JPH065359B2 - Radiation image information reader - Google Patents

Description

TECHNICAL FIELD The present invention relates to a device for reading radiation image information accumulated and recorded on a stimulable phosphor plate.

—Background of the Invention— When a stimulable phosphor is irradiated with radiation such as X-rays and ultraviolet rays, a part of the energy of this radiation can be accumulated, and when this is irradiated with excitation light, the accumulated energy is accumulated. It emits stimulated emission with an intensity corresponding to. Utilizing such a property, the radiation image information of the subject is recorded and accumulated as a latent image by irradiating the stimulable phosphor plate with the radiation that has passed through the subject. By irradiating excitation light such as light, the photodetector detects the photostimulated luminescence amount corresponding to the density of the latent image (energy storage amount at each site of the phosphor), and further processing the detection signal to obtain a radiation image Attention has been focused on a device for reading the image data, recording the read image information on a photographic film, and displaying it on a display device.

In such an apparatus, the afterimage after reading can be erased by irradiating the stimulable phosphor plate with a large amount of light, and by providing this erasing means, the stimulable phosphor plate can be repeatedly used. Is possible.

When the erasing means is provided, problems such as deterioration of image quality and delay of processing time occur when the control procedure of erasing for recording and reading of image information is not properly performed. This will be described in detail below.

First, in image reading, the scanning position is changed in a direction orthogonal to the scanning direction while irradiating the stimulable phosphor plate with a light beam scanning from an excitation light source (including an optical system) such as a laser,
The introduced light from the optical fiber condensing body arranged corresponding to the light beam scanning surface of the stimulable phosphor plate is converted into an electric signal by a photodetector such as a photomultiplier tube, and these excitation light source, condensing body, The excitation / reading unit in which the photodetector and the like are integrated is subjected to a sub-scan, which is a movement control, in a direction orthogonal to the main scanning direction of the light beam scanning by a mechanical system.

Therefore, image reading is completed by moving the excitation / reading unit from one end to the end of the stimulable phosphor plate and returning the unit to the reading start position at the end of image reading. After that, in the control procedure of entering the erasing control in which the erasing lamp is turned on for a certain period of time to erase the afterimage of the stimulable phosphor plate, the processing time required for one recording, reading and erasing becomes long.

Further, if an exciter / reader unit is integrally provided with an erasing lamp and the read-completed portion is sequentially erased while the image is being read, the reading and erasing can be performed in parallel, and the processing time can be shortened. it can. However, in this case, there is a problem that the light of the erasing lamp is incident on the light condensing body or the scanning line during reading is irradiated to generate a large noise in the read signal to deteriorate the quality of the read image. Further, since reading and erasing are performed in parallel, either reading or erasing is subject to a time restriction, which makes proper reading or erasing difficult. For example, in order to perform erasing within a relatively fast reading sub-scanning time, it is necessary to give a high intensity erasing light to a stimulable phosphor plate, which requires a large and heavy erasing light source and its driving mechanism. However, this also increases the noise level of the read signal.

Also, in any of the above erasing methods, if the interval between the end of erasing and the next imaging is long, the stimulable phosphor plate accumulates radiation energy from another radiation source and the next imaging is performed. There was a problem of causing fog in the image.

-Object of the Invention-It is an object of the present invention to provide a reading device that can reduce the processing time while eliminating noise in the read signal due to erasing light.

—Structure of the Invention— In a radiation image information reading apparatus of the present invention that achieves the above object, the position is reciprocally controlled with respect to the position of a stimulable phosphor plate on which radiation image information of a subject is recorded as a latent image by radiography. An excitation / reading unit and an erasing means are provided,
In a radiation image information reading device for reading radiation image information from the stimulable phosphor plate by the excitation / reading unit and erasing an afterimage of the stimulable phosphor plate that has been read by the erasing means, The erasing means is integrated with the excitation / reading unit,
A control means is provided for performing a reading operation of the radiation image information on the outward path of moving the excitation / reading unit, and for controlling to perform an afterimage erasing operation by the erasing means on a returning path immediately before the next radiographic imaging. It is characterized by that.

