JPH0541976B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a radiation image reading device that scans a stimulable phosphor plate with excitation light and reads a radiation image recorded on the stimulable phosphor plate. .

(Prior art) So-called radiography using silver salts has been used for a long time to obtain radiographic images, but in recent years, due to problems such as decreasing silver resources, methods of obtaining radiographic images without using silver salts have been developed. I became desired. Therefore, as an alternative to the conventional photographic method for obtaining radiographic images using silver salts, as shown in Fig. 1, radiation (generally Luminous plate (usually produced by mixing stimulable phosphor powder with a suitable binder, coating it on a base, and finishing it into a plate shape.
Hereinafter, this stimulable phosphor plate will simply be referred to as a phosphor plate)
This radiation is absorbed by the SP, and then the fluorescent plate on which the radiation has been recorded is excited with a certain kind of energy to emit the radiation energy stored in the fluorescent plate as fluorescent light, and this fluorescent light is detected. Therefore, a method for reading radiation images was devised. A radiation image reading device is necessary for carrying out this method.

FIG. 2 is an explanatory diagram showing the configuration of a conventional radiation image reading device. In this figure, laser light source 1
The power of the laser beam emitted from the laser beam is made constant by the light amount controller 2, and after being focused in one direction by the cylindrical lens 3, it is sent to the optical deflector via the beam expander 4 and mirror 5. The light is incident on the reflecting surface of the rotating polygon mirror 6. This rotating polygon mirror 6
rotates at a constant speed in the direction of the arrow in the figure in order to scan the laser beam in the main scanning direction X.
It is also possible to use a galvanometer or the like instead.
For sub-scanning, the fluorescent plate SP is transported by a conveyor belt (not shown).
This is done by placing it on a vehicle and moving it in the Y direction. As this conveyance means, a method in which a motor drives a conveyor belt wound between pulleys is common. The laser beam deflected by the rotating polygon mirror 6 is
After passing through the f/θ lens 7 and reflecting on the mirror 8, the fluorescent plate
The fluorescent plate SP is irradiated through a cylindrical lens 9 placed near the SP. For this reason, the fluorescent plate SP
Fluorescent light is produced. This fluorescent light enters the end surface (linear shape) of the light guide path 10, which is constructed by bundling optical fibers into a sheet shape, and then exits from the other end surface (circular shape) and enters a photomultiplier tube or the like. The light is incident on the photodetector 11 of No. 1. Note that this first photodetector 1
It is preferable to place a color filter in front of 1 to block excitation light. The second photodetector 12 detects the laser beam at the scan start end and obtains a synchronization signal in the main scanning direction X of the reading scan. Upon receiving this output, the control unit 13 processes the timing signal. 14. Based on this timing signal, the signal processing unit 14 processes the output signal of the first photodetector 11 and reproduces the radiation image recorded on the fluorescent plate SP. The cylindrical lenses 3 and 9 are used to correct errors in the angle of inclination of the reflecting surface of the rotating polygon mirror 6, and may not be used if there is no problem with accuracy.

By the way, in the conventional apparatus having the above-mentioned configuration, the fluorescent plate on which the radiation image is recorded is extracted from the cassette, and the image is read by transporting the fluorescent plate. Therefore, the following problems arise.

(1) Since the surface of the fluorescent plate comes into contact with various parts of the conveyance system, scratches and dirt may occur on the fluorescent plate, electrical discharge due to charging of the fluorescent plate, and rubber adhesion. All of these appear as noise in the reproduced image, so
In the case of reading medical radiation images, diagnostic errors may occur. Furthermore, the occurrence of scratches also causes the problem of shortening the life of the phosphor plate. Although it is possible to coat the surface of the phosphor plate with a suitable resin to prevent scratches, it has been difficult to sufficiently prevent scratches.

(2) Since the fluorescent plate is made of a thin support, it is difficult to transport it, and even a slight difference in curl can cause abnormal situations such as stopping the transport. Furthermore, in the worst case, the fluorescent plate may be destroyed, making it impossible to read the recorded image.

(3) Since the fluorescent plate is extracted from the cassette and transported and read, a complicated mechanism for extracting the thin fluorescent plate and a mechanism for storing it are required, which increases the size of the apparatus.

(4) Fluorescent plates are easily deformed by heat, especially when irradiated with light from an erasing lamp for reproduction, the heat deforms the plate, sometimes causing problems in subsequent use.

