JP5498061B2 - X-ray computed tomography system - Google Patents

Description

  The present invention relates to an X-ray computed tomography apparatus (X-ray CT apparatus) that generates a tomographic image of a subject based on the state of X-ray transmission through the subject.

  In the X-ray CT apparatus, the exposure dose of the subject is reduced by limiting the X-ray irradiation range to a necessary minimum by a diaphragm mechanism.

  A diaphragm mechanism in a conventional X-ray CT apparatus is configured to adjust the width of a slit formed between two sheets by changing the relative positions of the two shielding plates. The subject is irradiated with only X-rays that have passed through the slit.

  Patent Document 1 discloses a mechanism that enables each of the two shielding plates to be individually moved.

JP 2001-78994 A

  Conventionally, since the diaphragm mechanism has the above-described structure, only one X-ray irradiation range can be set. For this reason, when it is desired to simultaneously photograph a plurality of areas that are separated from each other, a large irradiation range including these areas must be set, and X-rays must be irradiated in areas other than the imaging area. For this reason, there has conventionally been a problem in that unnecessary exposure is caused depending on the photographing conditions.

  The present invention has been made in view of such circumstances, and its purpose is to further reduce the exposure dose of the subject by limiting the X-ray irradiation range to the minimum necessary. .

An X-ray computed tomography apparatus according to an aspect of the present invention includes an X-ray tube that emits X-rays, an X-ray detector that includes a plurality of X-ray detection elements that each detect the X-rays, A plurality of irradiation range setting means for individually and variably setting the X-ray transmission range in a section between the X-ray tube and the X-ray detector; and a plurality of regions of interest positioned apart from each other with respect to the subject And a plurality of irradiation ranges so as to shield the X-rays irradiated to the regions located between the plurality of regions of interest while irradiating each of the plurality of regions of interest with the X-rays. Generating to generate tomographic images for each of the plurality of regions of interest based on the detection status of the X-rays transmitted through the plurality of irradiation range setting means and the X-ray detector respectively through the control means for controlling the setting means hand Provided with a door.

  According to the present invention, it is possible to further reduce the exposure dose of the subject by limiting the X-ray irradiation range to the necessary minimum.

1 is a block diagram showing a configuration of an X-ray CT apparatus according to an embodiment of the present invention. The top view which shows the detailed structure of a part of X-ray restrictor in FIG. The top view of only the upper stage part of the X-ray restrictor shown by FIG. The top view of only the lower stage part of the X-ray restrictor shown by FIG. The figure which shows a mode that a part of structure shown by FIG. 2 was visually observed from the left in FIG. AA arrow sectional drawing in FIG. The figure which shows the modification of the structure of the X-ray restrictor in FIG. BB arrow sectional drawing in FIG. The figure which shows an example of the X-ray irradiation condition in a 1st operation state. The figure which shows an example of the X-ray irradiation condition in a 2nd operation state. The figure which shows an example of the X-ray irradiation condition in a 2nd operation state. The figure which shows an example of the X-ray irradiation condition in a 3rd operation state.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an X-ray CT apparatus 100 according to the present embodiment.

  As shown in FIG. 1, an X-ray CT apparatus 100 includes a mechanism unit 2, a mechanism control unit 3, an X-ray generation unit 4, a high voltage generation unit 5, an X-ray detection unit 6, an image calculation / storage unit 8, and a display unit 9. , An operation unit 10, a system control unit 11, and a top plate 12.

  The X-ray generation unit 4 and the X-ray detection unit 6 are mounted on an annular rotating mount (not shown) in an opposing relationship. The rotating gantry is driven to rotate by the gantry rotating mechanism 21. At this time, the X-ray generation unit 4 and the X-ray detection unit 6 rotate around the same rotation axis. The subject 200 is arranged inside the rotation trajectory of the X-ray generation unit 4 and the X-ray detection unit 6.

