JPS6352698B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray fluoroscope for obtaining X-ray fluoroscopic images using high-energy X-rays, and in particular, to an X-ray fluoroscope that has higher resolution at lower doses than conventional similar devices. It is.

FIG. 1 is a diagram showing the configuration of a conventional X-ray fluoroscope. In this Figure 1, 1 is an X-ray source, 2
3 is a fluorescent screen, 3 is a reflecting mirror, 4 is an imaging lens, 5 is a high-sensitivity imaging tube, and 6 is a sample to be viewed.

Next, the operation will be explained. X-ray source 1 is X
X-rays are generated, and the fluorescent screen 2 is irradiated with the X-rays that have passed through the sample 6 to be diagnosed. Fluorescent screen 2
generates fluorescent light proportional to the intensity of the irradiated X-rays, and forms an X-ray fluoroscopic image of the sample 6 to be diagnosed.

Further, the reflecting mirror 3 directs the light away from the path of the X-rays and protects the imaging lens 4 and the high-sensitivity image pickup tube 5 from exposure to the X-rays. The imaging lens 4 forms a transparent image of the fluorescent screen 2 onto the incident surface of the high-sensitivity image pickup tube 5, thereby making it possible to display the image on a television monitor (not shown).

The disadvantage of the conventional X-ray fluoroscope as described above is that the fluorescent screen 2 is thin, so most of the X-rays that form the fluoroscopic image pass through the fluorescent screen 2, and the amount of X-rays that are useful for forming the image is small. It is. For this reason, the intensity of the fluorescent light is low, and the screen flickers significantly due to a lack of fluorescent quantum numbers. Therefore, the fluoroscopic image is dark and the discrimination ability is insufficient.

This tendency becomes stronger as the energy of the X-rays increases, and at an energy of 1 MeV or more, only about 1% of the X-rays irradiated onto the fluorescent screen 2 are used to form an image.

There is a limit to increasing the thickness of the fluorescent screen 2 because it leads to a decrease in optical resolution, and although attempts have been made to improve the fluorescent material, sufficient improvements have not been made.

This invention was made in order to eliminate the above-mentioned conventional drawbacks, and is a novel method that increases the amount of X-rays that contribute to image formation, improves the sensitivity to the X-ray dose rate, and does not deteriorate the optical resolution. An object of the present invention is to provide an X-ray fluoroscopy device.

Embodiments of the X-ray fluoroscopy apparatus of the present invention will be described below with reference to the drawings. FIG. 2 is a diagram showing the configuration of one embodiment. In FIG. 2, the same parts as in FIG. 1 will be described with the same reference numbers.

1 is an X-ray generation source, 2a is a scintillator,
2b is a concave reflecting mirror as a reflecting member, which is formed by providing a metal film on a base material such as glass.
The scintillator 2a faces the X-ray source 1, and a concave reflecting mirror 2b is joined to the opposite side of the scintillator 2a. A plane reflector 3 is disposed between the scintillator 2a and the X-ray source 1, and the reflected light from the concave reflector 2b passes through an imaging lens 4 and is received by a high-sensitivity imaging tube 5. It's getting old.

Next, the operation of the X-ray fluoroscope according to the present invention will be explained. X-rays from the X-ray source 1 pass through a specimen to be viewed (not shown), are irradiated onto a scintillator 2a, and are converted into fluorescent light to form a fluoroscopic image.
At this time, the X-rays pass through the plane reflecting mirror 3 before entering the scintillator 2a, but the attenuation of the X-rays here can be ignored.

The thickness of the scintillator 2a is much thicker than the fluorescent screen of conventional devices, and is selected to be approximately 1 to 5 cm.
The amount of X-rays that are converted into fluorescence within the device is much greater than with conventional devices, allowing the formation of brighter perspective images.

The fluorescent image obtained by the scintillator 2a is reflected by a concave reflecting mirror 2b, further reflected by a flat reflecting mirror 3, and is incident on an imaging lens 4. This imaging lens 4
The fluorescent light image formed in the scintillator 2a is focused on the incident surface of the high-sensitivity image pickup tube 5.

However, in this case, the generation position of fluorescence corresponding to one path of X-rays is a linear region along the path of the X-rays within the scintillator 2a, and the imaging lens 4 You need to look at it from the point-wise direction.

This is a condition under which the fluorescent image within the thick scintillator 2a appears sharp, and this condition must be satisfied over the entire surface of the scintillator 2a. If the refractive index of the scintillator 2a is 1, this condition is met by placing the imaging lens 4 at the same position A as the X-ray source 1, but the refractive index n of the scintillator, for example NaI, is Since it is approximately 1.85, the distance from the scintillator 2a to the imaging lens 4 that satisfies this condition is 1/n times the distance l from the scintillator 2a to point A, that is, 1/1.
It becomes 85 times l/n.