-Embodiment- FIG. 1 is an apparatus configuration diagram showing an embodiment of the present invention, and is a case where it is applied to chest X-ray photography. The radiation image information reading apparatus 1 receives the radiation (indicated by an arrow) from the X-ray generation source (not shown) that has passed through the subject M by the stimulable phosphor plate 2 to receive the radiation of the subject M. Record the image as a latent image. The excitation / reading unit 3 is provided inside the reading device 1 so as to be vertically movable by a lifting mechanism (not shown) on the back surface of the stimulable phosphor plate 2.

The excitation / reading unit 3 extracts a light beam from a light beam generator (not shown) such as a laser light source as a fan-shaped scanning beam by a polarizer 4 such as a rotating polygon mirror, and this scanning beam is f-for focus adjustment. After passing through a condenser lens 5 such as a θ lens, the optical path is adjusted by reflection mirrors 6, 7 and 8, and a scanning beam on the back surface thereof is made as excitation light for the stimulable phosphor plate 2 via a semitransparent mirror 9. The light beam partially separated by the semi-transparent mirror 9 is taken into the light receiving element 11 through the focusing lens 10 and the like,
It is used for read signal processing synchronized with the scanning beam.

The condensing body 12 has optical fiber condensing ends arranged in parallel to the irradiation position of the scanning beam for exciting the stimulable phosphor plate 2, and the stimulable phosphor plate 2 excited by the scanning beam. It receives the stimulated emission from. The light introduced from the light collector 12 is incident on the photocathode of the photodetector 13 through a filter having a pass band in the stimulated emission wavelength region, and the photodetector 13 is a current signal proportional to the incident light amount. Taken from. This current signal is processed by a digital signal by an image information processing device (not shown) whose control center is a computer or the like.

By the excitation / reading unit 3 and the elevating mechanism thereof having such a configuration, the stimulable phosphor plate 2 is scanned with the excitation light by the scanning beam (main scanning) and is scanned in the vertical direction (Y direction in the drawing) orthogonal to the scanning direction. By moving the position, the stimulated emission from the stimulable phosphor plate 2 at each scanning point is collected by the condensing body 12 and the photodetector 13.
Is read as an electric signal and X-ray image information is obtained by processing the read signal.

Here, an erasing lamp 14 for erasing the afterimage of the stimulable phosphor plate 2 that has been read is provided integrally with the excitation / reading unit 3. As the erasing lamp 14, a tungsten lamp, a halogen lamp, a fluorescent lamp, or the like is used, and a light emitting surface is provided substantially parallel to the back surface of the stimulable phosphor plate 2 and slightly above the light collecting end of the light collecting body 12. Further, the reflection hood 15 is arranged so that the light of the erasing lamp 14 is efficiently concentrated on the surface of the stimulable phosphor plate 2.
Is provided, and the light of the erasing lamp 14 and the stimulable phosphor plate 2 are provided.
In order to prevent the reflected light from the light from deteriorating the photoelectric surface of the photodetector 13, the light collector 12 and the photodetector 13 have a light-shielding cover 16 and a light-shielding cover that shields the light-collecting end of the light-collector 12 (shown in the figure. No) is provided. When a lamp that emits radiation, such as a fluorescent lamp, is used as the erasing lamp 14, a light-shielding means that covers with a shutter is provided except when erasing, and the emission of the erasing lamp due to radiation during photographing is a stimulable phosphor. The plate 2 is not illuminated. In this case, when the light shielding means is made of lead glass, the movable means is unnecessary. The erasing lamp 14 is controlled to be turned off in the forward path where the excitation / reading unit 3 starts the reading operation and descends from the reading start position (the highest position in the figure) to the reading end position (the lowest position) to perform the reading operation. The lighting of the reading unit 3 is controlled in the returning path from the reading end position to the reading start position to perform the erasing operation of the stimulable phosphor plate 2.

