JPH0650895B2 - Radiation image reader - Google Patents

Description

TECHNICAL FIELD The present invention relates to a reading device for reading radiation image information accumulated and recorded in a radiation image conversion panel having a stimulable phosphor, and more specifically, to a reading device. The present invention relates to an efficient reading apparatus for radiation image information.

[Background of the Invention]

Radiation images such as X-ray images are often used for disease diagnosis. In order to obtain this X-ray image, X-rays that have passed through the subject are irradiated onto the phosphor layer (fluorescent screen), which produces visible light, and this visible light is used in the same way as when taking a normal photograph. A so-called radiograph in which a film using salt is irradiated and developed is used. However, in recent years, a method of directly taking out an image from the phosphor layer without using a film coated with silver salt has been devised.

As this method, the radiation that has passed through the subject is absorbed by the phosphor, and then the phosphor is excited by, for example, light or thermal energy so that the radiation energy accumulated by the absorption by the phosphor is emitted as fluorescence. , There is a method of detecting this fluorescence and imaging. Specifically, for example, U.S. Pat. No. 3,859,527 and JP-A-55-1214.
No. 4 discloses a radiation image conversion method using a stimulable phosphor and using visible light or infrared light as stimulated excitation light. This method uses a radiation image conversion panel in which a stimulable phosphor layer is formed on a support, and the radiation transmitted through the subject is applied to the stimulable phosphor layer of this radiation image conversion panel to apply the radiation to each part of the subject. A latent image is formed by accumulating the radiation energy corresponding to the radiation transmittance, and thereafter, the stimulable phosphor layer is scanned with stimulable excitation light to radiate the accumulated radiation energy of each part to generate a latent image. Convert it to light,
A radiation image is obtained by an optical signal depending on the intensity of the light.

The radiation image is visualized as it is or after being subjected to image processing in real time and output to a silver salt film, CRT or the like. Further, the radiation image is stored in an image storage device such as a semiconductor storage device, a magnetic storage device, an optical disk storage device or the like, and then, if necessary, taken out from these image storage devices and output to a silver salt film, a CRT or the like for visualization. May be.

The radiation image conversion panel in the radiation image conversion method as described above is generally prepared in several sizes similar to the screen and film used in the usual radiography method, and the size of the object Depending on
Used by the photographer.

However, when there are several types of radiation image conversion panels, there are the following drawbacks.

(1) The manufacturing cost of the radiation image conversion panel increases.

(2) It is troublesome for the photographer to select an appropriate radiation image conversion panel each time a radiographic image is captured and set it on the imaging device.

(3) It is necessary to manage a large number of radiation image conversion panels having different sizes.

(4) Since the radiation image capturing device, the reading device, the erasing device, the stock device, etc. have to be compatible with the radiation image conversion panels of various sizes, the transport mechanism, the reading mechanism, the erasing mechanism, the stock mechanism, etc. are complicated and the device Becomes larger.

In general radiography, the subject is sufficiently smaller than the radiation image conversion panel, and the radiation field (radiation irradiation area) is used for the purpose of reducing the exposure dose to the copy.
I am shooting down.

However, in the above-described radiation image conversion method, the radiation image is read on the entire surface of the radiation image conversion panel, and there are the following drawbacks.

(1) The required radiation image information is smaller than the read radiation image information, so that not only the utilization efficiency of the image recording apparatus is reduced but also the processing time such as image processing becomes long.

(2) Since the unnecessary portion is read, the reading time becomes long.

(3) The resolution of the radiation image of a necessary portion is relatively reduced.

(4) When a radiation image is output on a silver salt film or a CRT for visualization, a necessary radiation image and an unnecessary image coexist, which makes the image extremely difficult to see, and the diagnostic ability deteriorates.

[Object of the Invention]

The present invention has been made in view of the above-mentioned drawbacks in a radiation image reading method using a radiation image conversion panel, and an object of the present invention is a radiation image reading apparatus capable of reducing unnecessary radiation image information. To provide.

Another object of the present invention is to provide a radiation image reading apparatus capable of shortening the radiation image reading time.

Another object of the present invention is to provide a radiation image reading apparatus capable of obtaining a plurality of radiation images having different sizes from one radiation image conversion panel.

