JP2761638B2 - Cassette for stimulable phosphor sheet - Google Patents

Description

The present invention relates to a cassette for accommodating a stimulable phosphor sheet for storing and recording radiation image information, and more particularly, to a partial area on a stimulable phosphor sheet. The present invention relates to a cassette for a stimulable phosphor sheet in which the reading area and the recording area can be accurately matched when reading the radiation image information. (Prior art) Radiation (X-ray, α-ray, β-ray, γ-ray,
(Ultraviolet rays, electron beams, etc.), a portion of the energy of this radiation is accumulated in the phosphor, and when the subsequent phosphor is irradiated with excitation light, such as visible light, the phosphor is phosphorated according to the accumulated energy. Indicates stimulated emission. A phosphor exhibiting such properties is referred to as a storage phosphor (stimulable phosphor). Using this stimulable phosphor, radiation image information of a subject such as a human body is temporarily recorded on a stimulable phosphor sheet (hereinafter, referred to as a stimulable phosphor sheet), and the stimulable phosphor is scanned to emit light. There has been proposed a method in which the emitted light is emitted, the stimulated emitted light is read photoelectrically, an image signal is obtained, and the image signal is processed to obtain a radiation image of a subject having good diagnostic suitability (for example, Japanese Patent Application Laid-Open No. 55-1979). No. 12429, No. 55-116340, No. 55-16347
No. 2, No. 56-11395, No. 56-104645). This system has the practical advantage of being able to record images over a very large radiation exposure area compared to conventional radiographic systems using silver halide photography. That is, in the case of the stimulable phosphor, it has been recognized that the amount of emitted light that is stimulated by excitation after accumulation is proportional to the radiation exposure amount over an extremely wide range. Even if fluctuates considerably, the amount of the stimulating light emitted from the stimulable phosphor sheet is read by the photoelectric conversion means with the reading gain set to an appropriate value and converted into an electric signal. By outputting a radiation image as a visible image on a recording material such as a photographic light-sensitive material or a display device such as a CRT using, a radiation image which is not affected by a change in radiation exposure can be obtained. By the way, when the radiation image information is stored and recorded (photographed) on the stimulable phosphor sheet described above, the stimulable phosphor having a relatively large size is used in order to avoid an increase in the size of the sheet used and complicated handling. In some cases, the sheet is commonly used for a large subject and a small subject. When a small subject having a relatively large size is recorded (photographed), the reading process is not performed over the entire surface of the stimulable phosphor sheet, that is, the excitation light irradiation and the stimulated emission light detection are performed. It is preferable to perform the reading process only on a small partial area including. That is, in this way, meaningless reading processing is not performed on an area other than the subject recording portion, and the time required for reading is reduced. In order to perform the reading process only on the recording area of the subject as described above,
When the radiation irradiation field is narrowed according to the size of the subject, the irradiation field of each sheet may be detected, and the reading area may be set based on the detection result. The reading process can be simplified by selecting from several predetermined sizes, such as four-slice and six-slice, and determining the position on the sheet of the recording range of each size at a predetermined position.
