JPH0221848A - X-ray tomographic apparatus - Google Patents

Abstract

PURPOSE:To align the concerned region portion of a tested body with the optical axis of a gantry quickly and correctly by generating a sound signal from the concerned region portion of the tested body by a sound generator and receiving sound signals from the sound generator by plural sound collecting devices disposed in the scattering manner in the periphery of an opening portion of the gantry to calculate the position. CONSTITUTION:In case of taking a tomographic image of the head and neck, for example, as it is basic to take a tomograph parallel to OM line 8 connecting the external ear hole and the tail of the eye of a tested body 2 laid on a bed 7, it is necessary to align the OM line 8 with the optical axis 6 of the gantry 1. Plural sound collecting devices 10a, 10b, 10c, 10d are disposed in the scattering manner in the periphery of an opening portion 3 of the gantry 1, and a sound generator 9 adapted to generate a sound signal from the concerned region portion of the tested body 2 is installed along the OM line 8 of the tested body 2. A sound signal from the sound generator 9 is received by the respective sound collecting devices 10a-10d to calculate the position. According to a control signal of the calculated, result, the gantry 1 and the bed 7 are driven to align the concerned region portion of the tested body 2 with the optical axis 6 of the gantry 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an X-ray tomography apparatus that takes tomographic images of a diagnostic region of a subject, and in particular, to a The present invention relates to an X-ray tomography apparatus that can be automatically adjusted quickly and accurately.

[Conventional technology]

In general, X-ray tomography equipment takes tomographic images of a subject with a thin slice width of about 2 to 10 mm, so in order to obtain tomographic image data of the target region of interest, it is necessary to It is necessary to precisely align the optical axis connecting the X-ray tube and the X-ray detector with the region of interest of the subject.

Regarding this, the conventional device is
As described in FIG. 1 of Publication No. 1, a fault position setting device is provided at the upper part of the bed on the side where the top plate is placed on one side of the gantry, and this fault position setting device allows the X provided on the gantry to be A laser beam that spreads in a plane parallel to the X-ray beam emitted from the ray tube toward the X-ray detector is emitted, and a fan beam of this laser beam is applied to the region of interest of the subject lying on the bed. Check the position and angle of the top plate on which the subject is placed while observing so that the light hits the slice position of the desired tomographic plane! After 11 adjustments, the top plate was sent into the gantry opening.

In addition, other conventional devices include an X-ray tube and an
a gantry in which the radiation detectors are arranged opposite to each other and the entire body can be tilted with respect to the subject's body axis; and a bed on which the subject is placed and the subject is positioned in the opening of the gantry. It consists of

In the X-ray tomography apparatus that rotates the X-ray tube and the X-ray detector around the body axis of the subject to take a tomographic image, an aiming mechanism having a linear index indicating a tomographic plane is provided, and the aiming mechanism The X-ray tube and X-ray detector are tilted in conjunction with the tilting operation of the X-ray tube and X-ray detector.

Furthermore, recently, technology has been developed to take tomographic images of the auditory ossicles, vertebrae, etc., in the cranial area and in the neurological field, with ultra-thin slice widths of 1 to 2 meters, and to perform electrocardiographic synchronization by conducting 10 to 20 consecutive scans. Dynamic scanning technology, which captures tomographic data using
As the positioning of the tomographic plane becomes more distant from the region of interest of the subject, a method called a scanogram has generally been used in combination. This scanogram is created by moving the subject at a constant pitch in the body axis direction within the opening of the gantry without rotating the X-ray tube and X-ray detector, which are placed opposite each other on the gantry. A two-dimensional transmission image is obtained using a -dimensional array of X-ray detectors.

[Problem to be solved by the invention]

However, in the first conventional example, a fan beam of a laser beam emitted from a tomographic position setting device is applied to the region of interest of a subject lying on a bed, and the beam is directed to a slice position of a desired tomographic plane. The position ID and angle of the top plate on which the subject is placed must be adjusted while observing so that the subject is placed on the table, and it is up to the laboratory technician, etc., to manually align the region of interest of the subject with the optical axis of the gantry. This was done by relying on operations and visual confirmation. Also, in the second conventional example, if the tomographic plane of the region of interest of the subject is inclined with respect to the vertical line, the linear indicator of the aiming mechanism points to the inclined tomographic plane. However, the gantry provided with the above-mentioned aiming mechanism must be tilted to a desired angle, and this operation still relies on manual operation and visual confirmation by an inspection engineer or the like.

