JPS5827545A - X-ray photographing apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray imaging device using an X-ray detector consisting of one-dimensionally arranged solid elements or gas elements.

Conventionally, an X-ray imaging apparatus using an X-ray detector consisting of a solid-state element or a gas element arranged in a primary direction has been constructed as shown in FIG.

In FIG. 1, an X-ray tube 1, which is the Xll1I exposure part of the X-ray generator, and an X-ray detector 2, which detects the X-rays emitted from the Further, in front of the radiation opening of the X-ray tube 1, an X-ray beam emitted from the X-ray tube 1 is placed in front of the radiation opening of the X-ray tube 1.
A slit plate 5 is arranged to narrow the wire into a fan beam shape. Further, the X-ray tube 1 and the X-ray detector 2 are connected to a pedestal 6 and are driven integrally.

The analog signal of magnitude proportional to the amount of transmitted X-rays of the subject 4 detected by the X# detector 2 is converted into a digital signal by the A/Df converter 7 and temporarily stored in the image storage device 8.
Furthermore, a central processing unit 9 performs image processing such as signal correction and image composition.An image storage device 10 such as a magnetic desk or magnetic tape
The display device 11 is for reading images from the image storage device 10 and displaying them when necessary, and the system controller 12 is for controlling the entire system.

Here, when the X-ray tube 1, slit plate 5, and X-ray detector 2 are integrated and the bed top 3 on which the subject 4 is placed is moved relative to each other at an arbitrary set interval, as shown in FIG. To,
Fix the X-ray tube 1, slit plate 5 and X-ray detector 2,
Either move the bed top 5 on which the subject 40 is placed in a direction perpendicular to the arrangement direction of the detection elements of the X-ray detector 2 and perform X-ray scanning at a set interval (in the case of arrow (A) in the figure); Subject 4
Fix the top plate 3 of the bed, and attach the X-ray tube 1 and the slit plate 5.
and a case where the X-ray detector 2 is moved in a direction perpendicular to the arrangement direction of the detection elements of the X-ray detector 2 and X-ray scanning is performed at n9 intervals (in the case of arrow (b) in the figure). There was a method of 0. If you move the subject as in the case of arrow (a), vibrations will be added to the subject and the bed top, and especially in the case of a cantilevered top, it will cause deflection, making it difficult to take accurate pictures. The disadvantage is that it is not possible. Furthermore, when the subject is a patient, movement other than mechanical vibration of the bed top is likely to occur, and such movement will be magnified at the ViX-ray detector.

If you move the X-ray device as in the case of arrow (b), the weight of the moving parts is large, making the entire device larger. Furthermore, since the X-ray tube is driven, vibrations etc. may occur in the X-ray tube. This has the drawback of shortening the life of the X-ray tube itself.

Furthermore, the biggest drawback of the conventional 7Ic X-ray imaging device, which uses an X-ray detector in which all of the detection elements are one-dimensionally arranged, is that it cannot be used for treatment planning. That is, when determining a radiation treatment plan using a radiological diagnostic device, it is necessary to check the size, shape, and location of the affected area to be irradiated with radiation. Among these pieces of information, information in the depth direction (in a direction perpendicular to the plane of the bed top when the patient is lying on the bed top) can be detected by a CT device. is the spreading direction (if the patient lies on the bed top, the direction parallel to the bed top plane)
This information cannot be detected by a conventional X-ray imaging device in which the detection elements are arranged in the t-1 dimension, and can only be detected by a device equivalent to an X-ray positioning device. This is because, as shown in Fig. 3, in the X-ray positioning device, the distance between the X-ray focal point O1 and the patient is made equal to the distance between the radiation source of the radiation therapy device and the patient. Disease caused by X# s16
The direction of X-ray transmission is equal to the direction of the radiation transmission force of the treatment device, and the positional relationship between the image 15 of the affected area 13 obtained on the The position of the older brother matches. Friend, the dimension Lla 14 of the moat 15 of the affected area 13 also faithfully represents the shape of the affected area.

On the other hand, as shown in Fig. 4, the conventional one-dimensional array
In a companion X-ray imaging device using a radiation detector, the positional relationship between the patient and the XS focus is completely unrelated to the radiation source position of the treatment device;
The direction of X-ray transmission of the affected area by the X-rays from the line focus is not equal to the direction of radiation transmission of the treatment device. Here, 14' in Fig. 4 is the digital display image on the X-ray imaging device?
This is a tentative image plane for comparison with the film image in FIG. 6, and 02 e Os is the focal position of the X-ray tube that forms images of both longitudinal ends of the patient in the affected area 16. The obtained positional relationship between @15' of the affected area 16 and the surrounding image also does not match the positional relationship of the affected area from the radiation source in the vapor supply device. Mayu, the size of the image 15' of the affected area 16 is Ls - L4
In this case, the longitudinal dimension L1 of the patient is the actual size of the affected area itself, and since L4 is not the actual size, it does not faithfully represent the shape of the affected area in its entirety. In this way, when trying to formulate a treatment plan using a companion X-ray imaging device using a conventional one-dimensional array of tX-ray detectors, it was impossible to put it to practical use because extremely complex calculation processing was required.

