JP2796992B2 - Radiation imaging equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a radiation image capturing apparatus.

<Conventional technology> As a conventional radiographic imaging device, radiation (generally X
A line is radiated to a panel of a stimulable phosphor through a subject (generally a human body), and a part of radiation energy is accumulated in the phosphor. In this one, then
When the phosphor is irradiated with excitation light, the phosphor shows stimulated emission according to the stored energy, and the obtained stimulated emission light is photoelectrically read to obtain an image signal, and this image signal is processed. To obtain images with good diagnostic suitability.

<Problems to be Solved by the Invention> However, in this type of apparatus, a stimulable phosphor is used in the form of a panel, and the radiation exposure unit and the reading unit are different. There was a problem of becoming.

Further, as disclosed in Japanese Patent Application Laid-Open No. 60-149042,
Some use a rotating drum that holds a stimulable phosphor sheet on which the radiation image is accumulated and recorded, and read the image while rotating the drum.
It is used only for reading, and further disclosed in JP-A-58-6693.
As shown in No. 1, using an endless support,
There is an apparatus in which recording and reading of a radiation image are intermittently performed in a circulating manner. However, there is a problem in how to perform recording of a radiation image, and it has not been put to practical use.

An object of the present invention is to provide a practical and compact drum-type radiation image capturing apparatus in view of such conventional problems.

<Means for Solving the Problems> For this reason, the present invention provides a fan beam irradiation device that irradiates a subject with a fan beam (that is, a fan-shaped radiation beam) while relatively moving its irradiation region, A drum provided behind and having a stimulable phosphor layer formed on the circumference; and irradiating the stimulable phosphor of the drum with excitation light to photoelectrically convert the intensity of the stimulable emission light into image information. A reading device for reading the drum, the drum is rotated about an axis in synchronization with the relative movement of the fan beam, and is moved relative to the subject, so that a drum-type radiation image capturing apparatus is provided. Configure.

<Operation> In the above configuration, the irradiance of the drum is irradiated by irradiating the fan beam passing through the object while moving the irradiation area, and simultaneously, rotating and rotating the drum in synchronization with the movement. It becomes possible to store and record on the phosphor.

Further, the image information stored and recorded is immediately read in order (in parallel with the image recording) from the part recorded by the reading unit, and a radiation image is obtained.

<Example> An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a side view of a radiographic imaging apparatus, and FIG.
FIG.

The fan beam irradiation device A includes a radiation source (generally, an X-ray source), a slit forming member 2, and a modulator 3.

Here, the radiation source 1 is fixed, and a fan beam FB is formed by the slit forming member 2 in front thereof. Then, the fan beam FB moves up and down by the up and down movement of the slit forming member 2 by the actuator 4.

In the present invention, it is preferable that a modulator 3 having a plurality of shutter blades divided in the longitudinal direction of the slit is attached to the slit forming member 2 and a mechanism for adjusting the transmitted dose of each part of the slit for exposure correction is provided. .

The recording device B includes a drum 6 and the like housed inside a casing 5.

The drum 6 has a stimulable phosphor layer formed over the entire circumference of a cylindrical substrate.

FIG. 3 shows an example of the structure, in which the drum substrate 7 and the surface coat are provided.
8, a phosphor layer 9, a void 10, and a protective layer 11.

The drum base 7 may be hollow or solid, and examples of the material include glass, ceramics, metal, resin, carbon (graphite), wood, and the like, or a fibrous material (glass fiber, carbon Fiber or the like) may be formed into a drum shape.

As the surface coat 8, one or more surface coating agents (for example, ceramic particles, fibers, etc.) may be provided to adjust the reflectance of the surface, prevent diffusion of impurities into the phosphor layer, and improve the adhesion of the phosphor layer. Instead of providing a surface coating agent, the surface may be processed by etching, blasting or the like.

The phosphor layer 9 has a thickness of 100 to 500 μm (preferably 200 μm) by a film forming means such as spin deposition or coating of a stimulable phosphor.
400400 μ). According to the rotary evaporation, a stimulable phosphor layer can be easily formed uniformly.

Examples of the stimulable phosphor include those shown in the following i) to vi).

i) Alkaline earth fluorohalide phosphor represented by the general formula (Ba ₁ -XY Mg _X Ca _Y ) FX: eEu ^{2+ described} in JP-A-55-12143 ii) JP-A-55-12143 formula is described in -12144 JP LnOX: phosphor iii) the general formulas described in JP employed stimulable phosphors JP represented by ^{_{xA (Ba 1-X M II}} X) FX: represented by yA Iv) Phosphor represented by the general formula BaFX: xCe, yA described in JP-A-55-84389 v) General formula M ^II FX described in JP-A-55-160078 · xA: formula is described in the rare earth element activated divalent metal fluorohalide phosphor vi) JP 61-72087 JP represented by ^{yLn M I X · aM II X} '2 · bM III X "3 The void 10 of the alkali halide phosphor represented by: cA is composed of an air layer, a gas layer, or a vacuum layer.