It is an object of the present invention to provide a small and simplified radiation image reading apparatus for such a radiation image reading apparatus.

[Structure of Invention]

In order to achieve the above-mentioned object, the present inventors have conducted extensive studies on a radiation image reading device using a radiation image conversion panel having a photostimulable phosphor layer. As a result, a radiation image reading apparatus, which is an object of the present invention, has a radiation image conversion panel having a stimulable phosphor layer that is partially irradiated with radiation to store and record radiation image information, and the radiation image conversion panel. In a radiation image reading device comprising: an excitation light scanning means for scanning the accumulated and recorded radiation image information into stimulated emission by scanning with stimulated excitation light; and a photodetector for photoelectrically reading the stimulated emission. Based on an afterglow reading unit that collects an instantaneous afterglow generated by the irradiation of the radiation by an afterglow condensing body and photoelectrically converts it by a photoelectric converter, and an afterglow signal from the afterglow reading unit. An area calculation means for assessing the radiation irradiation area to determine the reading area, and a reading control means for selectively reading the radiation irradiation area based on a reading area designation signal from the area calculation means are provided. That the radiation image reading apparatus.

And a radiation image conversion panel having a stimulable phosphor layer that is partially irradiated with radiation to store and record radiation image information, and the radiation image conversion panel is scanned with stimulating excitation light to perform the storage and recording. In a radiation image reading device having an excitation light scanning unit for converting radiation image information into stimulated emission and a photodetector for photoelectrically reading the stimulated emission, in a side opposite to the radiation source of the radiation image conversion panel. A photoelectric conversion element which is provided to detect the instantaneous light emission generated by the irradiation of the radiation, an area calculation unit which evaluates a radiation irradiation area based on an instantaneous light emission signal from the photoelectric conversion element, and determines a reading area, The present invention is achieved by a radiation image reading device, which is provided with reading control means for selectively reading the radiation irradiation area based on a reading area designating signal from the area calculation means. .

In the present invention, the radiation irradiation region is narrowly referred to only as a portion that is truly irradiated with radiation, and is broadly referred to as a true radiation irradiation portion and its peripheral portion. However, the area of the peripheral portion is preferably 50% or less of the area of the true radiation irradiation portion.

In the present invention, in order to read the radiation irradiation area of the radiation image conversion panel, it is necessary to detect the radiation irradiation area and specify the reading area corresponding to the radiation irradiation area in the radiation image reading device.

As a method of detecting the radiation irradiation area, firstly, there is a method of instantaneous light emission of the radiation image conversion panel. This method detects the radiation irradiation area by detecting the instantaneous light emission of the stimulable phosphor emitted from the radiation image conversion panel while the radiation is being irradiated. The information obtained by the method may be used for setting a reading gain at the time of reading a radiation image or knowing the outline of the radiation image information, in addition to the purpose of knowing the radiation irradiation region.

Secondly, there is a method using afterglow of the radiation image conversion panel.
The method detects the afterglow of instantaneous light emission that occurs when a radiation image conversion panel is irradiated with radiation to know the radiation irradiation area. The information obtained in this method is used for setting a reading gain at the time of reading a radiation image, in addition to the purpose of knowing the radiation irradiation region as in the first method.
It may be used to know the outline of radiation image information.

In the present invention, the method of reading the radiation irradiation area of the radiation image conversion panel is as follows: first, a method of controlling the scanning area of the stimulable excitation light (scanning control of the stimulation excitation light); After scanning a large part with stimulated excitation light,
There are a method of selecting a signal of a radiation irradiation region as an image signal, and a third method of combining the first and second methods.

In the present invention, the stimulable phosphor means that, after being irradiated with light or high-energy radiation, it is stimulated by light, thermal, mechanical, optical or electrical (stimulation excitation) to give the first light or It refers to a phosphor that exhibits stimulated emission corresponding to the irradiation amount of high-energy radiation, but from the practical viewpoint, it is preferably a phosphor that exhibits stimulated emission by stimulated excitation light of 500 nm or more.

In addition, in the present invention, the afterglow of the instantaneous light emission of the radiation image refers to fluorescence that is continuously emitted after the irradiation of radiation is completed.

Further, in the present invention, the stimulable excitation light is a light that can efficiently emit the radiation energy accumulated in the stimulable phosphor as stimulated emission, preferably Ar laser, He-Ne laser, Kr laser. , YAG laser, He-Cd laser, semiconductor laser, and the like.

