JPS6186743A - Method for reading and erasing radiant-ray image information and its device - Google Patents

Abstract

PURPOSE:To miniaturize the system of the titled method, by using a deflector for reading also for erasion and almost simultaneously performing reading and erasion. CONSTITUTION:Exciting lights 1a from a light source 1 repeatedly makes main scan on a phospher sheet 4 in the direction shown by the arrow A and auxiliary scan in the direction shown by the arrow B through a rotary polygon mirror 3 and lights emitted from the sheet 4 enter into a transparent light condensing body 6. The rear end section 6c of the light condensing body 6, whose front end section 6b is formed to have a plate-like shape, is cylindrical and coupled with a photo-multiplier tube 7. The lights emitted from the sheet 4, whose accelerated phosphorescence is emitted at the tube 7, are converted into electric signals and the signals are processed at an image information processing circuit 8 and outputted to a CRT9 as a visual image. On the other hand, laser lights 2a for erasion from an erasing light source 2 are deflected by the rotary polygon mirror 3 and make main scan on the section of the sheet 4 which has been read by reading laser lights 10 in the direction shown by the arrow C and the radiant-ray energy remaining on the sheet 4 is eliminated by the irradiation of the erasing laser lights 2a, and thus, the sheet 4 can be used again for the recording or radiant-ray image information.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention provides a method for recording and reproducing radiation image information utilized in a stimulable phosphor sheet, in which radiation image information is read and the information remains on the stimulable phosphor sheet after reading. The present invention relates to a reading and erasing method for erasing noise, and a reading and erasing device for implementing this method.

(Technical Background and Prior Art of the Invention) When a certain kind of fluorescent substance is irradiated with radiation (X-rays, α-rays, β-rays, R-rays, electron beams, ultraviolet rays, etc.), part of this radiation energy is absorbed by the fluorescent material. When the energy is accumulated in the phosphor and the phosphor is then irradiated with excitation light such as visible light, the phosphor exhibits stimulated luminescence in response to the accumulated energy. A phosphor exhibiting such properties is called a stimulable phosphor.

Using this stimulable phosphor, radiation image information of a subject such as a human body is stored and recorded on a sheet of stimulable phosphor, which is then scanned with excitation light to cause stimulated luminescence. A radiographic image information recording and reproducing method has been proposed in which the image signal 7 is obtained by photoelectrically reading the radiograph, and this image signal is processed to obtain a radiographic image of a subject that is suitable for diagnosis. (For example, JP-A No. 5
No. 5-12429, No. 56-11395, No. 55-1
No. 63472, No. 56-104645, No. 55-11
6340, etc.) In this method, the final image is
- The image may be reproduced as a photocopy or reproduced on a display device such as a CRT. In such a radiation image recording and reproducing method, a stimulable phosphor sheet (strictly speaking, it can take various forms such as a panel shape or a drum shape, but is collectively called a "sheet") ) is economical to use repeatedly.

Read! Excitation light of sufficient intensity at 11 o'clock? If irradiated, the accumulated radiation energy caused by the recorded radiation image information should disappear, but in reality, it cannot be completely erased only by the excitation light irradiated during reading. Therefore, when the phosphor sheet is repeatedly used, there is a problem in that the previously recorded image remains, resulting in noise during the next recording.

According to experiments, the maximum level of accumulated energy when recording radiation image information is 0.01 to 0.00, assuming 100.
It has been found that if the image is not erased to about 0.01, that is, to 10-4 to 10-' times, an afterimage will be generated in the next recording and noise will interfere with proper diagnosis.

In order to eliminate the afterimage in such a system, the present applicant has proposed that after reading, the phosphor sheet is excited with light having a wavelength that includes light in the excitation light wavelength range of the phosphor to eliminate the residual radiation energy. How to release enough? Proposed. (Japanese Patent Laid-Open No. 57-116300) However, in conventional afterimage erasing methods, light emitted from a light source such as a fluorescent lamp, Na/P, He lamp, or tungsten lamp is used as noise erasing light to emit residual radiation energy. Since erasing is carried out by irradiating the entire surface of the erasing light T-sheet, the accumulated energy level of the afterimage is 'l 10-' ~ 1O
- To erase up to 6 times, for example, irradiation of 30,000j+x with a tungsten lamp is required.
Is it necessary to irradiate high-intensity erasing light for a long period of time, such as for 00 seconds, and there is an erasing zone where sheets that have been read are stored for a certain period of time for erasing?
It was necessary to set it up. Furthermore, since the above-mentioned light source generates not only light but also a large amount of heat, it is impossible to arrange the light source close to the sheet, and it is difficult to arrange the light source close to the sheet in the erasing zone. was necessary.

