JPS60120348A - 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 as to pre-read image information. 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. Then, the accumulative fluorescent material sheet 103 is irradiated at a pre- reading part 3 with laser light 302 from a laser light source 301 to generate accelerated phosphorescence. This accelerated phosphorescence is detected by a photodetector 308. The output of the photodetector 308 is inputted to a data processor 313 and only data within the irradiation field of radiation among pieces of read image information are processed. Further, the fluorescent material sheet 103 is read at a main reading part 4 by using a laser light source 401 and a photodetector 401 and a final image is reproduced by a reproducing and recording part 5.

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 recording and reading method and apparatus for optically reading the obtained stimulated luminescence light using a photodetector.

(Prior art) Radiographic image information of the human body, etc. is 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 stimulated luminescence 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 (
For example, JP-A No. 55-12429, JP-A No. 5G-11395
No. 55-163472, No. 55-116340
Disclosed in the issue etc. Among such systems, excitation light with an energy lower than that of the excitation light to be irradiated during a reading operation (hereinafter referred to as "main reading") to obtain a visible image for observation and interpretation is used. Prior to actual reading, a reading operation (hereinafter referred to as "pre-reading") is performed to grasp the recorded radiation image information in advance. > and set the reading conditions and image processing conditions for main reading based on the results of this pre-reading (for example, Japanese Patent Laid-Open Nos. 58-67240, 58-67242, 58-
It is disclosed in No. 67243 and the like. ) is preferable because it provides a radiation image particularly suitable for observation and interpretation.

Incidentally, in an XPa imaging device, an irradiation field diaphragm such as a collimator is sometimes provided near the X-ray source in order to control the X-ray irradiation range to the 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. It also serves to prevent scattered X-rays from entering the region to be diagnosed or observed and being recorded on the recording material, thereby reducing the contrast and image quality of the X-ray image in this region.

Using an irradiation field diaphragm in this way prevents the above-mentioned deterioration in image quality because the X-rays are irradiated only on the area of the subject that you want to photograph, but conversely, the irradiation field is narrowed down to be narrower than the size of the recording material. In some cases, scattered X-rays scattered by objects within the irradiation field are recorded at the outer edge of the recording material outside the irradiation field, and noise is likely to be formed. Particularly when a wide latitude recording material such as a stimulable phosphor sheet is used, the noise caused by this scattered X-ray becomes more noticeable than in conventional film/screen systems.

This noise not only spoils the appearance of the edges of the final image, but if this noise is read during the pre-reading in the aforementioned system that performs pre-reading before the main reading, the image data containing this noise will be processed. This can lead to serious problems such as incorrect or biased information being provided in order to set the conditions for book reading. This problem does not occur if a stimulable phosphor sheet that matches the size of the irradiation field is selected and used for each exposure, but
- Such operations are cumbersome and impractical. Particularly, today, systems have been developed that incorporate one type of relatively large stimulable phosphor sheet into the device to photograph and read any part of the body. (See Japanese Patent Application No. 57-84436.) In such a system, the size of the stimulable phosphor sheet is not changed every time an image is taken, so the above problem had to be solved by other means. .

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

(Structure of the Invention) The radiation image information recording and reading method according to the present invention is characterized in that data processing of image information in pre-reading 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 data processing only on image data within the irradiation field.

(Effects of the Invention) According to the method and apparatus for recording and reading radiation image information of the present invention, when image information is recorded on a stimulable phosphor sheet using an irradiation field aperture, data processing in pre-reading is performed on images within the irradiation field. Since this is performed only on the data, the scattered radiation recorded outside the irradiation field is not processed. Therefore, it is possible to set accurate main reading conditions regardless of the presence or absence of scattered radiation, and it is possible to obtain an excellent final image. become able to. Furthermore, by narrowing the data processing area, it is possible to shorten the data processing time in prefetching. Furthermore, since these effects are achieved, the troublesome operation of selecting a stimulable phosphor sheet according to the size of the irradiation field every time an image is to be taken becomes unnecessary. Therefore, a significant improvement in image quality can be achieved, particularly in a system in which a relatively large stimulable phosphor sheet of one kind is incorporated into the device for photographing and reading.

(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 is a photographing section, 3 is a pre-reading reading section, 4 is a main reading reading section, 5 is a reproduction/recording section, and 6 is an overall control section.