  The mechanism unit 2 includes a gantry rotating mechanism 21 and a bed moving mechanism 22. The gantry rotating mechanism 21 rotates the rotating gantry. The couch moving mechanism 22 moves the top 12.

  The mechanism control unit 3 controls the mechanism unit 2 according to a control signal from the system control unit 11 so as to form a desired shooting state.

  The X-ray generation unit 4 includes an X-ray tube 41, a filter (wedge) 42, and an X-ray restrictor 43. The X-ray tube 41 is a vacuum tube that emits X-rays, and the thermal electrons emitted from the cathode (filament) are accelerated by a high voltage applied between the anode and the cathode to collide with the tungsten anode to generate X-rays. . The filter 42 has a spatial distribution in the intensity of X-rays to compensate for the difference in distance transmitted through the subject 200 caused by the difference in X-ray radiation angle. The X-ray restrictor 43 is located between the X-ray tube 41 and the subject 200, and prevents the X-ray beam emitted from the X-ray tube 41 from being irradiated unnecessarily outside the observation site. We narrow down to field of view size.

  The high voltage generator 5 generates a high voltage to be applied between the anode and the cathode of the X-ray tube 41.

  The X-ray detector 6 includes an X-ray detector 61, a gate driver 62, and a data acquisition system 63.

  The X-ray detector 61 is configured by arranging a plurality of X-ray detection element arrays in a direction along the rotation axis. Each X-ray detection element of the X-ray detector 61 outputs a current signal having a magnitude corresponding to the intensity of the incident X-ray.

  The gate driver 62 drives the gate of the X-ray detector 61.

  Data acquisition system 63 further includes an IV converter, an integrator, a preamplifier, and an analog to digital converter. The IV converter converts the current signal output from the X-ray detector 61 into a voltage signal. The integrator periodically integrates the voltage signal output from the IV converter in synchronization with the X-ray exposure period. The preamplifier amplifies the output signal of the integrator. The analog / digital converter digitizes the output signal of the preamplifier and outputs it as scan data.

  The image calculation / storage unit 8 includes a data storage circuit 81 and an image calculation circuit 82. The data storage circuit 81 stores scan data output from the X-ray detection unit 6. The image arithmetic circuit 82 performs predetermined arithmetic processing on the scan data stored in the data storage circuit 81 to reconstruct a tomographic image. The data storage circuit 81 also stores image data representing the tomographic image reconstructed by the image calculation circuit 82.

  The display unit 9 includes a display image memory 91, a D / A converter 92, a display circuit 93 and a monitor 94. The display image memory 91 combines display data formed by synthesizing numbers and various characters representing supplementary information given from the system control unit 11 with the tomographic image represented by the image data stored in the data storage circuit 81. save. The D / A converter 92 converts the display data stored in the display image memory 91 into an analog signal. The display circuit 93 converts the analog signal into a TV format and generates a video signal. The monitor 94 displays the above video signal. As the monitor 94, for example, a display device such as a liquid crystal display or a CRT can be used.

  The operation unit 10 inputs various instructions given to the X-ray CT apparatus 100 by the apparatus operator. The operation unit 10 is an interactive interface including a display panel, a keyboard, various switches, a mouse, and the like.