By the way, conventionally, in treatment planning, a radiation shielding device that is housed in a shadow tray as shown in FIG. 5 has been used. This is done by matching the distance between the rotation center 04 of the ball 16 and the X-ray photograph 17 with the distance between the X-ray focal point and the X-ray film at the time of imaging, and further adjusting the distance between the rotation center 04 and the Styrofoam 18 from the III source of the treatment device and the shadow. The distance from the tray is adjusted, and the outer periphery of the image of the affected area to be irradiated in the X-ray photograph 17 is aligned with the tip of the ball 16, and the Styrofoam 18 is hollowed out using a heated wire 19 coaxial with the ball 16. , this is used as a mold for the radiation shield. It is sufficient that the X-ray photograph used here is one as shown in FIG. 6, but one taken as shown in FIG. 4 cannot be used in this method.

As I explained above, I explained to my friend that the conventional X-ray imaging device that uses one-dimensionally arranged detection sweets cannot be used for treatment planning that uses treatment devices such as cobalt-60 irradiation devices or particle accelerators. It is necessary to fix the X-ray focal position of the carefully planned KFi X-ray tube used for planning, and to use a companion imaging method.

The present invention was made under the above circumstances, and
The X-ray focal position # of the ll1 tube is fixed and the X-ray detector is moved in a direction perpendicular to the arrangement direction of its detection elements to perform X-ray scanning, and X-rays 11ij4a with less pre and distortion are obtained.
It is an object of the present invention to provide an X-ray imaging device f1t that extends the life of an X-ray tube and can also be used for radiation treatment planning.

The present invention will be described in detail below with reference to the drawings.

FIG. 6 is an external view showing an embodiment of the present invention.

In the figure, the X-ray tube 1 and slit plate 5 are XI! It faces the il detector 2 and is fixed integrally with the ball 20. 21H Cocoon xi This is a guide rail for moving the detector 2 according to the guide rail, and slots are provided so that the shafts extending from both ends of the X-ray detector 2 fit therein. 2
Reference numeral 2 denotes a motor attached to the end of the X-ray detector 2, and a gear 26 is provided at the tip of its rotating shaft.

Reference numeral 24 denotes unevenness provided on the guide rail 21, and the unevenness meshes with the gear 26 to move the X-ray detector 2 along the guide rail 2 according to the rotation of the motor 22.
Move along 1. As the X-ray detector 2 moves along the guide rail 21, the X-ray tube 1 swings around the X-ray focal position or center in the direction of the moving force of the X-ray detector 2*
and performs an Xm scan.

The radius of curvature of the arc-shaped Xls detector 2 and the guide rail 21 is the same, and both have the X-ray focal point position 0 of the X-ray tube 1 as the center of curvature.

Here, when creating a planar image from the data obtained from the arc-shaped Xll1i detector 20 arc movement, there is no need to correct the received signal itself, but it is necessary to correct the display position 11F of the image at the time of image display. There is.

An example of this correction method will be explained using the principle diagram shown in FIG.

In FIG. 7, it is assumed that O is the X-ray focal point position and that the center of the detection element row of the X-ray detector is arc-shaped with radius r. Here, B is a contact point on the II&ii image plane P image plane layer to be created. Now, when the X-ray detector is at point A where /BOA=ψ, the X-ray detector is defined as arc DAE, and the straight line passing through point A and parallel to the image plane P and the extension line of straight -OD and OE are The point where they intersect is t″LF.

Let G be the intersection of the extensions of straight lines OA and QC and the image plane P, and let AH and I be the intersection points, and let /AOD = #.

Considering when the X-ray detector is in AA, X-ray detection! DAE
Since the obtained 1st signal is projected onto the straight line FC, the obtained 9th signal at the orbital stone 7 of the X-ray detector is projected onto the straight line Moe, so in the end, from the above equation (1), t2), the final The position correction coefficient is: When displaying an image, each image display position 11 is set to X*
From the position ψ of the detector and the position θV of each detection element, (
3) The correction is made by multiplying by the correction coefficient expressed by the equation.

Note that the arc-shaped X-ray detector and guide rail in this embodiment can be changed to linear ones if the received signal itself or the method of correcting the pixel display position is changed. It goes without saying that it's good.

FIG. 8 is an external view showing another embodiment of the present invention. 8th
In the figure, the X-ray tube 1 is fixed and the X-ray detector 2 and the slit plate 5 are connected to the X-ray detector 2 and the slit plate 5.
It is moved by a rotatable ball 25 whose central axis is an axis in the same direction as the arrangement direction of the detection elements of the line detector 2.

