, according to the present embodiment, not only the increase in the preamplifier output due to the higher sensitivity of the sensor can be obtained, but also the influence of the leakage current can be eliminated, the sensitivity change due to the polarization effect can be avoided, and the X-ray CT measurement sensitivity. In addition, it is possible to provide an X-ray CT apparatus and a detection method using the X-ray CT apparatus in which the quality of a reconstructed image does not deteriorate even during long-time imaging.

  The sensitivity of the X-ray CT apparatus and the CT image quality can be improved.

It is a figure which shows the structure of one Example of this invention. 2 is a diagram illustrating a configuration of a signal processing device 110. FIG. It is a figure which shows the structure of the X-ray sensor currently used for the Example. 2 is a diagram illustrating a configuration of a preamplifier 121. FIG. It is the figure which showed the time change of the X-ray pulse which injects into an X-ray sensor, the output current of a sensor, the preamplifier output voltage, and the output voltage of the S / H amplifier of the next stage. It is a figure which shows the structure of the X-ray sensor and preamplifier of another one Example. It is a figure which shows the structure of the X-ray sensor and preamplifier in a 3rd Example. It is a figure explaining operation | movement of the structure of the X-ray sensor and preamplifier of a 3rd Example. It is a block diagram of the conventional industrial X-ray CT apparatus. It is an internal block diagram of the signal processing apparatus of the conventional industrial X-ray CT apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,101 ... Electron beam accelerator, 3,103 ... Scanner, 4,104 ... X-ray sensor, 5,
105 ... collimator, 6, 106 ... control device, 7, 107 ... image reconstruction device, 8, 108 ... display device, 9, 109 ... controller, 10, 110 ... signal processing device, 121 ... preamplifier, 122 ... S / H Amplifier 123, AD converter 124, timing controller 125, bus, 200 CdTe crystal 201, 202 Pt electrode 203, insulating substrate 204 heavy metal substrate

Claims (9)

  Means for emitting X-rays to the device under test; a plurality of X-ray sensors for detecting X-rays transmitted through the device under test; and an X-ray sensor signal processing circuit for processing output signals of the plurality of X-ray sensors; An X-ray CT apparatus comprising: an X-ray sensor signal processing circuit having a means for removing a direct current component from an output signal of the sensor, wherein the X-ray sensor is a CdTe sensor.   Means for emitting X-rays to the device under test; a plurality of X-ray sensors for detecting X-rays transmitted through the device under test; and an X-ray sensor signal processing circuit for processing output signals of the plurality of X-ray sensors; X-ray CT comprising: an X-ray sensor signal processing circuit having an AC coupling current integrating circuit for detecting the sensor output current, wherein the X-ray sensor is made of a material having polarization effect characteristics apparatus. The X-ray CT apparatus according to claim 1 or 2,
An X-ray CT apparatus characterized in that an anode and a cathode of the X-ray sensor are ohmic electrodes. The X-ray CT apparatus according to claim 1 or 2,
An X-ray CT apparatus characterized in that means for emitting X-rays to a device under test is a high energy accelerator.   An accelerator that emits pulsed X-rays with a repetitive period, a scanner that rotates or vertically moves a test object irradiated with the X-rays emitted from the accelerator, and the test object that is irradiated to the test object A plurality of X-ray sensors that detect X-rays transmitted through the X-ray, an X-ray sensor signal processing circuit that processes output signals of the plurality of X-ray sensors, and the X-ray sensor processed by the X-ray sensor signal processing circuit A CT control device for reconstructing a fluoroscopic image of a cross section of the device under test based on the output signal of the test object, and the X-ray sensor is a CdTe sensor provided with both ohmic electrodes and an anode of the sensor, An X-ray sensor signal processing circuit having a filter that removes a DC component from the output signal of the sensor and an integration circuit that integrates the signal from which the DC component has been removed by the filter. Industrial X-ray CT apparatus characterized.   An accelerator that emits pulsed X-rays with a repetition period to the device under test, a plurality of X-ray sensors that detect X-rays transmitted through the device under test, and an X that processes output signals of the plurality of X-ray sensors An X-ray CT apparatus comprising: a line sensor signal processing circuit; wherein the X-ray sensor is a CdTe sensor, and sensitivity reduction suppressing means for the CdTe sensor is provided. The X-ray CT apparatus according to claim 6,
An X-ray CT apparatus comprising means for changing a bias voltage applied to the CdTe sensor for each X-ray pulse. Means for emitting X-rays to the device under test; a plurality of X-ray sensors for detecting X-rays transmitted through the device under test; and an X-ray sensor signal processing circuit for processing output signals of the plurality of X-ray sensors; A detection method using an X-ray CT apparatus comprising:
A detection method using an X-ray CT apparatus, wherein the X-ray sensor is a CdTe sensor, and a direct current component is removed from an output signal of the CdTe sensor. Means for emitting X-rays to the device under test; a plurality of X-ray sensors for detecting X-rays transmitted through the device under test; and an X-ray sensor signal processing circuit for processing output signals of the plurality of X-ray sensors; A detection method using an X-ray CT apparatus comprising:
A detection method using an X-ray CT apparatus, wherein the X-ray sensor is made of a material having polarization effect characteristics, and the sensor output current is detected by an AC coupling current integration circuit.

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