JPH01204649A - X-ray photographing device - Google Patents

Abstract

PURPOSE:To photograph photographed sites having mutually different X-ray absorbing rates with the optimum contrast and resolution by forming both faces on the outer peripheral portion of a rotary positive electrode target into tapered shapes, providing different focal plane materials thereto, and independently radiating an electronic beam on each focal plane. CONSTITUTION:Both faces on the outer peripheral portion of the rotary positive electrode target 22 of an X-ray tube 13 are formed into tapered shapes. A first focal plane material such as Mo, etc., is provided on a zone side for placing a photographed object body 15 out of these taper faces, while providing a second focal plane material such as W, etc., having different atomic number from the first focal plane material on the end zone 16a of a photographed site 16. Independently controlled electronic beams are radiated on focal planes 22a, 22b respectively. Mainly an X-ray image on the end zone 16a side of the photographed site 16 is obtained by means of an X-ray beam Xa generated from the first focal plane material through an X-ray image reproducing device, and mainly an X-ray image on the body side zone 16b of the photographed site 16 is obtained by means of an X-ray beam Xb generated from the second focal plane material 22b equally through the X-ray reproducing device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an Xi imaging apparatus for use in mammography and the like.

(Prior art) In X-ray imaging equipment used for mammography, which performs X-ray imaging of the breast using low-energy X-rays, long-wavelength X-rays (soft X-rays) are used as the focal plane material of the anode target of the X-ray tube.
Molybdenum (Mo) or a Mo alloy (simply written as Mo), which can obtain a large amount of the wire component, is used for boat fishing.

By the way, although an object such as a breast is made up of soft tissue as a whole, the X-ray absorption rate in the body (near the chest wall) is higher than in the vicinity of the nipple, and the almost single wavelength generated from the MO is It is difficult to reproduce a uniform, high-contrast X-ray image over the entire area by irradiating distributed soft X-rays.

Therefore, with the aim of obtaining high-contrast images near the chest, xerography (Xerography) has recently been developed.
) is used. Compared to a system using an X-ray tube with an MO anode target,
The sensitive X-ray wavelength band of the photographic film used and the X-ray of the subject
From the viewpoint of radiation absorption, an X-ray tube using an anode target made of tungsten (W) or a W alloy (simply referred to as W) is generally used. However, in this case, the contrast in the vicinity of the nipple tends to decrease.

(Problem to be solved by the invention) Therefore, an X-ray tube with a Mo target is used to
It is also possible to adopt an imaging method that obtains a ray image and images near the chest wall using a W target X-ray tube, but with this method,
It is complicated, as it requires preparing two X-ray tubes and moving the focal position of the X-ray tubes.

On the other hand, as disclosed in Japanese Utility Model Application Publication No. 62-121771, an X-ray tube having a single anode target with Mo and W focal planes is also known. But this means that the corresponding 2
Since different voltages are applied to each cathode at the same time to emit X-rays with a bimodal wavelength distribution, high resolution cannot be obtained unless the X-ray focal point and the subject are sufficiently far apart, making it necessary to take images with a particularly fine focus. It is considered difficult to use for mammography, etc.

This invention eliminates the above-mentioned disadvantages and selectively emits X-rays of different ray quality using a single X-ray tube, allowing each site to be imaged with different X-ray absorption rates to be imaged with optimal contrast and resolution. The purpose of the present invention is to provide an X-ray imaging device that can take images.

[Structure of the Invention]' (Means for Solving the Problems) The present invention provides an X-ray tube that irradiates X-rays to a region to be imaged, and has a rotating anode target having tapered surfaces on both sides of the outer periphery thereof. A first focal plane material is provided on the side of the area where the body of the object to be imaged is located, and a second focal plane material having an atomic number different from the first focal plane material is provided on the side of the tip region of the area to be imaged. and each focal plane is irradiated with an independently controlled electron beam, and the first
An X-ray image of the distal region of the region to be imaged is obtained by the X-ray image reproducing device using the X-ray beam generated from the second focal plane material, and an X-ray image of the body of the region to be imaged is mainly obtained by the X-ray beam generated from the second focal plane material. This is an X-ray imaging device configured to similarly obtain an X-ray image of a side region using an X-ray image reproducing device.

(Function) According to the present invention, MO as the first focal plane material, for example.
If W is used as the second focal plane material, if the tip region of the region to be imaged is a soft tissue with relatively low X-ray absorption rate, this region will mainly be soft (long wavelength) from the Mo focal plane. It is possible to reproduce an X-ray image with good contrast and resolution using X-rays, and in contrast, the body side region with a relatively high X-ray absorption rate is
X-ray images can also be reproduced with good contrast and resolution. In particular, since the configuration is such that X-rays generated from each focal plane of the X-ray tube target cross each other and are emitted in opposite directions, the area to be imaged is irradiated and received by the X-ray image reproducing device. Although the elongated electron beam focal point has a planar shape, the effective X-ray focal point viewed from the imaged region can be as small as possible, and a square or circular X-ray focal point can be obtained, resulting in high resolution.

(Example) Examples thereof will be described below with reference to the drawings.

In addition, the same parts are designated by the same symbols.

The schematic configuration of the device is as shown in FIGS. 1 and 2.
The X-ray generator 12 provided at the top of the main body
A wire tube 13 is built-in. Also, an X-ray irradiation field limiting device 14 that defines an X-ray irradiation field in proximity to the X-ray radiation port 21a.
(Twobs) are provided.

Below these, there is a treatment table 17 on which the part to be imaged 16 protruding from the body 15 of the object to be imaged is grown, a compression plate 18, an ilm 19 that constitutes an X-ray image reproduction device, and a film loading table 20 for mounting the same. is installed.

