JPH06100789B2 - Radiation image information reader - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a radiation image information reading apparatus used in a radiation image information recording / reproducing system, and more particularly, to a radiation image information reading apparatus capable of forming the entire apparatus in a small size. It relates to the 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, the radiation image information of a subject such as a human body is once recorded in a sheet-shaped stimulable phosphor, and this stimulable phosphor sheet (hereinafter, simply referred to as a sheet) is used for laser light or the like. Scanning with excitation light produces stimulated emission light, the resulting stimulated emission light is read photoelectrically to obtain an image signal,
The applicant has already proposed a radiation image information recording / reproducing system for outputting a radiation image of a subject on the basis of this image signal as a visible image on a recording material such as a photographic photosensitive material or a CRT. (JP-A-55-12429, 56-11395,
55-163472, 56-104645, 55-116340, etc. ) The stimulable phosphor sheet in the above system stores and records radiation image information, and temporarily holds the recorded image information until it is read by the excitation light scanning. After completing the step, it is desirable to erase the image information remaining on the sheet and reuse the sheet.

Based on such a request, a radiation image information reading apparatus has been proposed which includes a reading unit for reading image information recorded on a sheet and an erasing unit for erasing the image information remaining on the sheet. .

In the radiation image information reading apparatus, a cassette containing a stimulable phosphor sheet that has been photographed by an external imaging device is loaded in a cassette holding unit, and the stimulable phosphor sheet is taken out of the cassette and read by the reading unit. The image information is read by sending the image information to the erasing unit, and the read sheet is further sent to the erasing unit to erase the image information remaining on the sheet. The erased sheet is taken out of the reading device and is in a state in which image information can be recorded again.

It is desirable that these radiation image information reading devices be made as small as possible so that they can be used even in a limited space. Therefore, the applicant of the present invention has already proposed various reading devices that are designed to be downsized by devising the arrangement of the reading unit and the erasing unit.

For example, in JP-A-60-264482, as shown in FIG. 7, a stimulable phosphor sheet 10 in which image information is stored and recorded
A cassette holding unit 110 that stores 1 and detachably holds a cassette 102 that can be opened and closed at one end is provided with a reading unit 120 and an erasing unit 130.
In the apparatus provided with the above, the distance L from one end of the cassette to the scanning position P at which the excitation light 121 is reflected and deflected by the optical deflector 122 in the reading unit 120 and main scanning is performed.
An apparatus has been proposed in which the size of the stimulable phosphor sheet 101 is made smaller than that of the stimulable phosphor sheet 101 to reduce the overall size. That is, in the cassette holding unit 110, the roller 111, which is a sheet take-out means, moves from the position shown by the broken line in the figure to the position shown by the solid line and rotates, and after taking out the stimulable phosphor sheet 101 inside the cassette 102, The stimulable phosphor sheet 101 is read by the sheet feeding means 140 by the reading unit 120.
However, since the distance L is smaller than the length 1 of the stimulable phosphor sheet, the leading end of the stimulable phosphor sheet is read while the rear end of the stimulable phosphor sheet is inside the cassette. Is started. If the distance L is set to the length l or less as described above, the inside of the cassette can be used as a transport zone for the stimulable phosphor sheet at the time of reading, so that the reading unit can be made compact accordingly. The excitation light 12
The stimulated emission light emitted from the first scanning position is photoelectrically detected by the long photomultiplier 123 arranged along the main scanning line.

Further, as described in, for example, Japanese Patent Application Laid-Open No. 58-67240, the reading of image information in the radiation image information recording / reproducing system is performed to obtain the image signal for visible image output described above (main reading). Prior to the above, pre-reading is performed to read the outline of the radiation image information that has been stored and recorded in advance on the sheet, and the reading conditions etc. for performing the main reading are determined based on the image information obtained by this pre-reading. According to the above, the main reading may be performed. Therefore, in the reading section 120, when pre-reading is also performed prior to the main reading, the stimulable phosphor sheet 101 is conveyed by the sheet conveying means 140 and first the excitation light is scanned over the entire surface of the stimulable phosphor sheet to pre-read. Then, the conveying means is switched back to return the stimulable phosphor sheet to the scanning start position, and the stimulable phosphor sheet is conveyed in the same direction as when pre-reading is performed again to perform the main reading. To be In the above device, the cassette holder
Since the cassette 102 in 110 can also be used as a switchback zone after the pre-reading is completed, pre-reading can be performed without increasing the size of the reading unit itself.

