JP2014188287A - Radiation tomography system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a spatial resolution in a view direction in a reconstructed image while suppressing an increase in a cost, in imaging by a radiation tomography system.SOLUTION: Provided is a radiation tomography system in which, when projection data items of each of plural views are collected, imaging means controls a radiation source so that the radiation source can radiate a radiation over a second time Δt2 shorter than a first time Δt1 obtained by dividing a time per one turn of the radiation source by the number of views per one turn. Irradiation of a radiation is enabled or disabled by enabling or disabling feed of a supply voltage KV to the radiation source, a response speed of which is high, so as to enable or disable feed of a supply current mA to the radiation source.

Description

  The present invention relates to a technique for improving spatial resolution in radiation tomography.

  Conventionally, the projection data (data) of multiple views is created by rotating the radiation source and detector around the object to be imaged, irradiating the object to be imaged with radiation and detecting the transmitted radiation with the detector. A radiation tomography apparatus that collects images and reconstructs an image based on the collected projection data is known (see, for example, Patent Document 1 and FIG. 3).

JP 2012-130542 A

  In such a radiation tomography apparatus, as shown in FIG. 7, the radiation source 2 and the detector 3 usually rotate around an iso-center ISO at a constant speed V, and the radiation source 2 is an object to be imaged 9. Is continuously irradiated with the radiation XR, and the detector 3 continues to detect the transmitted radiation. Then, a DAS (Data Acquisition System) (not shown) connected to the detector 3 integrates the output of the detector 3 at every time Δt1 corresponding to one view, and each integrated value is used as projection data of each view Vi. Collect as.

  Typically, the time per one rotation of the radiation source is, for example, about 0.35 [s (seconds) / rot (rotation)], and the number of views per one rotation of the radiation source is, for example, 1000 [view / rot (rotation)]. In this example, the time Δt1 corresponding to one view is about 0.35 [ms], and the rotation angle width of the radiation source corresponding to one view is about 2π / 1000 [rad]. As described above, the time Δt1 corresponding to one view and the rotation angle width Δθ1 of the radiation source 2 are very small, but the radiation source 2 and the detector 3 move while the DAS is integrating the output of the detector 3. There is no change in being. Therefore, the projection data of each view Vi includes a blur caused by the radiation source 2 and the detector 3 moving in the rotation direction, that is, the view direction, which causes the spatial resolution in the view direction to deteriorate in the reconstructed image. It has become.

  As a technique for solving this problem, it is conceivable to increase the number of views per one rotation of the radiation source to reduce the time Δt1 or the rotation angle width Δθ1 corresponding to one view. However, for this purpose, it is necessary to use a DAS that enables high-speed processing, which leads to a cost increase.

  Under such circumstances, there is a demand for a technique capable of improving the spatial resolution in the view direction in the reconstructed image while suppressing an increase in cost in imaging by the radiation tomography apparatus.

The invention of the first aspect
A radiation source whose radiation output is controlled by a supply voltage and a supply current, and a detector, rotating the radiation source and the detector around the object, irradiating the object from the radiation source, A radiation tomography apparatus comprising: imaging means for detecting transmission radiation of the object by a detector and collecting projection data of a plurality of views; and reconstruction means for reconstructing an image based on the collected projection data There,
In the projection data collection of each of the plurality of views, the imaging means emits radiation for a second time shorter than a first time obtained by dividing the time per rotation of the radiation source by the number of views per rotation. A radiation tomography apparatus for controlling the radiation source to irradiate is provided.

The invention of the second aspect is
Setting means for setting a supply voltage of the radiation source for each of the plurality of views;
In the projection data collection of each of the plurality of views, the imaging means controls the supply voltage of the radiation source of the view to be a set supply voltage for the view, and sets the supply voltage of the radiation source of the view The radiation tomography apparatus according to the first aspect, which performs control to obtain a supply voltage at which a supply current of a radiation source is cut off, is provided.

The invention of the third aspect is
The radiation tomography apparatus according to the second aspect, wherein the tube voltage at which the tube current is cut off is substantially 0V.

The invention of the fourth aspect is
The setting means sets a supply current of the radiation source for each of the plurality of views;
When the imaging unit performs control to make the supply voltage of the radiation source of the view the set supply voltage for the view in the projection data collection of each of the plurality of views, the supply of the radiation source of the view Provided is the radiation tomography apparatus according to the second aspect or the third aspect, wherein control is performed so that the current is set to a supply current larger than a set supply current for the view.

