JPH0533376B2 - - Google Patents

Description

Detailed Description of the Invention (Field of the Invention) The present invention provides a radiation image information recording and reproducing method using a stimulable phosphor sheet, in which radiation image information is read and the information remaining on the stimulable phosphor sheet after reading is read. 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) Certain phosphors are exposed to radiation (X-rays, α-rays, β-rays,
When irradiated with γ-rays, electron beams, ultraviolet rays, etc., some of this radiation energy is accumulated in the phosphor, and when the phosphor is then irradiated with excitation light such as visible light, the accumulated energy is In response, the phosphor exhibits stimulated luminescence. 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, and this is scanned with excitation light to cause stimulated luminescence. A radiation image information recording and reproducing method has been proposed in which an image signal is obtained by photoelectrically reading the radiation image, and this image signal is processed to obtain a radiation image of a subject that is suitable for diagnosis. (For example, JP-A-55-12429
No. 56-11395, No. 55-163472, No. 56-
(No. 104645, No. 55-116340, etc.) In this method, the final image may be one reproduced as a hard copy or one reproduced on a display device such as a CRT. In such a radiation image recording and reproducing method, a stimulable phosphor sheet (strictly speaking, a panel-shaped sheet or a drum-shaped sheet, etc.) is used.
Although it can take various forms, it will be collectively referred to as a "sheet". ) is economical to use repeatedly.

If sufficient intensity of excitation light is applied during reading, the accumulated radiation energy caused by the recorded radiographic image information should be erased, but in reality, it cannot be completely erased only by the excitation light applied during reading. . Therefore, when the phosphor sheet is used repeatedly, the previously recorded image remains.
There is a problem in that noise occurs during the next recording.

According to experiments, if the maximum level of accumulated energy when recording radiation image information is 100, it is 0.01~
It has been found that if the image is not erased to about 0.0001, that is, 10 ^-4 to ^{10 -6} times, it will become an afterimage in the next recording and become noise that hinders proper diagnosis.

In order to eliminate the afterimage in such a system, the applicant excites the phosphor sheet with light of a wavelength including light in the excitation light wavelength range of the phosphor after reading, so as to sufficiently release the remaining radiation energy. proposed a method. (Japanese Patent Laid-Open No. 57-116300) However, in the conventional afterimage erasing method, light emitted from a light source such as a fluorescent lamp, Na lamp, He lamp, tungsten lamp, etc. is used as noise erasing light to emit residual radiation energy. Erasing is performed by irradiating the entire surface of the sheet with this erasing light, so in order to erase the accumulated energy level of the afterimage to 10 ^-4 to ^{10 -6} times, it is necessary to use a tungsten lamp, for example.
It is necessary to irradiate the eraser with high-intensity erase light for a long time, such as irradiation of 30,000 lx for 100 to 1,000 seconds, and an erase zone is created in which the sheet that has been scanned is stored for a certain period of time and erased. 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 necessary to leave a wide gap between the light source and the sheet in the erasing zone. was necessary. Furthermore, a cooling device is also required to cool 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 for the light source, which poses a risk of electric shock, and also has disadvantages in that it consumes a large amount of power and is not economical.

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

(Structure of the Invention) The reading/erasing method and apparatus of the present invention is such that the excitation light emitted from the excitation light light source and the erasing light emitted from the erasing light source are incident on the same deflector to obtain radiation image information. is characterized by scanning different positions of a stimulable phosphor sheet on which information has been accumulated and recorded, and causing the erasing light to scan a portion of the sheet where scanning for reading by the excitation light has been completed. It is. That is, a sheet that is relatively moved in the sub-scanning direction at a constant speed within the reading/erasing device is first scanned by excitation light, and the image information is read by generating stimulated luminescence light from the scanning location. Subsequently, the portion of the sheet that has been read 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 a perspective view showing an outline of a reading/erasing device according to an embodiment of the present invention.

The reading laser beam 1a, which is excitation light emitted from the excitation light source 1, is transmitted through a rotating polygon mirror 3, which is a deflector.
As the rotating polygon mirror 3 rotates, it is reflected and deflected, and the arrow marks the stimulable phosphor sheet 4 on which radiation image information is stored and recorded, which is placed below the rotating polygon mirror 3. Repeatedly scan in direction A. Since the sheet 4 is attracted to the endless belt device 5 and conveyed in the direction of arrow B for sub-scanning, main scanning is repeated in a direction substantially perpendicular to this sub-scanning, and the reading laser beam is applied over 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.
This emitted light (not shown) enters a transparent light condenser 6 having an incident end face 6a arranged parallel to the main scanning line near the sheet. This light condenser 6 is the sheet 4
The front end 6b located nearby is formed into a flat plate shape, and gradually becomes cylindrical toward the rear end, and the rear end 6c becomes almost cylindrical to form a photodetector 7. The stimulated luminescent light incident from the incident end face 6a is focused on the rear end 6c and received by the photomal 7. In this photomultiplier 7, the stimulated luminescent light is converted into an electrical signal, and the obtained electrical signal is sent to an image information processing circuit 8 for image processing, and then outputted as a visible image to a CRT 9, for example, or It is recorded on tape 10.