(Objective of the Invention) The present invention has been made in view of the above-mentioned problems, and its purpose is to solve the problems (1) to (4) above, and to eliminate noise in reproduced images and to eliminate fluorescent light. The object of the present invention is to realize a radiographic image reading device that can transport a body reliably and without deformation, and is miniaturized.

(Structure of the Invention) The present invention achieves this object in a radiation image reading device that scans a fluorescent plate with excitation light and reads a radiation image recorded on the fluorescent plate, in which the fluorescent plate is fixed to a support member. a cassette insertion port for inserting the cassette into the radiation image reading apparatus, the cassette housing the fluorescent plate in the cassette and covering the scanned surface of the fluorescent plate with an openable and closable light-shielding lid; and the cassette insertion port. a transport mechanism for transporting a cassette inserted from the transport mechanism; a lid-opening means for opening the light-shielding lid of the cassette being transported by the transporting mechanism; The apparatus is characterized by comprising an image reading means for reading a radiation image from the fluorescent plate in the cassette being transported in an exposed state.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Fig. 3 is a diagram showing a schematic configuration of an embodiment of the present invention, Fig. 4 is a perspective view showing the main parts of the cassette used in the embodiment of Fig. 3, and Fig. 5 is a cross-sectional view along AA of Fig. 4. be. First, in FIGS. 4 and 5 showing the cassette, 40 is a support substrate (support member) to which the fluorescent plate 30 is fixed, and the convex portion 40a is the side wall member 4.
It is slidably fitted into the recess 41a of No. 1.
The fluorescent plate 3 is attached to the surface of the side wall member 41 on the fluorescent plate 30 side.
The light-shielding lid 42 is fixed with a constant gap from 0,
Further, an elastic light shielding body 43 (for example, felt) is fixed to the peripheral edge of the fluorescent plate 30 so that there is no gap between it and the light shielding lid 42. This cassette 50
In this case, since the light-shielding lid 42 moves in parallel relative to the phosphor 30, the space occupied by the cassette 50 is reduced, and the radiation image reading apparatus shown in FIG. 3, which will be described later, can be miniaturized.

Next, a radiation image reading apparatus shown in FIG. 3 using this cassette 50 will be explained. In Figure 3, 26
2 is a cassette insertion opening formed in the case 27, and a cassette 50 equipped with a light-shielding lid 42 is inserted or taken out through the insertion opening 26. Reference numeral 51 denotes a cassette holding part that is guided so as to be movable in the horizontal direction by a guide member (not shown), and the end of a cable 52 wound around pulleys 53 and 54 is locked to the cassette holding part 51. ing. This cassette holding section 51 holds the support substrate 40 of the cassette 50. Reference numeral 55 denotes a motor that drives the cassette holding section 51 via the cable 52, whereby the support substrate 40 of the cassette 50 moves together with the cassette holding section 51. In addition, cassette 5
The light-shielding lid 42 of No. 0 is configured such that it is stopped at the position where the cassette 50 is inserted into the cassette insertion opening 26. The reading optical system of this embodiment has a second
This is the same as in the case shown in the figure, and FIG. 3 shows the main elements of the reading optical system, such as a rotating polygon mirror 31, an f/θ lens 32, a mirror 33, a light guide path 34, and a photoelectron multiplier. Tube 35 is shown. In this embodiment, in addition to the reading optical system, an erasing lamp 56 for removing afterimages on the fluorescent plate 30 is adjacent to the reading optical system with a partition 57 interposed therebetween, and exposes the portion of the fluorescent plate 30 that has been read. I'm starting to do that. The motor 55 is configured to be driven in the reverse direction when the afterimage removal is completed to return the cassette holding portion 51 to the cassette insertion opening 26 side.

Next, the operation of the above embodiment will be explained.

First, the cassette 50 containing the fluorescent plate 30 on which a radiation image is recorded is pushed into the reading device through the cassette insertion opening 26. As a result, the support substrate 40 of the cassette 50 is held by the cassette holding portion 51, and the light-shielding lid 42 is restrained in that position. Then, when a reading start button (not shown) is pressed, the motor 55 is started and the cassette 50 starts moving rightward in FIG. 3. During this transportation, since the light-shielding lid 42 is stopped, the light-shielding lid 42 of the cassette 50 is opened, and the surface of the fluorescent plate 30 to be scanned is exposed. Thereafter, image reading by the reading optical system is started. This reading operation is similar to that shown in FIG. When the scanning surface of the fluorescent plate 30 after reading passes the partition wall 57, the afterimage is erased by the erasing lamp 56. When the exposure for erasing this afterimage is completed, the motor 5
5 is reversed, and the cassette 50 returns to its original position. During this return trip, the light shielding lid 42
is closed again and returns to its inserted position.