Furthermore, a cooling device is also required to cool down the erasing zone which generates a large amount of heat, resulting in the problem that the entire erasing device becomes large in size. Furthermore, this erasing device is usually placed in close proximity to other devices such as a reading device that reads images, and sheets are transported and circulated between each device by a conveyance mechanism. If the device emits a large amount of heat, it will have an adverse effect on other devices and electrical circuits located nearby. Further, in the conventional erasing method, a high voltage power source is provided as a light source, which poses a risk of electric shock, and also has the disadvantage of increasing power consumption and being uneconomical.

(Object of the Invention) The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to omit the erasure zone in a radiographic image information recording and reproducing system by incorporating the afterimage erasing device Wjtr in a radiographic image information reading device. It is an object of the present invention to provide a method and apparatus for reading and erasing radiation image information, which can solve the problems of large amounts of heat generation and installation of a high voltage power source.

(Structure of the Invention) The reading and erasing method and apparatus of the present invention provide radiation image information by making excitation light emitted from an excitation light source and erasing light emitted from an erasing light source enter the same deflector. scanning mutually different positions on the stimulable phosphor sheet where the stimulable phosphor sheet has been stored and recorded, and causing the erasing light to scan a portion of the sheet that has been scanned for reading by the excitation light. It is something. That is, the sheet, which is relatively moved in the sub-scanning direction at a constant speed within the reading/erasing device, is first scanned with excitation light, and stimulated luminescence light is generated from the scanning location, and image information is read. Subsequently, the portion of the sheet where this reading has been performed is scanned by erasing light to remove residual radiation energy, and reading and erasing are performed almost simultaneously.

(Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The drawing is an overview of a reading and erasing device according to an embodiment of the present invention.
FIG.

The laser beam 1a for reading 9, which is the excitation light emitted from the excitation light source 1, is made incident on the rotating polygon mirror 3, which is a deflector, and is reflected and deflected as the rotating polygon mirror 3 rotates. A stimulable phosphor sheet 4 disposed below the polygon mirror 3 and on which radiation image information is stored and recorded is repeatedly main-scanned in the direction of arrow A. The sheet 4 is attracted to the Fi/don belt device 5 and is conveyed in the direction of arrow B for sub-scanning, so that the main scanning is repeated in a direction substantially perpendicular to this sub-scanning, and the reading laser beam covers the entire surface of the sheet 4. A two-dimensional scan of 1a is performed.

The sheet 4 irradiated with the reading laser beam 1a as it is scanned by the reading laser beam 1a emits stimulated light according to the image information accumulated and recorded thereon, and this emitted light (not shown) is transmitted to the sheet 4. The light enters a transparent light condenser 6 having an incident end surface 6a7 arranged parallel to the main scanning line in the vicinity.

The light condenser 6 has a front end 6b located near the sheet 4 formed into a flat plate shape, gradually becoming cylindrical toward the rear end, and becomes almost cylindrical at the rear end 6c. The photomultiplexer 7 is connected to a photomultiplexer 7, which is a photodetector, and the stimulated luminescence light incident from the incident end face 6a is focused on the rear end portion 6c, and is received by the photomultiplexer 7. In this photomultiplier 7, the stimulated luminescence light is converted into an electric signal, and the obtained electric signal is sent to an image information processing circuit 8 where it undergoes image processing and is then output as a visible image to a CBr 4, for example. It is recorded on the magnetic tape 10.

On the other hand, the erasing laser beam 2 emitted from the erasing light source 2
a is made incident on the rotating polygon mirror 3 from a different direction and at a different angle from the reading laser beam 1a, is reflected and deflected by the rotating polygon mirror, and the sheet 4 is read by the reading laser beam 10. The completed partial tone is main-scanned in the direction of arrow C, which is substantially parallel to the main-scanning direction of the reading laser beam 1a. In the part where sheet 4 has finished reading,
Although some of the accumulated radiation energy remains,
By being irradiated with the erasing laser beam 2a, this residual energy is removed, and the sheet 4 becomes ready for new recording 7 of radiation image information. The erasing laser beam for this afterimage erasing 7 has a wavelength of 4.
00-600nm? It is preferable to use Also, if the residual energy is large, increase the output of the erasing light source to determine the amount of light necessary for sufficient erasing7. What is necessary is to irradiate the sheet. Furthermore, since high resolution is not required for erasing, the beam diameter of the erasing laser beam can be made larger than the beam diameter of the reading laser beam, making it possible to ensure erasing over the entire surface of the sheet. can.