In other words, in this case, when reading the radiation image information, the excitation light scanning range is selected and set for each recording size from several predetermined ranges without performing difficult irradiation field recognition. With just a simple operation, only the subject recording area can be read. Further, in this way, even if the radiation irradiation field is not narrowed, only the partial area where the subject is recorded can be read. On the other hand, the above-mentioned stimulable phosphor sheet is disclosed in, for example,
As shown in No. 13350, it is often handled in a cassette. Of course, a small subject may also be recorded on the stimulable phosphor sheet stored in the cassette as described above, and in this case, as described above, the reading range is naturally increased to speed up the reading process. May need to be limited to only a partial area on the sheet. (Problems to be Solved by the Invention) However, when a conventional cassette for a stimulable phosphor sheet is used, it is difficult to set a subject recording (photographing) area on the sheet to coincide with a predetermined partial reading area. Was. Therefore, the present invention provides a stimulable phosphor sheet that can accurately and easily match a recording area of the subject with a predetermined partial reading area when a small subject is recorded on a relatively large stimulable phosphor sheet. It is intended to provide a cassette for use. (Means for Solving the Problems) A cassette for a stimulable phosphor sheet according to the present invention is provided on a cassette front plate parallel to the stimulable phosphor sheet, for reading radiation image information when reading radiation image information from the sheet. A display is provided which indicates a partial reading area smaller than the sheet size and set at a predetermined position on the sheet, which is set in advance by the apparatus. (Operation) When the cassette is used, if the subject is arranged so as to be opposed to the display portion and the radiography is performed, the subject can be correctly stored in a partial area to be read later and recorded. (Examples) Hereinafter, the present invention will be described in detail based on examples shown in the drawings. FIG. 1 shows a cassette for a stimulable phosphor sheet according to an embodiment of the present invention. The cassette 1 includes a flat box-shaped front plate 2 and a lid 4 hinged to the front plate 2 by a hinge 3 to cover the front plate 2 so as to be freely opened and closed. Although not shown, a latch means for connecting the front plate 2 and the lid 4 is provided on a side surface opposite to the side surface on which the hinge 3 is attached. The stimulable phosphor sheet 10 is accommodated in the cassette 1 so as to be parallel to the front plate 2 and the lid 4. As an example, the stimulable phosphor sheet 10 is of a half-cut size, and the cassette 1 is formed in a size that tightly stores the sheet 10 of this size. The front plate 2 displays lines 5, 6, and 7 indicating areas of a large-angle size, a quarter-size size, and a six-size size smaller than the half-size size, respectively. In this example, the large angle size is defined by the line 5 at the lower portion of the half-cut size, and the lines 6 and 7 define the quarter-size and the 6-size size at the lower right portion of the half-size size. At positions along the lines 5, 6, and 7, character displays 5a, 6a, and 7a indicating the sizes defined by the lines are written. The cassette 1 having the above configuration is set on an imaging table 8 as shown in FIG. 2 and used for radiation imaging. At this time, if the subject 9 is small enough to be photographed without using the entire surface of the stimulable phosphor sheet 10 of a half-cut size, the subject 9 falls within the size specified by the line 5, 6, or 7. The cassette 1 is arranged so as to be able to move. Second
The figure shows, as an example, a state in which the cassette 1 is arranged so that the subject 9 can fit within the six-cut size defined by the line 7. After arranging the cassette 1 in this manner, for example, X
Radiation is irradiated from a radiation source such as a ray tube toward the cassette 1, and a transmitted radiation image of the subject 9 is accumulated and recorded on the stimulable phosphor sheet 10 in the cassette 1. At the time of this imaging, the radiation irradiation field may or may not be narrowed according to the size of the subject 9. The stimulable phosphor sheet 10 on which the radiation image of the subject 9 has been accumulated and recorded as described above is taken out of the cassette 1 and applied to, for example, a radiation image information reading apparatus as shown in FIG. In this device, the stimulable phosphor sheet 10
Is conveyed in the direction of arrow Y for excitation light sub-scanning by sheet conveying means 11 such as an endless belt. Also, a laser beam 13 as excitation light emitted from the laser light source 12
Is deflected by an optical deflector 14 such as a galvanometer mirror, and scans the stimulable phosphor sheet 10 in an arrow X direction substantially perpendicular to the sub-scanning direction Y. Thus the laser beam 13
Is irradiated from the portion of the sheet 10 irradiated with the stimulable luminescence light 15 in an amount corresponding to the radiation image information stored and recorded. Photoelectrically detected by a photomultiplier (photomultiplier tube) 17 as a detector. The light collector 16 is formed by molding a light-guiding material such as an acrylic plate so that the linear incident end face 16a extends along the beam scanning line on the stimulable phosphor sheet 10. The light receiving surface of the photomultiplier 17 is connected to the light emitting end face 16b which is arranged and formed in an annular shape. Stimulated luminescence light 15 entering the light collector 16 from the incident end face 16a
Travels through the interior of the light collector 16 by repeating total reflection, exits from the exit end face 16b, is received by the photomultiplier 17, and the amount of the stimulating light 15 carrying the radiation image information is Detected by pliers 17. The analog output signal of the photomultiplier 17 is logarithmically converted and amplified in the log amplifier 20, and the photostimulated light 15
Is input to the A / D converter 21 as a read image signal S carrying the radiation image information, that is, radiation image information. The read image signal S is
The data is digitized by the A / D converter 21. The digital read image signal Sd thus obtained is then sent to the image processing device 23.
