JPH0731374B2 - Radiation image information recording / reading device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention stores and records radiation image information on a stimulable phosphor sheet, and then irradiates it with excitation light to stimulate irradiation according to the image information stored and recorded. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation image information recording / reading device that detects emitted light and reads image information and converts it into an electric signal, and more particularly to a radiation image information recording / reading device that can downsize the entire device.

(Prior Art) When a certain kind of phosphor is irradiated with radiation (X-ray, α-ray, β-ray, γ-ray, electron beam, ultraviolet ray, etc.), a part of this radiation energy is accumulated in the phosphor, It is known that when a phosphor is irradiated with excitation light such as visible light, the phosphor exhibits stimulated emission depending on the stored energy, and a phosphor having such a property is a stimulable phosphor (luminescent material). Exhaustible phosphor).

Using this stimulable phosphor, radiation image information of a subject such as a human body is once recorded on a stimulable phosphor sheet, and this stimulable phosphor sheet is irradiated with excitation light such as laser light to stimulate emission. Generates light, photoelectrically reads the obtained stimulated emission light with a photodetector to obtain an image signal, and based on this image signal, a radiation image of the subject on a recording material such as a photographic photosensitive material or a display device such as a CRT. The present applicant has already proposed a radiation image information recording / reproducing system that outputs a visible image. (JP-A-55-12429, JP-A-56-11395, etc.) This system is practical in that it can record an image over an extremely wide radiation exposure area as compared with a conventional radiographic system using silver salt photography. Have advantages. That is, in the stimulable phosphor, it has been recognized that the amount of emitted light stimulated by excitation after storage is proportional to the radiation exposure amount over a very wide range,
Therefore, even if the radiation exposure amount fluctuates considerably due to various photographing conditions, the amount of stimulated emission light emitted from the stimulable phosphor sheet is read by the photoelectric conversion means by setting the reading gain to an appropriate value. A radiation image that is not affected by fluctuations in radiation exposure is obtained by converting it into an electrical signal and using this electrical signal to output a radiation image as a visible image on a recording material such as a photographic photosensitive material or a display device such as a CRT. be able to.

In the above-mentioned radiation image information recording / reproducing system, the stimulable phosphor sheet does not finally record image information, but temporarily carries image information in order to give an image to the final recording medium as described above. Therefore, this stimulable phosphor sheet may be used repeatedly, and if it is used repeatedly, it is extremely economical.

Therefore, the applicant of the present invention has proposed to a radiation image information recording / reading apparatus that realizes efficient circulating reuse of the stimulable phosphor (for example, JP-A-58-200269).

The above-mentioned apparatus includes a support, a recording body comprising a stimulable phosphor layer fixed on the support and capable of storing and recording a radiation image, and the recording body by irradiating the recording body with radiation through a subject. An image recording unit for accumulating and recording a radiation transmission image of a subject, an excitation light source for emitting excitation light for scanning the recording body on which the radiation image is accumulatively recorded, and a recording medium scanned by the excitation light. The image reading unit having a photoelectric reading unit for reading the stimulated emission light to obtain an image signal, and the support and the image reading unit are repeatedly moved relatively to each other, and the recording body on the support is Means for cyclically moving relative to the reading unit and emission of residual radiation energy on the recording medium prior to image recording on the recording medium after image reading by the image reading unit. Let Built an erasing unit to one unit,
The recording medium is adapted to be efficiently recycled and reused.

By the way, the radiation image information recording / reading device is used very suitably mainly for medical diagnosis.
In recent years, there is an increasing demand for making the entire device as small as possible. That is, if the device is large,
The device can only be installed and used in the central part of a relatively large hospital, but if the device is downsized, it can be installed and used in each diagnostic room by a medical practitioner, etc. Will spread greatly.

As such a recording / reading device for the purpose of downsizing, the stimulable phosphor sheet is held so as to face the radiation source, and the image reading means and the erasing means are integrated with the stimulable phosphor sheet. An apparatus has been proposed in which a reading and erasing unit, which is physically unitized, is reciprocally moved to read the stimulable phosphor sheet that has been photographed in the forward path and erase it in the backward path (Japanese Patent Laid-Open No. 62-1).
15148, No. 62-119537). According to such an apparatus, since the erasing means moves while erasing the stimulable phosphor sheet, the erasing means which has been required to have a size equal to or larger than one stimulable phosphor sheet in the past is sufficient. Since the reading / erasing unit is compact, the entire apparatus can be downsized.

(Problems to be Solved by the Invention) However, in the above-mentioned device, the reading and erasing unit performs reading on the outward path and erases on the returning path, so that the stimulable phosphor sheet that has been photographed is It is necessary to reciprocate the reading / erasing unit before the next photographing is possible, and the required time is the reading time + erasing time, which is a disadvantage in that processing takes time.

