JPH03212638A - Radiograph information reader - Google Patents

Abstract

PURPOSE:To miniaturize a radiograph information reader by narrowing the scanning width of excitation light, reading the partial area of a phosphor sheet, and then relatively moving a scanning read unit and the sheet, thereby reading the other area of the sheet. CONSTITUTION:While the accumulative phosphor sheet 10 where radiograph information is accumulated and recorded is fed in a direction Y on a sheet feeding means 11 held on a frame 30 which is at a specified position, a laser beam 13 reflected by a mirror 18 is allowed to scan in a direction X. Thus, the beam 13 scans the area A of the sheet 10 with a main scanning width L1. Next, the frame 30 is moved by the width L1 in a direction W and the sheet 10 is returned to a subscanning starting position to read the area B of the sheet 10. Furthermore, the operation is repeated so as to read the area C of the sheet 10. With such constitution, the information is read from the large-sized sheet 10 by using a small-sized device.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is directed to irradiating excitation light to a stimulable phosphor sheet on which radiographic image information is accumulated and recorded, thereby stimulating stimulated luminescence emitted from the sheet. The present invention relates to a radiation image information reading device that photoelectrically detects light to read the radiation image information, and more particularly, it relates to a radiation image information reading device that is smaller and lighter.

(Prior art) When a certain type of phosphor is irradiated with radiation (X-rays, α-rays, β-rays, γ-rays, electron beams, ultraviolet rays, etc.), a part of the energy of this radiation is accumulated in the phosphor. It is known that when this phosphor is then irradiated with excitation light such as visible light, the phosphor exhibits stimulated luminescence depending on the stored energy. (stimulable phosphor).

Using this stimulable phosphor, radiation image information of a subject such as a human body is recorded on a sheet having a layer of stimulable phosphor (hereinafter referred to as a ``stimulable phosphor sheet''). A phosphor sheet is irradiated with excitation light such as a laser beam to generate stimulated luminescent light, the resulting stimulated luminescent light is read photoelectrically to obtain an image signal, and this image signal is processed to determine the suitability for diagnosis. A radiation image information recording and reproducing method for obtaining a good radiation image of a subject has been proposed (for example, Japanese Patent Laid-Open No. 55-12
No. 429, No. 55-116340, No. 55-1634
No. 72, No. 56-11395, No. 56-104645
number, etc.).

The above-mentioned apparatus for reading radiation image information generally includes a main scanning means for main scanning excitation light on a stimulable phosphor sheet;
A sub-scanning means for moving the sheet relative to the excitation light in a direction substantially perpendicular to the main scanning direction, and a photodetection means for detecting stimulated luminescence light emitted from a location of the stimulable phosphor sheet irradiated with the excitation light. It is often composed of.

In addition, the stimulable phosphor sheet is moved relative to the excitation light, and the excitation light itself is deflected two-dimensionally to cause the excitation light to main and sub-scan on the stimulable phosphor sheet. Devices that do this are also being considered.

(Problem to be Solved by the Invention) By the way, in the latter of the two types of reading devices described above, the larger the size of the stimulable phosphor sheet to be read, the more the excitation light is , it is necessary to ensure a long sub-scanning width. On the other hand, in the case of a one-sided device, the sub-scanning width can be maintained as long as possible by increasing the distance of the above-mentioned relative movement, but in order to deal with large-sized stimulable phosphor sheets, the excitation light It is necessary to ensure a long main scanning width.

In order to ensure a long excitation light scanning width, for example, in a device that deflects the excitation light beam for excitation light scanning, the optical path length from the optical deflector to the stimulable phosphor sheet must be adjusted. In addition, a long mirror or the like for changing the optical path of the deflected beam is required, which inevitably makes the device large and heavy.

On the other hand, even in a reading device that uses a large number of minute optical shutters integrated in an array or matrix for excitation light scanning, in order to ensure a long excitation light scanning width, the optical shutter assembly must be made long. Alternatively, since it is necessary to increase the size, the device tends to be large and heavy in this case as well.

Therefore, it is possible to reduce the size and weight of the reading device by installing multiple small scanning reading units with relatively narrow excitation light scanning areas, but in that case, the cost of the entire reading device would become extremely high. .