After undergoing image processing such as gradation processing, the image is input to an image reproducing device 24 such as a CRT or an optical scanning recording device, where the stimulable phosphor sheet 10
Reproduces the radiation image that has been stored and recorded. Here, the drive control circuit 30 of the optical deflector 14 and the drive control circuit 31 of the sheet conveying means 11 are each supplied with a drive control signal S1 from the reading control device 32, and accumulate fluorescent light in accordance with the drive control signal S1. The beam scanning range on the body sheet 10 is changed. That is, the sheet conveying means 11 first conveys the stimulable phosphor sheet 10 at a relatively high speed, and starts sheet conveyance for beam sub-scanning at a predetermined sub-scanning speed when the sheet 10 reaches a predetermined position. However, the timing of the sub-scanning start, in other words, the time during which the sheet 10 is conveyed at a relatively high speed as described above is a drive control signal.
Can be changed according to S1. Further, the timing of the beam scanning start of the optical deflector 14 synchronized with the timing of the sub-scanning and the beam deflection range are changed according to the drive control signal S1. The drive control signal S1 for changing the beam scanning range on the stimulable phosphor sheet 10 as described above is changed according to the imaging size information S2 input to the reading control device 32 using the imaging information input terminal 33, for example. Can be That is, when the shooting sizes indicated by the shooting size information S2 are half cut, large angle, four cut, and six cut sizes, respectively, the drive control signal
The beam scanning range specified by S1 is set so that the points P1, P2, P3, and P4 shown in FIG. 4 are set as the scanning start points, and the area is on the lower right side of the scanning start point in the figure. In FIG. 4, the beam scanning range of the six-section size is shown by hatching as an example. By controlling the beam scanning range in this manner, only the recording area (the irradiation field area when the irradiation field is stopped) containing the small subject is subjected to the reading process when the radiation image is captured. No portion is unnecessarily subjected to the reading process and the reading process time is not unnecessarily lengthened. (Effects of the Invention) As described above in detail, in the cassette for a stimulable phosphor sheet of the present invention, a display indicating a partial reading area set in advance by the radiation image information reading apparatus is provided on the cassette front plate. According to this cassette, it is possible to easily record a radiation image so that the subject can be accurately placed in the partial area on the stimulable phosphor sheet where the reading processing is to be performed, which is advantageous in shortening the reading processing time. ,
Partial reading can be performed without failure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a cassette for a stimulable phosphor sheet according to an embodiment of the present invention, FIG. 2 is a plan view showing a set state of the cassette at the time of photographing, FIG. FIG. 4 is a schematic view showing an example of an apparatus for reading radiation image information from a stimulable phosphor sheet on which a radiographic image has been taken using the above-described cassette; FIG. 4 is a reading area set for the stimulable phosphor sheet; FIG. 1 cassette 2 cassette cassette 5, 6, 7 reading size display line 10 stimulable phosphor sheet

Claims (1)

(57) [Claims] In a cassette for a stimulable phosphor sheet for storing a stimulable phosphor sheet for accumulating and recording radiation image information, a radiation image information reading device previously reads radiation image information from the sheet on a cassette front plate parallel to the sheet. A cassette for a stimulable phosphor sheet, wherein a display indicating a reading area smaller than a set sheet size and located at a predetermined position on the sheet is provided.