  The system control unit 11 includes a CPU and a storage circuit (not shown). Based on the signal sent from the operation unit 10, the system control unit 11 controls the above units to operate so as to realize a well-known function in the X-ray CT apparatus 100. Furthermore, the system control unit 11 has the following functions. One of the functions is to set two regions of interest that are positioned apart from each other with respect to the subject 200. One of the functions is to irradiate each of the two regions of interest with X-rays, and to shield the X-rays irradiated to the region located between these two regions of interest. 43 is controlled. One of the above-described functions is to perform image computation and generation so as to generate a tomographic image for each of a plurality of regions of interest based on the detection status of the X-rays irradiated to each of the two regions of interest by the X-ray detector 61. The storage unit 8 is controlled. One of the functions is to monitor a change in CT value in the monitor region based on the detection state of the X-rays irradiated to the monitor region, which is one of the two regions of interest, in the X-ray detector 61. One of the functions described above is that the X-ray detector 61 for X-rays irradiated to the imaging region which is the other of the two regions of interest at the imaging timing determined according to the change in the CT value monitored as described above. The image calculation / storage unit 8 is controlled so as to generate a tomographic image relating to the imaging region based on the detection state in FIG. One of the functions described above controls the X-ray diaphragm 43 so as to form two different irradiation ranges. One of the functions described above sets a region of interest for the subject 200. One of the functions is to control the bed moving mechanism 22 to move the subject 200 so that the region of interest passes through each of the plurality of irradiation ranges. Another function is to generate a plurality of tomographic images related to the region of interest based on each of the detection states of the X-ray detector 61 of the X-rays that have passed through the region of interest in the plurality of irradiation ranges. The calculation / storage unit 8 is controlled.

  FIG. 2 is a plan view showing a detailed structure of a part of the X-ray restrictor 43 in FIG. FIG. 3 is a plan view of only the upper portion of the X-ray restrictor 43 shown in FIG. FIG. 4 is a plan view of only the lower part of the X-ray restrictor 43 shown in FIG. FIG. 5 is a plan view showing a part of the structure shown in FIG. 2 viewed from the left in FIG. 6 is a cross-sectional view taken along line AA in FIG.

  The X-ray diaphragm 43 includes shielding plates 43a, 43b, 43c, 43d, lead screws 43e, 43f, 43g, 43h, LM guides 43i, 43j, 43k, 43m, support members 43n, 43p, 43q, 43r, 43s, 43t. , 43u, 43v and motors 43w, 43x, 43y, 43z.

  The shielding plates 43a, 43b, 43c, and 43d are thin plates formed of a material such as lead that does not transmit X-rays.

  The lead screws 43e, 43f, 43g, and 43h have an elongated cylindrical shape, and a spiral groove is formed on the outer peripheral surface thereof. The LM guides 43i, 43j, 43k, and 43m have an elongated cylindrical shape. The lead screws 43e, 43f, 43g, and 43h and the LM guides 43i, 43j, 43k, and 43m are all arranged in a state parallel to the longitudinal direction of the top 12 and are directly or a housing (not shown) of the X-ray restrictor 43. To the housing (not shown) of the X-ray generation unit 4. The LM guide 43j, the lead screw 43e, the LM guide 43i, and the lead screw 43f are arranged in a line in this order. The LM guide 43m, the lead screw 43g, the LM guide 43k, and the lead screw 43h are arranged in a line in this order. The row formed by the LM guide 43j, the lead screw 43e, the LM guide 43i, and the lead screw 43f is parallel to the row formed by the LM guide 43m, the lead screw 43g, the LM guide 43k, and the lead screw 43h.

  The support members 43n, 43p, 43q, and 43r are formed with screw holes that pass therethrough, and lead screws 43e, 43f, 43g, and 43h are inserted into the screw holes, respectively. The screw holes of the support members 43n, 43p, 43q, and 43r mesh with the spiral grooves of the lead screws 43e, 43f, 43g, and 43h.

  The support members 43s, 43t, 43u, and 43v have through holes, and LM guides 43i, 43j, 43k, and 43m are inserted into the through holes, respectively. The diameters of the through holes of the support members 43s, 43t, 43u, 43v are slightly larger than the outer diameters of the LM guides 43i, 43j, 43k, 43m, and the support members 43s, 43t, 43u, 43v are LM guides 43i, 43j, 43k. , 43m.

  The support member 43n and the support member 43s, the support member 43p and the support member 43t, the support member 43q and the support member 43u, the support member 43r and the support member 43v form a pair, and the shield plates 43a, 43b, 43c and 43d are formed by each pair. Support each one. More specifically, the support member 43n, the support member 43s, the support member 43p, and the support member 43t support the shielding plate 43a and the shielding plate 43b in a state of being aligned along the longitudinal direction of the top plate 12. The support member 43q, the support member 43u, the support member 43r, and the support member 43v hold the shielding plate 43c and the shielding plate 43d in a state of being aligned along the longitudinal direction of the top plate 12.