Further, the apparatus disclosed in Japanese Patent Application No. 62-94548 previously proposed by the present applicant to eliminate the above-mentioned inconvenience is that the erasing means is provided on both sides of the image reading means in the reading and erasing unit. By using the erasing means on the upstream side of the reading means on the forward path and the returning path, reading and erasing can be performed simultaneously on both the outgoing path and the returning path. However, in the above apparatus, since the erasing means is operated in the same housing while the image reading means performs reading, it is difficult to block the erasing light to the image reading means, and the erasing light affects the image reading and is read. However, there is a problem that the S / N of image information decreases. Further, in the above device, the reading speed and the erasing speed are always the same, and normally the erasing time is required to be longer than the reading time. Therefore, if the unit moving speed is set to a speed suitable for reading, the erasing can be sufficiently performed. There is also the inconvenience of not being able to do so.

The present invention has been made in view of the above problems, and it is possible to downsize the device by moving the reading means and the erasing means with respect to the stimulable phosphor sheet to perform reading and erasing, The time required for reading and erasing the stimulable phosphor sheet can be shortened as much as possible, and both reading and erasing can be performed sufficiently.
It is an object of the present invention to provide a radiation image information recording / reading device that does not reduce the radiation.

(Means for Solving Problems) The radiation image information recording / reading device of the present invention is a stimulable phosphor sheet, in which the subject is placed on the stimulable phosphor sheet by irradiating the stimulable phosphor sheet with radiation. Image recording means for accumulating and recording the radiation image of, the excitation light irradiating means for irradiating the stimulable phosphor sheet in which the radiation image has been accumulated and recorded with the exciting light in a certain direction, and the excitation light irradiating from the sheet. A reading head provided with a photoelectric reading means for photoelectrically reading the stimulated emission light and outputting an image signal, and an erasing means for erasing the radiation energy remaining in the stimulable phosphor sheet which has been read are provided. An erasing head provided separately from the read head, and a read head transfer for reciprocating the read head in a direction perpendicular to the irradiation direction of the excitation light. And an erasing head that reciprocates independently of the reading head in a direction perpendicular to the irradiation direction of the excitation light so that the erasing head is upstream in the forward direction and downstream in the backward direction. A moving means, wherein the stimulable phosphor sheet is held at a photographing position facing the image recording means, and the reading head and the erasing head reciprocate facing the stimulable phosphor sheet held at the photographing position. In the forward path, the reading head reads the image information and the erasing head erases the image information.

It is desirable that the reading head be as compact as possible in order to reduce the size of the entire apparatus. For example, a long photomultiplier described later is suitable as the photoelectric reading unit, and the excitation light irradiation is also described above. The scanning is not limited to such excitation light, and a method in which the excitation light is linearly irradiated and the stimulated emission light emitted from this irradiation position is read by a line sensor may be used. This method is particularly preferable for downsizing the image reading means.

(Operation) According to the recording / reading device, the stimulable phosphor sheet is held at the photographing position, and the read head and the erase head are reciprocally moved with respect to the stimulable phosphor sheet to perform reading and erasing. The erasing head can be miniaturized to make the entire device compact. Along with this, the device of the present invention has various advantages described below because the read head and the erase head can be independently moved. That is, if both heads can move independently, even if both reading and erasing are performed in the forward path as described above, the reading head and the erasing head can be moved by a desired distance, so that light shielding is easy. Become. Since the reading speed and the erasing speed can be independently set, sufficient erasing can be performed by setting the erasing speed lower than the reading speed.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

1 (a), (b) and (c) are side views showing an outline of a radiation image information recording / reading apparatus according to an embodiment of the present invention.

This apparatus comprises an apparatus main body 1 and a radiation source 12 such as an X-ray source arranged above the imaging table 11 which is the upper surface of the apparatus main body 1, and below the imaging table 11 inside the apparatus main body. The stimulable phosphor sheet 2 is fixedly held by a holding means (not shown). The stimulable phosphor sheet 2 comprises a substrate 2A and a stimulable phosphor layer 2B formed on the substrate 2A.
No. 11 has radiation transparency. Below the photographing table 11, a grid 13 is provided to cover the entire surface of the stimulable phosphor sheet 2. When photographing a region with a large body thickness such as the chest, scattered radiation emitted from the subject at the time of photographing may cause deterioration of image quality. Therefore, the grid 13 is used for the photographing table 11 and the stimulable phosphor sheet 2.
It is arranged so that the scattered radiation is absorbed by the grid. Since this grid is not necessary when photographing an area with a thin body, it does not necessarily have to be provided and may be detachable depending on the area to be imaged. In the present apparatus, the above-mentioned radiation source 12, imaging stand 11, grid 13, and photo timer 14 described later constitute an image recording means 10. It should be noted that in FIG. 1 it is a fluorescent plate 14a that is a part of the phototimer 14 disposed between the grid 13 and the stimulable phosphor sheet 2, and this fluorescent plate 14a has a radiation transmissive property. Has become.

