JPH02247637A - Radiograph reader - Google Patents

Abstract

PURPOSE:To obtain a radiograph reader which is capable of high speed processing by remarkably shortening the processing time of image reading by dividing an image region and performing parallel reading. CONSTITUTION:The radiograph reader divides the fluorescent plate region into several regions, performs parallel reading using separate reading units arranged on each divided region and shortens the reading time to the reciprocal of the number of the reading units. For example, when a stimulable phosphor sheet 21 arranged at equal intervals with three pairs of the reading units 22 - 24 is fixed on an X stage 22 and shifted in the arrowed direction, the reading units 22 - 24 scans each divided stimulable phosphorsheet region, and read image data are stored in frame memories 25 - 27. An image processor 29 reads the image data from the frame memories 25 - 27 sequentially through a multiplexer 28, receives the data as the read image data by one piece of the stimulable phosphorsheet 21 and processing is performed.

Description

[Detailed description of the invention] 〔overview〕 Two-dimensional images of radiation such as X-rays are temporarily stored.

Next, by irradiating it with electromagnetic radiation such as laser light. Relating to a radiation image reading device for reading a two-dimensional radiation image by emitting a second electromagnetic radiation according to the accumulated radiation energy and converting it into an electrical signal. 9. A radiation image reading device capable of high-speed processing. By irradiating high-energy neutron beams and other hard or transparent electromagnetic waves or particle radiation, optical scanning equipment and optical detection are applied to a phosphor plate or sheet that temporarily stores the transmitted image as a latent image. A plurality of sets of reading units each consisting of a set of devices are installed at equal intervals, five phosphor plates or sheets and the plurality of sets of reading units are moved relative to each other in one direction, and each reading unit is configured to read in parallel. .

[Industrial application field]

The present invention first stores a two-dimensional image of radiation such as X-rays and then irradiates it with electromagnetic radiation such as a laser beam, thereby emitting a second electromagnetic radiation according to the accumulated radiation energy. .

The present invention relates to a radiation image reading device for reading two-dimensional radiation images by converting them into electrical signals.

[Conventional technology]

In recent years, high-sensitivity, high-resolution X-ray imaging systems have replaced the conventional method of recording two-dimensional images of indirect or direct radiation on a film coated with a sheet of silver salt photosensitizer.
Methods using stimulable phosphors are beginning to be utilized.

Such a system is described in detail in US Pat. No. 3,859,527 as a basic method.

When the phosphors used in this system receive energy from radiation such as xvA, they store some of that energy. To the phosphor in this state.

When the first light is irradiated anew, the stored energy is released as a second light. At this time, the first light is not limited to visible light, but also light with a wide wavelength range from infrared to ultraviolet. However, the selection depends on the phosphor material used. There are also various types of second light, from infrared light to ultraviolet light, and the difference also depends on the phosphor material used.

When this type of phosphor is irradiated with visible or near-infrared light,
There are those that emit visible to ultraviolet light with shorter wavelengths, and those that emit visible to infrared light when irradiated with long wavelength infrared rays, which have a large thermal effect. The phosphors used for the former are called stimulable phosphors, and the phosphors used for the latter are called thermophosphors.

However, the method disclosed in US Pat. No. 3,859,527 was difficult to read at high speed and was not practical. Therefore, since then, many improvements have been proposed regarding stimulable phosphors, excitation light scanning methods, and the like.

A radiation image reading device that uses stimulable phosphors.

Compared to the method using silver halide film.

■ It has high sensitivity to radiation, and when used for medical purposes, the amount of X-rays irradiated to patients can be reduced to less than a fraction of that of conventional methods.

■ Images are converted into time-series electrical signals and read, making them suitable for image processing by computers.

There is an advantage, but on the other hand.

■ Demand to further increase sensitivity and reduce irradiation dose to patients ■ Because it takes a long time to take an image, it is difficult to use for medical purposes because the processing speed per person is slow.

There were requests for improvements and shortcomings.

In particular, when radiation reading devices using stimulable phosphors are applied to, for example, mass screening for chest X-ray shadows, the time taken for conventional indirect photography is 45 seconds or more per person, compared to 15 to 20 seconds per person. This method was insufficient as a method to replace conventional indirect photography.