  The motors 43w, 43x, 43y, and 43z have lead screws 43e, 43f, 43g, and 43h attached to their rotation shafts, respectively. The motors 43w, 43x, 43y, 43z rotate the lead screws 43e, 43f, 43g, 43h, respectively. As the motors 43w, 43x, 43y, and 43z, those having a known structure capable of reversible rotation can be used. The rotations of the motors 43w, 43x, 43y, and 43z are individually controlled by the system control unit 11.

  It should be noted that the shielding plates 43a and 43b, the lead screws 43e and 43f, the LM guides 43i and 43j, the support members 43n, 43p, 43s and 43t, and the mechanism unit including the motors 43w and 43x, the shielding plates 43c and 43d, the lead screw 43g, 43h, the LM guides 43k and 43m, the support members 43q, 43r, 43u, and 43v, and the mechanism unit including the motors 43y and 43z are spaced apart from each other along the central direction of the X-ray radiation direction by the X-ray tube 41. doing.

  FIG. 7 is a view showing a modification of the structure of the X-ray diaphragm 43 in FIG. 8 is a cross-sectional view taken along arrow BB in FIG. 7 and 8, the same parts as those in FIGS. 2 to 6 are denoted by the same reference numerals, and detailed description thereof is omitted. 7 and 8, only the mechanism portion on the side including the shielding plates 43a and 43b is shown.

  In the structure shown in FIGS. 7 and 8, the distance between the lead screw 43f and the LM guide 43m is substantially the same as the distance between the lead screw 43e and the LM guide 43i. The lead screw 43e and the LM guide 43i, and the lead screw 43f and the LM guide 43m are positioned away from each other along the central direction of the X-ray radiation direction by the X-ray tube 41.

  Further, the structure shown in FIGS. 7 and 8 includes support members 43n ′, 43p ′, 43s ′, and 43t ′ instead of the support members 43n, 43p, 43s, and 43t. Similarly to the support members 43n, 43p, 43s, 43t, the support members 43n ', 43p', 43s ', 43t' are inserted with lead screws 43e, 43f and LM guides 43i, 43j, respectively. The support members 43n ′ and 43s ′ support the shielding plate 43a, and the support members 43p ′ and 43t ′ support the shielding plate 43b between the lead screw 43e and the LM guide 43i.

  The X-ray restrictor 43 is configured by using a similarly modified mechanism portion including the shielding plates 43c and 43d.

  The structure shown in FIGS. 7 and 8 can be used in exactly the same way as the structure shown in FIGS. However, in the following, description will be continued assuming that the X-ray diaphragm 43 has the structure shown in FIGS.

  Next, the operation of the X-ray CT apparatus 100 configured as described above will be described.

  When the lead screw 43e is rotated by rotating the motor 43w, the support member 43n moves along the lead screw 43e due to the meshing of the spiral groove of the lead screw 43e and the screw hole of the support member 43n. In response to this, the shielding plate 43a and the support member 43s also move, but the movement of the support member 43s is restricted in the direction along the LM guide 43i. Accordingly, the shielding plate 43 a moves along the longitudinal direction of the top plate 12. The direction of this movement changes by 180 degrees according to the rotation direction of the motor 43w. Therefore, the shielding plate 43 a can arbitrarily reciprocate along the longitudinal direction of the top plate 12. Similarly, the shielding plates 43b, 43c, 43d can arbitrarily reciprocate along the longitudinal direction of the top plate 12 by the rotation of the motors 43x, 43y, 43z.