Below the stimulable phosphor sheet 2, a reading head 4 including an excitation light irradiation means 20 and a photoelectric reading means 30 is provided in the housing 3, and an erasing means 50 is provided in the housing 5. An erasing head 6 is provided. The reading head 4 is located between the right end position shown in FIG. 1A and the left end position shown in FIGS. 1B and 1C, and the erasing head 6 is located at the right end position shown in FIG. 1A. From the to the left end position shown in FIG. 1 (c), the stimulable phosphor sheet 2 can be reciprocated while facing the stimulable phosphor sheet 2. In this embodiment, for both the reading head 4 and the erasing head 6, the moving path from the right end position to the left end position is the forward path, and the moving path from the left end position to the right end position is the return path. The read head moving means 60 for moving the read head 4 back and forth is, for example, a screw rod 61 extending in the head moving direction, and this screw rod.
Head support portion 62 fitted to 61, gear 63 axially supported by a screw rod, gear 64 meshing with this gear 63, this gear
It consists of a motor 65 that rotates 64 in both forward and reverse directions.
When the screw rod 61 is rotated by the gears 65 and 64 by the gear 65, the head support 62 is moved to reciprocate the read head 4. Further, an erasing head moving means for reciprocating the erasing head 6
70 also has the same structure as the read head moving means 60,
It is arranged slightly inward of the read head moving means 60.

When the subject 15 is placed on the imaging table 11 of the image recording means 10 with the reading head 4 and the erasing head 6 in the right end position as shown in FIG.
Is operated, a transmission radiation image of the subject 15 is projected onto the stimulable phosphor sheet 2, and radiation image information of the subject is accumulated and recorded in the phosphor layer 2B of the stimulable phosphor sheet 2. Further, the image recording unit 10 of the embodiment apparatus, when performing the above-mentioned shooting,
The photo-timer 14 controls the dose of radiation applied to the stimulable phosphor sheet 2 to an appropriate amount.

As shown in FIG. 2, the photo timer 14 has the fluorescent plate 14a arranged at a position for receiving the radiation transmitted through the subject.
And a photodetector 14b such as a photomultiplier
And a condensing optical element 14c for optically coupling the light receiving surface of the photodetector 14b and the fluorescent plate 14a, and a control section 14d to which the output S1 of the photodetector 14b is input. As shown in FIG. 1, the fluorescent plate 14a is attached to the subject 1
It is arranged between 5 and the stimulable phosphor sheet 2. Therefore, when the transmission radiation image of the subject 15 is stored and recorded in the stimulable phosphor sheet 2 as described above, the fluorescent plate 14a is set to the subject 1
It receives the irradiation of radiation that has passed through 5, and thereby emits fluorescence. This fluorescence is detected by the photodetector 14b via the condensing optical element 14c.
And is photoelectrically detected by the photodetector 14b. The control unit 14d is a photodetector 14b that indicates the level of the fluorescence.
When the light amount of the fluorescence (integrated light amount) reaches the set light amount, the radiation source stop signal S2 is output. The stop signal S2 is sent to the drive circuit 16 of the radiation source 12, and the drive circuit 16 stops the operation of the radiation source 12 when receiving the stop signal S2. By doing so, the dose of radiation applied to the stimulable phosphor sheet 2 is controlled to an appropriate predetermined amount. It should be noted that the above-mentioned set amount of fluorescence is preferably selected according to the reading gain at the time of reading the stimulable phosphor sheet, which is appropriately selected depending on the imaging site and the purpose of imaging, and the adjusting means 14e that can be adjusted from the outside. It is also possible to adjust the set light amount by sending an instruction signal S3 from the above to the control unit 14d.

When the photographing is completed, the reading head 4 reads the image information accumulated in the stimulable phosphor sheet 2. This reading is started from the right end position of the reading head shown in FIG. 1 (a) where excitation light can enter the end of the stimulable phosphor sheet 2.

The excitation light irradiation means 20 in the read head 4 of this embodiment is
Excitation light source 21 such as a semiconductor laser, a condenser lens 22 provided on the optical path on the excitation light 21A emitted from this excitation light source,
A rotating polygon mirror 23, which is an optical deflector for deflecting the excitation light 21A that has passed through the condenser lens 22 in a direction perpendicular to the paper surface of FIG. 1 to cause main scanning on the stimulable phosphor sheet 2, and the optical path of the excitation light. Is provided with mirrors 24A and 24B for changing the above, and the excitation light 21A repeatedly causes the excitation light 21A to be main-scanned on the stimulable phosphor sheet 2. On the other hand, the excitation light 21 described above
When the reading head 4 is conveyed in the direction of arrow A by the reading head moving means 60 at a constant speed suitable for image reading along with the main scanning of A, the scanning position of the excitation light 21A is indicated by arrow A.
Then, the stimulable phosphor sheet 2 is irradiated with the excitation light 21A over substantially the entire surface of the stimulable phosphor sheet 2. From the portion of the stimulable phosphor sheet that has been irradiated with this excitation light, stimulated emission light corresponding to the accumulated radiation energy level (that is, carrying accumulated radiation image information) is emitted. This stimulated emission light is photoelectric reading means 30 in the reading head 4.
Detected by.