[Problem to be solved by the invention]

In the method using a photostimulable phosphor, the stimulated luminescence when irradiated with excitation light causes temporal tailing (t
i), and is the fundamental factor in determining the shooting time. For this reason.

In order to read the stimulated luminescence of one pixel and then read the next pixel, the stimulated luminescence of the previous pixel must be considerably weakened, which reduces the image reading required to obtain the target dynamic range. The minimum time is limited.

For example, if the tailing of stimulated luminescence decreases in 4 μs after irradiation with excitation light to obtain a 60 dB dynamic range, then the excitation light is irradiated to a certain pixel, and the stimulated luminescence is collected and received. The time from when the excitation light is applied to the next pixel, that is, the reading time for one pixel, is 4 microseconds at the shortest.

In the case of chest XvA shadow, if the size of one pixel is 175 μ-square and the reading area is about 35 On, the @ prime number is about 4,000,000, so the time to read the previous pixel is 16 seconds. In short, and considering the effect of excitation light scanning, if the time to erase one image and move the photostimulated phosphor or excitation light scanning and light collection/receiving system to prepare for the next X-ray irradiation is 10 seconds, then The time required to print and read the image is approximately 33
2 seconds, and mass screening using conventional XvA film is now 1
Compared to the previous 5 to 20 seconds, it now takes an hour.

An object of the present invention is to provide a radiation image reading device capable of high-speed processing.

[Means to solve the problem]

The time required for each process of reading a radiation image using stimulated luminescence described above is an indispensable time, and it seems impossible to shorten the required time. For example, by erasing the latent image and using photostimulated phosphor or excitation light scanning and focusing/
It is difficult to shorten the 10 seconds required to move the light receiving system and prepare for the next X-ray irradiation, and the reading time for one pixel is determined by the stimulated luminescence lifetime, and the efficiency of excitation light scanning is also limited. It is difficult to obtain more than 80%. Therefore, the present invention makes it possible to significantly shorten the image reading processing time by dividing the image area and performing parallel reading.

FIG. 1 shows the basic configuration of the present invention.

In FIG.

1 is a radiation image reading device.

2 is a phosphor plate (including a sheet), which temporarily stores a latent image of the transmitted image of the object by irradiating the object with Lugie neutron beam and similar hard or transparent electromagnetic waves or particle radiation, and then makes it visible. By irradiating light or infrared rays.

Emit electromagnetic waves with a shorter wavelength than visible light or infrared rays depending on the latent image.

3 is a feeding means for moving the phosphor plate 2 in one direction.

4.5 is a reading unit that reads the latent image on the phosphor plate 2 and converts it into an electric signal;
They are installed at predetermined intervals so that the divided reading areas are main-scanned and sub-scanned in parallel.

6.7 are lines along which the phosphor plate 2 is main scanned by the reading unit 4.5.

8.9 are optical scanning devices each forming a part of the reading unit 4.5, each of which irradiates the phosphor plate 2 in a scanning manner using visible light or infrared rays, as shown by line 6.7. do.

10.11 is a light detection device constituting the remaining part of the 5 reading unit 4.5, and a light scanning device 8.9
Based on line scanning of the phosphor plate 2 by the phosphor plate 2, electromagnetic waves emitted from the lines are collected and received, and converted into analog image signals.

12 and 13 are the photodetector devices 10 and 10, respectively. This is an A/D converter that amplifies the analog image signal output from the li with amplifiers 18 and 19 and then converts it into digital image data pixel by pixel.

Frame memories 14 and 15 store image data output from the A/D converters 12 and 13, respectively.

16 is a multiplexer that sequentially reads image data from frame memory 14 and frame memory 15 and outputs the same.

Reference numeral 17 denotes an image processing device that performs storage and display of image data and other image processing.

[For production]

The present invention divides the area of the phosphor plate into multiple areas and performs reading in parallel using separate reading units installed in each divided area, so the reading time is shortened to 1/the number of sets of reading units. be able to.

When there are two sets of reading units shown in FIG.