  Thus, the shielding plates 43a, 43b, 43c, and 43d can individually and arbitrarily set positions in the longitudinal direction of the top plate 12. Therefore, it is possible to form slits between the shielding plate 43a and the shielding plate 43b, and between the shielding plate 43c and the shielding plate 43d, thereby forming two X-ray irradiation ranges that are separated from each other. can do. By using such a feature, it is possible to perform shooting in an operation state as described below, for example.

(First operation state)
FIG. 9 is a diagram illustrating an example of an X-ray irradiation state in the first operation state. 9 schematically shows the positional relationship among the X-ray tube 41, the shielding plates 43a, 43b, 43c, and 43d, the X-ray detector 61, and the subject 200, and their distances are shown accurately. Absent. The subject 200 is typically a human body, but is omitted from the rectangle.

  In the first operation state, the system control unit 11 first sets two regions of interest R1 and R2 related to the subject 200, respectively. The region of interest is set according to a user instruction using the operation unit 10, for example. Then, the system control unit 11 sets the positions of the shielding plates 43a and 43b so as to form an X-ray irradiation range that completely includes the region of interest R1, and forms an X-ray irradiation range that completely includes the region of interest R2. Thus, the positions of the shielding plates 43c and 43d are set. Thereby, the system control unit 11 forms a state as shown in FIG.

  In this state, the system control unit 11 controls the image calculation circuit 82 so as to reconstruct a tomographic image for the two regions of interest R1 and R2 based on the fluoroscopic image acquired by the X-ray detection unit 6.

  As described above, in the first operation state, two separated regions of interest can be imaged at the same time, but the X-ray irradiation dose to the region of the subject 200 located in the region sandwiched between the two regions of interest is reduced. Can do. Thereby, the exposure dose of the subject 200 can be reduced.

  Both of the two regions of interest may be set as a region for obtaining an image for medical diagnosis, but only one region for obtaining an image for medical diagnosis may be used, and the other may be a region for monitoring. good. For example, in the case of imaging using a contrast agent, a change in contrast agent concentration (CT value) is monitored on the upstream side of a blood vessel leading to an organ that is the subject of medical diagnosis, and medical diagnosis is performed at an appropriate timing detected in accordance with this. So-called real prep imaging is performed in which an organ to be subjected to imaging is performed, and the first operation state described above is useful even when applied to such imaging.

  Conventionally, in this real prep, first, a region of interest R1 is first positioned in a single X-ray irradiation range, and a change in CT value in the region of interest R1 is monitored. Then, in response to the CT value becoming a set value, the subject 200 is moved so that the region of interest R2 is located in the X-ray irradiation range, and then the main imaging is performed for the region of interest R2. As described above, conventionally, it is necessary to secure a time for moving the subject 200 from when the CT value reaches the set value to when the main imaging is started, which is about 2 seconds at the shortest.

  However, in the first operation state described above, it is possible to immediately start the main imaging without moving the subject 200. In addition, if the X-ray irradiation range including the region of interest to be subjected to the main imaging is formed before the monitored CT value reaches the set value, the main imaging is performed immediately after the CT value reaches the set value. It is possible to start. However, if this is done, unnecessary exposure will occur in the region of interest that is the subject of actual imaging. Therefore, X including the region of interest that is the subject of actual imaging after the CT value reaches the set value. It is desirable to form a line irradiation range. However, in the present embodiment, such an operation can be realized only by moving the shielding plate, and it is not necessary to move the subject 200, so that it can be shortened to about 0.5 seconds, for example, as compared with the conventional case.

(Second operating state)
10 and 11 are diagrams showing an example of an X-ray irradiation state in the second operation state. 10 and 11 schematically show the positional relationship among the X-ray tube 41, the shielding plates 43a, 43b, 43c, and 43d, the X-ray detector 61, and the subject 200, and their distances are accurately shown. Is not shown. The subject 200 is typically a human body, but is omitted from the rectangle.