The stimulable phosphor sheet that has been read by the reading unit 120 is sent to the erasing unit 130, and the entire surface thereof is irradiated with erasing light from the erasing light beam 131 at the position indicated by the broken line in the drawing, and the stimulable phosphor sheet is read after the reading is completed. Erasing is performed so that the remaining radiation image information is emitted. The erased stimulable phosphor sheet 101 is switched back by the sheet conveying means 140, and the empty cassette 102 in the cassette holding unit 110 is switched.
It is brought in.

(Problems to be Solved by the Invention) However, in the above apparatus, the stimulable phosphor sheet that has been read by the reading unit is further conveyed in the conveying direction at the time of reading and then sent to the erasing unit. Therefore, it is necessary to provide a relatively long transport path for the stimulable phosphor sheet between the excitation light irradiation position and the erasing zone, and the erasing section must have a size to accommodate at least one stimulable phosphor sheet. Therefore, it is relatively large. Therefore, in such an apparatus, there is a disadvantage that the portion on the side opposite to the cassette holding portion side (the portion on the erasing portion side) becomes large.

The present invention has been made in view of the above-mentioned problems, and it is possible to miniaturize the reading device, prevent the device from becoming large due to the erasing device, and extremely effectively downsize the entire device. It is an object of the present invention to provide a radiation image information reading device capable of performing the above.

(Means for Solving Problems) The radiation image information reading apparatus according to the present invention includes:
The stimulable phosphor sheet taken out from the cassette in the cassette holder is conveyed to the reading unit together with the erasing unit and the cassette holder, and the read-out stimulable phosphor sheet is carried into the cassette in the cassette holder by switchback. A sheet transport means is provided, and the transport distance of the stimulable phosphor sheet from one end of the cassette in the cassette holding section to the excitation light irradiation position of the reading section is smaller than the length in the transport direction of the sheet, and the erasing section holds the cassette. It is provided in the conveyance path of the stimulable phosphor sheet between the reading section and the reading section.

The erasing section may operate the erasing means such as the erasing light source only when erasing the stimulable phosphor sheet, and may stop the operation of the erasing means at other times. The erasing means may be always operated and the erasing means may be cut off from the outside of the erasing section except when erasing.

(Operation) According to this device, the distance from the excitation light irradiation position to one end of the cassette is made smaller than the length of the stimulable phosphor sheet, so that the cassette in the cassette holding unit is used as a sheet conveyance space during reading. The reading unit can be downsized. Further, when performing pre-reading, the inside of the cassette can be used as a space for allowing the switchback of the stimulable phosphor sheet, so that both pre-reading and main reading can be performed in the reading unit without increasing the size of the reading unit. Further, according to this apparatus, since the erasing unit is provided between the reading unit and the cassette holding unit, it is possible to perform erasing while returning the stimulable phosphor sheet into the cassette after the reading is completed. There is no inconvenience that the device becomes large.

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

FIG. 1 is a perspective view showing an outline of a radiation image information reading apparatus according to an embodiment of the present invention, and FIG. 2 is a side conceptual view thereof.

The reading device of the present invention comprises a cassette holder 10 for detachably holding a cassette 2 capable of accommodating a stimulable phosphor sheet 1,
The cassette 2 is provided with a reading unit 20 for reading the image information accumulated and recorded on the stimulable phosphor sheet 1, and an erasing unit 30 for erasing the image information remaining on the sheet 1 after the reading is completed. The stimulable phosphor sheet 1 thus taken out is received and conveyed to the reading section 20 and the erasing section 30.
Sheet conveying means 40 including a conveying roller 41 and an endless belt 42 is provided.

In an external photographing device (not shown), the cassette 2 photographed on the stimulable phosphor sheet 1 housed inside is
The cassette holder 10 is loaded horizontally as indicated by the arrow in the figure. The cassette 2 is, as shown in FIG.
It is composed of a cassette body 2A and an openable / closable lid portion 2B provided at the front end in the insertion direction to the cassette holding portion 10. When loaded in the cassette holding portion 10, the lid portion 2B is closed. It is rotated from the position to the open position shown by the solid line in the figure. In the cassette holder 10, a roller 11 is a sheet take-out means for taking out the stimulable phosphor sheet 1 from the cassette 2.
The roller 11 is provided with a lid portion 2B of the cassette 2.
When it reaches the open position, the stimulable phosphor sheet 1 moves from the first position shown by the broken line in the figure to the second position shown by the solid line in the figure.
The stimulable phosphor sheet 1 is carried out from the cassette 2 by rotating in contact with.

The position of one end of the stimulable phosphor sheet housed in the cassette 2 loaded in the cassette holding unit 10 on the reading unit side is the position P ₁ . By rotating the roller 11 in contact with the portion near the leading edge of the sheet 1 as described above. The carrying out of the stimulable phosphor sheet 1 from the cassette 2 is started, and the stimulable phosphor sheet 1 is delivered to the conveying roller 41. The stimulable phosphor sheet 1 is carried into the reading unit 20 by the carrying roller 41 and the endless belt 42.