Therefore, in both the above-mentioned first and second conventional examples, alignment of the region of interest of the subject and the optical axis of the gantry is not performed automatically, which takes time and requires visual inspection by a laboratory technician. This resulted in inaccurate positioning.

Furthermore, in the scanogram performed for fine adjustment of the slice plane after the alignment between the region of interest of the object and the optical axis of the gantry is completed as described above, the two-dimensional transmitted light collected by the region of interest of the object is In order to avoid areas outside the image area, unnecessary parts were also photographed. Therefore, there was a large amount of invalid radiation exposure for the subject.

Therefore, an object of the present invention is to provide an IAI tomography apparatus that can solve such problems.

[Means to solve the problem]

In order to achieve the second object, an X-ray tomography apparatus according to the present invention includes a gantry in which an X-ray tube and an X-ray detector are disposed facing each other around an opening, and a gantry on which a subject is placed. an X-ray tomography apparatus comprising: a bed for positioning the subject into the opening of the gantry; the X-ray tomography apparatus rotates the X-ray tube and the XG detector around the body axis of the subject to take a tomographic image; A sound generator is provided to generate a sound signal from the region of interest of the subject, and a plurality of sound collectors are provided in a scattered manner around the opening of the gantry, and the sound signal from the sound generator is provided. The gantry and bed are moved to align the region of interest of the subject with the optical axis of the gantry based on control signals received by each sound collector and calculated as a result of position calculation.

[For production]

The X-ray tomography apparatus configured as described above generates a sound signal from the region of interest of the subject using a sound generator, and a plurality of sound collectors arranged at scattered points around the opening of the first gun. The gantry and bed are driven to align the region of interest of the subject with the optical axis of the gantry, based on a control signal resulting from position calculation after receiving sound signals from the sound generator. Thereby, the region of interest of the subject and the optical axis of the gantry can be automatically aligned quickly and accurately.

〔Example〕

EMBODIMENT OF THE INVENTION Below, one embodiment of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is an explanatory diagram of main parts showing an embodiment of an X-ray tomography apparatus according to the present invention. In the figure, a gantry 1 is used to take a tomographic image of an examination part of a subject 2, and is formed as a rectangular parallelepiped of an appropriate size as a whole, with a circular opening 3 formed in its center. , around this opening 3 are an X-ray tube 4 that emits X-rays to the subject 2 and the subject 2.
An X-ray detector 5 for detecting X-rays transmitted through the tube is disposed opposite to each other, and the X-ray tube 4 and X-ray detector 5 are rotatable around the center of the opening 3. There is. In FIG. 1, reference numeral 6 is an optical axis connecting the X-ray tube 4 and the X-ray detector 5 of the gun 1-1. Further, although the gantry 1 is normally positioned so that its front axis 6 is vertical, depending on the region of interest of the diagnosis site, the entire gantry 1 may be tilted with respect to the body axis of the subject 2 as shown in the figure. Above optical axis 6
may be tilted at an appropriate angle.

A bed 7 is provided near the gantry 1. This bed 7 is for placing the subject 2 on its top plate and positioning the subject 2 into the opening 3 of the gantry 1, and is movable within a predetermined range with respect to the gantry 1. At the same time, the subject 2 can be placed in 11 positions up, down, left and right.

In order to take a tomographic image of, for example, the head and neck of the subject 2 using an X-ray tomography apparatus having such a configuration, normally the external ear canal and the buttocks of the subject 2 lying on the bed 7 are connected. Basically, the connected so-called 0M line 8 is used as a reference cutting line, and the photograph is taken parallel to this 0M line 8. Therefore, it is necessary to align the 0M line 8 of the subject 2 with the optical axis 6 of the gantry 1.

Here, in the present invention, one sound generator 9 is provided as shown in FIG.
is provided. The sound generator 9 generates a sound signal from the region of interest of the subject 2, and is composed of, for example, a pen-shaped ultrasonic generator, and is attached along the 0M line 8 of the subject 2. For example, there are different sound sources on the external ear canal side and on the outer corner side of the subject 2,
Ultrasonic waves are emitted from each sound source at different timings or at different frequencies, and are designed to provide directivity in the direction of the 0M line 8.