The invention of the fifth aspect is
In the projection data collection of each of the plurality of views, the imaging means makes the time integration of the setting tube current for the view substantially the same as the time integration of the actual supply current of the radiation source for the view. The fourth aspect of the radiation tomography apparatus for controlling the supply current of the view is provided.

The invention of the sixth aspect is
The radiation tomography apparatus according to any one of the first to fifth aspects, wherein the second time in each of the plurality of views is set at a constant time interval.

The invention of the seventh aspect
The radiation tomography apparatus according to any one of the first to sixth aspects, wherein the imaging unit makes a data collection integration time per view shorter than the first time.

The invention of the eighth aspect
The radiation tomography apparatus according to the seventh aspect, wherein the data collection integration time per view is the same time as the second time.

The invention of the ninth aspect is
The radiation tomography apparatus according to any one of the first to eighth aspects, wherein the first time is 0.1 ms (milliseconds) or more and 1 ms or less.

The invention of the tenth aspect is
The radiation tomography apparatus according to the ninth aspect, wherein the second time is 20% or more and 60% or less of the first time.

The invention of the eleventh aspect is
The radiation tomography apparatus according to any one of the first to tenth aspects, wherein the setting unit sets a plurality of different supply voltages for each of the plurality of views according to a specific order. provide.

The invention of the twelfth aspect is
The radiation source is a radiation tube having a filament cathode and a target anode;
The supply voltage is a voltage applied between the filament cathode and the target anode;
The radiation tomography apparatus according to any one of the first to eleventh aspects, wherein the supply current is a current flowing between the filament cathode and the target anode.

The invention of the thirteenth aspect is
The radiation source is a radiation tube having a filament cathode, a target anode, and a grid electrode disposed between the filament cathode and the target anode;
The supply voltage is a voltage applied between the filament cathode and the grid electrode,
The radiation tomography apparatus according to the first aspect, in which the supply current is a current flowing between the filament cathode and the target anode.

  According to the above aspect of the invention, since the radiation irradiation time per view can be shortened without changing the number of views per rotation of the radiation source, projection of each view can be performed while using the DAS having the conventional processing capability. Blur in the view direction on the data can be reduced. As a result, it is possible to improve the spatial resolution in the view direction in the reconstructed image while suppressing an increase in cost.

1 is a diagram schematically showing a configuration of an X-ray CT (Computed Tomography) apparatus according to an embodiment of the invention. It is a figure which shows control of the X-ray tube 2 and DAS5 in the X-ray CT scan by the conventional method. It is a figure which shows control of the X-ray tube 2 and DAS5 in the X-ray CT scan by the method of a 1st Example. It is a figure which shows control of the X-ray tube and DAS in the X-ray CT scan by the method of a 2nd Example. It is a figure which shows control of the X-ray tube and DAS in the X-ray CT scan by the method of the 3rd Example. It is a flow figure showing an example of the flow of processing in the X-ray CT apparatus concerning this embodiment. It is a figure for demonstrating a mode that X-ray irradiation is made and the projection data are acquired while the X-ray tube and the X-ray detector are rotationally moved for each view.

  Hereinafter, embodiments of the present invention will be described. Note that the present invention is not limited thereby.

  FIG. 1 is a diagram schematically showing a configuration of an X-ray CT apparatus according to the present embodiment.

  As shown in FIG. 1, the X-ray CT apparatus 1 includes an X-ray tube 2, an X-ray detector 3, an X-ray tube controller 4, a DAS 5, a scan condition setting unit 6, A scan control unit 7 and an image reconstruction unit 8 are included. Note that the X-ray tube 2, the X-ray detector 3, the X-ray tube controller 4, the DAS 5, and the scan control unit 7 are examples of imaging means in the present invention. The scan condition setting unit 6 is an example of a setting unit in the present invention, and the image reconstruction unit 8 is an example of a reconstruction unit in the present invention.

  The X-ray tube 2 and the X-ray detector 3 are arranged to face each other with the imaging space B interposed therebetween. The X-ray tube 2 and the X-ray detector 3 are supported rotatably about an isocenter ISO that is the center of the imaging space B as a rotation axis. The subject 9 is placed on a table (not shown) and placed in the imaging space B. Here, the rotation axis direction of the X-ray tube 2 and the X-ray detector 3 is the z-axis direction, the vertical direction is the y-axis direction, and the horizontal direction perpendicular to the z-axis direction and the y-axis direction is the x-axis direction. The rotation direction of the X-ray tube 2 and the X-ray detector 3 is referred to as a view direction.

