JPH01270855A - X-ray generator - Google Patents

Abstract

PURPOSE:To obtain an X-ray generating device, in which the X-ray of background is minimum and energy is stable, by providing the decelerating means of an electron beam, the energy selecting means of this electron beam, a shield and a collimator. CONSTITUTION:In order to utilize an electron beam (e), which comes from a linear accelerator 1 of a medical linac, for X-ray generation, it is important to suppress the X-ray of the background, which is generated by loosing the most of the energy by a decelerating board 2, to go into a detector 9. Thus, a decelerating means 2 and an energy selecting means 4 are positioned far from the detector 9 and collimators 5a and 5b and an X-ray 7 to go into the detector 9 is enough decreased by shields 3a-3c. The energy band of the electron beam is narrowed by a magnetic field B and an energy selecting slit 4 and the energy band of the X-ray 7 is also narrowed. Further, the generating position of the X-ray, which is used for diagnosis, is limited by the collimators 5a and 5b and the collimators 5a and 5b are double arranged. Then, the background of the X-ray, which is generated from the collimator, is also decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an X-ray generator, and particularly relates to an X-ray generator using a medical linac.

[Conventional technology]

Figure 2 shows a conventional X-ray tomography device (X-ray CT).
An X-ray generator (22) is arranged opposite to the electron gun (21), and a high voltage application device (23) is provided to the x-ray gun (21).
is connected. Output I of the X-ray generator (22)! ec
The diaphragm device (24) provided is a fan-shaped radiation X-ray (25)
form. Detectors (27) are arranged around a central axis of rotation (26) perpendicular to the plane of the paper. The rotational drive device (28) includes an X-ray generator (22) and a detector (2
7) is rotated about the central axis (26), and its rotational position is detected by a rotational position detector (29). An object to be imaged, such as a patient, is placed on the top plate (30) of the medical table.

Each of the above parts is assembled on a pedestal (31). The data processing system (32) including a computer includes a detector (
27) and a rotational position detector (29) are connected.

With the above configuration, when a high voltage of about 1OUkV is applied to the electron gun (21) from the high voltage application device (23)K, an electron beam is generated, and the X-ray generator (22LK) generates an electron beam. The beams collide.The X-ray generator (22) generates X-rays whose maximum energy is determined by the voltage of the high-voltage application device (23).This X-ray is generated isotropically, so the X-ray generation The periphery of the device (22) is shielded, but the X-rays in the direction of the central axis 1 (26) are squeezed into a fan shape by the aperture device (24) and radiated as X-rays (26).
Position the object to be photographed on the top plate (30HC) so that the center of the image you want to photograph is on the X-ray (26).
passes through this object and reaches the detector (27),
It is detected as the intensity of transmitted X-rays. In recent years, in order to increase the amount of information and shorten the imaging time, a structure has been adopted in which a large number of detection t'czr>s are arranged. In order to create an image χ as an X-Wan CT, it is necessary to emit X-rays from around the object and detect the attenuation of the X-rays, so an X-ray generator (22) and a detector (27) are required. , and are rotated while facing each other across the central axis (26). This takes place with a rotary drive (28), the position of which is detected with a rotary position detector 6rz9> and sent together with the data of the detector (27) to a data processing system (32)K. This rotating part is assembled on a fixed pedestal (31). Based on this information, the data processing system (32) forms an image as a distribution of X-ray absorption multiple values of the object to be imaged, and calculates the CR
Display on T. Algorithms for creating images include well-known photographic reconstruction methods.

[Problem to be solved by the invention]

In the conventional X-ray generator as described above, the X-ray energy of the treatment linac device is higher than that of X-ray CT, so the X-ray energy of the linac must be significantly lowered. background x
There were problems such as lines easily appearing and the energy of Sara K being unstable.

This invention was made to solve the above-mentioned problems, and can be used as a medical linac for treatment without reducing the energy of the linac, and can also be used for diagnosis as an X@CT. The purpose is to obtain an X-ray generator with stable characteristics.

[Means to solve the problem]

The X-ray generator according to the present invention is equipped with a deceleration means for decelerating an electron beam, an energy selection means for selecting the energy of the electron beam, and a shield and a collimator that are effective for low background. It is something.