The sound collectors 10a to 10d receive sound signals generated from the sound generator 9, and are composed of, for example, microphones, and are placed around the opening 3 of the gantry 1 as shown in FIG. A total of four pieces are provided, one at each corner equidistant from the center O.

Then, the sound signal from the sound generator 9 is transmitted to each sound collector 1.0a~
Based on the control signal received by 10d and the result of position calculation,
The gantry 1 and bed 7 are driven to align the region of interest of the subject 2 with the optical axis 6 of the gantry 1.

FIG. 3 is a block diagram showing a schematic configuration of the control mechanism. This control mechanism controls each of the sound collectors 10a to 10d based on the time when the sound signal from the sound generator 9 is received by each of the sound collectors 10a to 10d and the time when the ultrasonic wave is emitted from the sound generator 9.
A propagation time calculator 11 calculates the propagation time from the sound generator 9 to each of the sound collectors 10a to 10d based on the calculated value of the propagation time of the sound signal to each of the sound collectors 10a to 10d by the propagation time calculator 11. 10d and the angle between the 0M line 8 and the optical axis 6 of the gantry 1 shown in FIG. A gantry controller 13 that generates a control signal S for controlling the position angle of the bed 7, and a bed control that generates a control signal S2 for controlling the position of the bed 7 based on the calculation result of the distance/angle calculator 12. 14, a gantry stirring section 15 that drives the gantry 1 with the control signal S□ from the gantry controller 13, and a bed drive section 16 that drives the bed 7 with eight control signals from the bed controller 14. , the above distance/angle calculator 1
Gantry 1 is activated at the operation console by the signal of the calculation result of step 2.
and a monitor device 17 that changes and displays the contents of the position display of the bed 7.

Next, position control (optical axis alignment) of the gantry 1 and bed 7 by the control mechanism having such a configuration will be explained with reference to FIGS. 2 and 4. First, in Figure 2,
For simplicity, it is assumed that the sound generator 9 and the sound collectors 10a to 10d are all located in the same plane, and considering a rectangular position #x+y passing through the center O of the opening 3 of the gantry 1, the sound generator 9 The position of the first sound collector 10a is represented by the coordinates (Xzy ya), and the position of the second sound collector 10b is represented by the coordinates (-x, yz). and the position of the third sound collector 10c is expressed in coordinates (-x to Hyz),
Assume that the position of the fourth sound collector 10d is expressed by coordinates (x2°-y2). Also, the straight line distance from the sound generator 9 to the first to fourth sound collectors 10a to 10d is d
d21 d31 ci4. Next, in FIG. 4, let t be the time when the ultrasonic wave is emitted from the sound generator 9,
If the times at which the ultrasonic waves are received by each of the sound collectors 10a to 10d are tag jt)+tc and td, then the propagation time of the ultrasonic waves from the sound generator 9 to the first to fourth sound collectors 10a to 10d is take the difference between them and calculate t
It is assumed that t2e t31t4. Assuming that the sound speed of ultrasonic waves in the air is va (4340 m/s), the following equations are derived from the calculation of each distance in FIG.

dt"" (xi-xt) "+ (yz+yJ"
”' (i) d, =t1Xva
・= (2) az”= (xz+x
z) ”+ (yz+yJ ” ”' (a
)d, =t2Xva −
(4) d3m= (xt+xz) ”+ (-yz+y
t) ” ”' (s) d, = t, Xva・
...(6) d42= (X2-xl)"+ (-yz+yt)"
”' (7) d, =t4Xva
...(8) Substituting and transforming equation (2) into equation (1) above, we get (X□-X2) ” + (yyo+yz) ”= (t
engineering/va) 2...(9) Also, the above (3)
) by substituting the equation (4) into the equation, we get (X□+xz) 2+ (yyo+yz) ”” (ti
・va) 2...(10) Furthermore, the (5)
Substituting equation (6) into the equation and transforming it, we get (xt+xz) ” + (y knee yz) 2= (t
3.va) ” ... (11) Also, No. (7)
Substituting equation (8) into the equation and transforming it, (xz-X2) 2+(yz-yz) 2= (t4"
va) ” ”' (12) is obtained.