  The X-ray tube 2 has a filament cathode (not shown) and a target anode (not shown). The X-ray tube 2 accelerates the thermoelectrons generated at the filament cathode by a tube voltage applied between the cathode and the anode, and collides with the target anode. An X-ray focal point is formed on the target anode by electron collision, and X-rays are generated from the X-ray focal point. The energy distribution of X-rays output from the X-ray tube 2 depends on the tube voltage applied between the cathode and the anode, and the dose of X-rays output from the X-ray tube 2 depends on the tube current flowing between the cathode and anode. Dependent. Thus, the output of the X-ray tube 2 is controlled by the supplied tube voltage and tube current.

  The X-ray detector 3 has a detection surface that is curved so that the distance from the X-ray focal point of the X-ray tube 2 to each position is substantially equal. The detection surface is composed of a plurality of detection elements arranged in a matrix. Each detection element of the X-ray detector 3 detects X-rays (partially transmitted through the subject 9) emitted from the X-ray tube 2 toward the subject 9, and depends on the detected X-ray intensity. Output an analog signal. The detection element includes, for example, a scintillator and a photo-diode.

  The X-ray tube controller 4 controls the tube voltage and tube current of the X-ray tube 2 under the control of the scan control unit 6. The X-ray tube controller 4 has a high voltage generating circuit, and controls the voltage applied to the cathode-anode of the X-ray tube 2 by this circuit. The X-ray tube controller 4 has a constant current circuit, and controls the current flowing to the filament cathode of the X-ray tube 2 by this circuit.

  The DAS 5 converts the analog signal output from each detection element of the X-ray detector 3 into a digital signal and collects it as projection data. The DAS 5 integrates the analog signal from the detection element for each time corresponding to one view, and collects projection data of each view.

  The scan condition setting unit 6 sets scan conditions for performing an X-ray CT scan in accordance with an operation by the operator. The scan conditions include time per rotation of the X-ray tube (rotation speed of the X-ray tube) RT, the number of views VN per rotation of the X-ray tube, the tube voltage KV of the X-ray tube 2, the tube current mA, and the like. . The tube current mA may be set to the same current value for each view, or an independent current value may be set for each view or a group consisting of a plurality of views by an automatic exposure mechanism. . The time RT per one rotation of the X-ray tube is, for example, 0.35 s (seconds) / rot (rotation), and the view number VN is, for example, 1000.

  The scan control unit 7 controls the rotation of the X-ray tube 2 and the X-ray detector 3, the generation of X-rays from the X-ray tube 2, the data acquisition of the DAS 5, etc., and performs the X-ray CT scan. By performing this X-ray CT scan, projection data of a plurality of views of the subject 9 are collected.

  The image reconstruction unit 8 reconstructs an image based on the collected projection data of a plurality of views.

  The scan condition setting unit 6, the scan control unit 7, and the image reconstruction unit 8 are realized, for example, by causing a computer to execute a predetermined program.

  Hereinafter, the control of the X-ray tube and the DAS in the X-ray CT scan by the X-ray CT apparatus 1 according to the present embodiment will be described in detail.

(First embodiment)
FIG. 2 is a diagram showing control of the X-ray tube 2 and the DAS 5 in the X-ray CT scan according to the conventional method. FIG. 3 is a diagram showing the control of the X-ray tube 2 and the DAS 5 in the X-ray CT scan according to the method of the first embodiment. These figures are graphs of the time variation of the tube voltage KV and tube current mA of the X-ray tube 2 and the data acquisition integration period (time for integrating the output of the detection element) of the DAS 5 for each view during scanning. It is. Here, as the scanning conditions, the set tube voltage of the X-ray tube 2 is the first tube voltage KV1, and the set tube current is the first tube current mA1. Further, the DAS 5 data acquisition integration time per view is a first time corresponding to one view width obtained by dividing the time RT per one rotation of the X-ray tube by the number of views VN per one rotation of the X-ray tube. It corresponds to the width Δt1. Therefore, for example, if the time RT per one rotation of the X-ray tube is 0.35 s and the view number VN per one rotation of the X-ray tube is 1000, the first time width Δt1 is 0.35 ms, and per view. The data collection integration time ST is also 0.35 ms. The first time width Δt1 is generally assumed to be 0.1 ms or more and 1 ms or less.