However, in the imaging lens 4, the scintillator 2a
The X-ray source 1 side of is a flat surface. This condition does not change even if the scintillator 2a is provided with a window such as glass.

The plane reflecting mirror 3 moves the position of the imaging lens 4 from the path of the X-rays to protect the imaging lens 4 from X-ray irradiation. The position of the imaging lens 4 is point C, where the optical distance from the scintillator 2a is equal to point B. This movement of the imaging lens 4 is also useful in creating a space for arranging the sample to be viewed.

One side of the scintillator 2a is a convex surface,
Although it is in contact with the concave reflecting mirror 2b having the same curvature as this, the boundary between the two is filled with oil or the like to achieve contact with little optical loss.

The concave reflecting mirror 2b is provided to use the light directed in the opposite direction of the optical system out of the fluorescent light generated within the scintillator 2a to form a perspective image. The virtual image of the light-emitting site must be on one straight line with the actual light-emitting site. Therefore, the center of curvature of the concave reflecting mirror 2b is A
The points are matched.

Here, the concave reflecting mirror 2b is a base material such as glass provided with a metal film. However, depending on the material of the scintillator, such as a plastic scintillator, a design in which a metal film is directly deposited or plated on the convex surface of the scintillator, thereby eliminating the need for a concave reflector, is also possible.

Next, the advantages of this invention will be listed.

(1) Fluorescent images formed in thick scintillators can be observed without distortion or blurring, resulting in a large amount of fluorescent light and good optical resolution.

(2) Since the number of optical interfaces is small, there is little reduction in image contrast. Normally, a condenser lens is required in front of the scintillator to satisfy the condition in item (1) above.

(3) Since both the fluorescent light directed toward the front and rear of the scintillator can be used for image formation, there is a large amount of usable light, which makes it possible to reduce the aperture of the imaging lens or reduce the thickness of the scintillator. It is possible to increase the optical resolution.

As described above, according to the X-ray fluoroscopy apparatus of the present invention, a fluorescent image is generated by the transmitted X-ray image after irradiating the sample with X-rays from the high-energy X-ray generation source, and the A scintillator having a flat surface on the side facing the radiation source and a convex surface on the opposite side, and a reflecting member having the same curvature on the convex surface of the scintillator and joining with the center of curvature coincident with the X-ray radiation source side. Since the fluorescent image obtained by the scintillator is focused on the imaging tube by the imaging lens through the reflecting member, even at low doses,
This has the effect of providing an X-ray fluoroscope with a large amount of fluorescent light and a high resolution suitable for high-energy rays.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a conventional X-ray fluoroscope,
FIG. 2 is a diagram showing the configuration of an embodiment of the X-ray fluoroscope of the present invention. 1... X-ray generation source, 2a... scintillator, 2b...
concave reflecting mirror, 3... plane reflecting mirror, 4... imaging lens,
5...High-sensitivity imaging tube. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A high-energy X-ray generation source, which generates a fluorescent image by an X-ray fluoroscopic image transmitted by irradiating a sample to be diagnosed from this X-ray generation source, and a side opposite to the X-ray generation source. A scintillator having a flat surface and a convex surface on the opposite side, and a reflecting member having the same curvature on the convex surface of the scintillator and joining with the center of curvature coincident with the X-ray generation source side, an imaging lens that forms a fluorescent image on an imaging tube via the reflecting member, and the optical distance between the scintillator and the imaging lens is l/n, where the radius of curvature of the scintillator is l and the refractive index is n. An X-ray fluoroscopy device characterized by: 2. The X-ray fluoroscopy apparatus according to claim 1, wherein the reflecting member is a concave reflecting mirror formed by directly depositing a metal film on the convex surface of the scintillator. 3. The X-ray fluoroscopy apparatus according to claim 1, wherein the reflecting member is a concave reflecting mirror formed by plating the convex surface of a scintillator. 4 The connection between the convex surface of the scintillator and the reflective member is
The X-ray fluoroscopy device according to claim 1, wherein the X-ray fluoroscopy device is closely attached with oil interposed therebetween. 5. A flat reflecting mirror that reflects the fluorescent image of the scintillator obtained through the reflecting member to an imaging lens placed at a position where it will not be irradiated with X-rays from an X-ray source and forms the image on the imaging tube. The X-ray fluoroscopy device according to claim 1, wherein the X-ray fluoroscopy device is disposed between an X-ray generation source and a scintillator.