JPS60120349A - Method and device for recording and reading radiation image information - Google Patents

Abstract

PURPOSE:To prevent deterioration in picture quality due to scattered rays which are scattered to the outside of an irradiation field by processing only image data within the irradiation field of radiation during the image recording of an accumulative fluorescent material sheet. CONSTITUTION:X-Ray image information on an object 102 is stored and recorded in the accumulative fluorescent material sheet 103 at a photographing part 1. The fluorescent material sheet 103 is irradiated with laser light 402 from a laser light source 401 at a reading part 4 to generate accelerated phosphorescence. This accelerated phosphorescence is detected by a photodetector 410. The output of the photodetector 410 is inputted to a signal processing circuit 413 to process only image data within the irradiation field. A reproducing and recording part 5 outputs an X-ray image on a photosensitive material 505.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention causes radiation image information to be stimulated to emit light by irradiating excitation light to a stimulable phosphor sheet that stores and records radiation image information. The present invention relates to a radiation image information reading method and apparatus for optically reading the obtained stimulated luminescence light using a photodetector.

(Prior art) Radiographic image information of a human body, etc. is once recorded on a stimulable phosphor sheet, and this phosphor sheet is scanned with excitation light such as a laser beam to generate stimulated luminescence light. A radiation image information recording and reproducing system is known that photoelectrically reads out the exhaustion light to obtain an image signal and outputs it as a visible image to a recording material such as a photographic light-sensitive material, a CRT, etc. based on this image signal (
% 1986 No. 55-12429, No. 56-11395, No. 55-163472, No. 55-116340, etc.).

On the other hand, in an X-ray imaging apparatus, an irradiation field diaphragm such as a collimator is sometimes provided near an X-ray source in order to control the X-ray irradiation range of a subject. This irradiation field aperture not only has the humane effect of preventing X-rays from being irradiated to areas unrelated to diagnosis, but also prevents X-rays from being scattered by objects located outside the area to be diagnosed or observed. Scattered X
It also serves to prevent rays from entering the region to be diagnosed or subjected to mW and being recorded on the recording material, thereby reducing the contrast and image quality of the X-ray image in this region.

If you use an irradiation field aperture in this way, the X-rays will be irradiated only on the area of the subject that you want to photograph, which will prevent the above-mentioned deterioration in image quality, but conversely, if the irradiation field is narrower than the thickness of the recording material, When the object is exposed, the scattered X-rays scattered by the object within the irradiation field are recorded on the outer edge of the recording material outside the irradiation field,
Noise is more likely to form.

Particularly when using wide latitude recording materials such as stimulable phosphor sheets, the noise caused by these scattered X-rays becomes significantly more noticeable than in traditional film/screen systems, and the final image becomes The appearance of the peripheral area is damaged.

This problem does not occur if a stimulable phosphor sheet that matches the size of the irradiation field is selected and used for each photograph, but such operations are cumbersome and impractical. In particular, in a system that incorporates one kind of relatively large stimulable phosphor sheet in the device to photograph and read any body part (see Japanese Patent Application No. 84436/1983), the stimulable phosphor sheet is Since the size cannot be changed every time a photograph is taken, the above problem had to be solved by other means.

(Object of the Invention) An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide an excellent radiation image information reading method and apparatus that is not affected by noise caused by scattered radiation scattered in the irradiation field. .

(Structure of the Invention) The radiation image information recording and reading method 4- according to the present invention is characterized in that data processing of image information is performed only on image data within the irradiation field at the time of recording, and the radiation image information recording and reading apparatus according to the present invention is The present invention is characterized in that means is provided for performing the data processing only on image data within the irradiation field based on information regarding the irradiation field at the time of recording.

(Effects of the Invention) According to the radiation image information recording and reading method and apparatus of the present invention, when image information is recorded on a stimulable phosphor sheet using an irradiation field aperture, data processing of the image information is performed within the irradiation field. Since this is performed only for image taking, the scattered radiation recorded outside the irradiation field is not subjected to data processing, making it possible to obtain an excellent final image regardless of the presence or absence of scattered radiation. In addition, the data processing time can be shortened by narrowing the take processing area.Furthermore, in order to achieve these effects, a storage phosphor is used according to the size of the irradiation field for each great image. The troublesome operation of selecting a sheet is no longer necessary.Therefore, the image quality is significantly improved, especially in systems that incorporate one type of relatively large phosphor sheet into the device for photographing and reading. can be achieved.

(Embodiment) Hereinafter, the present invention will be described in detail based on the drawings.

The drawing is a schematic diagram showing a radiation image information recording/reproducing system including a radiation image information recording/reading device according to a preferred embodiment of the present invention.

In the drawings, 1 indicates a photographing section, 4 a reading section, 5 a reproduction/recording section, and 6 an overall control section.