The X-ray tube 13 includes a vacuum vessel 2L rotating anode target 22,
A rotor 23 supporting it; two cathode structures 24-32;
5. It has a stator 2B, and its drive is controlled by a power supply controller 27. The anode target 22 is entirely composed of a disk made of Mo, and both surfaces of the outer periphery are tapered to form a focal plane. Rotor 2
The MO material of the disc is arranged so that the target surface far from the target surface 3 emits a soft (long wavelength) X-ray beam Xa due to the impact of the electron beam (not shown) emitted from the cathode assembly 24 facing the target surface. It is exposed as it is, forming a first focal plane 22a made of Mo. A thin layer of W, which is a metal material with a higher atomic number than MO, is bonded to the tapered surface of the target closer to the rotor, thereby forming the second focal plane 22b. A hard (short wavelength) X-ray beam xb is emitted to the second focal plane 22a upon being impacted by the electron beam emitted from the opposing cathode structure 25. Note that each of the cathode assemblies 24 and 25 is independently controlled by the controller 27 so as to selectively emit X-rays from each focal plane.

As described above, in the imaged part 16 such as a breast protruding from the chest wall of the imaged object body 15 such as a human body, the tip region Lea near the nipple has a relatively small X-ray absorption rate. There is. On the other hand, the area ■Gb near the body side is
It has a relatively high X-ray absorption rate.

Therefore, in this device, the distal region 1 [i
Soft X-rays Xa emitted from a first focal plane 22a made of Mo are irradiated onto the film 19 to reproduce an X-ray image on the film 19. The positions and dimensions of each part are set so that this X-ray irradiation field is within a very small angle of elevation from the extension of the focal plane 22a. As a result, even if the planar shape of the electron beam focus on the focal plane is elongated in the radial direction,
The effective X-ray focus seen from the part to be imaged is as small as possible, and an excellent focus that is close to a square or a perfect circle can be obtained. Thereby, an X-ray image with excellent resolution can be obtained.

This also means that the electron beam input to the target can be increased.

For photographing a region 18b close to the body 15, a hard xmx beam emitted from the other W second focal plane 22b of the target is used.
By the irradiation of b, an X-ray image is reproduced on the film 19 that has been replaced separately. In this case as well, the taper angle of the focal plane, the irradiation field limiting device, and the dimensions of each part are set to be suitable for imaging this region, and the configuration is such that imaging can be performed with small focus X-rays. In this way, the mutually different X-rays selectively emitted from both focal planes are irradiated to the respective corresponding imaging regions in the irradiation fields that intersect with each other, thereby reproducing an X-ray image.

As described above, the soft X-ray emitting material is placed on the first focal plane 22a of the target 22 that is far from the rotor 23, and the hard X-ray emitting material is placed on the second focal plane 22b that is close to the rotor. This makes it suitable for imaging objects where the body side of the region to be imaged has a relatively high X-ray absorption rate. Moreover, since the X-ray tube and its accommodation portion do not undesirably protrude toward the direction in which the body is placed, it is possible to reliably and easily place the region to be imaged in the X-ray irradiation field.

Furthermore, the focal plane material on both the front and back surfaces of the target is Mo.
, W, but may be a combination of metals having different atomic numbers. Furthermore, this apparatus can be applied to imaging a part of the object to be imaged that protrudes from the body of the object and has a partially different X-ray absorption rate. Furthermore, X
As the ray image reproducing device, an X-ray image intensifier (X-ray II) or other means for reproducing an X-ray image may be used in place of the film.

[Effects of the Invention] As explained above, according to the present invention, X-ray beams of different X-ray quality are irradiated to each region to be imaged which has partially different X-ray absorption rates, thereby achieving good contrast and resolution. X-ray images can be reproduced. i.e. a single X
In a ray tube, areas with relatively low X-ray absorption are mainly generated by soft X-rays from the focal plane with a small atomic number, and areas with relatively high X-ray absorption are generated from the focal plane with a large atomic number. Using hard X-rays, it is possible to reproduce X-ray images with good contrast. Moreover, since the configuration is such that the X-rays generated from each focal plane of the X-ray tube target cross each other and are emitted in opposite directions, the area to be imaged is irradiated and received by the X-ray image reproducing device, so that The effective X-ray focal point has the smallest possible focal spot size and a square or circular X-ray focal point, each with a high resolution.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing the main parts thereof. 13... X-ray tube, 15... object body, 16.
...Site to be imaged, tea...Tip region side, 16b...
・Body side region, 19... X-ray image reproducing device (film), 22... Rotating anode target, 24.25...
Cathode structure, 22a...first focal plane, 22b...second
Focal plane, XaSXb...X-ray beam. Applicant's representative Patent attorney Takehiko Suzue; Figure 1

Claims (1)

[Scope of Claims] An X-ray imaging apparatus including an X-ray tube and an X-ray image reproducing device sandwiching a region to be imaged protruding from the body of the object to be imaged, wherein the X-ray tube is connected to the outer periphery of a rotating anode target. Both surfaces of the part have a tapered shape, and a first focal plane material is provided on the side of the area where the body is positioned among these tapered surfaces, and atoms different from the first focal plane material are provided on the side of the distal end area of the imaged part. and is configured such that each focal plane is irradiated with an independently controlled electron beam, and is mainly irradiated with an X-ray beam generated from the first focal plane material. An X-ray image of the distal region side of the region to be imaged is obtained by the X-ray image reproducing device, and an X-ray image of the body side region of the region to be imaged is mainly obtained by the X-ray beam generated from the second focal plane material. An X-ray imaging device configured to obtain an X-ray image using the above-mentioned X-ray image reproducing device.