The photoelectric reading means 30 in this apparatus is a long photomultiplier 31 as disclosed in JP-A-62-16666.
This photomultiplier 31 is provided on the light-receiving surface of the photomultiplier 31, and selectively transmits only stimulated emission light to the photomultiplier of the excitation light reflected on the sheet surface. The filter 32 that cuts off the incidence of light and the light guide 33 that is mounted on the light-receiving end surface of the photomultiplier 31 through this filter 32 and that favorably transmits the stimulated emission light to the photomultiplier 31 are integrally formed. It is installed. Further, in the figure, reference numeral 34 is a reflection mirror that reflects the light emitted to the side opposite to the light guide 33 among the stimulated emission light and makes it incident favorably on the light guide 33. The long photomultiplier 31 extends in the main scanning direction over the length of the main scanning line, and its light-receiving surface is arranged so as to face the main scanning line, and as is well known, a Venetian blind. It is made by extending a photomultiplier provided with a multiplying part composed of various types of electrodes such as molds and boxes.

The stimulated emission light generated from the stimulable phosphor sheet 2 by the scanning of the excitation light 21A is favorably transmitted by the light guide 33 and is incident on the photomultiplier 31, and the photomultiplier 31 is stimulated to emit light. The light is photoelectrically read to generate an image signal for outputting a visible image, and the image signal is sent to the image information reading circuit 35 to perform necessary image processing and the like.

On the other hand, in the apparatus of this embodiment, the erasing head 6 sequentially erases the portion of the stimulable phosphor sheet whose image information has been read substantially in parallel with the above-described reading of image information. The erasing by the erasing head 6 is started when the reading head 4 starts reading, moves in the direction of arrow A, and reaches the position shown by the broken line in FIG.
The reason for slightly delaying the start of erasing from the start of reading is that the read head 4 and the erasing head 6 are separated from each other by a certain amount or more.
This is to prevent the erasing light from leaking into the reading head and reducing the S / N of the image signal.

The erasing means 50 in the erasing head 6 is, for example, an erasing light source 51 such as a fluorescent lamp extending in the width direction of the stimulable phosphor sheet 2, and an erasing light source 51.
Of the light emitted from the erasing light source 51, the reflecting plate 52 reflects downward light to the stimulable phosphor sheet side. The erasing head 6 moves behind the reading head 4 in the direction of the arrow B, and the stimulable phosphor sheet 2 is irradiated with the erasing light immediately after the reading head 4 reads the image information, and the erasing means 50 operates. As it moves, the entire surface is irradiated with erasing light. The erasing light source 51 mainly emits light in the excitation wavelength region of the stimulable phosphor sheet, and the radiant energy remaining in the stimulable phosphor sheet 2 after the image reading is transferred to the stimulable phosphor sheet 2. The sheet is emitted by being irradiated with such light.

By the way, in the present embodiment, since the erasing by the erasing head 6 is performed only in the forward path, the erasing head 6 is moved at a speed capable of sufficiently erasing the radiation energy remaining in the stimulable phosphor sheet after the reading is completed. There is a need. The appropriate moving speed of the erasing unit becomes slower as the amount of radiation energy remaining in the stimulable phosphor sheet increases, and the remaining amount of radiation energy is taken when the moving speed of the reading unit and the intensity of excitation light are constant. Sometimes it is determined by how much radiation energy is stored in the stimulable phosphor sheet. Therefore, in this embodiment, the moving speed of the erasing head 6 is determined by obtaining information on the amount of radiation energy accumulated in the stimulable phosphor sheet at the time of photographing from the photo timer 14.

The control unit 14d of the photo timer 14 monitors the amount of radiation energy accumulated in the stimulable phosphor sheet by the amount of fluorescence emitted from the fluorescent plate 14a as described above,
The amount of radiation energy is controlled to be a predetermined amount. Therefore, as shown in FIG. 2, this control unit 14d outputs a signal indicating the above-mentioned predetermined radiation energy amount.
Give S _4, the motor of this signal of the erase head moving means 70
75 (see FIG. 1 (a)), the erasing head 6 is moved at a slower speed as the radiation energy amount increases, and the speed corresponding to the radiation energy amount remaining in the stimulable phosphor sheet is increased. It is possible to erase while moving the erase head.

The moving speed of the erasing head 6 set as described above is slower than the moving speed of the reading head 4 in general, as shown in FIG.
As shown in FIG. 5, the reading head 4 which has finished reading waits at the left end position until the erasing by the erasing head 6 is completed. As shown in FIG. 1 (c), when the erasing head 6 reaches the left end position and the erasing is completed on the entire surface of the stimulable phosphor sheet 2, the stimulable phosphor sheet 2 is newly photographed. In this state, both the reading head 4 and the erasing head 6 are returned to the right end position shown in FIG. 1C to prepare for the next photographing.