In the present apparatus, an erasing unit including a erasing light source 31 extending in the width direction of the stimulable phosphor sheet in a semi-cylindrical reflecting plate 32 is provided between the cassette holding unit 10 and the reading unit 20. Although an erasing unit 30 is provided, the erasing light source 31 of the erasing unit 30 is extinguished until the reading of the image information stored and recorded in the stimulable phosphor sheet 1 in the reading unit 20 is finished as will be described later.

The reading unit 20 scans the stimulable phosphor sheet 1 on which image information is stored and recorded with excitation light 21A such as a laser beam emitted from a laser light source 21, and the scanning causes the emission of light from the sheet 1. The emitted light is photoelectrically read by a long photomultiplier 22 which is a photoelectric reading means to obtain an electric image signal for outputting a visible image. 25 in the figure
Is an optical deflector such as a galvanometer mirror, and 23 and 24 are excitation lights 2
Mirror for reflecting 1A and making it incident on the optical deflector 25, 26 is f
A scanning lens such as a θ lens, and 27 are mirrors that reflect the excitation light 21A and make it enter the stimulable phosphor sheet 1. The long photomultiplier 22 is, as disclosed in JP-A-62-16666, a photomultiplier having an electrode structure called Venetian blind type as an example, along the main scanning line. It is formed by extension, and a small light guide 22A is provided on its light receiving surface. The excitation light 21A two-dimensionally scans the stimulable phosphor sheet 1 conveyed by the sheet conveying means 40 (sub-scanned) by repeatedly performing main scanning, and the excitation light is scanned. From the position, stimulated emission light carrying image information is emitted. This stimulated emission light enters the photomultiplier 22 through the light guide 22A,
The photomultiplier 22 photoelectrically reads the stimulated emission light and outputs an image signal.

The stimulable phosphor sheet 1 is transferred to the second
As shown in the figure, it is transported in the direction of arrow A ₁ , and one end of
When the position P ₂ which is the scanning position of the excitation light 21A is reached, it becomes possible to read by scanning the excitation light. On the other hand, the transport distance of the stimulable phosphor sheet 1 from the one end on the reading side of the cassette in the cassette holder 10 to the scanning position P ₂ is smaller than the length of the stimulable phosphor sheet 1 in the transport direction. And the tip of the stimulable phosphor sheet 1 is
When it is at P ₂ , as shown by the solid line in FIG. 2, the portion near the rear end of the sheet 1 remains in the cassette 2. Therefore, the stimulable phosphor sheet 1 is read out before it is completely carried out of the cassette 2. When the reading unit 20 also performs the above-described pre-reading together with the main reading, the stimulable phosphor sheet 1 is irradiated with the excitation light 21A while the tip of the stimulable phosphor sheet 1 moves from the position P ₂ to the position P _{3 in the} direction of the arrow A _2. First, the look-ahead is performed.

When pre-reading is completed as described above, the endless belt 42
And the transport roller 41 is reversed by switchback,
The stimulable phosphor sheet 1 is conveyed in the direction of arrow A ₃ and is returned from the position where the one end is at position P ₃ to the position where one end is at position P ₂ . When the stimulable phosphor sheet 1 is returned to the position where one end is at the position P ₂ , that is, the scanning start position, the arrow A ₄ again
It is conveyed in the direction and the main reading is performed. As aforementioned,
In the apparatus of this embodiment, since the cassette 2 is loaded relatively close to the reading unit 20, the pre-reading of the stimulable phosphor sheet is performed, and then the stimulable phosphor sheet is fed back by switchback and stored again. The interior of the cassette 10 is used as a space for moving the stimulable phosphor sheet when the stimulable phosphor sheet is conveyed into the reading unit 20, and the rear end of the stimulable phosphor sheet 1 remains in the cassette 2. The main reading is started in response to the irradiation of the excitation light. As described above, in the apparatus of the present invention, by using the inside of the cassette as a space for moving the stimulable phosphor sheet, it is not necessary to provide a space for switchback or the like in the reading unit itself, and the reading unit is downsized. be able to.