  In the conventional method, as shown in FIG. 2, the tube current mA is controlled to maintain the first tube current mA1 and the tube voltage KV is controlled to maintain the first tube voltage KV1 regardless of the view. In this case, during the scan, the X-ray tube 2 always outputs X-rays at the first tube voltage KV1 and the first tube current mA1. That is, the X-ray irradiation period for each view coincides with the one-view corresponding period as it is.

  As the control in the X-ray tube controller 4, for example, the control target value of the tube current mA is set to the first tube current mA1, and the control target value of the tube voltage KV is set to the first tube voltage KV1. Keep it.

  On the other hand, in the method of the first embodiment, as shown in FIG. 3, for each view, the tube current mA is a second time width that is shorter than the first time width Δt1 in one view corresponding period. Control is performed so that a predetermined tube current mA2 is obtained only during a specific period of Δt2 and substantially 0 mA in other periods. Further, the tube voltage KV is controlled so as to maintain the first tube voltage KV1 during the specific period in which the tube current flows. In this case, during scanning, the X-ray tube 2 outputs X-rays at the first tube voltage KV1 and the second tube current mA2 only for the specific period. That is, the X-ray irradiation period for each view is only the specific period shorter than the time corresponding to one view. As a result, in the collection of projection data for each view, blurring on the projection data caused by the X-ray irradiation position moving in the view direction (X-ray tube rotation direction) can be suppressed, and the view direction in the reconstructed image It is possible to improve the spatial resolution.

  As the control in the X-ray tube controller, for example, the control target value of the tube current mA is set to the second tube current mA2, and the control target value of the tube voltage KV is set to the first in the X-ray irradiation period. The tube voltage KV1 is set to a voltage that cuts off the tube current mA in other periods, for example, 0V. Here, what is characteristic is that the control target value of the tube voltage KV is not changed, but the control target value of the tube voltage KV is changed. Conventionally, an X-ray tube often does not have a grid electrode for controlling an electron flow that collides with a target anode. The grid electrode is generally disposed between the filament cathode and the target anode, and has a hole or notch to ensure a path for electron flow. The on / off state of the electron flow and the flow rate are controlled by the voltage applied between the filament cathode and the grid electrode. In the case of an X-ray tube not having such a grid electrode, the tube current is controlled by changing the temperature of the filament cathode by changing the current flowing through the filament cathode filament of the X-ray tube, and then being emitted from the electrode. The tube current is controlled by adjusting the amount of thermionic electrons. However, the followability of the temperature of the filament cathode with respect to changes in the current flowing through the filament is not very good. For this reason, it is difficult to switch the tube current at high speed even if the current flowing through the filament is switched at high speed. On the other hand, the tube voltage is usually controlled by adjusting the output voltage of the high voltage generation circuit applied to the X-ray tube. Generally, the output response of the high voltage generation circuit to the control signal can be made sufficiently fast, so that the tube voltage can be switched at high speed. When the tube voltage is set to a voltage at which the tube current is cut off, the tube current becomes 0 mA without depending on the temperature of the filament cathode. In the present embodiment, this principle is used to realize high-speed switching of the tube current mA by high-speed switching of the tube voltage KV. This method enables high-speed switching of the tube current even for an X-ray tube that does not have a grid electrode. In the case of an X-ray tube having a grid electrode, high-speed switching of the tube current mA may be realized by high-speed switching of the voltage applied between the filament cathode and the grid electrode.

  By the way, when the X-ray irradiation period is shortened while the tube current mA remains the first tube current mA1, which is the set tube current, the X-ray dose irradiated to the subject 9 becomes insufficient, and the detection signal from the detection element The SN ratio is reduced. Therefore, in this embodiment, in order to prevent this, the control target value of the tube current mA is set to the second tube current mA2 that is larger than the first tube current mA1 that is the set tube current. In order to secure the X-ray dose irradiated to the subject 9 to the same extent as in the conventional method, the mAs value, that is, the time integration of the tube current mA may be made the same. Therefore, in this example, the time integration S (= mA1 · Δt1) of the first tube current mA1 based on the first time width Δt1 and the time integration S ′ ((mA1 · Δt1) of the second tube current mA2 based on the second time width Δt2 = MA2 · Δt2) is determined to be substantially equal to the second tube current mA2.