The present invention has been made in view of the above circumstances, and provides a device that can be made smaller and lighter, can be formed at low cost, and can read radiation image information from a large stimulable phosphor sheet. The purpose is to provide the following.

(Means for Solving the Problems) A radiation image information reading device according to the present invention includes an excitation light scanning means for main and sub-scanning the excitation light in a part of a stimulable phosphor sheet, and a part of the sheet irradiated with the excitation light. In addition to a scanning reading unit equipped with a photodetection means for photoelectrically detecting the emitted stimulated luminescence light, this scanning reading unit and a stimulable phosphor sheet are connected so that at least the main scanning area on the sheet changes. The present invention is characterized in that a scanning area changing means for moving the scanning area relative to the scanning area is provided.

As mentioned above, in a radiation image information reading device of the type in which the stimulable phosphor sheet is moved relative to the excitation light for sub-scanning of the excitation light, the scanning area changing means is particularly suitable for sub-scanning the sub-scanning area. Of course, there is no need to configure the system to change the .

(Function) As mentioned above, if the excitation light is used for main and sub-scanning in a part of the stimulable phosphor sheet, the main-scanning width or the main- and sub-scanning width can be increased even if the sheet is large in size. There is no need to secure it. Even if the excitation light is used for main and sub-scanning in a part of the stimulable phosphor sheet in this way, if the scanning area of the excitation light is changed by relatively moving the scanning reading unit and the stimulable phosphor sheet, , radiation image information can be read over the entire surface of the sheet.

(Example) Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 1 shows a radiation image information reading device according to a first embodiment of the present invention. For example, the stimulable phosphor sheet 10 on which radiation image information of the subject is accumulated and recorded by irradiating radiation that has passed through the subject is conveyed in the direction of arrow P by a conveying means (not shown), and is conveyed by a sheet conveying means such as an endless belt. Translated onto 11. The sheet transport means 11 constitutes a scanning reading unit together with various elements described below housed in the casing 5, and is held on a pedestal 30. This sheet transport means 11 is driven by a motor IIA, and transports the stimulable phosphor sheet 11 transferred thereon in the direction of arrow Y.

On the other hand, a rod receiving part 31 and a rod screwing part 32 having an internal thread are fixed to the pedestal 30.

A guide rod 33 extending in a direction substantially perpendicular to the direction of the arrow Y mentioned above is slidably inserted into the rod receiving portion '3■.
Further, a screw rod 34 extending parallel to the guide rod 33 is screwed into the threaded portion 32 .

This screw rod 34 is rotated forward and backward by a motor 35, thereby causing the pedestal 30, that is, the sheet transport means 1
1 is capable of reciprocating as a whole in a direction perpendicular to the direction of arrow Y. In addition, in this example, each of the above elements 30 to
35 constitutes a scanning area changing means.

When reading radiation image information from the stimulable phosphor sheet IO, the pedestal 30 is first set at the illustrated position. Under this condition, the stimulable phosphor sheet 1o is transferred to the sheet transport means 1.
1, the excitation light is transported in the direction of arrow Y for sub-scanning. At the same time, a laser beam 13 as excitation light emitted from a laser light source 12 inside the housing 5 is deflected by an optical deflector 14 such as a rotating polygon mirror, passes through a scanning lens 16 consisting of an fθ lens, and passes through a mirror 18. , an arrow X that is approximately perpendicular to the sub-scanning direction Y is reflected on the stimulable phosphor sheet 10.
Main scan in the direction.

Stimulated luminescence light 15 is emitted from the portion of the stimulable phosphor sheet 10 irradiated with the laser beam 13 in an amount corresponding to the radiation image information stored there. This stimulated luminescent light 15 enters a light guide 25 made of glass, for example, which is disposed so that a light incident end surface 25a extends along the main scanning line of the laser beam on the sheet 10, and is transmitted through the light guide 25, which is made of glass. It is detected by a long photomultiplier tube 17. This long photomultiplier tube 17 is, for example,
-16666, and the light guide 2
It has a light-receiving surface as long as that of 5. Note that a filter 26 is disposed between the light receiving surface and the light guide 25, which allows the stimulated luminescence light 15 to pass through satisfactorily, while cutting off the laser beam 13 reflected on the stimulable phosphor sheet 10.