Using the previous example, the reading time is 1/2 (approximately 11
seconds), and the total processing time is 2 seconds.
It is possible to set the time to 21 seconds (10+22/2 seconds) in the case of a set of installations, 18 seconds (10+22/3 seconds) in the case of three sets of installations, and 16 seconds in the case of four sets of installations.

The number of units to be installed depends on the size of the phosphor plate and the size of the pixels, but the number of units that can be installed is limited by the size of the unit.

〔Example〕

The present invention will be explained in detail below.

FIG. 2 shows an example of a radiation image reading device using three sets of reading units, in which the photostimulable phosphor plate 21 is
2, and three sets of reading units 22. 23. 24 are installed at equal intervals.

For example, the length of the stimulable phosphor plate 21 is 430 m, and the interval between each reading unit is set to 144 m.

Each reading unit 22. 23.
24 scans each divided stimulable phosphor plate area, and each read image data is stored in a frame memory 25. 26. 27. After all scanning is completed, first, the image data in the frame memory 25 is read out and sent from the multiplexer 28 to the image processing device 29.

Next, the image data in the frame memory 26 is read out and sent to the image processing bag W29, and finally the image data in the frame memory 27 is read out and sent out to the image processing device 29.

In the image processing device 29, each frame memory 25°26
, 27 is received as read image data for one photostimulated phosphor plate 21,
Perform processing.

FIG. 3 shows a specific example of the optical system in the embodiment of the present invention.

In each read unison l-22, 23, 24.

Optical scanning device 30. 31. Each of the 32 optical systems.

Gas laser or laser diode, collimated system,
It is composed of a polygon mirror or a galvanometer mirror, an fθ lens, a reflection mirror, etc., and a photodetector 33. 34. Each of the 35 optical systems includes a condensing mirror, a condensing fiber array, an interference filter that separates and transmits the wt exhaust emission light from the excitation light, a photomultiplier tube, and the like. The output terminal of the condensing fiber array is shaped to match the size of the light section of the photomultiplier tube.

In order to carry out the present invention, necessary techniques different from conventional techniques are alignment when installing a plurality of optical systems on a photostimulable phosphor plate or sheet, and correction of changes over time in the amount of stimulated luminescence. It is sufficient to position the optical system with an accuracy of about 1/1O of one pixel, and correction of changes in the amount of stimulated luminescence over time can be handled by applying conventional techniques.

Further, when the number of pixels in the sub-scanning direction is not divisible by the number of optical systems installed, it is possible to install them at equal intervals by increasing or decreasing the number of pixels by several pixels so that it is evenly divisible by 2.

〔Effect of the invention〕

As explained above, according to the present invention, the reading time is
Since the processing time can be reduced to one-fold or several-fold, and the overall processing time can be significantly shortened, it greatly contributes to improving the performance of the two-radiation image reading apparatus.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the basic configuration of the present invention, FIG. 2 is a diagram showing the configuration of one embodiment of the invention, and FIG. 3 is a diagram showing the configuration of an optical system in one embodiment of the invention. In Figure 1. 1: Radiation image reading device. 2: Phosphor board. Feeding means 5: reading unit. 7: Line. 9: Optical scanning device. 11: Photodetection device. 13! A/D converter. 15: Frame memory. multiplexer. Image processing device.

Claims (2)

[Claims] (1) By irradiating X-rays through the subject, the transmitted image is temporarily stored as a latent image on a phosphor plate or sheet.
A scanning device irradiates visible light or infrared rays in a scanning format, and the electromagnetic waves emitted at that time, which have a shorter wavelength than the irradiated visible light or infrared rays, are collected by a photodetector and converted into electrical signals to obtain a digital image. In the apparatus, a plurality of sets of reading units (4, 5) each consisting of a light scanning device and a light detection device are installed at equal intervals for the phosphor plate or sheet, and the phosphor plate or sheet and the plurality of sets are read. A radiation image reading device characterized in that the reading units (4, 5) are moved relative to each other in one direction, and each reading unit (4, 5) is operated in parallel. (2) In claim (1), each reading unit (4
, 5) is installed in correspondence with the reading unit (4, 5), and after all pixels have been read out, the information of each frame memory is stored. What is claimed is: 1. A radiation image reading device characterized by sequentially transmitting images to an image processing device.