Furthermore, in the embodiment shown in the figure, there is a width greater than the length of the scanning line between the scanning position by the reading laser beam 1a and the scanning position by the erasing laser beam 2a on the sheet 4. A light shielding plate 11 standing upright is provided.

This light-shielding plate 11 is made of a light-absorbing plate or a reflecting mirror, etc. When the erasing laser beam 2a irradiates the sheet 4, the light emitted from the irradiation position is directed to the light condenser 6 by the light-shielding plate 11. entry is prevented. Also, this light shielding plate 1
If the reflective mirror is placed sufficiently close to the condenser 6, the stimulated luminescence light emitted from the scanning position of the reading laser beam 1a will be absorbed by the light shielding plate. 1
1 toward the incident end surface 6a of the light collector 6, the light collection efficiency of the light collector 6 can be improved. Note that this light shielding plate 11 may be used in cases where the scanning positions of the reading laser beam and the erasing laser beam can be separated sufficiently, or where there is no risk of condensing light emitted from a far position on the sheet. It may be omitted if the light emitted from the sheet by the erasing laser beam does not affect the reading, such as when using the laser beam for erasing.

(Effects of the Invention) As explained above, according to the reading and erasing method and device of the present invention, the deflector for reading can be used as a deflector for reading. Since it is also used for erasing, a large erasing device can be omitted, and the overall system can be made more compact. Also, erasing the afterimage? Since the erasing is performed by scanning the erasing light, there is no need to irradiate the erasing light with high illuminance for a long time, and the amount of heat generated is significantly reduced, so that the adverse effects on other devices and electric circuit systems can be greatly reduced. Furthermore, since a high-voltage power source for the erasing light source is not required, the power consumption is reduced, which is economical, and the risk of electric shock is eliminated, so its practical value is extremely great.

[Brief explanation of the drawing]

The drawing is a perspective view showing an outline of a reading/erasing device according to an embodiment of the present invention. la...For reading -'ff12b...
・Erasing laser beam 3・・・Rotating polygon mirror
4... Accumulative phosphor sheet 6...
・Light condenser 7...Photometer 11...Light blocking plate

Claims (1)

[Claims] 1) A stimulable phosphor sheet on which radiation image information has been accumulated and recorded is conveyed at a constant speed in the sub-scanning direction, and excitation light deflected by a deflector is caused to main-scan the sheet. This generates stimulated luminescence light, and this stimulated luminescence light is read photoelectrically to obtain an image signal, and after reading, the sheet is irradiated with erasing light to eliminate residual radiation energy, etc. In the radiation image information reading and erasing method for erasing noise, the deflector is caused to scan different positions on the sheet with excitation light and erasure light emitted from an excitation light light source and an erasure light light source, respectively. Reading and erasing are performed almost simultaneously by making the light incident on the sheet and reflecting and deflecting it onto the sheet, and causing the erasing light to scan a portion of the sheet that has been scanned for reading by the excitation light. A radiation image information reading and erasing method characterized by: 2) a light source for excitation light that emits excitation light that irradiates a stimulable phosphor sheet on which radiation image information is accumulated and recorded to produce stimulated luminescent light according to the image information accumulated and recorded on the sheet; a deflector that is provided on the optical path of the excitation light, reflects and deflects the excitation light onto the sheet, and repeatedly scans the excitation light over the sheet in the main scanning direction; A sub-scanning means that performs sub-scanning by moving in a substantially perpendicular direction, having an entrance end surface extending in the main scanning direction at one end and an exit end surface at the other end, the light incident from the entrance end surface is transmitted to the exit end surface. A light condenser that guides the light to the excitation light, a photodetector connected to the exit end surface of the light condenser, and a downstream side in sub-scanning of the part of the sheet that is being main-scanned by the excitation light by the deflector. A radiation image information reading and erasing device comprising an erasing light light source that is reflected and deflected so as to main scan a portion of the sheet, and emits erasing light for erasing radiation image information remaining on the sheet. 3) A patent characterized in that a light shielding plate having a width at least equal to the length of the scanning line and standing up on the sheet surface is provided between the scanning position by the excitation light and the scanning position by the erasing light. A radiation image information reading and erasing device according to claim 2.