It should be noted that the erasing head 6 does not necessarily have to perform erasing only on the outward path as described above, and may erase on both the outward path and the returning path. That is, after moving the erasing head at a constant distance from the reading head in the forward direction at the same speed as the reading head, the erasing head is moved in the backward direction at a speed suitable for compensating for the lack of erasing in the forward direction. You may allow it. In that case, the information from the photo timer described above may be used to determine an appropriate moving speed of the erasing head in the backward direction. Further, when the moving speed of the erasing head is adjusted in the return path as described above, the reading of the image information has already been completed when the moving speed of the erasing head is determined, so the moving speed of the erasing head in the backward direction is determined. The information to be read can be obtained from the image information reading circuit 35 of the reading head. That is, when the image signal level input to the image information reading circuit is high (the amount of stimulated emission light emitted from the stimulable phosphor sheet is large), the radiation accumulated in the stimulable phosphor sheet at the time of photographing It is considered that the amount of energy is large and the amount of radiation energy remaining in the stimulable phosphor sheet after the erasing on the outward path is also large. Therefore, if the signal indicating the total amount of the image signal is obtained from the image reading circuit 35 and the drive of the motor 75 is controlled by this, the erasing head can be moved at an appropriate speed to perform erasing in the return path.

As described above, according to the present apparatus, the reading head and the erasing head are provided separately, and both heads can be moved independently, so that the erasing light can be easily blocked during reading. Further, in this device, both the reading head and the erasing head can be operated in the forward path, and both heads can be moved at desired speeds, so that the time required to complete reading and erasing can be shortened. , And can be erased sufficiently.

The reading head of the apparatus of the present invention two-dimensionally scans the stimulable phosphor sheet with the excitation light as described above to generate stimulated emission light, and the stimulated emission light is photomultipliered. It is not limited to those detected by a photodetector such as, but it is possible to irradiate the excitation light linearly and read the stimulated emission light emitted from the linear excitation light irradiation position by dividing it into pixels by the layer sensor. It may be. Next, an apparatus using a method of linearly irradiating excitation light will be described with reference to the drawings starting from FIG. The same parts as those in the embodiment shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

In the device shown in FIG. 3, the excitation light irradiation means 120 of the read head 104 irradiates the stimulable phosphor sheet 2 with the excitation light in a line shape substantially orthogonal to the moving direction of the read head 104, As an example, the Japanese patent application filed by the applicant earlier
It uses the fluorescent light condensing sheet disclosed in No. 62-21957. The photoelectric reading means of the reading head 104 includes the excitation light irradiating means 120 and the stimulable phosphor sheet 2.
Line sensor 130 provided at a position where it can face each other via
It consists of As shown in FIG. 4, this line sensor is fixed to the housing 103 of the reading head 104 by the supporting means 103A and is movable together with the housing 103. The substrate 2A of the stimulable phosphor sheet 2 is transparent.

The fluorescent light condensing sheet is a sheet-shaped molded product containing a phosphor, and when the surface thereof is irradiated with light, the phosphor excites the phosphor inside the fluorescent light condensing sheet to generate fluorescence. , This fluorescence repeats total reflection inside and advances to the end face side. Therefore, the excitation light irradiation means in this device
As shown in FIG. 4, 120 is an elongated fluorescent lamp 121, a fluorescent light condensing sheet 122 formed so as to surround the entire circumference of this fluorescent lamp 121, and provided on one end surface of this fluorescent light condensing sheet. It is composed of a cylindrical lens 123, the fluorescent lamp 121 is turned on at the time of irradiating the excitation light, and the fluorescence emitted from the fluorescent lamp 121 causes fluorescence in the fluorescent condensing sheet 122, and the fluorescence is emitted from the cylindrical lens 123. The fluorescent light-condensing sheet is emitted from one end surface of the fluorescent light-collecting sheet via the light source and the fluorescent light is used as linear excitation light. As the fluorescent light condensing sheet, one that emits fluorescence in the excitation wavelength region of the stimulable phosphor sheet by light emitted from the fluorescent lamp may be selected and used. It is also possible to use a sodium lamp, a mercury lamp, an electroluminescent panel or the like instead of the fluorescent lamp. In this embodiment, the excitation light irradiating means 120 excites the lower surface of the stimulable phosphor sheet 2 with the excitation light, and the line sensor 130 stimulates the stimulated emission light emitted from the upper surface of the stimulable phosphor sheet. Detected by.

As shown in FIG. 5, the line sensor 130 includes a support 131 extending in the width direction of the stimulable phosphor sheet 2 and a light receiving element array 132 divided into pixels fixed to the support 131. Further, on the light receiving element array 132, a filter 133 is arranged which transmits stimulated emission light emitted from the stimulable phosphor sheet 2 and absorbs excitation light transmitted through the stimulable phosphor sheet 2. The stimulated emission light is received by the light receiving element array 132 of the line sensor 130 via the filter 133.