In the imaging unit 1, X-rays irradiated from an X-ray source 101 toward a subject 102 are transmitted through an irradiation field diaphragm 11 such as a collimator.
The irradiation field is narrowed down by 0, and after passing through the subject 102, it is absorbed by the stimulable phosphor sheet 103, and X-ray image information of the subject is accumulated and recorded in the stimulable phosphor sheet 103. The irradiation field diaphragm 110 is adjusted by an irradiation field diaphragm control device 115, and an irradiation field 103A indicated by diagonal lines is formed on the stimulable phosphor sheet 103. Also,
The irradiation field diaphragm control device 115 controls the aperture size d of the irradiation field diaphragm 110, the respective distances l and L from the X-ray source 101 to the irradiation field diaphragm 110 and the stimulable phosphor sheet 103,
Furthermore, when irradiating X-rays obliquely, the angle θ between the X-ray source 101 and the stimulable phosphor sheet 103 (more specifically, the
(Angle formed by a line descending vertically from the focal point of the source 101 and a line connecting the focal point and the center of the aperture of the irradiation field diaphragm)
Each piece of information is output to the overall control device 604. Here, the term "one size of the aperture of the irradiation field diaphragm 110" means the diameter if the aperture of the diaphragm is circular, and the length of the side or diagonal line if the aperture is rectangular.

The overall control device 604 calculates the size of the irradiation field 103 based on the information output from the irradiation field aperture control device 115. Here, the size D of the irradiation field 7- is determined by tilting the X-ray source 101 with respect to the phosphor sheet 103 when performing imaging without tilting the X-ray source 101 with respect to the phosphor sheet 103.
When the line is irradiated diagonally, it is determined by .

Further, the calculation of the size D of the irradiation field 103A may be performed in the irradiation field aperture control device 115, and the result may be output to the overall control device 604.

In this embodiment, the relative positions of the X-ray source 101 and the stimulable phosphor sheet 103 are such that, for example, the center of the stimulable phosphor sheet coincides with a line passing through the center of the X-ray source 101. Therefore, once the size of the irradiation field 103A is determined, the position of the irradiation field 103A on the stimulable phosphor sheet (1.03) can be uniquely determined. (In other words, position information is included in size information). On the other hand, if the positional relationship between the X-ray source 101 and the stimulable phosphor sheet is not constant, this positional relationship is detected in the imaging unit and the information is output to the reading control device 414 via the overall control device 604. (1°) This photographing section may be separate from the reading section, or may be configured integrally with it.

In the reading unit 4, the laser beam 402 emitted from the laser light source 401 passes through a filter 403 that cuts the wavelength region of the stimulated luminescent light emitted from the stimulable phosphor sheet 103 due to the excitation of the laser beam 402. , B
The beam diameter is strictly adjusted by an expander 404, and the stimulable phosphor sheet 103 is passed through a flat reflector 406 by an optical polarizer 405 such as a galvanometer mirror.
The incident light is deflected upward. An fθ lens 407 is disposed between the optical deflector 405 and the plane reflecting mirror 406, so that even when the laser beam 402 scans the phosphor sheet 103, it always has a uniform beam diameter. On the other hand,
The phosphor sheet 103 is moved in the direction of arrow 408 for sub-scanning, and as a result, the entire surface of the phosphor sheet 103 is irradiated with laser light. When the laser beam 402 is irradiated in this way, the stimulable phosphor sheet 103 emits stimulated luminescent light with an amount proportional to the accumulated and recorded X-ray energy, and this emitted light is transmitted to the light guiding sheet for book reading. 409. This light guide sheet 409
The plane of incidence is on a straight line, and the stimulable phosphor sheet 1
03, and its exit surface is annular, and is brought into close contact with the light-receiving surface of a photodetector 410 such as a photomultiplier.

This light guiding sheet 409 is made by processing a transparent thermoplastic resin sheet such as acrylic resin, and is configured so that the light incident from the incident surface is transmitted to the exit surface while being totally reflected inside. The stimulable phosphor sheet 103
The stimulated luminescence light from the photodetector 410 is guided through the light guide sheet 409, exits from the exit surface, and is received by the photodetector 410. The preferred shape, material, etc. of the light-guiding sheet are disclosed in Japanese Patent Application Laid-open No. 1983.
-87970, No. 56-11397, etc. A filter that selectively transmits only the wavelength range of the stimulated luminescent light is attached to the light receiving surface of the photodetector 410, so that the photodetector 410 detects only the stimulated luminescent light. .

In the present invention, it is preferable that the wavelength range of the excitation light and the wavelength range of the stimulated luminescent light do not overlap in order to improve the SZN ratio, and the excitation light source and the storage temperature are adjusted so as to satisfy such a relationship. It is preferable to choose a light body. Specifically, as disclosed in JP-A-55-12429, it is desirable that the wavelength of excitation light be 600 to 7QQ nm and the wavelength of stimulated emission light be 300 to 500 nm.

The stimulable phosphor that can be preferably used in the present invention is JP-A-55-12142, JP-A-55-14143, JP-A-55
-14144, No. 55-14145, etc.