Output S of the photomultiplier tube 17 indicating the amount of stimulated luminescence light 15
1 is input to the reading circuit 20 and subjected to processing such as amplification and logarithmic conversion. The analog read image signal S2 outputted by the reading circuit 20 is converted into digital image data S3 by the A/D converter 21, and then subjected to signal processing (image processing) such as gradation processing and frequency processing in the image processing circuit 22. receive.

Here, as shown in FIG. 2, the main scanning width L1 of the laser beam 13 on the stimulable phosphor sheet 10 is set to ⅓ of the total width L2 of the recording area of the sheet 10.

Therefore, even if the stimulable phosphor sheet 10 to be read is large in size, the optical path length from the optical deflector 14 to the stimulable phosphor sheet 10 can be shortened, and the mirror 18
, the light guide 25, and the elongated photomultiplier tube 17 can be relatively short, so that the scanning reading unit can be made small and lightweight.

However, on the other hand, once the above-mentioned sub-scanning with the excitation light is completed, the area that has been scanned with the excitation light, that is, the area where the radiation image information has been read, is only the area A shown in FIG. Then, the motor 35 is driven, and the pedestal 30 is moved to the first position.
It is moved in the direction of arrow W in the figure by a distance equal to the main scanning width L1. At the same time, the motor IIA is driven in the opposite direction to that in the above case, and the stimulable phosphor sheet 10 is returned so that the leading end is at the sub-scanning start position.

Then, when the reading process is performed in the same manner as in the above case,
Radiographic image information is read in the scanning area indicated by B in FIG. 2 of the stimulable phosphor sheet 10.

Then, when the above-described operation is repeated one more time, radiation image information is read for the scanning area shown by C in FIG. 2 of the stimulable phosphor sheet 10.

Therefore, the image processing circuit 22 includes the ASB shown in FIG.
Digital image data S3 indicating radiographic image information accumulated and recorded in each partial area of and C is sequentially input. The image processing circuit 22 synthesizes these three sets of digital image data S3 so that the partial areas A, B, and C are shown in the positional relationship shown in FIG. This image data synthesis is performed, for example, as follows.

That is, as schematically shown in FIG.
Areas C1 and C2 of frame memory 22M built in
Image data S3 obtained in the 1st, 2nd and 3rd reading processes are written in C3 and C3, respectively. that time,
Image data for the n-th main scanning line during each reading is written to a common line address n. and 3
After the set of image data S3 is written in the frame memory 22M, if these image data S3 are read out in the same way as normal reading of image data for one image, they are accumulated in the entire recording area of the stimulable phosphor sheet IO. Image data S4 indicating the recorded image information is obtained.

Note that when the third reading process is completed, the sheet transport means 11 continues to be driven as it is, so that the stimulable phosphor sheet 10 is sent out from above the sheet transport means 11 in the direction of arrow Q. The motor 35 is then driven in the opposite direction to that in the above case, and the pedestal 30 is returned to its original position.

The composite image data S4 obtained in this manner is transferred from the image processing circuit 22 to an image reproducing device 2 such as a CRT or printer.
3 and is used to reproduce the radiation image recorded on the stimulable phosphor sheet 10.

Note that the composition of the image data S3 may be performed before or after the processing such as the gradation processing. Further, in order to perform this data synthesis, a dedicated synthesis means separate from the image processing circuit 22 may be provided.

Furthermore, smoothing processing may be performed as appropriate to make the joints of the regions to be combined less noticeable. Specifically, as shown in FIG. 4, this smoothing process involves processing the image data of the first pixel and second pixel counted from the joint between areas A and B as AM, AM-1, and B1 s B2, respectively. Then, they are respectively 1+M114 image data AM', Av-+', B1',
Examples include processing for converting to BZ.

Next, a second embodiment of the present invention will be described with reference to FIG. Note that in FIG. 5, elements that are equivalent to those in FIG. 1 are given the same numbers, and detailed explanations thereof will be omitted.