The light-receiving element array 132 has a large number of solid-state photoelectric conversion elements 132a arranged in the width direction of the stimulable phosphor sheet 2 and each corresponding to one pixel. The light is simultaneously received by 132a. Each element 132a that receives light generates a photo carrier, and temporarily stores the signal obtained by this. The accumulated signals are sequentially read by the scanning circuit 134, and the reading of information from one linear irradiation unit (corresponding to a scanning line) is completed.

Next, the reading head 104 is conveyed by the reading head moving means 60 to the stimulable phosphor sheet 2 in the forward direction indicated by the arrow A in FIG. 3 by one scanning line, and the above reading steps are repeated. By repeating this step for the entire surface of the stimulable phosphor sheet 2, the stimulable phosphor sheet 2
The radiation image information recorded on the entire surface is read.

Next, the scanning circuit 134 following the line sensor 130 will be described. FIG. 6 is an equivalent circuit of a line sensor and a scanning circuit using a photoconductor. The signal due to the photocarrier generated when the photostimulable emitted light hits the solid-state photoelectric conversion element 132a using the photoconductor is the capacitor Ci in the photoconductor 132a.
It is stored in (i = 1,2, ... n). The accumulated photocarrier signals are sequentially read by sequentially opening and closing the switch unit 134A controlled by the shift register 134B, whereby a time-series image signal can be obtained.
The image signal is then amplified by the amplifier 135 and output from the output terminal 136 thereof. Using this image signal, for example, the radiation image can be displayed on a CRT, or a hard copy of the radiation image can be obtained by a scanning recording device or the like. The MOS unit including the switch unit 134A and the shift register 134 may be replaced with a CCD. Further, the erasing head 6 in this embodiment has the same structure as the erasing head of the device shown in FIG. 1, and the control of the speed of the reciprocating path of the erasing head 6 is the same as that of the device shown in FIG. Done.

Further, as the excitation light irradiating means for linearly irradiating the excitation light, in addition to the one utilizing the above fluorescent light condensing sheet, a normal LE
D arrays can also be used. An embodiment in which this LED array is used as excitation light irradiation means is shown in FIG.

In the apparatus shown in FIG. 7, the reading head 204 and the erasing head 6 are movable between the photographing table 11 and the stimulable phosphor sheet 2, and the reading head moving means 160 is arranged as shown in FIG. It is composed of two rails 161 extending in the moving direction of the read head, and two wheels 163 attached to the side surface of the read head 204 and driven by a motor 162 so as to travel in the reciprocating direction on the rail. The erasing head moving means 170 is composed of the rail 161 and two wheels 173 attached to the side surface of the erasing head 6 and driven by a motor 172 to travel on the rail in the reciprocating direction.

Excitation light irradiation means 220 in the read head 204 of the present device,
The light emitting diodes are arranged in the width direction of the stimulable phosphor sheet.
The LED array 221, and the cylindrical lens 222 provided on the excitation light emission surface of the LED array 221, and focusing the excitation light only in the moving direction of the read head 204. L above
The ED array 221 emits light in the excitation growth region of the phosphor layer of the stimulable phosphor sheet 2, and stimulated emission from the location of the stimulable phosphor sheet that is irradiated with this light (excitation light). Light is emitted. This stimulated emission light is detected by the line sensor 130 disposed in a position where the irradiation position of the excitation light is expected in both reading heads. Further, in the present device, since the line sensor 130 is disposed slightly apart from the stimulable phosphor sheet 2, the line sensor 130 corresponds to each light receiving element of the line sensor 130 between the stimulable phosphor sheet 2 and the line sensor 130. A microlens array 137 in which a plurality of microlenses are integrally connected is provided, and the stimulated emission light emitted from the stimulable phosphor sheet 2 is efficiently supplied to the line sensor 13.
It is designed to be incident on 0.

When the excitation light, the stimulated emission light, and the erasing light are all irradiated from the stimulable phosphor layer 2B side of the stimulable phosphor sheet 2 as described above, Substrate 2A need not be transparent.

By the way, in each of the above-described embodiments, since one reading head and one erasing head are provided, the reading of the image information is performed only on the outward path, and a state where a new photographing can be performed after the reading is completed. However, if a read head or an erase head is additionally provided in addition to the read head and the erase head described above, reading can be performed in the forward path and the return path. it can. An embodiment having two erasing heads will be described below with reference to FIG. The internal structure of the reading head and the erasing head in FIG. 9 may be any of the reading head and the erasing head shown in FIGS. 1, 3, and 7, and details thereof are shown here. do not do. The moving means of each head may be the same as that shown in FIG.

