JPS585950A - X-ray tube - Google Patents

Abstract

PURPOSE:To make a control circuit or the like unnecessary, and stabilize the pulse width and the pulse dose by making a conversion layer which is used for X-ray conversion and located on the focus forming surface of a rotary anode, such as a heavy-metal layer, discontinuous in the rotational direction of the anode so as to prevent any X-ray conversion from being carried out at the gaps of the said heavy-metal layer. CONSTITUTION:An anode (P) is prepared from a truncated-cone-shaped base 21 made of a non-heavy-metal member, and a heavy-metal layer 22 is formed on the side surface of the truncated cone 21. In addition, parts 23 and 23', which are indicated in the figure and are located on loci facing to the cathode, are removed so as to make parts of the heavy-metal layer 22 to be removed, or a plural number of (only one will do) straight fluted grooves 24, 24', 25, 25' and 25'' as indicated in the figure are regularly formed so as to make the regularly arranged parts of the heavy metal layer 22 to be removed. As a result, a stable X-ray pulse with a good quality is obtained only by discharging an electron beam while rotating the anode (P).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of the XH tube installed in the xlIm imaging scissors device.

One type of xII tube is a rotating anode X-ray tube with a rotating anode structure. This X@ tube has a truncated conical shape as shown in Fig. 1 (a), and a conversion layer for X-ray conversion, for example, a layer of heavy metal such as tungsten, is formed on the rounded slope part of the anode P. The anode Kl is fixed at the rotation 8 of the anode P, and the anode Kl is disposed at a fixed position facing a part of the anode P in the circular direction, and these are covered with a housing T made of glass or the like. While rotating, the electron e is emitted by the cathode and collided with the opposite surface of the anode P as shown in Fig. 1(b).
xst- is emitted from the ls focal point).

The colliding point of the anode P becomes red-hot due to the collision of the electrons e, but since the anode P is rotated, heating at only one point can be prevented.
It is possible to suppress the dissolution of X* and to enable continuous exposure. Anode P
The actual focal area of the X41 focal point, which is the electron collision point above, is 1
Even if it is relatively large (1), a focal point is formed on the circular nodal slope of the truncated cone, and when X@Xr is irradiated in the radial direction of the anode P (this focal point), the effective focal point becomes as small as 9. This effective focus! The X-rays become an X-beam with an area of , and are emitted to the outside.

By the way, using such a Xil tube,
In the case of continuous irradiation 1, that is, in the case of intermittently emitting This is carried out by controlling the grid potential of the X-ray tube to turn on and off the X-ray tube. Therefore, a tetrode vacuum tube must be used as a switching element, which has the disadvantage that the control circuit is complicated.

However, X-ray equipment for CT (combinatorial tomography), cine X-ray equipment for examination of the circulatory system, digital radiography equipment that obtains Xm fluoroscopic images from digital data, cardiovascular X@ equipment, X-ray reduction equipment, etc. designed to suppress the amount of X-ray exposure as a radiation pattern often requires a continuous nollus x*t.]
In order to improve the image quality, especially when the image is obtained as isotal data, it is necessary to improve the image quality and stabilize the image quality.
4rus Xll1i is required.

However, as in the past, pulse x! i) The control characteristics fluctuate due to residual charges due to the stray capacitance of the power cable used to supply the tube voltage and tube current switching system for controlling the irradiation. Width medium x
! 9. It is difficult to suppress fluctuations in one dose.

The present invention has been made in view of the above circumstances, and a conversion layer for x11 conversion, such as a heavy metal layer, on the focal point forming surface of a rotating anode is formed discontinuously in the rotation direction of the anode, and at the discontinuous part of the heavy metal layer. The purpose is to provide an ixawt system that can generate nine X-ray pulses with stable pulse width and dose without requiring any control circuits (by preventing X-ray conversion from occurring). shall be.

An embodiment of the present invention will be described below with reference to FIG.