Reference numeral 26 denotes a guide rail 69 for moving the X-ray detector 2 according to the guide rail, and is provided with slots into which shafts provided at both ends of the X-ray detector 20 fit. Mano Sai Ball 2
5 is also provided with slots into which the shafts at both ends of the X-ray detector 2 fit. Further, at one end of the X-ray detector 2, in addition to the shaft, another shaft is provided in the direction of the XS focal point and is fitted only into the slot of the ball 25.
always has its incident surface facing the focal direction of X41 of the X-ray f1. 27 is the slit plate 5't-son
This is a linear guide rail that is moved according to the slit plate 5, and slots are provided at both ends of the slit plate 5 into which shafts are fitted. Friend, the ball 25 also has the slit plate 5.
A slot is provided at one end of the lrL shaft into which the lrL shaft fits. Reference numeral 28 denotes a motor, which is fixed to the pedestal VC, and has a tooth 29 at the tip of its rotating shaft. The rotation of the motor 28 is controlled by the gear machine 11 by a chain 60° 32.
The X-ray detector 2 is transmitted to the X-ray detector F!52 via the slit plate 5 and is driven to move in parallel in synchronization with the slit plate 5.

In this way, in this embodiment, the X-ray detector 2 has the slit 5.
X-ray scanning is performed by moving in parallel in synchronization with [
does not need to be corrected, but it is necessary to correct the received 'fC' signal itself.An example of this correction method will be explained again using FIG. In the figure, 0 is the X-ray focal position, P is the moving plane Ifi of the X-ray detector 2, and the distance between the two is *oBvr. Linear trajectory of X-ray detector 2 'kHBI
Then, all points at a distance of radius r on the straight lines OH and OI are nzorb
Let them be A and C. Point H where X-ray detector 2 is /B OH=ψ
If we consider the case where the received signal is at point B, the signal received here will not become the correct X-ray dose unless it is multiplied by a multiplier equal to the signal received at point B.

Suppose there is a detector 2 that detects X-rays at a point on the P plane that includes point H. In the following case, considering the detection element at the lower point where /FOA=θ, the signal received here will be the same as that at point A. If you do not multiply the received signal by a factor of 4, the correct x, *** will not be obtained.In the end, from equations (4) and (5), the final signal strength correction coefficient is coztcθXcaperψ--- −”'(6), and when processing one image, the position ψ of the X-ray detector for each pixel
Then, the position θV of each detection element is multiplied by n correction coefficient obtained from equation (6) to obtain the complementary IFt/).

Although a linear X-ray detector and a guide rail were used in this embodiment, if the received fs signal itself or the method of correcting the pixel door position is not changed, the X-ray detector and guide It is not necessary that one or both of the rails may be arcuate.

As explained above, in the present invention, X111! Fix the blue focal position txt and integrate the slit and X-ray detection gain V
By moving C and performing XII+1 scanning, X-ray scanning imaging can be performed without moving the object using the -dimensionally arranged X-ray detection elements, and the focal position of the X-ray tube does not move. Therefore, the device itself is simple, the life of the X-ray tube is extended, and it can also be effectively used for treatment planning.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the U path of a conventional X-ray imaging device using an X-ray detection gain using a one-dimensional V-shaped array, and Fig. 2 is an explanatory diagram of the operation of the conventional X-ray imaging device shown in Fig. 1. 9. FIG. 3 is an explanatory diagram of the X-ray positioning device, FIG. 4 is an explanatory diagram of the operation of the conventional X-ray imaging device shown in FIG. 1, FIG. 5 is an explanatory diagram of the radiation shielding device, and FIG. The figure is an external view showing one embodiment of the present invention.
The figure is a principle diagram for explaining the correction of image artifacts in an embodiment of the present invention, and FIG. 8 is an external view showing another embodiment of the present invention. 1... X-ray tube, 2... X-ray detector, 4...
・Subject, 5...slit, 13...affected area,
20.25...ball, 21,26,27...
・Guide rail, 22゜28...Motor, 23
, 29...Gear, 30.32...Chain.

Claims (3)

[Claims] (1) An X-ray tube that generates Xlit, and a slit plate that focuses the X-ray emitted from the X-ray tube into an X-ray tube-dimensional fan beam;
an X-ray detector having a one-dimensional array of detection elements for detecting x*'i that has passed through the wrinkled slit plate and transmitted through the object; and an image processing means for processing the rt-multiplied signal detected by the X-ray detector. In the X-ray imaging device, the focal position of the X-rays generated from the X-ray tube is fixed, and the X-ray detector is moved in a direction perpendicular to the arrangement direction of its detection elements to scan the object. An X-ray imaging device capable of depicting a transparent image of a subject. (2) The X@ imaging device according to claim 1, wherein Xa'# performs an integral Ktlli operation with the operation of the X-ray detector around the X-ray focal position. (3) The X-ray imaging device according to claim 311, wherein the slit plate moves integrally with the operation of the X-ray detector.