In the embodiment shown in FIG. 9, the first erasing head 306A and the second erasing head 30 are provided at both ends in the moving direction of the read head 304.
6B are provided, and each head can move back and forth independently. At the start of use of the apparatus, each head is at the right end position as shown in FIG. 9 (a), and in this state, radiation is emitted from the radiation source 12 through the subject and imaging is performed. When the photographing is completed, the reading head 304 moves in the direction of arrow A as shown in FIG. 9B to read the image information stored and recorded in the stimulable phosphor sheet 2. At the same time, the second erasing head 306B moves at a speed equal to or higher than the speed of the read head 304 so as not to hinder the movement of the read head 304 by arrow A.
Move in the direction. At this time, the second erasing head 306B does not erase the stimulable phosphor sheet. Further, when the reading head 304 starts reading and moves, the first erasing head 306A moves in the direction of arrow B as shown in FIG. 9 (b) to the portion of the stimulable phosphor sheet 2 where reading has finished. Erase it. The moving speed of the erasing head is controlled according to the amount of radiation energy stored and recorded in the stimulable phosphor sheet 2 by a signal from the above-mentioned photo timer or the like. Thus, following the reading by the reading head 304, the erasing by the first erasing head 306A is completed over the entire surface of the stimulable phosphor sheet 2, and the reading head 304 and the first and second erasing heads 306A, 306B are When the stimulable phosphor sheet 2 is moved to the left end position as shown in FIG. 9 (c), the stimulable phosphor sheet 2 is ready for a new photographing.

When the next photographing is performed in the state shown in FIG. 9 (c), the reading head 304 reads the image information while moving in the direction of arrow A'as shown in FIG. 9 (d). At that time, the first erasing head 306A does not perform erasing and
It moves in the direction of arrow A'at the same speed as 304 or higher. When the reading head 304 starts reading and starts moving in the direction of arrow A ', the second erasing head 30
6B is erased while moving in the direction of arrow B '. The speed control of the erase head 306B is performed by the first erase head 306A described above.
Similarly to the above, it is performed by a photo timer or the like. When the reading and erasing of the image information are completed and the three heads are returned to the right end positions shown in FIG. 9 (a) in this manner, a new image can be captured.

In this way, if two erasing heads are provided at both ends of the reading head and erasing is performed substantially in parallel with reading by using the erasing heads on the upstream side of the reading head in each of the forward and backward paths, the forward and backward paths can be performed. In any of the above, reading can be performed, and shooting can be performed at shorter intervals. In the apparatus of this embodiment, it is also possible to use a method in which the erasing head for erasing is moved at the same speed as the reading head, and the insufficient erasing is compensated by returning the erasing head to the original position. That is, for example, the first erasing head 306A is moved in the direction of arrow B (see FIG. 9 (b)) at the same speed as the reading head 304, and all the heads are gathered at the left end position as shown in FIG. 9 (c). After the first
It is also possible to move only the erasing head 306A in the right direction at a speed suitable for compensating for the insufficient erasing, and to perform the next photographing with the erasing head returned to the right end position. In this case, the speed control of the first erasing head may be performed when it is returned to the right, so that the control signal can be obtained from the above-mentioned image information reading circuit in the reading head in addition to the photo timer. it can.

Next, an embodiment in which two reading heads are provided at both ends of the erasing head will be described with reference to FIG.

In the embodiment shown in FIG. 10, the first read head 404A and the second read head 40 are provided at both ends in the moving direction of the erasing head 406.
4B are provided respectively, and each head can independently move back and forth. At the start of use of the apparatus, each head is at the right end position as shown in FIG. 10 (a), and in this state, radiation is emitted from the radiation source 12 through the subject and imaging is performed. When the photographing is completed, the first reading head 404A moves to the arrow A as shown in FIG. 10 (b).
Image information stored in the stimulable phosphor sheet 2 is read. When the first reading head 404A starts reading and moves by a predetermined distance, the erasing head
As shown in FIG. 10 (b), 406 moves in the direction of arrow B to erase the portion of the stimulable phosphor sheet 2 that has been read. The second reading head 404B also moves in the direction of arrow B as the erasing head 406 moves.
At this time, the second reading head 404B does not irradiate the stimulable phosphor sheet 2 with excitation light.

The moving speed of the erasing head is controlled according to the amount of radiation energy stored and recorded in the stimulable phosphor sheet 2 by the signal from the above-mentioned photo timer or the like. In this way, the reading of the first read head 404A is followed by the erasing head 406.
When the erasing is completed over the entire surface of the stimulable phosphor sheet 2 and the first and second reading heads 404A and 404B and the erasing head 406 move to the left end position as shown in FIG. The phosphor sheet 2 is in a state where a new image can be taken.

When the next shooting is performed in the state shown in FIG. 10 (c), the second reading head 404B reads the image information while moving in the direction of arrow A'as shown in FIG. 10 (d). When the second reading head 404B starts reading and starts moving in the direction of arrow A ', the erasing head 406 moves in the direction of arrow B'and performs erasing. At that time, the first reading head
404A moves in the direction of arrow B'with the erasing head 406 without irradiating the stimulable phosphor sheet 2 with excitation light. The speed of the erasing head 406 moving in the direction of arrow B'is also controlled by a photo timer or the like. When the reading and erasing of the image information are completed and the three heads are returned to the right end positions shown in FIG. 10 (a) in this manner, a new photographing state becomes possible. Even when two reading heads are provided at both ends of the erasing head as described above, the reading and erasing can be performed in both the forward and backward passes, so that the interval for shooting can be shortened.