In the imaging unit 1, the X-rays irradiated from the X-ray source 101 toward the subject 102 are passed through an irradiation field aperture 1 such as a collimator.
10 narrows down the irradiation field, and after passing through the subject 102, it is absorbed by a 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. Further, the irradiation field aperture control device 115 is an irradiation field aperture control device 11.
0 aperture size d, irradiation field aperture from the X-ray source 101 1
10 and the stimulable phosphor sheet 103, and when irradiating X-rays 7- obliquely, the angle θ (from For details, see X-ray source 1
01 and the line connecting the focal point and the center of the aperture of the irradiation field diaphragm. Here, the "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 it is rectangular. The overall control device 604 calculates the size of the irradiation field 103A based on the information output from the irradiation field aperture control device 115. Here, the size D of the irradiation field is LD=- when taking images without tilting the X-ray source 101 with respect to the phosphor sheet 103.
When X-rays are irradiated obliquely, it is determined by -8=.

Also, the size D of this irradiation field 103A is calculated using the irradiation field aperture method t! It is also possible to perform this in the II device 115 and output the result to the overall control device 604.

In this embodiment, the relative positional relationship between the X-ray source 101 and the stimulable phosphor sheet 103 is, for example,
Since the center of the stimulable phosphor sheet is fixed on the line passing through the center of 1, the irradiation field 1
Once the size of the irradiation field 103A is determined, the position of the irradiation field 103A on the stimulable phosphor sheet can be uniquely determined (that is, the size information includes the position information). On the other hand, if the relative 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 this information is sent to the overall control unit 604 along with information on the size of the irradiation field 103A. All you have to do is output it to .

This photographing section may be separate from the pre-reading section and the main reading section, or may be configured integrally with them.

In the pre-reading reading unit 3, a laser beam 302 emitted from a laser light source 301 passes through a filter 303 that cuts the wavelength range of stimulated luminescence light emitted from a stimulable phosphor sheet 103 by excitation of this laser beam 302. Thereafter, the light is one-dimensionally deflected onto the stimulable phosphor sheet 103 via a plane reflecting mirror 305 by a light deflector 304 such as a galvanometer mirror, and then enters the stimulable phosphor sheet 103. Here is the laser light source 30
1 is a stimulable phosphor sheet in which the wavelength range of the laser beam 302 is
The wavelength range is selected so as not to overlap with the wavelength range of the stimulated luminescence light from 103.

On the other hand, the phosphor sheets 1 to 103 are moved in the direction of arrow 306 for sub-scanning, and as a result, the entire surface of the phosphor sheet 103 is irradiated with laser light.

Here, the power of the laser light source 301, the beam diameter of the laser light 302, the scanning speed of the laser light 302, the phosphor sheet
The transport speed 103 is selected so that the energy of the laser beam 302 for pre-reading is smaller than that for main reading.

In the present invention, the energy of excitation light refers to the effective energy of excitation light received per unit area of the stimulable phosphor sheet.

In the present invention, it is sufficient that the energy of the excitation light to be applied to the stimulable phosphor sheet during pre-reading is lower than the energy of the excitation light during main reading. If the ratio between the excitation light energy of the pre-reading and that of the main reading is close to 1, the amount of radiation energy remaining and accumulated at the time of the near-excitation reading will be small; however, if this ratio is less than 1, the value of the reading gain should be It has been found that by making appropriate adjustments, radiographic images suitable for observation and interpretation can be obtained. However, in order to obtain radiographic images that are highly suitable for observation and interpretation, the stored radiographic image information stored in the stimulable phosphor by pre-reading must be used to select reading conditions or optimal image processing conditions. In other words, as long as the stimulated luminescence light emitted from the stimulable phosphor can be sufficiently detected in the above sense, the ratio of the energy of the excitation light in the pre-reading and the main reading is small. Desirable, 5
0% or less, preferably 10% or less, more preferably 3%
The following are desirable. The lower limit of this ratio is determined by the accuracy of the pre-read 11-stimulated luminescence detection system.

Methods of making the energy smaller than the actual energy include reducing the output of the laser light source, increasing the beam diameter of the laser beam, increasing the scanning speed of the laser beam, and using stimulable fluorophores. Known methods can be used, such as increasing the sheet transport speed.

When the laser beam 302 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 pre-reading light guiding sheet. 307. The light guide sheet 307 has a linear incident surface, is placed adjacent to and opposite to the scanning line on the stimulable phosphor sheet 103, and has an annular exit surface. It is brought into close contact with the light-receiving surface of a photodetector 308 such as a circle. This light guiding sheet 307 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. and stimulable phosphor sheets 103 to 12
- The stimulated luminescence light is guided through the light guide sheet 307, passes through the exit surface, and is received by the photodetector 308.

The preferred shape, material, etc. of the light guide sheet are disclosed in Japanese Patent Application Laid-Open No. 55-8
No. 7970, No. 5 (No. 3-11397, etc.).

A filter is attached to the light-receiving surface of the photodetector 308, which transmits only light in the wavelength range of stimulated luminescence light and cuts light in the wavelength range of excitation light, and detects only stimulated luminescence light. It's getting wet. The output of the photodetector 308 is sent to the amplifier 309
The signal is amplified and input to the data processing device 313.

