JP4146268B2 - Radiation computed tomography equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radiation computed tomography apparatus (hereinafter referred to as a radiation CT apparatus), and in particular, when performing a percutaneous needle biopsy for a tumor in the body, the position of the needle is displayed almost in real time to accurately position the needle. The present invention relates to a radiation CT apparatus capable of guiding.
[0002]
[Prior art]
Conventionally, an X-ray fluoroscopic apparatus has been used to guide a treatment by inserting a needle or a catheter when performing a percutaneous needle biopsy for a tumor such as a lung in a patient's body. In other words, the X-ray fluoroscopic apparatus obtains a fluoroscopic image by irradiating a subject with X-rays from a predetermined direction, and can perform display in real time. In addition, a conventional X-ray fluoroscopic apparatus can only obtain a fluoroscopic image from one direction. However, since only a fluoroscopic image from one direction cannot detect a positional shift along the direction from the fluoroscopic image, the patient's body axis However, an X-ray fluoroscopic apparatus is also used that can obtain fluoroscopic images from two directions perpendicular to each other and perpendicular to each other.
[0003]
When guiding with an X-ray diagnostic apparatus that performs bi-directional fluoroscopy, if the direction in which the needle, catheter, etc. is inserted coincides with one of the two directions, an accurate position display is performed. Can do. However, if it does not coincide with any of the two directions, it is difficult to guide because it requires skill to accurately determine the position in the cross section. For this reason, there was a problem that the insertion direction of a biopsy needle etc. was limited. In addition, there has been a problem that small tumors and the like cannot be identified with an X-ray fluoroscopic apparatus.
[0004]
Therefore, a guide using an X-ray CT apparatus capable of imaging almost all lesions such as small tumors by reconstructing the multi-directional projection data of the patient and obtaining a tomographic image of the patient body. There is a way to do it. On the other hand, a method for obtaining a plurality of tomographic images or three-dimensional images by reconstructing a large number of tomographic images using a two-dimensional detector has been proposed.
[0005]
[Problems to be solved by the invention]
When a percutaneous needle biopsy is performed under the guidance of a tomographic image using the conventional X-ray CT apparatus as described above, there are the following problems. That is, when the needle or catheter deviates from the tomographic plane where the tomographic image exists, that is, when the needle or catheter is displaced in the body axis direction, there is a problem that the needle or catheter is not reflected in the image. In addition, there is a problem that a time lag occurs only for the time for performing projection data collection and reconstruction calculation, and it is difficult to obtain an image in real time. Further, in the method of obtaining a stereoscopic image, there is no possibility of deviating from the tomographic plane, but the time for obtaining the image is longer than that for normal CT, and it is difficult to obtain the image in real time.
[0006]
Therefore, an object of the present invention is to provide a radiation CT apparatus capable of performing accurate and real-time guidance when inserting a needle, catheter, or the like for a percutaneous needle biopsy.
[0007]
[Means for Solving the Problems]
The present invention provides an X-ray source for irradiating X-rays, a multi-row detector including a plurality of detection element rows arranged in a body axis direction of the subject, and an output of the multi-row detector. Based on this, an image generating means for generating a fluoroscopic image of the subject and reconstructing the CT image of the subject, a display means for displaying the fluoroscopic image and the CT image, a fluoroscopic mode and a CT mode are provided. When the operation means for switching and the fluoroscopic mode are selected, the X-ray source and the multi-row detector are fixed in an arbitrary direction, and X-rays are exposed from the X-ray source at a relatively low dose. When the CT mode is selected, the X-ray source and the multiple sources are controlled so that the fluoroscopic image is instantaneously generated by the image generating unit, and the fluoroscopic image is immediately displayed on the display unit. Relatively high X-rays from the X-ray source while rotating the row detector The image generating means performs control to instantly generate a fluoroscopic image corresponding to the same direction as the fluoroscopic mode by the image generating means and to display the fluoroscopic image immediately on the display means. wherein a immediate the CT image of the subject, at the same position in the body axis direction were repeatedly generated at every predetermined rotation, control immediate and to continuously display the repeatedly generated CT image on the display means by And a control means for performing the above.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing a configuration of an X-ray CT apparatus which is one of the radiation CT apparatuses according to the first embodiment of the present invention.