In any of the above-described embodiments, the storage phosphor sheet 2 is not photographed for a long time because the use of the device is interrupted after the storage phosphor sheet 2 is erased. If left unattended, the radiation emitted from radioisotopes such as ²²⁶ Ra and ⁴⁰ K, which are contained in trace amounts in the stimulable phosphor, and environmental radiation such as cosmic rays and X-rays from other X-ray sources. Radiation energy may be accumulated, and this radiation energy may become noise for the next captured image. Therefore, when the stimulable phosphor sheet is made to stand by for a long time in this way, the so-called secondary light is irradiated again on the stimulable phosphor sheet with erasing light prior to taking an image of the stimulable phosphor sheet. It is preferable to erase. When performing the secondary erasing, it is sufficient to move only the erasing head so as to face the stimulable phosphor sheet.
In the apparatus shown in FIGS. 3, 7, and 10 having only one erase head, the read head in front of the erase head must be moved together when performing the secondary erase. Although it has to be done, in the apparatus shown in FIG. 9, it is convenient because only the erasing head in the forward path or the backward path can be moved.

As described in detail above, according to the radiation image information recording / reading apparatus of the present invention, the stimulable phosphor sheet is fixed, and the read head and the erase head are reciprocally moved with respect to the stimulable phosphor sheet. By performing the reading and erasing by doing so, the erasing means can be downsized and the entire apparatus can be downsized.
In addition, according to this apparatus, the read head and the erase head can be moved independently of each other, so that the read head and the erase head can be moved with a space between them, and the erase light can be shielded during reading. Easy to do. Further, since the moving speeds of the read head and the erase head can be independently set, the erase can be sufficiently performed even if the read and erase are performed at the same time.

[Brief description of drawings]

1 (a), (b), and (c) are side views of a radiation image information recording / reading apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic view for explaining control of a radiation source by a photo timer, 3 and 7 are side views of an apparatus according to another embodiment of the present invention, FIG. 4 is a perspective view of image reading means provided with a fluorescent light collecting sheet, and FIG. 5 is a schematic perspective view of a line sensor. 6 is a scanning circuit diagram following the line sensor, FIG. 8 is a perspective view showing a reading / erasing unit and its moving means in the apparatus shown in FIG. 7, FIGS. 9 (a), (b), (c), (D) and FIGS. 10 (a), (b), (c), and (d) are schematic views of an apparatus according to still another embodiment of the present invention. 2 ... Accumulative phosphor sheet 4,104,204,304 ...... Read head 6,406 ...... Erase head, 10 ...... Image recording means 12 ...... Radiation source 20,120,220 ...... Excitation light irradiation means 30 ...... Photoelectric reading means, 50 ...... Erase means 60 ...... Reading head moving means 70 …… Erasing head moving means 130 …… Line sensor 306A …… First erasing head 306B …… Second erasing head 404A …… First reading head 404B …… Second reading head

Claims (3)

[Claims] 1. A stimulable phosphor sheet, image recording means for accumulating and recording a radiation image of a subject on the stimulable phosphor sheet by irradiating the stimulable phosphor sheet with radiation through the subject, wherein the radiation image is Excitation light irradiating means for irradiating the accumulated and recorded stimulable phosphor sheet with excitation light in a certain direction, and photoelectrically reading stimulated emission light emitted from the sheet by this excitation light irradiation to output an image signal A read head provided with a photoelectric reading means; an erasing head provided separately from the read head, having an erasing means for erasing the radiation energy remaining in the stimulable phosphor sheet that has been read, The read head moving means for moving the head back and forth in a direction perpendicular to the irradiation direction of the excitation light, and the erasing head in the forward direction. The storage phosphor sheet is composed of an erasing head moving means that reciprocates independently of the reading head in a direction perpendicular to the irradiation direction of the excitation light so that it becomes the upstream side of the head and the downstream side in the backward direction. The reading head and the erasing head are held at a shooting position facing the image recording means, and the reading head and the erasing head are reciprocally moved so as to face the stimulable phosphor sheet held at the shooting position. A radiation image information recording / reading device, characterized in that reading and erasing are performed by the erasing head. 2. A second erasing head, which is reciprocable in a direction perpendicular to the irradiation direction of the excitation light, is provided on the side opposite to the erasing head via the reading head, and the reading head reads even in the return path. The radiation image information recording / reading apparatus according to claim 1, wherein the second erasing head performs erasing on the return path. 3. A second read head, which is reciprocable in a direction perpendicular to the irradiation direction of the excitation light, is provided on the side opposite to the read head through the erasing head, and the second read head is a return path. 2. The radiation image information recording / reading apparatus according to claim 1, wherein the erasing head performs erasing on the backward path as well as reading at the same time.