On the other hand, the overall control device 604 outputs the size information including the position information of the irradiation field 103Δ or the position and size information as a control signal to the data processing device 3131\ via the look-ahead control device 312 or directly.

Based on the control signal, the data processing device 313 processes only the information within the radiation irradiation field 103A from among the read image information, and its output is input to the control circuit 414 of the main reading reading section 4. Ru. The control circuit 4 sets amplification factor setting value a1 recording scale factor setting value b1 reproduction image processing condition setting value C according to the obtained accumulated recording information.
Output.

The stimulable phosphor sheet 103 that has undergone pre-reading is transferred to the reading section 4 for main reading.

In the main reading reading unit 4, a main reading laser light source 40
The laser beam 402 emitted from 1 is this laser beam 402
After passing through a filter 403 that cuts the wavelength range of the stimulated luminescent light emitted from the stimulable phosphor sheet 103 by excitation, the beam diameter is strictly adjusted by a beam expander 404, The light is deflected onto the stimulable phosphor sheet 103 via a plane reflecting mirror 40G by a light deflector 405 such as the above. An fθ lens 407 is disposed between the optical deflector 405 and the plane reflecting mirror 406, and the laser beam 4 passes over the phosphor sheet 103.
Even when 02 is scanned, the beam diameter is always uniform.

On the other hand, the phosphor sheet 103 is moved in the direction of arrow 408 to perform sub-scanning, and as a result, the phosphor sheet 1
- The entire surface of 103 is irradiated with laser light. When the laser beam 402 is irradiated in this manner, 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 guide sheet for main reading. 409. The light guide sheet 409 for main reading has the same material and structure as the light guide sheet 307 for prereading. Light guide sheet for book reading 4
The stimulated luminescence light guided through the photodetector 410 through repeated total reflection is emitted from the exit surface and is received by the photodetector 410. 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. .

The main reading may be performed over the entire surface of the stimulable phosphor sheet. However, the signal processing at this time is preferably performed on image data only within the irradiation field by the same method and means as the above-mentioned pre-reading, since the signal processing time can be shortened. In addition, information regarding the irradiation field (that is, information on the size including the position information of the irradiation field or information on the position and size of the irradiation field) is input from the overall control device 604 to the main reading control device 15-, and this information is input to the reading control device 15-. By controlling the sub-scanning motor for main reading and the main reading moonlight deflector tri based on this, the reading area for main reading can be narrowed down to within the irradiation field. In this way, the reading time can be reduced, and by increasing the reading density according to the characteristics of the image recorded in the radiation field, better image quality can be achieved in the same or shorter time than scanning the entire sheet. A achievable image signal can be obtained.

In the present invention, it is preferable that the wavelength region of the excitation light and the wavelength region of the stimulated luminescent light do not overlap in order to improve the S/N ratio, and the excitation light source and the stimulable fluorescent light are selected 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 excitation light wavelength be 600 to 7000 m and the stimulated emission light wavelength be 300 to 50011 m.

In this way, it emits stimulated luminescence light of 300 to 500 nm,
Examples of stimulable fluorophores that can be preferably used in the present invention include rare earth element-activated alkaline earth 16-metal fluorohalide fluorophores [specifically, JP-A-55
-12143 (Ba1-X-γ
.

M'J X, Ca y) VX:'a El
” (However, X is at least one of C9J and Br, × and y are O<
y≠0 and a is 10-6≦a≦5×10”), (Ba s −x, MIrx ) FX : V A (
However, MI[ is at least one of M(], Ca, Sr, 7n, and Cd, X is at least one of C9,, 3r, and ■, and A is ELI.

Tb, Ce, Tm, DV, Pr XH
o, Nd, Yl) and Er, X is O≦x≦0.6, y is 0≦y≦0.2), etc.; Listed zns:cu.

Pb, Ba Q-x AL203: Eu (however, 0.8≦×≦1,0) and M”O・X Si 02
:A (However, M8 is Mg, Ca, Sr, zn,
cd or Ba, A is Ce, 1bXEu, Tm,
F'b, T9. , B1 or Mn, and × is 0.5
≦X≦2.5); and JP-A-55-1214
l n○X: ×△ (where Ln is La, Y, G (at least one of l and lu, X is at least one of C and Br, △ is C
at least one of e and TII, x is O<x
<0.1): etc. Among these, rare earth element-activated alkaline earth metal fluorohalide phosphors are preferred, and among these, barium fluorohalides shown as specific examples are particularly preferred because of their excellent stimulable luminescence.

Furthermore, barium fluorohalide phosphor was developed in Japanese Unexamined Patent Application Publication No. 5 (1985) (
Nos. 3-23135 and 5 (added with metal fluorides as disclosed in No. 3-2386, or metal chlorides, metal bromides, and metal iodides as disclosed in Japanese Patent Application No. 1508734 of 1982) Addition of at least one of these is preferable because stimulated luminescence is further improved.