[0009]
The X-ray CT apparatus according to the present embodiment includes a gantry 10 that is rotatably provided in the direction of the arrow in the figure, X-ray tubes 11a and 11b that are disposed on the gantry 10 at intervals of 90 °, and these X-ray tubes. Two-dimensional detectors 12a and 12b are provided on the balls 11a and 11b, respectively, at positions facing each other through a patient P whose body axis is orthogonal to the paper surface. As shown in FIG. 2, each of the two-dimensional detectors 12a and 12b has a large number of X-ray detection elements 13 arranged two-dimensionally on a curved surface or on a multi-surface or a plane circumscribing the curved surface, and arranged along a curved line. The number of detected elements is the number of ch. The width W in the body axis direction of the patient P of the two-dimensional detectors 12a and 12b may be as narrow as about 20 to 30 mm.
[0010]
The X-ray tubes 11a and 11b are connected to an X-ray controller 20, and the X-ray controller 20 is connected to a system controller 50 described later. The gantry 10 is connected to a gantry controller 30, and the gantry controller 30 is connected to a system controller 50.
[0011]
The outputs of the two-dimensional detectors 12a and 12b are connected to A / D conversion units 40a and 40b, respectively. The outputs of these A / D conversion units 40a and 40b are a data collection controller 41, a buffer memory 42, and a first described later. The display controller 61 and the second display controller 62 are connected. The data collection controller 41 is connected to the system controller 50 and the preprocessing device 43. The buffer memory 42 is connected to the preprocessing device 43 and the magnetic disk 44. The preprocessing device 43 is connected to the magnetic disk 44 and the reconstruction device 45. The reconstruction device 45 is connected to the system controller 50, the magnetic disk 44, and the image processing device 46. The image processing device 46 is connected to a third display controller 63 described later.
[0012]
On the other hand, reference numeral 50 in the figure denotes a system controller, which controls the X-ray controller 20, the gantry controller 30, and the data acquisition controller 41, respectively. Reference numeral 51 denotes an operation controller that sends a command from the operator to the system controller 50.
[0013]
The output of the system controller 50 is connected to a first display controller 61, a second display controller 62, and a third display controller 63. These first to third display controllers 61 to 63 are a first CRT 71, a second CRT 72, and a third CRT 73, respectively. It is connected to the.
[0014]
A case where a percutaneous needle biopsy guide is performed on the abdomen of the patient P schematically shown in FIG. 3 using the X-ray CT apparatus configured as described above will be described. In FIG. 3, N is a percutaneous needle, P1 and P2 are slice width ends, Q1 is a tumor, Q2 is a viscera, the X direction is the direction from the X-ray tube 11a to the two-dimensional detector 12a, and the Y direction is A direction Z from the X-ray tube 11b toward the two-dimensional detector 12b indicates a body axis of the patient P. 4A, 4B, and 4C show images displayed on the first CRT 71, the second CRT 72, and the third CRT 73, respectively, and C1 to C3 in the figure show CRT screens.
[0015]
First, the operator places the patient P on a bed (not shown) and introduces the patient P into the opening of the gantry 10. Next, the fluoroscopic mode and the CT mode are appropriately switched via the console 51 by the console 51.