〔Example〕

Next, the radiation image reading apparatus of the present invention will be described in more detail with reference to examples.

FIG. 1 is a schematic view of a radiation image reading apparatus using afterglow which is one of the embodiments of the present invention.

In FIG. 1, 1 is an imaging unit, 101 is a radiation source, and 1
Reference numeral 02 is a subject, and 103 is a radiation image conversion panel according to the present invention. 2 is an afterglow reading unit, 207 is an afterglow condenser, 208
Is a photoelectric converter. Reference numeral 3 is a main reading unit, 301 is a photostimulation excitation light source for main reading, 303 to 307 are optical scanning members, 309 is a photostimulated luminescence condensing body, and 310 is a photoelectric converter. Reference numeral 4 is a radiation image reproducing unit.

The radiation transmitted through the subject 102 in 1 is absorbed by the radiation image conversion panel 103, a part of the energy is accumulated in the stimulable phosphor, a part is emitted as an instantaneous light emission, and a part is also the radiation source 101. Is emitted as afterglow of instantaneous light emission even after the irradiation of radiation from is stopped. The radiation image conversion panel 103 irradiated with the radiation in 1 is sent to the afterglow reading unit 2.

2, the entire surface of the radiation image conversion panel 103 is read by the afterglow condensing body 207, and the radiation irradiation region is assessed by the region calculation unit 209 by the afterglow signal from the photoelectric converter 208, and at the same time, the radiation irradiation region is detected. The reading area is determined based on Next, in the main reading unit 3, the radiation image conversion panel 103 is main-read, but a reading control unit is operated by a signal (hereinafter referred to as a “reading region designation signal”) designating the determined reading region from the region computing unit 209. 312
Supplies a signal to the light deflector 305 and the sub-scanning unit 308 to control the scanning of the stimulated excitation light to specify the reading area.

In this way, the radiation irradiation area is selectively read. The signal from the photoelectric converter 310 passes through the analog / digital converter 311, and is then sent to the radiation image reproducing unit 4 to be visualized.

In the above example, the reading area is specified by the light deflector 305 and the sub-scanning unit 308, but as shown in FIG.
May be controlled to change the sampling start position and the end position to specify the area.

This method will be described in detail with reference to FIG. Fig. 2 (b)
Radiation irradiation area 52 of the radiation image conversion panel 103
Is determined by the area calculation unit 209 based on the signal detected by the afterglow reading unit 2 in FIG. After that, in the main reading unit 3, for example, almost the entire surface of the radiation image conversion panel 103 is scanned by the stimulated excitation light. As for the signal from the photoelectric converter 310, only the signal within the radiation irradiation area of the radiation image conversion panel 103 is subjected to analog / digital conversion and selectively taken out as an image signal. Further, the reading area may be specified by a method shown in FIG. 3 by combining the above two examples. In FIG. 9A, after the radiation irradiation area of the radiation image conversion panel 103 is determined by the same method as described above, the reading area designation signal from the area designation calculation unit 209 in the main reading unit 3 is used, for example. The reading control unit 312 gives a signal to the light deflector 305, the sub-scanning unit 308, and the analog / digital converter 311, and controls the scanning of the stimulated excitation light and the analog / digital converter 311 to specify the reading area. To do.

As a result, the radiation image conversion panel 10 as shown in FIG.
In the third main scanning method, the reading area is designated by the sampling period, and in the sub-scanning method, the reading area is designated by the scanning width of the stimulated excitation light.

Further, in the above example, the afterglow reading unit and the main reading unit have separate mechanisms, but the main reading unit may also function as the afterglow reading unit, or the photographing unit, the afterglow reading unit, and the book reader. The reading unit may be integrated.

FIG. 4 is a schematic view showing a part of a system based on a radiation image reading method using instantaneous light emission which is another embodiment of the present invention.

In FIG. 4, 61 is a photographing device, 62 is a radiation source, 63 is a radiation image conversion panel according to the present invention, and 64 and 65 are for instantaneous light emission detection located on the opposite side of the radiation image conversion panel 63 from the radiation source 62. Is a photoelectric conversion element array.