On the other hand, the erasing laser beam 2a emitted from the erasing light source 2 is made incident on the rotating polygon mirror 3 from a different direction and at a different angle from the reading laser beam 1a, and is reflected and deflected by the rotating polygon mirror. , the reading laser beam 10 of the sheet 4
The portion where reading has been completed is main-scanned in the direction of arrow C, which is substantially parallel to the main-scanning direction of the reading laser beam 1a. Although some of the accumulated radiation energy remains in the portion of the sheet 4 where reading has been completed, this residual energy is removed by being irradiated with the erasing laser beam 2a, and the sheet 4 is replaced with a new one. It is now possible to record radiation image information. The wavelength of the laser beam used to erase this afterimage is 400 to 600 nm.
It is preferable to use If the residual energy is large, the output of the erasing light source may be increased to irradiate the sheet with the amount of light necessary for sufficient erasing. moreover,
Since high resolution is not required for erasing, the beam diameter of the erasing laser light can be made larger than the beam diameter of the reading laser light, thereby ensuring erasing over the entire sheet surface.

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, A light shielding plate 11 is provided. This light-shielding plate 11 is made of a light-absorbing plate or a reflecting mirror, and when the erasing laser beam 2a illuminates the sheet 4, the light emitted from the irradiation position enters the light condenser 6 through this light-shielding plate 11. This will be prevented. Furthermore, if at least the reading surface of this light shielding plate 11 is a reflective mirror and is placed close to the light condensing body 6, the stimulated luminescence light emitted from the scanning position of the reading laser beam 1a will be reflected by the light shielding plate 11 to the light condensing body 6. Since the light is reflected toward the incident end surface 6a, the light collecting efficiency of the light collecting body 6 can be increased. Note that this light shielding plate 11 is used when the scanning positions of the reading laser beam and the erasing laser beam can be separated sufficiently, or when a condenser is used that does not cause the possibility of condensing light emitted from a far position on the sheet. etc., may be omitted if the light emitted from the sheet by the focusing laser beam does not affect reading.

(Effects of the Invention) As explained above, according to the reading and erasing method and device of the present invention, since the deflector for reading is also used for erasing, a large erasing device can be omitted, resulting in a compact system as a whole. can be realized. In addition, since afterimages are erased by scanning the erasing light, there is no need to irradiate high-intensity erasing light for a long time, and the amount of heat generated is significantly reduced, greatly reducing the negative impact on other devices and electrical circuit systems. I can do it. 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. 1a...Laser light for reading, 2a...Laser light for erasing, 3...Rotating polygon mirror, 4...Storage phosphor sheet, 6...Concentrator, 7...Photomar, 11
...Shading plate.

Claims (1)

[Scope of 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 stimulated luminescence light is generated by photoelectronic reading to obtain an image signal, and after reading, erasing light is irradiated onto the sheet to remove residual radiation energy, etc. In the radiation image information reading and erasing method for erasing noise caused by noise, the deflector is provided with excitation light and erasure light emitted from an excitation light light source and an erasure light light source, respectively, while scanning different positions on the sheet with each other. By making the light incident on the sheet and reflecting and deflecting it onto the sheet, and causing the erasing light to scan the part of the sheet where scanning for reading by the excitation light has finished, reading and erasing can be performed almost simultaneously. 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 radiographic image information is accumulated and recorded to produce stimulated luminescence light according to the image information accumulated and recorded on the sheet; a deflector that is provided on an optical path of light and reflects and deflects the excitation light onto the sheet, and repeatedly scans the excitation light on the sheet in a main scanning direction; A sub-scanning means that performs sub-scanning by moving in a vertical direction, having an entrance end face extending in the main scanning direction at one end and an exit end face at the other end, and transmitting light incident from the entrance end face to the exit end face. A guiding light condenser, a photodetector connected to the exit end surface of the light condenser, and a portion of the sheet that is downstream of the part of the sheet that is being scanned in the main scan by the excitation light by the deflector. A radiation image information reading and erasing device comprising an erasing light light source that is reflectively deflected so as to main scan the side portion and emits erasing light for erasing radiographic image information remaining on the sheet. 3. A patent claim characterized in that a light shielding plate is provided between the scanning position by the excitation light and the scanning position by the erasing light, having at least the same width as the length of the scanning line and standing up on the sheet surface. range 2nd
The radiation image information reading and erasing device described in 2.