In the above equations (9) to (12), the sound velocity va is known and each propagation time ttip t3F t4 is calculated by the propagation time calculator 11 shown in FIG. Coordinates X□ indicating the position of.

y□ is uniquely determined by calculation by the distance/angle calculator 12 shown in FIG. As a result, the position of the sound generator 9 in FIG. 2 is determined, and the positional relationship with the center Q of the opening 3 of the gantry 1 is calculated.

The signals resulting from this position calculation are input to the gantry controller 13 and bed controller 14 shown in FIG. Then, move the bed 7 so that the sound generator 9 aligns with the center ○ of the opening 3 of the gantry 1 in FIG. It operates so that the axes 6 are aligned. In this way, the positions of the gantry 1 and the bed 7 are automatically controlled.

In addition, in FIG. 2, the sound generator 9 and each sound collector 10a~
10d shows a two-dimensional arrangement in which the sound collectors 9 are located within the same plane, but a three-dimensional arrangement in which the sound generator 9 is located in a different place away from the plane in which each of the sound collectors 10a to 20d is located is shown. In the case of placement, the position td of the sound generator 9 can be found in the same way as above, and if the correlation with the positions of two or more sound collectors is found three-dimensionally, then only the distance from the sound collector 9 can be found. However, the angle can also be calculated.

FIG. 5 is an explanatory diagram of main parts showing another embodiment of the present invention.

In this embodiment, the sound generator 9 is a pen-shaped sound generator connected to an ultrasonic generator 18, and when the sound generator 9 is lightly applied to the area of interest of the subject 2, such as the abdomen, and the switch 19 is pressed, This is to make it appear as if the sound signal is directly generated from the region of interest. The subsequent signal processing is performed by the control mechanism shown in FIG. 3 in the same manner as shown in FIGS. 2 and 4. In this case, since the region of interest of the subject 2 can be seen as a plane rather than a line, it is suitable for aligning the optical axis 6 of the gantry 1 with the region of interest such as the abdomen where organs are located in a complex manner. be.

Although FIG. 2 shows a total of four sound collectors 10a to 10d provided around the opening 3 of the gantry 1, one at each corner equidistant from the center O, the present invention is not limited to this, and may be provided at any known location. Further, the number is not limited to four, but may be any number as long as it is two or more.

〔Effect of the invention〕

Since the present invention is configured as described above, the sound signal is generated from the region of interest of the subject 2 by the sound generator 9, and the gantry 1
A plurality of sound collectors 1 are provided scattered around the opening 3 of the
At 0a to 10d, the sound signal from the sound generator 9 is received and the control signal resulting from the position calculation is used to drive the gantry 1 and the bed 7 to align the region of interest of the subject 2 with the optical axis 6 of the gantry 1. Can be matched. Thereby, the region of interest of the subject 2 and the optical axis 6 of the gantry 1 can be automatically aligned quickly and accurately. In addition, since the position of the gantry 1 and the bed 7 can be precisely controlled for optical axis alignment, the scanogram performed for fine adjustment of the slice plane of the subject 2 can be performed without photographing unnecessary parts as in the conventional method. , it is possible to reduce ineffective radiation exposure for the subject 2.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the main parts showing an embodiment of the X-ray tomography apparatus according to the present invention, Fig. 2 is an explanatory diagram showing the arrangement of the sound collector provided in the gantry, and Fig. 3 is a schematic diagram of the configuration of the control mechanism. 4 is a graph showing the propagation time until the sound signal generated from the sound generator reaches each sound collector, and FIG. 5 is an explanatory diagram of main parts showing another embodiment of the present invention. It is. 1... Gantry, 2... Subject, 3...
Opening, 4... X-ray tube, 5... X-ray detector, 6
...Optical axis, 7...Bed, 9...Sound generator, 1
0a to 10d...Sound collector. Figure 5

Claims (1)

[Claims] The gantry includes an X-ray tube and an X-ray detector arranged opposite to each other around an opening, and a bed on which a subject is placed and positioned within the opening of the gantry. , an X-ray tomography apparatus that takes a tomographic image by rotating the X-ray tube and the X-ray detector around the body axis of the subject,
A sound generator is provided that generates a sound signal from the region of interest of the subject, and a plurality of sound collectors are provided in a scattered manner around the opening of the gantry, and each sound signal from the sound generator is collected. An X-ray tomography apparatus characterized in that the gantry and the bed are driven to align the region of interest of the subject with the optical axis of the gantry using a control signal received by a sound device and calculated as a result of position calculation. .