The stimulated luminescent light detected by the photodetector 410 is converted into an electrical signal, and after being amplified to an appropriate level electrical signal by the amplifier 411 whose sensitivity is set by the amplification factor setting value a, the stimulated luminescence light is converted to an electrical signal at an appropriate level. is input. A/D converter 4
At step 12, the signal is converted into a digital signal with a scale factor suitable for the signal fluctuation range according to the recording scale factor setting value, and is input to the signal processing circuit 413. In the signal processing circuit, signal processing is performed based on the reproduced image processing condition setting value C so as to obtain an X-ray image excellent in suitability for observation and interpretation.

In order to perform data processing in such a series of amplification/conversion/signal processing operations only on the image data within the irradiation field 103A, the following operations are performed.

That is, the reading control device 414 uses the size information including the position information of the irradiation field 103A input from the overall control device 604, or the position and size information as a control signal, to control the amplifier 411, the A/D converter 412, and the signal. The signal is output to one of the processing circuits 413, and in either of these, only the image signal within the irradiation field 103A is selected based on this control signal.

The processed signal is transmitted to the reproducing/recording section 5, and the optical modulator 5
01.

In the reproducing/recording section 5, a laser beam 503 from a recording laser light source 502 is modulated by an optical modulator 501 based on an image signal, and scanned by a scanning mirror 504 over a photosensitive material 505 such as a photographic film. At this time, since the photosensitive material 505 is transported in a direction perpendicular to the scanning direction (arrow 506) in synchronization with scanning, the photosensitive material 505
An X-ray image is output on 05.

In this embodiment, a light modulator control device 507 is provided, and the irradiation field 103 receives input from an overall control device 604.
Image information is outputted to form an image recording area 505A on the photosensitive material 505 based on the size information (including position information) or the size and position information of A, and the irradiation field is By displaying only the inner image, a clearer final image is obtained.

The overall control unit 6 includes the overall control device 604 and the console 6.
03, which not only calculates the size including positional information to the irradiation field 103, or both the size and position, but also the reading density and speed, the amplification factor setting value a, and recording scale factor setting value. b. Reproduction image processing condition setting value C
etc. can be set.

The present invention is not limited to the embodiments described above (it goes without saying that various modifications are possible).

For example, JP-A-58-67240, JP-A-58-6724
As disclosed in No. 2, No. 58-67243, etc., prior to the reading operation in the reading section 4, a reading operation ("pre-reading") for grasping image information in advance using low-energy excitation light. The amplification factor setting value a, the recording scale factor setting value b, the reproduction image processing condition setting value C, etc. may be set based on the result of this pre-reading.

Further, as shown in Japanese Patent Application Laid-Open No. 58-89244, a desensitizing section may be provided between the photographing section and the pre-reading section.

Furthermore, the laser light source serving as the excitation light source in the reading section may be replaced with an LED array having a wavelength range different from that of the stimulated destination light, thereby omitting the optical deflector.

Further, the photodetector is not limited to a single one with a light-guiding sheet, but may be one in which a plurality of photomultiples or phototransistors are arranged in a straight line in the main scanning direction, for example.

The recording method in the reproducing/recording section 5 is not limited to the direct recording method using a laser light source, but may also be a method of displaying on a CRT, video printer, etc., for example.

[Brief explanation of drawings]

The drawing is a schematic diagram of an Xa image information recording/reading system including an X-ray image information recording/reading device that is an embodiment of the present invention. 1... Photography section 101... X-ray source 102.
...Subject 103...Storage phosphor sheet 10
Kasa...Radiation field 110...Irradiation field aperture 115
...Irradiation field aperture control device 4...Reading unit 401...Laser light source 402...
...Laser light 403...Filter 404...Beam expander 405...Light deflector 406...
Planar reflecting mirror 407...Fθ lens 408...Transfer direction 409...Light guide sheet=16- 410...Photodetector 411...Amplifier 412
... A/D converter 413 ... Signal processing circuit 414
...Reading control device...Reproduction/recording section 501...Light modulator 502...Recording laser light source 503.
...Laser light 504...Scanning mirror 505...Photosensitive material 50...Image recording area 507...Light modulator control device 6...Overall control section 603...Console 604...
・Overall control device

Claims (1)

[Claims] 1) Radiation image information is accumulated and recorded on a stimulable phosphor sheet by applying an irradiation field aperture, and the stimulable phosphor sheet is irradiated with excitation light. In a radiation image information recording/reading method, the radiation image information stored in a storage medium is stimulated to emit light, the obtained stimulated emitted light is optically read, and image information for observation and interpretation is obtained by data processing. A radiation image information recording and reading method characterized in that the data processing is performed only on image data within a radiation irradiation field during image recording on the stimulable phosphor sheet. 2) An imaging unit having an irradiation field aperture for accumulating and recording radiation image information on a stimulable phosphor sheet and excitation light irradiated to the stimulable phosphor sheet, thereby emitting radiation image information from the sheet. In a radiographic image information recording/reading device having a reading section that photoelectrically reads the stimulated luminescence light responsible for the stimulable luminescence and performs data processing to obtain an image signal, when an image is recorded on a stimulable phosphor sheet in the imaging section. A radiation image information recording/reading apparatus, comprising means for performing the data processing only on image data within the radiation field based on information regarding the radiation field.