  In the second operation state, the system control unit 11 first sets one region of interest R3 related to the subject 200 and a time difference for imaging the region of interest R3. The region of interest and the time difference are set according to a user instruction using the operation unit 10, for example. Then, the system control unit 11 sets the positions of the shielding plates 43a, 43b, 43c, and 43d so as to form two X-ray irradiation ranges that are separated from each other by a distance determined according to the time difference. Thereby, the system control unit 11 forms a state as shown in FIG.

  The system control unit 11 moves the subject 200 at a constant speed by controlling the bed moving mechanism 22 and moving the top 12. Then, the system control unit 11 displays the fluoroscopic image acquired by the X-ray detection unit 6 in a state where the region of interest R3 is in one of the two X-ray irradiation ranges set as described above as shown in FIG. Based on this, the image calculation circuit 82 is controlled to reconstruct a tomographic image for the region of interest R3. Note that when the fluoroscopic image necessary for reconstructing the tomographic image for the region of interest R3 has been acquired, the system control unit 11 moves the shielding plate 43d to move the shielding plate 43c between the shielding plate 43d. Close the slit.

  The system control unit 11 further moves the subject 200 and the fluoroscopic image acquired by the X-ray detection unit 6 in a state where the region of interest R3 is in the other of the two X-ray irradiation ranges as shown in FIG. The image calculation circuit 82 is controlled to reconstruct a tomographic image for the region of interest R3 based on the above. Note that the slit between the shielding plate 43a and the shielding plate 43b may be closed until the state shown in FIG.

  Thus, in the second operation state, imaging is performed twice with respect to one region of interest R3. The two imaging operations are performed with the distance L between the positions P1 and P2 where the imaging is performed and the subject. It is performed with a time difference determined from the moving speed of 200.

  As described above, according to the second operation state, time difference imaging for the same part can be realized by a simple operation. In the interval between two imaging timings, the region of interest R3 is not irradiated with X-rays, so that the exposure dose of the subject 200 can be reduced.

  Note that helical imaging may be performed and the two X-ray irradiation regions may be set narrower than the region of interest R3.

  In the above description, the separation distance between the two X-ray irradiation ranges is determined based on the time difference on the assumption that the moving speed of the subject 200 is constant. However, the separation distance between the two X-ray irradiation ranges is constant. As described above, the moving speed of the subject 200 may be changed based on the time difference, and both the separation distance between the two X-ray irradiation ranges and the moving speed of the subject 200 may be changed based on the time difference.

(Third operation state)
FIG. 12 is a diagram illustrating an example of an X-ray irradiation state in the third operation state. In FIG. 12, the positional relationship among the X-ray tube 41, the shielding plates 43a, 43b, 43c, 43d, the X-ray detector 61, and the subject 200 is schematically shown, and their distances are shown accurately. Absent. The subject 200 is typically a human body, but is omitted from the rectangle.

  In the third operation state, the system control unit 11 first sets one region of interest R4 related to the subject 200. The region of interest is set according to a user instruction using the operation unit 10, for example. Then, the system control unit 11 sets the positions of the shielding plates 43a and 43b so as to form an X-ray irradiation range that completely includes the region of interest R4, and the X-rays thus formed by the shielding plates 43a and 43b. The positions of the shielding plates 43c and 43d are set so as not to disturb the irradiation range. Thereby, the system control unit 11 forms a state as shown in FIG.

  In this state, the system control unit 11 controls the image calculation circuit 82 so as to reconstruct a tomographic image for the region of interest R4 based on the fluoroscopic image acquired by the X-ray detection unit 6.

  As described above, in the third operation state, it is possible to perform imaging exactly the same as an existing general X-ray CT apparatus.

  Note that the positions of the shielding plates 43c and 43d are set so as to form an X-ray irradiation range that completely includes the region of interest R4, and the X-ray irradiation range formed by the shielding plates 43d and 43c is thus prevented. It is also possible to set the positions of the shielding plates 43a and 43b so as not to be present.

  This embodiment can be variously modified as follows.

  The X-ray generation unit 4 and the X-ray detection unit 6 may be moved without moving the subject 200, and the subject and the X-ray generation unit 4 and the X-ray detection unit 6 are positioned relative to each other. It may be moved at the same time so as to change.