The present invention focuses on a rotating anode that converts the energy of electrons into t-x* by colliding with an electron beam, and makes the conversion layer for XMl conversion, such as a heavy metal layer, of this rotating anode discontinuous. Therefore, X-ray conversion (conversion into high-voltage tX-ray energy) is not performed at the discontinuous part of the heavy metal layer, and therefore, the heavy metal is appropriately adjusted to obtain the desired Δlux width, taking into account the rotation speed of the rotating anode and the area of the focal point. By setting the area between the metal part and the non-heavy metal part, the collision position of the electrons emitted from the cathode will change from the heavy metal part to the non-heavy metal part and then back to the heavy metal part as the anode rotates. The rotation of the anode and the structure of the anode P were such that it was positioned on a locus facing the non-heavy metal part in the shape of a truncated concavity, and the heavy metal layer (721kl) was removed as shown by 2J, JJ'.
7. Figure 2(b) (,) shows 14.114', 11. J
As shown in IS'21, a plurality of vertical grooves (even one groove) are formed regularly and the heavy metal layer 321 is formed in that portion.
-1jJ) can be removed.

In addition, even if grooves or the like are not formed, the heavy metal layer may be pressed so as to be discontinuous on the base 21, or may be formed as a through hole in some cases.

If the rotating anode PI having such a structure is used as the anode P of the
* 14 Rus obtained.

Therefore, there is no need for a control circuit for electrical control such as opening and closing of tube voltage and tube current as in the past.Therefore, the X-ray generator only needs a rectifier circuit, and a protection circuit for load fluctuations and surge prevention. Therefore, there is an advantage that O countermeasures are not required and the cost is reduced.

Also, as a result of stabilizing %X4!1ilii, for example, CT
The stability of images and the reliability of devices are improved in devices such as digital and 2-geo Datsufi devices.

In this way, Xll1! on the X-ray focus forming surface of the rotating anode!
A structure in which the heavy metal layer for conversion is removed at appropriate intervals in the rotational direction of the anode %X! Since the I focal point is formed intermittently by this discontinuous heavy metal layer,
When the X-ray tube' is supplied with power, it emits X as a nollus-like
@ Because of the irradiation, the distribution of the heavy metal layer of the anode on the nest 11
X-rays with the desired pulse width can be regularly irradiated by simply changing the t-t, and since the pulse width is determined by the structure and rotation speed of the anode, the Notarus X@ exposure control circuit is It is not necessary at all, making the equipment cheaper, and since it is completely unaffected by electrical influences such as stray capacitance, the pulse width and X-ray dose are stable, and the detected value of the X-rays transmitted through the object obtained by this pulsed X-ray is high. It is possible to provide an Xa tube that is inexpensive, has a simple structure, and can easily obtain high-quality xstq pulses with high accuracy and high image quality.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, and can be implemented with appropriate modifications within the scope of the gist thereof.) For example, the rotation speed of the rotating anode may vary depending on the application) The rotation speed is 20 to 40 revolutions per second, but recently there are many faster speeds, so it is necessary to consider the dynamic balance of the heavy metal removal part Fi on the focal point forming surface and to consider the dynamic balance of the rotating body. By applying the νP balancing method to the record, it can be produced! In addition to tungsten, it is of course possible to use carbon or ceramic porcelain as the material for the anode.

[Brief explanation of drawings]

FIG. 1(a) If a diagram showing XmW of a conventional rotating anode type,
FIG. 1(b) is a diagram showing the relationship between the anode, cathode, and focal point, and FIG. 2(a) is a perspective view showing the shape of the rotating anode of the X-ray tube according to the present invention. 21... Base, 22... Heavy metal layer, xs, is'r
x4+x4'*xs, xs', zs'...Removed portion of heavy metal layer. Applicant's agent Patent attorney Takehiko Suzue 1 (a) ] (a) (b) (b) ? b (C) 5

Claims (1)

[Claims] In a rotary X@ tube, the electron tX-ray conversion material emitted from the cathode collides with a formed conversion layer to irradiate X-rays, and the anode is located at least at the electron extraction position of the conversion layer. is discontinuous, and this] exposure X *
An X-ray tube characterized by 't' russification.