FIG. 2 is a time chart showing one cycle control of photographing, reading and erasing. At the time of photographing, the excitation / reading unit 3 is stopped at the reading start position, which is the highest position. When the photographing operation is performed, the operation control of the moving mechanism is started from the time when the photographing signal is given (time t ₁ ), and the excitation / reading unit 3 starts descending to stabilize the moving speed (time t ₁ ). excitation light source _2), polarizer 4, the photodetector 13, and only the on control time T _R required to read the shading means such as a light-shielding cover to perform the read operation. The life is extended by controlling each part to be turned on only when necessary for this reading. When the reading control is completed, the excitation / reading unit 3 is lowered to the lowest position and is stopped and controlled, and when the unit 3 is raised to the reading start position (highest position) for the next reading (time t ₃ ).
Then, the erasing lamp 14 is controlled to be turned on. Then, when the excitation / reading unit 3 is raised to the reading start position (time t
₄ ) Turn off the light.

Therefore, reading and erasing are completely separated in time, and the light of the erasing lamp 14 does not enter as noise of the read signal. Since the reading time and the erasing time can be set independently of each other, it is possible to set proper speeds for reading and erasing to obtain good reading and erasing operations, and the erasing time is longer than the reading time. Erase lamp 14
Can be small and lightweight.

Here, the erasing operation is performed immediately before shooting when the shooting interval is long to obtain a more suitable erasing state. That is, when the reading operation is completed, the excitation / reading unit 3 is stopped in a state where it is moved to the lowest position, and the erasing lamp 14 is turned on while erasing the unit 3 while raising the unit 3 to the reading start position immediately before starting the next photographing. The operation is performed, and the photographing operation is started at the end of this erasing operation. This control time chart is as shown in FIG.

By such erasing control, the time from erasing to photographing is shortened, during which the stimulable phosphor plate 2 accumulates radiation energy from another radiation source, or leakage light from the outside of the main body causes the next time. Prevents fogging that causes noise in the captured image. Further, there is an advantage that the excitation / reading unit 3 is at the lowest position and is in a stopped state, so that a safety mechanism for preventing the unit 3 from dropping due to an external force or the like is not necessary and the moving mechanism is simplified.

In the embodiment, the case where the excitation / reading unit 3 is moved up and down is shown. However, as shown in FIG. 4 which is the same as that shown in FIG. The same operation and effect can be obtained not only by being applied to a reading device of a system of moving in a direction or a system of moving in an oblique direction, but also raising the unit at the time of reading and lowering it at the time of erasing.

-Effects of the Invention As described above, according to the present invention, in the reading apparatus in which the erasing unit is integrally provided in the excitation / reading unit, the reading operation is performed on the outward path of the unit and the erasing operation is performed on the return path. It is possible to completely separate the erasure and the reciprocating operation of the unit, and there is an effect that the processing time can be shortened while eliminating noise intrusion into the read signal due to the erasing light.

[Brief description of drawings]

FIG. 1 is a device configuration diagram showing an embodiment of the present invention, FIG. 2 is a control time chart for photographing, reading and erasing in the embodiment, and FIG. 3 is a time chart showing a relation between photographing and erasing in the embodiment. FIG. 4 is a block diagram of another reading device according to the present invention. DESCRIPTION OF SYMBOLS 1 ... Reading device, 2 ... Photostimulable phosphor plate, 3 ... Excitation / reading unit, 4 ... Polarizer, 5 ... Condensing lens, 12 ... Condenser, 13
… Photo detector, 14… Erase lamp, 15… Reflective hood, 16… Shading cover.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mikio Takeuchi 1 Sakura-cho, Hino City, Tokyo Photo Konishi Roku Photo Industry Co., Ltd. (72) Inventor Mitsuru Ishii 1 Sakura-cho, Hino City Tokyo, Photo Roku Konishi Photo Industry Co., Ltd. (56) Reference JP-A-58-200269 (JP, A)

Claims (1)

[Claims] 1. An excitation / reading unit for controlling reciprocating movement of a position with respect to a stimulable phosphor plate on which radiation image information of a subject is recorded as a latent image by radiography, and an erasing means are provided, and the excitation / reading is performed. A radiation image information reading device that reads radiation image information from the stimulable phosphor plate by a unit, and erases an afterimage of the stimulable phosphor plate that has been read by the erasing unit, wherein the erasing unit is: It is integrated with the excitation / reading unit, and performs the reading operation of the radiation image information on the forward path of moving the excitation / reading unit, and the erasing means on the return path immediately before the next radiographic imaging. 2. A radiation image information reading apparatus, comprising: a control unit that controls to perform an afterimage erasing operation by the.