  The number of shielding plates may be further increased so that more X-ray irradiation ranges can be formed.

  As a mechanism for moving the shielding plate, another structure such as a mechanism using a linear motor can be employed.

  By reducing the number of the filters 42, it is possible to further reduce exposure.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  DESCRIPTION OF SYMBOLS 2 ... Mechanism part, 3 ... Mechanism control part, 4 ... X-ray generation part, 5 ... High voltage generation part, 6 ... X-ray detection part, 8 ... Image calculation and storage part, 9 ... Display part, 10 ... Operation part, DESCRIPTION OF SYMBOLS 11 ... System control part, 12 ... Bed, 12 ... Top plate, 41 ... X-ray tube, 43 ... X-ray restrictor, 43a, 43b, 43c, 43d ... Shielding plate, 43e, 43f, 43g, 43h ... Lead screw, 43i, 43j, 43k, 43m ... LM guide, 43n, 43p, 43q, 43r, 43s, 43t, 43u, 43v, 43n ', 43p', 43s ', 43t' ... support members, 43w, 43x, 43y, 43z ... Motor, 61 ... X-ray detector, 100 ... X-ray CT apparatus.

Claims (3)

An X-ray tube emitting X-rays;
An X-ray detector in which a plurality of X-ray detection elements each detecting the X-ray are arranged;
A plurality of irradiation range setting means each individually variably setting the transmission range of the X-rays in a section between the X-ray tube and the X-ray detector;
Setting means for setting a plurality of regions of interest that are spaced apart from each other with respect to the subject;
Control means for controlling the plurality of irradiation range setting means so as to irradiate each of the plurality of regions of interest with the X-ray and shield the X-rays irradiated to the region located between the plurality of regions of interest. and,
Generating means for generating a tomographic image for each of the plurality of regions of interest based on the detection state of the X-rays transmitted through the plurality of irradiation range setting means by the X-ray detector. X-ray computed tomography apparatus. An X-ray tube emitting X-rays;
An X-ray detector in which a plurality of X-ray detection elements each detecting the X-ray are arranged;
A plurality of irradiation range setting means each individually variably setting the transmission range of the X-rays in a section between the X-ray tube and the X-ray detector;
Setting means for setting a plurality of regions of interest including at least one monitor region and at least one imaging region with respect to the subject ;
Control means for controlling the plurality of irradiation range setting means so as to irradiate each of the plurality of regions of interest with the X-ray and shield the X-rays irradiated to the region located between the plurality of regions of interest. When,
Monitoring means for monitoring a change in an X-ray absorption coefficient in the monitor area based on a detection state of the X-rays irradiated to the monitor area set by the setting means in the X-ray detector;
A tomographic image relating to the imaging region is generated based on the detection state of the X-rays irradiated to the imaging region at the imaging timing determined according to the change in the X-ray absorption coefficient monitored by the monitoring means. X-ray computed tomography apparatus characterized by comprising a generating means for. An X-ray tube emitting X-rays;
An X-ray detector in which a plurality of X-ray detection elements each detecting the X-ray are arranged;
A plurality of irradiation range setting means each individually variably setting the transmission range of the X-rays in a section between the X-ray tube and the X-ray detector;
Control means for controlling the plurality of irradiation range setting means so as to make the respective transmission ranges of the plurality of irradiation range setting means different from each other;
Setting means for setting one region of interest for the subject;
The subject, the X-ray tube, and the X-ray so that X-rays transmitted through each of the plurality of transmission ranges set by the plurality of irradiation range setting means pass through the region of interest in a plurality of different periods. Moving means for moving at least one of a line detector and the plurality of irradiation range setting means;
Generating means for generating a plurality of tomographic images relating to the region of interest based on each of detection states of the X-rays transmitted through the region of interest in the X-ray detector in each of the plurality of periods. X-ray computed tomography apparatus.

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