The stimulable phosphor sheet 1 whose image information has been read in the reading section 20 is fed back by the sheet conveying means 40 in the direction of arrow A ₅ and is carried into the empty cassette 2 in the cassette holding section 10. Further, prior to being carried into the cassette 2, the stimulable phosphor sheet passes through the erasing section 30 and is irradiated with erasing light over the entire surface thereof, and remains on the stimulable phosphor sheet after completion of reading. Radiation energy is emitted.
Although any erasing method in the erasing unit 30 may be used, in the present embodiment, as described above, the erasing light source 31 such as a fluorescent lamp, a tungsten lamp, a sodium lamp, a xenon lamp, or an iodine lamp is used. By passing the stimulable phosphor sheet below, the residual radiation energy on the stimulable phosphor sheet is released by receiving light irradiation from the erasing light source 31. The erasing light source 31 is turned on only from the start of conveyance of the stimulable phosphor sheet 1 in the direction of the arrow A ₅ until the sheet is carried into the cassette 2 and completed.

In this device, the erasing unit 30 and the cassette holding unit 10 are arranged very close to each other, so that the stimulable phosphor sheet is carried into the cassette 2 while being irradiated with the erasing light, and is positioned at the second position in the cassette 2. The roller 11 located at the position is rotated in the direction opposite to the direction in which the stimulable phosphor sheet 1 is carried out of the cassette 2, and the sheet 1 is completely carried in the cassette 2. When the loading of the sheet 1 is completed, the roller 11 returns to the first position again to prepare for the loading of the next cassette, the lid portion 2B of the cassette 2 is returned to the closed position, and the cassette 2 is pulled out from the cassette holding portion 10. .

As described above, if the erasing unit is provided between the reading unit and the cassette holding unit and the stimulable phosphor sheet is returned to the cassette for erasing, the erasing unit can be extremely small. There is no need for a special transport path for.
Therefore, the device does not become large for erasing,
The entire device can be made extremely compact.

Note that the specific configurations of the reading unit, the erasing unit, and the like in the apparatus of the present invention are not limited to those shown in the above embodiment, and for example, the reading unit and the erasing unit shown in FIG. 3 may be used. Good.

The reading unit 220 in the embodiment shown in FIG. 3 is a LED array 221 that linearly emits excitation light by connecting light emitting diodes in a line shape substantially orthogonal to the transport direction of the stimulable phosphor sheet 1.
And an excitation light irradiating means 223 provided on the excitation light emission surface of the LED array 221 and a cylindrical lens 222 for focusing the excitation light only in the transport direction of the stimulable phosphor sheet.
And a line sensor 22 which is a photoelectric reading means arranged at a position where the irradiation position of the excitation light by the excitation light irradiation means is expected and which receives the stimulated emission light emitted from the linear excitation irradiation position.
It consists of 4.

As shown in FIG. 4, the line sensor 224 includes a support 224B extending in the width direction of the stimulable phosphor sheet 1, and a light receiving element array 224A divided into pixels is fixed to the support 224B. Further, on the light receiving element array 224A, a filter 225 is arranged which transmits the stimulated emission light emitted from the stimulable phosphor sheet 1 and absorbs the excitation light reflected on the stimulable phosphor sheet 1. The stimulated emission light is received by the light receiving element array 224A of the line sensor 224 via the filter 225. Photodetector array 224A
Has a large number of solid-state photoelectric conversion elements 224a, which are aligned in the width direction of the stimulable phosphor sheet 1 and each correspond to one pixel, and stimulated emission light is simultaneously received by these solid-state photoelectric conversion elements 224a. It Each element 224a that receives light generates a photo carrier and temporarily stores the signal obtained by this. The accumulated signals are sequentially read out by the number of times of scanning 226, and the reading of the information of the single-line irradiation unit (corresponding to the scanning line) is completed.

Next, the stimulable phosphor sheet is conveyed by one scanning line by the above-mentioned sheet conveying means, and the above reading step is repeated. By repeating this step for the entire image recording area of the stimulable phosphor sheet 1, the radiation image information recorded on the stimulable phosphor sheet 1 is read.

Next, the scanning circuit 226 following the line sensor 224 will be described. FIG. 5 is an equivalent circuit of a line sensor and a scanning circuit using a photoconductor. The signal due to the photocarrier generated when the photostimulated luminescence light impinges on the solid-state photoelectric conversion element 224a using the photoconductor is the capacitor Ci in the photoconductor 224a.
It is stored in (i = 1,2, ... n). The accumulated photocarrier signals are sequentially read by sequentially opening and closing the switch unit 228 controlled by the shift register 227, whereby a time-series image signal can be obtained.
The image signal is then amplified by the amplifier 229 and output from the output terminal 230 thereof. The MOS unit including the switch unit 228 and the shift register 227 may be replaced with a CCD.