  In order to effectively suppress the blur on the projection data by the method of the present embodiment, the X-ray irradiation duty R which is the ratio of the second time width Δt2 to the first time width Δt1 is set. Just make it smaller. However, if the duty R is too small, the second tube current mA2 becomes very large when an S / N ratio of a certain level or more is to be secured in the detection signal of the detection element, and the output capability of the X-ray tube 2 is increased. Or a heavy burden is placed on the subject 9. Therefore, the duty R is preferably, for example, 20% or more and 60% or less, and more preferably, for example, 25% or more and 50% or less.

  In addition, the above-described specific period for outputting X-rays basically suppresses the blur on the projection data at any timing (timing) in the one-view corresponding period. However, if the timing of this specific period is different for each view, the uniformity of the step angle width in the X-ray irradiation direction of each view is lost. If this uniformity is lost, it becomes necessary to correct the projection data by interpolating projection data so that the step angle width in the X-ray irradiation direction of each view becomes uniform in the image reconstruction process. Technically, if it is known at which view position the X-ray was output, the projection data in the non-uniform view direction can be corrected to the projection data in the uniform view direction. In addition, the accuracy of projection data may be degraded due to interpolation. Therefore, it is preferable to set this specific period at the same fixed interval as the view so that the step angle width in the X-ray irradiation direction of each view becomes uniform.

(Second embodiment)
FIG. 4 is a diagram showing the control of the X-ray tube and DAS in the X-ray CT scan by the method of the second embodiment. As shown in FIG. 4, the method of the second embodiment is almost the same as the method of the first embodiment, but the data collection integration period for each view is different. In other words, in the first embodiment, the data acquisition integration period of DAS 5 for each view coincides with the one-view corresponding period as in the conventional case, and is longer in time than the X-ray irradiation period. On the other hand, in the second embodiment, the data acquisition integration period of DAS 5 for each view is synchronized with the X-ray irradiation period for each view. In this case, since the data acquisition integration time ST of the DAS 5 is shorter than the conventional one, the background noise contained in the output signal of the detection element per view can be reduced, and the SN ratio of the detection signal can be reduced. Can be improved.

(Third embodiment)
FIG. 5 is a diagram showing the control of the X-ray tube and the DAS in the X-ray CT scan by the method of the third embodiment. As shown in FIG. 5, the third embodiment is an example in which the method of the first embodiment is applied to multi-energy imaging that switches the tube voltage KV at high speed. That is, the X-ray is output for a specific period shorter than the one-view corresponding time for each view while switching the tube voltage KV to a plurality of different tube voltages, for example, a high tube voltage KV2 and a low tube voltage KV3. To control.

  In multi-energy imaging, it is necessary to collect projection data of a certain number of views or more for each of a plurality of tube voltages, but the rotational speed of the X-ray tube 2 cannot be made very slow in order to suppress the influence of body movement of the subject. That is, the one-view correspondence time tends to be shorter than normal shooting. Therefore, in multi-energy imaging, the technique of switching the tube current to 0 mA at a high speed by setting the tube voltage to 0 V has a greater effect.

  Hereafter, the flow of processing in the X-ray CT apparatus according to the present embodiment will be described.

  FIG. 6 is a flowchart showing an example of a processing flow in the X-ray CT apparatus according to the present embodiment.

  In step S1, some of the scanning conditions are received. Scan conditions for receiving input include a time RT per one rotation of the X-ray tube, a first tube voltage KV1, a first tube current mA1 for each view, and a ratio of the second time Δt2 to the first time Δt1. X-ray irradiation duty R is included.

  In step S2, other scan conditions are determined based on the input scan conditions. The view number VN per rotation of the X-ray tube is set in advance. The first time Δt1 is calculated as RT / VN. The second time Δt2 is calculated by R · Δt1. The data collection integration time ST per view of the DAS 5 is set to the first time Δt1 or the second time Δt2. The second tube current mA2 is calculated by mA1 · Δt1 / Δt2.

  In step S3, the X-ray tube 2 and DAS 5 are controlled as shown in FIG. 3 or FIG. 4 according to the set scanning conditions. That is, for each view, the X-ray CT scan is performed with the second time Δt2 shorter than the first time Δt1 corresponding to one view corresponding time as the X-ray irradiation time. Thereby, projection data of a plurality of views in which the blur in the view direction is suppressed is collected.

  In step S4, an image is reconstructed based on the collected projection data of a plurality of views. A known image reconstruction process is used for the image reconstruction.