[0016]
In the perspective mode, the gantry controller 30 controls the gantry 10 not to rotate but to be fixed at a predetermined position. The X-ray controller 20 controls the applied X-ray conditions of the X-ray tubes 11a and 11b to a low dose of, for example, 80 kV 4 mA. Further, the data collection controller 41 performs control as follows. That is, the data collected by the two-dimensional detectors 12a and 12b are converted into digital signals by the A / D conversion units 40a and 40b, and the first CRT 71 and the second display controller 62 respectively. A fluoroscopic image is displayed on the second CRT 72 in real time. Here, the perspective images displayed on the first CRT 71 and the second CRT 72 are as shown in FIGS. 4A and 4B, respectively. In this perspective mode, the pre-processing device 43, the reconstruction device 45, the image processing device 46, the third display controller 61, and the third CRT 71 are controlled not to operate via the data collection controller 41, or other images are displayed. It may be used for display.
[0017]
These projection data are stored in the magnetic disk 44 via the buffer memory 42 as necessary. It is also possible to record in a video device not shown.
[0018]
On the other hand, in the CT mode, the gantry controller 30 controls the gantry 10 to rotate in the direction of arrow R in the figure at a predetermined rotation speed. The X-ray controller 20 controls the applied X-ray condition of the X-ray tubes 11a and 11b to 120 kV 300 mA, for example. Further, the data collection controller 41 performs control as follows. That is, the projection data collected by the two-dimensional detectors 12a and 12b at the time when the fan beam angle of the 90 ° + X-ray tube is rotated is converted into a digital signal by the A / D conversion units 40a and 40b, and then the buffer memory. Pre-processing is performed by the pre-processing device 43 via 42. Next, after the tomographic image is reconstructed by the reconstruction device 45 based on the projection data that has been subjected to preprocessing, image processing is performed by the image processing device 46, and one sheet is applied to the third CRT 73 via the third display controller 63. A tomographic image or a stereoscopic image is displayed if necessary. A three-dimensional image can be obtained indirectly by performing three-dimensional processing on tomographic images of a large number of slices or directly by performing three-dimensional reconstruction. Here, the tomographic image displayed on the third CRT 73 is as shown in FIG. Thereafter, projection data of a new tomographic image or a stereoscopic image is obtained continuously for every certain rotation. Here, the time for obtaining the tomographic image or the stereoscopic image is, for example, 0.5 sec. If so, in the half scan, 0.15 sec. It will be about. Therefore, if it is continuously rotated, 0.15 sec. A tomographic image or a three-dimensional image is obtained with a delay, and an image close to real time is obtained.
[0019]
Furthermore, when the position of the rotating two-dimensional detectors 12a and 12b comes to the same position as the predetermined position in the above-described fluoroscopic mode, the outputs of the A / D conversion units 40a and 40b are the first display controller 61 and the second output. The fluoroscopic images are displayed on the first CRT 71 and the second CRT 72 via the display controller 62, respectively. In the CT mode, since the fluoroscopic images are detected only when the two-dimensional detectors 12a and 12b are at a predetermined angle, the previous fluoroscopic images are detected until the next fluoroscopic image is detected when they are not at the predetermined angles. An image will be displayed.
[0020]
As described above, according to the X-ray CT apparatus according to the present embodiment, the percutaneous needle biopsy guide can be used by switching between the fluoroscopic mode and the CT mode. In the CT mode, it is possible to guide a case that is difficult to image in the fluoroscopic mode. Further, since a three-dimensional image or a plurality of tomographic images are obtained in the CT mode, a needle can be inserted outside one cross section, which was a problem in conventional CT, and the permissible range of the percutaneous needle insertion angle is wide. Become. In addition, since the two-dimensional detectors 12a and 12b are used as the X-ray detectors, the number of projection data columns to be obtained increases, and the rotation angle of the gantry 10 is almost 90 ° + the fan beam angle of the X-ray tube. Since direction projection data can be collected, the scan time is greatly shortened, and a near real-time stereoscopic image can be displayed.
[0021]
Further, since the X-ray exposure amount in the fluoroscopic mode is much smaller than that in the case where the CT mode is always used, the X-ray exposure amount and the exposure amount when guided are reduced. In addition, since a fluoroscopic image and a tomographic image can be obtained with a single device, it is not necessary to move the subject and various conditions can be saved, thereby reducing the burden on the operator.