The protective layer 11 is a measure for preventing moisture absorption, adjusting reflectance, and preventing scratches, and is provided with one or more inorganic substances such as a polymer film, a resin, and glass. In the present embodiment, the gap 10 is interposed between the phosphor layer 9 and the air gap 10, but may be in close contact with the phosphor layer 9.

The size of the drum 6 is basically determined by its perimeter,
The length L of the subject to be photographed in the vertical direction is set to 1: 1; however, other values can be set. This is because compression recording and the like can be performed depending on the rotation speed of the drum.

The drive structure of the drum 6 will be described.
Are rotatably supported at both ends by a carrier 12, and can be rotated clockwise in FIG. 1 by a pulse motor 13 in a direct drive system. And career 12
Is screwed to a screw rod 14 arranged in the vertical direction, and can be moved up and down by rotation of the screw rod 14 by the pulse motor 15.
The operation of the actuator 4 for vertically moving the slit forming member 2 and the pulse motors 13 and 15 is performed by the controller 16 in synchronization.

The slit forming member 1 and the line detector 18 are provided on the subject side of the drum 6. These are attached to the carrier 12 via a bracket (not shown), and move up and down integrally with the drum 6. The slit width of the slit forming member 17 in the narrow direction is smaller than the drum diameter, and preferably smaller than 1/2 of the drum diameter.
A signal from the line detector 18 is input to a controller 19, which controls the opening degree of each shutter blade of the modulator 3 via an actuator 20.

A reading device C and an erasing device D are further provided in the casing 5. These are sequentially arranged around the drum 6 along the rotation direction of the drum starting from the recording portion of the drum 6 on the side where the slit forming member 17 is arranged.

As shown in FIGS. 4 and 5, the reading device C includes a laser light source 21, such as a laser diode, as an excitation light source, a galvanometer mirror 22, a light collector 23 composed of an optical fiber, a photomultiplier (photomultiplier tube) 24. Etc., which are attached to the carrier 12 via brackets not shown,
It moves up and down integrally with the drum 6.

The erasing device D is composed of an erasing lamp 25 with a light-shielding cover, which is also attached to the carrier 12 via a bracket (not shown), and moves up and down integrally with the drum 6.

 Next, the operation will be described.

At the time of photographing, the subject is placed between the fan beam irradiation device A and the recording device B (in front of the casing 5), and the fan beam FB is received from the radiation source 1 through the slit forming member 2.
Is irradiated. Therefore, the radiation transmitted through the copy is accumulated and recorded on the stimulable phosphor of the drum 6 via the slit forming member 17 and the line detector 18. Meanwhile line detector 18
The radiation dose is controlled via the modulator 3 in accordance with the transmitted dose detected by.

Also, during imaging, the slit forming member 2 moves up and down to irradiate each part of the subject with radiation, and in synchronization with this, the carrier 12 moves up and down, and the drum 6, the slit forming member 17 and the line The detector 18 and the like are also moved. Then, the drum 6 rotates in synchronization with the vertical movement, and the radiation image information of each part of the subject is continuously accumulated and recorded on the phosphor of the drum 6.

Further, the portion on which the accumulated recording is performed reaches the reading device C by the rotation of the drum 6.

Here, laser light from a laser light source 21 is incident on a galvanomirror 22. The galvanomirror 22 deflects the laser light so that the laser light main scans in the width direction of the drum 6 thereunder. Irradiate. Further, since the drum 6 rotates, sub scanning is performed in the rotation direction. Therefore, the main scanning and the sub scanning are repeated,
Two-dimensional scanning by laser light is performed over the entire surface of the drum 6.

For this reason, the portion irradiated with the laser beam in accordance with the scanning with the laser beam emits stimulated emission with an intensity corresponding to the stored and recorded image information, and this emitted light is parallel to the main scanning line near the drum 6 and the incident end face. Enters the light collector 23 in which is formed. The light collector 23 is formed so as to gradually become cylindrical toward the rear end, and becomes substantially cylindrical at the rear end and is coupled to the photomultiplier 24. The emitted light is collected at the rear end and transmitted to Photomaru 24.
The light collector 23 is an optical fiber bundle here, but may be made of resin, glass, or the like. Photo Mar
At 24, the stimulating light is converted to an electrical signal. Then, the electric signal is sent to an image information reading circuit (not shown). The image information reading circuit processes and outputs the electric signal, and for example, it can be output as a visible image on a CRT, recorded on a magnetic tape, or directly recorded as a hard copy on a photographic material. .