Although the embodiment described above uses a cassette 50 having a sliding light-shielding lid 42, a similar radiation image reading apparatus can be realized using a cassette having other opening/closing methods. Another type of cassette that opens and closes is a structure in which a light-shielding lid is opened and closed by rotating around a hinge, and the light-shielding lid is provided with a latch that prevents the lid from being opened.

For image reading when using a cassette with a light-shielding lid that opens and closes, for example, the cassette is pushed into the reading device through the cassette insertion slot with the light-shielding lid facing down, and the latch is released at the beginning of the cassette's transport. The light-shielding lid is opened so as to hang downward under its own weight, and an image is read by a reading optical system disposed below the surface to be scanned of the fluorescent plate.

In addition to the above-mentioned cassettes, there are cassettes with various structures. The apparatus of the present invention is modified to accommodate these various cassettes, and it goes without saying that the present invention is not limited to the above embodiments. In addition, in the embodiment shown in FIG. 3, in order to recycle (reuse) the fluorescent plate, an erasing lamp is provided, and the erasing lamp erases the afterimage on the fluorescent plate after reading, returning the fluorescent plate to its initial state. However, this configuration is not an essential component of the present invention.

(Effects of the Invention) As explained above, according to the present invention, since the fluorescent plate housed in the cassette is exposed and read in the reading device, the fluorescent plate is not scratched or dirty. In addition, no discharge occurs due to charging of the fluorescent plate, and no dust adheres to the fluorescent plate. Therefore, noise does not occur in the reproduced image, and diagnostic errors due to noise do not occur when reading medical radiation images. Furthermore, the life of the fluorescent plate will not be shortened due to scratches. Furthermore, as in this embodiment, the radiographic image is read while the cassette is being transported with the fluorescent plate housed inside the cassette, so there is no problem with transportation as in the past, and there is no need for a special extraction mechanism for the fluorescent plate. is no longer necessary, and the device can be made more compact. Furthermore, since the fluorescent plate is housed in the cassette, its deformation can be prevented.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing recording of a radiation image on a fluorescent plate, FIG. 2 is an explanatory diagram showing the configuration of a conventional radiation image reading device, and FIG. 3 is a diagram showing a schematic configuration of an embodiment of the present invention. , FIG. 4 is a perspective view showing the main parts of the cassette used in the embodiment shown in FIG. 3, and FIG. 5 is a sectional view taken along line AA in FIG. 4. S...radiation source, OBJ...object, SP...fluorescent plate,
DESCRIPTION OF SYMBOLS 1... Laser light source, 2... Light amount control part, 3, 9... Cylindrical lens, 4... Beam expander,
5, 8, 33... Mirror, 6, 31... Rotating polygon mirror,
7, 32... f/θ lens, 10, 34... light guide path,
11...first photodetector, 12...second photodetector,
DESCRIPTION OF SYMBOLS 13... Control part, 14... Signal processing part, 26... Cassette insertion slot, 27... Case, 30... Fluorescent plate, 35...
Photomultiplier tube, 40... Support substrate, 41... Side wall member, 42... Light shielding lid, 43... Elastic light shielding body, 50... Cassette, 51... Cassette holding part, 52... Cable, 55... Motor, 56... Erasing lamp, 57 ...bulkhead.

Claims (1)

[Scope of Claims] 1. In a radiation image reading device that scans a stimulable phosphor plate with excitation light and reads a radiation image recorded on the stimulable phosphor plate, the stimulable phosphor plate is supported. The stimulable phosphor plate is housed in a cassette by being fixed to a member, and the cassette, which has a scanned surface of the stimulable phosphor plate covered with an openable and closable light-shielding lid, is placed in a radiation image reading device. a cassette insertion opening for insertion, a conveyance mechanism for conveying the cassette inserted from the cassette insertion opening, a lid opening means for opening a light-shielding lid of a cassette being conveyed by the conveyance mechanism, It is characterized by comprising an image reading means for reading a radiation image on the stimulable phosphor plate in the cassette which is opened by the lid opening means and is being transported with the surface to be scanned exposed. A radiation image reading device.