[0022]
Note that the third display controller 63 and the third CRT 73 may be omitted, and the first display controller 61 or the second display controller 62 and the first CRT 71 or the second CRT 72 may be used respectively.
[0023]
As a modification of the first embodiment, when only one set of an X-ray tube and a two-dimensional detector is used, the imaging condition is, for example, 140 kV 100 mA. In this case, a fluoroscopic image in only one direction cannot be displayed in the fluoroscopic mode, but if necessary, a fluoroscopic image in an arbitrary direction can be obtained by changing the fluoroscopic direction by rotating the gantry. If it is difficult to guide in this state, a tomographic image or a stereoscopic image can be obtained by switching to the CT mode as in the first embodiment. Therefore, substantially the same effects as those of the first embodiment can be obtained, and the X-ray tube and the two-dimensional detector need only be one set, so that the configuration is simple.
[0024]
FIG. 5 is a diagram showing the X-ray tubes 11a and 11b and the two-dimensional detectors 12a and 12b incorporated in the gantry of the X-ray CT apparatus according to the second embodiment of the present invention. Note that the configuration of the present embodiment is the same as that of the first embodiment described above, and is omitted.
[0025]
The difference between this embodiment and the first embodiment is that the center position of the X-ray tube 11b is offset from the two-dimensional detector 12b by the amount corresponding to the detection element 1 / 4ch. . If the detection elements of the two-dimensional detectors 12a and 12b are arranged so as to be offset by 1 / 2ch from the center of rotation, the X-ray irradiated from the X-ray tube 11a and incident on the two-dimensional detector 12a. The X-ray path irradiated from the X-ray tube 11b and incident on the two-dimensional detector 12b differs from the X-ray path by 1/4 channel. Further, an X-ray path irradiated from the X-ray tube 11a and incident on the two-dimensional detector 12a and an X-ray path irradiated from the position where the X-ray tube 11a is rotated by 180 ° and incident on the two-dimensional detector 12a Is different by only 1/2 ch, projection data in increments of 1/4 ch of the detection element can be obtained. Therefore, the scan time for constructing one image is longer than that in the case where no offset is arranged, so that the sampling rate becomes coarse, but the same effect as when the number of detection elements is quadrupled is obtained, so that the resolution can be obtained. Can be increased. At this time, the scan time, that is, the time lag until the stereoscopic image is displayed, is 0.3 to 0.5 sec. In the case of a half scan in which data acquisition is performed with rotation of 180 ° + fan beam angle, about 0.2 to 0.3 sec. It becomes. The offset arrangement is not limited to the above.
[0026]
FIG. 6 is a view showing the two-dimensional detectors 12a and 12b incorporated in the gantry of the X-ray CT apparatus according to the third embodiment of the present invention. Note that the configuration of the present embodiment is the same as that of the first embodiment described above, and is omitted.
[0027]
This embodiment according to this embodiment is different from the first embodiment in that the two-dimensional detectors 12a and 12b are offset by W1 in the body axis direction of the patient P, that is, in the slice width direction. According to the X-ray CT apparatus according to this embodiment, it is possible to obtain a stereoscopic image having a thick slice width even when the slice widths of the two-dimensional detectors 12a and 12b are small. Further, the X-ray tube 11b and the two-dimensional detector 12b may be configured to be movable in the slice width direction.
[0028]
With such a configuration, it is possible to scan a thick slice in the same time as in the case of the first embodiment, and a wider range of stereoscopic images can be obtained .