Further, in the embodiment shown in FIG. 3, as the erasing light source of the erasing section 230, the LE extending in the width direction of the stimulable phosphor sheet is used.
D array 231 is used. The LED array 231 has the same lighting period as the erasing light source in the above-described embodiment. It should be noted that both the erasing light source and the LED array in the above-described first embodiment are always turned on to cover these erasing means at the time of taking out and reading the stimulable phosphor sheet from the cassette, and at the time of erasing. A shutter that is movable so as to be exposed may be provided.

As the excitation light irradiating means, in addition to the LED array as described above, the one using the fluorescent light-condensing sheet disclosed in Japanese Patent Application No. 62-21957 filed by the applicant earlier is used. You may use. That is, the fluorescent light condensing sheet is a sheet-shaped molded article containing a phosphor, and when the surface thereof is irradiated with light, the light excites the phosphor inside the fluorescent light condensing sheet to generate fluorescence. This fluorescent light repeats total internal reflection and proceeds to the end face side. Therefore, as shown in FIG. 6, an elongated fluorescent lamp 322, a fluorescent light condensing sheet 321 formed so as to surround the entire circumference of this fluorescent lamp 322, and a cylindrical lens provided on one end surface of this fluorescent light condensing sheet. Excitation light irradiation means is constituted by 323, and the fluorescent lamp 322 is turned on when the excitation light is irradiated.
The fluorescent light is generated in the fluorescent light condensing sheet 321 by the light emitted from the cylindrical lens.
If emitted from one end surface of the fluorescent light-collecting sheet via 323, this fluorescence can be 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.

Further, in the apparatus of the present invention, the cassette holding unit, the reading unit,
The arrangement of the erasing portion and the like are not limited to those shown in the above-mentioned embodiment, and the transporting direction of the stimulable phosphor sheet does not necessarily have to be a linear direction.

(Effects of the Invention) As described above, according to the radiation image information reading apparatus of the present invention, the cassette is mounted in the vicinity of the reading unit, and the accumulation property from the tip of the cassette in the mounting direction to the excitation light scanning position of the reading unit. By making the transport distance of the phosphor sheet smaller than the length of the stimulable phosphor sheet, the stimulable phosphor sheet can be moved using the space in the cassette,
Even if the possibility of performing pre-reading is taken into consideration, the reading unit can be downsized. Along with this, according to the apparatus of the present invention, an erasing unit is provided between the reading unit and the cassette holding unit, and erasing is performed while the stimulable phosphor sheet is carried into the cassette, thereby reducing the size of the erasing unit. In addition, it is not necessary to provide a special conveying path for conveying the stimulable phosphor sheet to the erasing section. Therefore, in the present apparatus, the size of the entire apparatus is substantially defined by the small reading section and the cassette holding section described above, so that the entire apparatus can be made extremely compact.

[Brief description of drawings]

FIG. 1 is a perspective view showing an outline of a radiation image information reading apparatus according to an embodiment of the present invention, FIG. 2 is a side conceptual view of the apparatus, and FIG. 3 is a reading unit and erasing in another embodiment of the present invention. FIG. 4 is a schematic front view of the line sensor, FIG. 5 is a scanning circuit diagram following the line sensor, and FIG. 6 is a perspective view of excitation light irradiation means using a fluorescent light condensing sheet. FIG. 7 is a conceptual side view of a conventional radiation image information reading apparatus. 1 ... Accumulative phosphor sheet, 2 ... Cassette 10 ... Cassette holding section, 11 ... Roller 20 ... Read section, 21A ... Excitation light 22 ... Photomultiplier 30 ... Erase section, 31 ... Erasing light source 40 ... Sheet conveying means

Claims (1)

[Claims] 1. A stimulable light irradiating means irradiates an stimulable phosphor sheet on which radiation image information is stored and recorded with exciting light, and the stimulated luminescent light emitted from the sheet by this irradiating exciting light is read by a photoelectric reading means. A reading unit for reading the image signal to obtain an image signal, a cassette which can store a stimulable phosphor sheet and which can be opened and closed at one end is detachably held, and the stimulable phosphor sheet in the cassette is taken out from the one end. A cassette holding unit having means, conveying the stimulable phosphor sheet taken out of the cassette to the reading unit, and carrying the read stimulable phosphor sheet into the cassette in the cassette holding unit by switchback. The sheet conveying means includes an erasing section for erasing the radiation image information remaining on the stimulable phosphor sheet after the reading is completed. The transport distance of the stimulable phosphor sheet from one end of the cassette held in the cassette holder to the irradiation position of the excitation light in the reading unit is smaller than the length of the sheet in the transport direction, and the erase unit is A radiation image information reading device, which is arranged in a conveyance path of a stimulable phosphor sheet between the cassette holding unit and the reading unit.