  As described above, according to the present embodiment, since the X-ray irradiation time per view can be shortened without changing the number of views per one rotation of the X-ray tube, each DAS having the conventional processing capability can be used. The blur in the view direction on the projection data of the view can be reduced. As a result, it is possible to improve the spatial resolution in the view direction in the reconstructed image while suppressing an increase in cost.

  In addition, according to the current staring mode, the X-ray output is turned on and off for each view to increase the spatial resolution in the view direction, so that data collection integration is performed for each view in a state where X-rays are continuously output. Compared to the on / off method, there is no wasteful exposure to the subject (exposure due to X-rays that are not effectively used for image reconstruction). Further, even when the setting relating to data collection integration is not changed from the conventional setting, the spatial resolution in the view direction can be improved. In this case, the development cost of application software to be executed by a computer constituting the X-ray tube controller 4 and the scan control unit 7 can be suppressed.

  The invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention.

  For example, in the above embodiment, an X-ray tube is used as an X-ray source whose X-ray output is controlled by a supply voltage and a supply current, but other types of X-ray sources such as a semiconductor X-ray source are used. Also good.

  Moreover, although the said embodiment is an X-ray CT apparatus, invention is applicable also to the PET-CT apparatus, SPECT-CT apparatus, etc. which combined X-ray CT apparatus and PET or SPECT.

1 X-ray CT apparatus 2 X-ray tube 3 X-ray detector 4 X-ray tube controller 5 DAS
6 Scan condition setting unit 7 Scan control unit 8 Image reconstruction unit 9 Subject ISO Isocenter

Claims (13)

A radiation source whose radiation output is controlled by a supply voltage and a supply current, and a detector, rotating the radiation source and the detector around the object, irradiating the object from the radiation source, A radiation tomography apparatus comprising: imaging means for detecting transmission radiation of the object by a detector and collecting projection data of a plurality of views; and reconstruction means for reconstructing an image based on the collected projection data There,
In the projection data collection of each of the plurality of views, the imaging means emits radiation for a second time shorter than a first time obtained by dividing the time per rotation of the radiation source by the number of views per rotation. A radiation tomography apparatus for controlling the radiation source to irradiate. Setting means for setting a supply voltage of the radiation source for each of the plurality of views;
The imaging means controls the supply voltage of the radiation source of the view to be a set supply voltage for the view in the projection data collection of each of the plurality of views, and sets the supply voltage of the radiation source of the view to the The radiation tomography apparatus according to claim 1, wherein control is performed so that a supply current of a radiation source is cut off to be a supply voltage.   The radiation tomography apparatus according to claim 2, wherein a supply voltage at which the supply current is cut off is substantially 0V. The setting means sets a supply current of the radiation source for each of the plurality of views;
In the acquisition of projection data of each of the plurality of views, the imaging unit performs supply of the radiation source of the view to the set supply voltage for the view, and performs supply of the radiation source of the view. The radiation tomography apparatus according to claim 2, wherein control is performed so that the current is set to a supply current larger than a set supply current for the view.   In the projection data collection of each of the plurality of views, the imaging unit is configured so that the time integration of the set supply current for the view and the time integration of the actual supply current of the radiation source for the view are substantially the same. The radiation tomography apparatus according to claim 4, wherein a supply current of the view is controlled.   The radiation tomography apparatus according to any one of claims 1 to 5, wherein the second time in each of the plurality of views is set at a constant time interval.   The radiation tomography apparatus according to any one of claims 1 to 6, wherein the imaging unit makes a data collection integration time per view shorter than the first time.   The radiation tomography apparatus according to claim 7, wherein the data collection integration time per view is the same time as the second time.   The radiation tomography apparatus according to claim 1, wherein the first time is 0.1 ms or more and 1 ms or less.   The radiation tomography apparatus according to claim 9, wherein the second time is 20% or more and 60% or less of the first time.   The radiation tomography apparatus according to any one of claims 1 to 10, wherein the setting unit sets a plurality of different supply voltages for each of the plurality of views in a specific order. The radiation source is a radiation tube having a filament cathode and a target anode;
The supply voltage is a voltage applied between the filament cathode and the target anode,
The radiation tomography apparatus according to any one of claims 1 to 11, wherein the supply current is a current flowing between the filament cathode and the target anode. The radiation source is a radiation tube having a filament cathode, a target anode, and a grid electrode disposed between the filament cathode and the target anode,
The supply voltage is a voltage applied between the filament cathode and the grid electrode,
The radiation tomography apparatus according to claim 1, wherein the supply current is a current that flows between the filament cathode and the target anode.

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