[0029]
The present invention is not limited to the above-described embodiments. That is, in each of the above embodiments, the case of the third generation has been described, but it may be applied to the fourth generation. Further, although a two-dimensional detector in which detector elements are two-dimensionally arranged is used as a detector, the present invention is not limited to such a detector, and an image intensifier (hereinafter referred to as “I.I”) as shown in FIG. . ") May be used. In FIG. 7, reference numeral 80 denotes a frame, 81a and 81b are X-ray tubes, and 82a and 82b are I.D. I. Is shown. Further, a combination of a fluorescent plate and a CCD or a combination of a scintillator and an image sensor may be used. Furthermore, in the above-described embodiment, it is used as a guide for a percutaneous needle or a catheter, but it may be used as a volume CT for obtaining a stereoscopic image . Also of et, with each direction of the projection data obtained by CT mode of the apparatus, it is also possible to perform DA (digital angiography) or DSA (digital subtraction angiography) for each rotation angle. Of course, various modifications can be made without departing from the scope of the present invention.
[0030]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the radiation CT apparatus which can perform a guide accurately and in real time at the time of insertion of the needle | hook of a percutaneous needle biopsy, a catheter, etc. can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an X-ray CT apparatus according to a first embodiment of the present invention.
FIG. 2 is a perspective view showing the arrangement of detectors incorporated in the apparatus.
FIG. 3 is a view showing directions in which a fluoroscopic image and a tomographic image of a subject are taken using the apparatus.
FIG. 4 is a view showing a fluoroscopic image and a tomographic image of a subject obtained using the same apparatus.
FIG. 5 is a front view showing the arrangement of detectors incorporated in an X-ray CT apparatus according to a second embodiment of the present invention.
FIG. 6 is a perspective view showing the arrangement of detectors incorporated in an X-ray CT apparatus according to a third embodiment of the present invention.
FIG. 7 shows an X-ray tube incorporated in an X-ray CT apparatus and I.D. I. The front view which shows arrangement | positioning.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Base, 11a, 11b ... X-ray tube, 12a, 12b ... Two-dimensional detector, 13 ... X-ray detection element, 20 ... X-ray controller, 30 ... Base controller, 40a, 40b ... A / D conversion unit, 41 ... Data collection controller, 42 ... Buffer memory, 43 ... Pre-processing device, 44 ... Magnetic disk, 45 ... Reconstruction device, 46 ... Image processing device, 50 ... System controller, 51 ... Operation controller, 61 ... First display controller 62 ... 2nd display controller, 63 ... 3rd display controller, 71 ... 1st CRT, 72 ... 2nd CRT, 73 ... 3rd CRT.

Claims (3)

An X-ray source that emits X-rays;
A multi-row detector comprising a plurality of detection element rows in which a plurality of detection elements are arranged in the body axis direction of the subject;
Image generating means for generating a fluoroscopic image of the subject based on the output of the multi-row detector and reconstructing a CT image of the subject;
Display means for displaying the fluoroscopic image and the CT image;
Operating means for switching between fluoroscopic mode and CT mode;
When the fluoroscopic mode is selected, the X-ray source and the multi-row detector are fixed in an arbitrary direction, and X-rays are emitted from the X-ray source at a relatively low dose. When the CT mode is selected, the X-ray source and the multi-row detector are rotated when the CT mode is selected. However, the X-ray source is irradiated with a relatively high dose, and the fluoroscopic image corresponding to the same direction as the fluoroscopic mode is instantaneously generated by the image generating unit, and the fluoroscopic image is immediately displayed on the display unit. performs control to display on a CT image of said subject an immediate by said image generating means, at the same position in the body axis direction were repeatedly generated at every predetermined rotation, the said repeating generated CT images or immediate on the display means Radiation computed tomography apparatus characterized by comprising a control means for performing control to sequentially display.   The radiation computed tomography apparatus according to claim 1, wherein when the CT mode is selected, the image generation unit reconstructs a stereoscopic image of the subject.   The radiation computed tomography apparatus according to claim 2, wherein the image generation unit obtains a stereoscopic image of the subject by three-dimensional reconstruction.

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