[Effect]

In the present invention, the deceleration means and the energy selection means, which are the main background sources of X-rays, are located at positions where they can be effectively shielded from the detector, thereby achieving a low background.

Furthermore, the energy selection means is provided after the electron beam deceleration means.If the order of the two is reversed, electron beams with uniform energies will stabilize the X-ray energy. Also, if the collimator has double slits, the X-ray background will be further reduced.

〔Example〕

FIG. 1 shows an embodiment of the present invention, in which on the output side of a linear accelerator (linac) (1) that generates an electron beam (e-),
An electron beam deceleration plate (2), which is an electron beam deceleration means, is arranged. The radius of rotation of the electron beam (e-) in a magnetic field (B) perpendicular to the plane of the paper differs depending on the momentum of the electron, and this phenomenon is used to select the energy of the electron M (e''). A selection slit (4) is provided.

Shields (aa), (3b), (3c) are installed downstream of the electron beam deceleration plate (2), energy selection slit (4), etc.
is arranged to prevent the X-ray background from the electron beam deceleration plate (2) and the energy selection slit (4) from being input to the detector (9). X-ray generation plate (6
) produces X-rays (7) due to the collision of electron beams (e-).
However, in order to collide the electron beam (e-) at a precise position on the X-ray generation plate (6), a collimator (5a), (
5b) are spaced apart from each other. X-rays (
7), the signal is input to the detector (9) via the patient to be diagnosed (8). Ko! 7) -It (5b) ToXs generation plate (6
) Now, we will explain the arrangement and operation of the suppressor (10), which consists of an electrode that repels secondary electrons. First, an electron beam (e-
) to generate X-rays for XpCT, it is important to prevent background X-rays from entering the detector (9) by causing most of the energy to be lost in the deceleration plate (2). be. For this reason, the deceleration means (2) and the energy selection means (4) are arranged far from the detector (9) and the collimator, and the X-rays (7) entering the detector (9) with the shields (3a) to (3C) sufficiently reduce. Further, the energy band of the electron beam is narrowed by the magnetic field CB) and the energy selection slit (4), and the energy band of the X-ray (7) is also narrowed. Furthermore, a collimator (5a). (5b) limits the generation position of the X-rays used for diagnosis, and by arranging the collimators (5a) and (5b) in duplicate, the background of the X-rays generated from the collimators is also reduced.

Note that the number, position, and shape of each of the shields (3a) to (3C) may be changed as necessary.

Based on the above, (a) The electron beam deceleration plate (2) is used to set the low energy level and energy of the electron beam (e-) and X@(7) of the linear accelerator (1) that forms the therapeutic linac. can.

(b) The particle beam deceleration plate (2) can be used as a low-background charged particle beam deceleration means for general accelerators (X-rays, R-rays, neutron beams) such as research accelerators.

It can also be used as an energy setting mechanism.

〔Effect of the invention〕

As described above, the present invention provides a deceleration means for decelerating an electron beam from a linear accelerator, and an energy selection means for determining the energy of the decelerated electron beam using a magnetic field and a slit. By reducing the energy of the generated X-rays with a low background,
It can also be used as a T device, allowing diagnosis and treatment without moving the patient, making treatment planning more accurate and efficient.
The burden on seriously ill patients due to transportation can also be reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic elevational view of an embodiment of the present invention, and FIG. 2 is an elevational view of essential parts of a conventional X-ray generator. (1)--Linear accelerator, (2)--Electron beam deceleration plate, (3
a) ~ (3C) - φ shield, (4) - energy selection slit, (5a), (5b) @ medium collimator, (
6)...X-ray generation plate, (7)...X-ray, (8)...patient, (9)...X-ray detector, (4u)...-suppressor, (
11)・-X-ray monitor. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] A deceleration means that decelerates the electron beam from the linear accelerator, an energy selection means that determines the energy of the decelerated electron beam using a magnetic field and a slit, and the electron beam that has passed through the collimator collides to generate X-rays. an X-ray generating plate that generates X-rays from the deceleration means and the energy selection means;
A shield that shields the wire and the X that passes through the object to be photographed.
An X-ray generator comprising a detector for detecting rays.