In the apparatus shown in FIG. 5, the housing 5 is reciprocated in a direction parallel to the main scanning direction X by rotating the motor 35 in forward and reverse directions.

This housing 5 is the same as that shown in FIG. 1, and contains the same elements as shown in FIG. 1, such as a laser light source 12 and an optical deflector 14.

In this device, by moving the housing 5,
The excitation light scanning area on the stimulable phosphor sheet 10 is changed to the main scanning direction. Therefore, in the apparatus of the second embodiment as well, the main scanning width is set small as in the apparatus of the first embodiment, thereby making it possible to reduce the size and weight of the apparatus.

It goes without saying that in the present invention, the main scanning width L1 can be set to 1/3 of the total width L2 of the recording area of the stimulable phosphor sheet 10, or to various other values such as 1/2 or 1/4. The smaller the ratio of the main scanning width L1 to the total recording area width L2 is, the more advantageous it is in terms of making the reading device smaller and lighter. However, in general, the more the number of times a single stimulable phosphor sheet is read, the longer the time required for reading becomes. Therefore, it is preferable that the ratio between Ll and L2 is appropriately determined in consideration of both the size and weight of the device and the time required for reading.

Furthermore, in a radiation image information reading device configured such that the scanning reading unit deflects the excitation light two-dimensionally without transporting the stimulable phosphor sheet for excitation light sub-scanning, , the main scanning width is set to be smaller than the total width of the recording area of the stimulable phosphor sheet, and the sub-scanning width is also set to be smaller than the total length of the recording area, and such a scanning reading unit is changed in the main scanning direction by the scanning area changing means. and may be moved in the sub-scanning direction. In this way, for example, as shown in FIG. 6, each area (
In the illustrated example, 2×2-4 areas of A, B5C5D) can be sequentially read.

(Effects of the Invention) As explained in detail above, in the radiation image information reading device of the present invention, the excitation light scanning width of the scanning reading unit is made small to read the stimulable phosphor sheet one part at a time, and By relatively moving the unit and the stimulable phosphor sheet to change the excitation light scanning area, radiation image information is read over the entire surface of the sheet. The optical path length from the to the stimulable phosphor sheet can be shortened, and small and lightweight devices can be used as excitation light scanning and stimulated emission light detection means. Therefore, the radiation image information reading device of the present invention can read radiation image information from a large-sized stimulable phosphor sheet, and can also be made smaller and lighter.

Furthermore, since the radiation image information reading device of the present invention requires only one small scanning reading unit, it can naturally be formed at a lower cost than a device using multiple such small scanning reading units. It is.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing an apparatus according to a first embodiment of the present invention, and FIG. 2 is a plane view showing each partial area of a stimulable phosphor sheet that is read in multiple times by the apparatus according to the first embodiment. 3 is an explanatory diagram for explaining the writing of the read image signal into the frame memory in the apparatus of the first embodiment, and FIG. 4 is an explanatory diagram for explaining the smoothing process of the read image signal in the apparatus of the first embodiment. The explanatory diagram, FIG. 5, shows the second embodiment of the present invention.
FIG. 6 is a schematic perspective view showing the apparatus of the embodiment. FIG. 6 is a plan view showing another pattern of partial reading of a stimulable phosphor sheet by the apparatus of the present invention. 5... Housing 10... Stimulable phosphor sheet 11... Sheet transport means 11A, 35...
- Motor 12... Laser light source 14... Optical deflector 17... Long photomultiplier tube 31... Rod receiving part 33... Guide rod 13... Laser beam 15... Brightness Exhaustive light 30... Frame 32... Rod threaded part 34... Screw port

Claims (1)

[Claims] Excitation light scanning means for main and sub-scanning the excitation light in a part of the stimulable phosphor sheet on which radiation image information is stored and recorded; a scanning reading unit equipped with a light detecting means for detecting the stimulable phosphor; and a scanning area changing means for relatively moving the scanning reading unit and the stimulable phosphor sheet so that at least the main scanning area on the sheet is changed. A radiation image information reading device.