After reading, the erase lamp 25 emits light while rotating the drum 6 to erase the record on the phosphor of the drum 6.

When the drum 6 has a small diameter and is rotated one or more rounds in one photographing operation, the erase lamp 25 is caused to emit light during photographing so that the phosphor on the drum 6 can be reused. However, in this case, it is necessary to provide a light-shielding cover or the like to take measures against the leakage of the erasing lamp light.

 Next, various modifications will be described.

As shown in FIG. 6, the rotation drive mechanism of the drum 6 may be configured such that a worm wheel 31 is integrally attached to an end of a shaft of the drum 6 and is driven to rotate via a worm gear 32 meshed with the worm wheel 31. .

As shown in FIG. 7, a pulley 37 fixed to the end of the shaft of the drum 6 with respect to a belt 36 wound between a driving pulley 33 and a driven pulley 34 and given tension by a guide roller 35. And the drum 6 may be rotationally driven by a belt drive method.

As shown in FIG. 8, a pinion gear 38 is integrally attached to the end of the shaft of the drum 6 and meshed with a rack gear 39 arranged in the up and down direction. The rotation of the drum 6 may be synchronized with the rotation of the drum 6.

In addition, as a method of moving the irradiation region of the fan beam, the radiation source 1 is fixed, the slit forming member 2 is moved, the beam is shaken, and the tube of the radiation source itself is moved. Good.

Further, since it is sufficient to move the drum relative to the subject, the position of the fan beam may be fixed, the position of the drum may be fixed, and the subject may be moved so that the drum rotates.

In the above embodiment, the drum 6 is placed horizontally, but it may be arranged vertically and moved in the horizontal direction. In this case, the fan beam also swings sideways.

Next, another example of the layout of the reading device and the erasing device will be described.

That is, in the above embodiment, the reading device and the erasing device are arranged outside the drum. However, for example, the reading device and the erasing device can be arranged as follows.

The laser light source is located outside the drum and the concentrator and erase lamp are located inside the drum. In this case, the surface coat, the phosphor layer, the void, and the protective layer are laminated on the drum substrate in this order, or the phosphor layer, the void, and the protective layer are laminated without the surface coat.

The laser light source, condenser, and erase lamp are all located inside the drum. In this case, a surface coat, a phosphor layer, a void, and a protective layer are laminated in this order inside the drum.

The condenser and the erase lamp are arranged outside the drum, and the laser light source is arranged inside the drum. In this case, a phosphor layer, a void, and a protective layer are laminated in this order inside the drum.

When the fan beam is irradiated on the drum, as shown in FIG. 9 (a), the peripheral surface on the opposite side of the drum 6 is double-exposed, so it is necessary to eliminate the influence.

To this end, as in the above-described embodiment, the reading may be performed by the reading device at the previous site.
As shown in FIG. 2B, a radiation absorbing member (for example, a lead plate) 41 may be provided inside the drum 6 over the entire circumference. Alternatively, as shown in FIG. 9C, a radiation absorbing member 42 independent of the rotation of the drum 6 may be provided.

<Effects of the Invention> As described above, according to the present invention, the stimulable phosphor is formed in a drum shape, so that the radiation image capturing apparatus can be configured to be compact. Can be recorded on the phosphor,
Further, an effect that recording and reading can be performed simultaneously can be obtained.

[Brief description of the drawings]

FIG. 1 is a side view of a radiographic imaging apparatus showing one embodiment of the present invention, FIG. 2 is a view taken in the direction of the arrow II in FIG. 1, FIG. 3 is a structural view of a drum, and FIG. FIG. 5, FIG. 5 is a side view around the drum, FIG. 6 to FIG. 8 are diagrams showing another embodiment of the rotary drive mechanism of the drum, FIG. 9 (a) to (c).
FIG. 4 is a diagram showing an example of a countermeasure for double exposure. DESCRIPTION OF SYMBOLS 1 ... Radiation source 2, ... Slit forming member, 3 ... Modulator, 6 ... Drum, 9 ... Phosphor layer, 12 ... Carrier, 13 ... Pulse motor, 14 ... Screw rod, 15 ... Pulse motor, 16 …… Controller, 17 …… Line detector, 19 …… Controller

Claims (1)

(57) [Claims] 1. A fan beam irradiation apparatus for irradiating an object with a fan beam while relatively moving an irradiation area thereof, and a stimulable phosphor layer formed on a circumference provided behind the object. A drum, and a reading device for reading image information by photoelectrically converting the intensity of the stimulating light while irradiating the stimulable phosphor of the drum with excitation light, wherein the drum has a relative movement of the fan beam; A radiographic image capturing apparatus that moves relative to a subject while rotating about an axis in synchronization.