Further, as disclosed in Japanese Patent Application Laid-Open No. 55-163500, when the phosphor layer of a stimulable phosphor plate prepared using the above-mentioned stimulable phosphor is colored using one size or a dye, ,
This is preferable because the sharpness of the finally obtained image is improved.

By this reading, the stimulated luminescence 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 A/D It is input to converter 412 . The A/D converter 412 converts the digital signal into a digital signal with a scale factor suitable for the signal fluctuation width according to the recording scale factor setting value, and inputs the digital signal to the signal processing circuit 413. In the signal processing circuit, signal processing is performed based on the reproduction image processing condition setting value C so as to obtain an X-ray image excellent in suitability for observation and interpretation, and the signal is transmitted to the reproduction recording section and input to the optical modulator 501.

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 on a photosensitive material I4505 such as a photographic film. On this occasion,
The photosensitive material 505 is perpendicular to the scanning direction (arrow 506)
Since the X-ray image is transferred in synchronization with scanning, an X-ray image is output on the photosensitive material 505.

Here, a light modulator control device 507 is provided, and image information is provided to form an image recording area 505A on the photosensitive material 505 corresponding to the irradiation field 103A in the phosphor sheet 103 calculated by the overall control device 604. By performing the output and displaying the image only inside the irradiation field, a clearer final image is obtained.

The overall control unit 6 includes the overall control device 604 and the console 6.
03, and as described above, it not only calculates the size or both the size and position of the irradiation field 103A in the phosphor sheet 103, but also can set the pre-reading density, speed, etc.

It goes without saying that the present invention is not limited to the above-described embodiments, and that various modifications can be made.

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

In addition, as in JP-A No. 58-67243, the pre-reading and main reading = 20 = 20 = the same reading section is used, and the scanning conditions of the excitation light are changed using a single reading device to perform the pre-reading and main reading. may be done.

Furthermore, the laser light source serving as the excitation light source in the pre-reading reading section and the main reading reading section can be replaced with an LED array having a wavelength range different from that of the stimulated emission 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 recording unit 5 is not limited to the direct recording method using a laser light source, but also a method of displaying on a CRT, video printer, etc., for example, can be used.

[Brief explanation of the drawing]

The drawing is a schematic diagram of an X-ray image information recording system including an X-ray image information reading device that is an embodiment of the present invention. 1... Photography Department 101...
X-ray source 102...Subject 103...Storage phosphor sheet 103A...
Radiation irradiation field 110...Irradiation field aperture 115.
...Irradiation field narrowing! lI control device 3...
・Pre-reading reading unit 301... Pre-reading laser light source 302...
...Laser light 303...Filter 304.
.....Light deflector 305 .....Flat reflecting mirror 3
06... Transfer direction 307... Light guiding sheet for pre-reading 308...
...Photodetector 309...Amplifier 312
...... Pre-reading control device 313... Data processing device 4... Reading unit for main reading 401... Laser light source for main reading 402...
...Laser light 403...Filter 404...
...Beam expander 405...Light deflector 406...Flat reflecting mirror 407...
・・fθ lens 408・・Transfer direction 409・
...Light guide sheet for main reading 410...Photodetector 411...Amplifier 412...
...A/D converter 413...Signal processing circuit 414...Control circuit 5...Reproduction/recording section 501...
Light modulator 502... Recording laser light source 503... Laser light 504... Scanning mirror 505... Photosensitive material 505A... Image recording area 507. ...... Optical 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. Prior to actual reading, the radiation image information stored and recorded in the excitation light is stimulated to emit light, and the resulting stimulated light is optically read to obtain image information for observation and interpretation. In a radiation image information recording/reading method for reading and pre-reading image information accumulated and recorded on the stimulable phosphor sheet using excitation light of the stimulable phosphor sheet, data processing of the image information in the pre-reading is carried out using A radiation image information recording and reading method characterized in that the method is performed only on image data within a radiation irradiation field during image recording. 2) A radiographic image emitted from the sheet by irradiating excitation light onto an imaging unit having an irradiation field aperture and the stimulable phosphor sheets 1 to 1 for accumulating and recording radiation image information on the stimulable phosphor sheet. In a radiation image information recording/reading device that has a reading section that photoelectrically reads stimulated luminescence light carrying information to obtain an image signal, prior to the actual reading, excitation light with an energy lower than that of the excitation light for the actual reading is used. It has a means for pre-reading, and performs data processing in the pre-reading only on the image data of the irradiation field based on information regarding the radiation irradiation field at the time of image recording on the stimulable phosphor sheet in the imaging unit. A radiographic image information recording/reading device characterized by comprising means.