Radiation from the radiation source 62 is absorbed by the radiation image conversion panel 63 after passing through the subject, and a part of the energy is emitted as instantaneous light emission. This instantaneous light emission is detected by the photoelectric conversion element arrays 64 and 65, the radiation irradiation area is assessed by the area calculation unit (not shown) from this signal, and the reading area is determined based on the radiation irradiation area. Next, the reading area of the radiation image conversion panel 63 is read by a reading unit (not shown) that is integral with or separate from the imaging device 61.

[Effects of the Invention] As described above, according to the radiation image reading apparatus of the present invention, the radiation image information obtained has a small amount of unnecessary image information, so that the utilization efficiency of the image storage device is improved.

Further, according to the present invention, the radiation image information obtained has a small amount of unnecessary image information, so that processing time such as image processing is shortened.

Further, according to the present invention, it is not necessary to read an unnecessary portion, so that the reading time of the radiation image conversion panel is shortened.

Further, according to the present invention, when a radiation image is visualized, unnecessary images are not mixed, so that the image is easy to see and the diagnostic ability is improved.

Further, according to the present invention, it is not necessary to select the size of the radiation image conversion panel depending on the size of the subject, and the complexity is eliminated.

Further, according to the present invention, since it is not necessary to select the size of the radiation image conversion panel according to the size of the subject,
The size of the radiation image conversion panel becomes one, and the radiation image capturing device, the reading device, the erasing device, the stock device, etc. are simplified and downsized.

The present invention has the above effects and is industrially very useful.

[Brief description of drawings]

1, FIG. 2, FIG. 3, and FIG. 4 are schematic diagrams for explaining a radiation image reading apparatus according to an embodiment of the present invention. 1 ... Imaging unit, 101 ... Radiation source, 102 ... Subject, 103 ... Radiation image conversion panel, 2 ... Afterglow reading unit, 206 ... Sub scanning unit, 207 ... Afterglow condensing body, 208 ...... Photoelectric converter, 209 ...... Area calculation unit, 3 ...... Main reading unit 301 …… Main reading stimulated excitation light source, 305 …… Light redirector, 308 …… Sub scanning unit, 309 …… Stimulated emission Condenser, 310 ... Photoelectric converter, 311 ... A / D converter, 312 ... Read control section, 4 ... Radiation image reproducing section, 401 ... Optical modulator, 402 ... Recording light source, 404 ...... Light redirector, 405 …… Sensitive material, 406 …… Sub scanning unit, 51 …… Scan line, 52 …… Radiation irradiation area, 61 …… Shooting device, 62 …… Radiation source, 63 …… Radiation image Conversion panel, 64 and 65 ... Photoelectric conversion element array.

Claims (2)

[Claims] 1. A radiation image conversion panel having a stimulable phosphor layer which is partially irradiated with radiation to store and record radiation image information, and the radiation image conversion panel is scanned with stimulable excitation light to obtain the information. In a radiographic image reading device having an excitation light scanning means for converting the stored and recorded radiation image information into stimulated emission and a photodetector for photoelectrically reading the stimulated emission, an instantaneous residue generated by the irradiation of the radiation An afterglow reading unit that collects light with an afterglow condensing body and photoelectrically converts it with a photoelectric converter and detects the radiation irradiation region based on an afterglow signal from the afterglow reading unit to determine a reading region. A radiation image reading apparatus comprising: a region calculating means for determining; and a reading control means for selectively reading the radiation irradiation region based on a reading region designating signal from the region calculating means. 2. A radiation image conversion panel having a stimulable phosphor layer that is partially irradiated with radiation to store and record radiation image information, and the radiation image conversion panel is scanned with stimulating excitation light to obtain the radiation image information. In a radiation image reading device having an excitation light scanning means for converting the accumulated and recorded radiation image information into stimulated emission, and a photodetector for photoelectrically reading the stimulated emission, a radiation source of the radiation image conversion panel, Is provided on the opposite side of the photoelectric conversion element for detecting the instantaneous light emission generated by the irradiation of the radiation, and the area calculation for evaluating the radiation irradiation area based on the instantaneous light emission signal from the photoelectric conversion element to determine the reading area. A radiation image reading apparatus comprising: a reading unit and a reading control unit that selectively reads the radiation irradiation region based on a reading region designation signal from the region calculation unit.