JPH04242736A - Radial ray image photographing device - Google Patents

Abstract

PURPOSE:To eliminate effects of scattered rays, and photograph a radial ray image at a high speed in a radial ray image photographing device. CONSTITUTION:A radial ray source 12 is disposed in a rotary cylinder 13 having a slit 13a extending in a center axis direction in a circumferential surface 13b, a rotary cylinder 14 having a slit 14a extending in a center axis direction in a circumferential surface 14b similarly is disposed to face the slit 13a having a subject body 19 between them, these cylinders 13, 14 are rotated while the subject body 19 is scanned by a linear radial ray 18, thereby an accumulative phosphor sheet 2 is slit exposed by the linear radial ray 18 transmitted through it.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to a radiation image capturing device that captures a radiographic image of an object by irradiating radiation that has passed through the object onto a radiation detection means. The present invention relates to a slit exposure type radiation image capturing apparatus that is capable of eliminating .

0002

2. Description of the Related Art Conventionally, there has been known an apparatus that irradiates an X-ray photographic film with radiation that has passed through the subject, thereby photographing a radiographic image of the subject. In addition, radiation that has passed through the subject is irradiated onto a fluorescent screen to generate fluorescence, and the fluorescence is read photoelectrically using an image intensifier, etc., to obtain the electrical signal that represents the radiation image of the subject. Image capture devices are also known.

[0003] Also, certain types of phosphors are exposed to radiation (X-rays, α
When this phosphor is irradiated with excitation light such as visible light, some of this radiation energy is accumulated in the phosphor, and when this phosphor is irradiated with excitation light such as visible light, the accumulated energy is It is known that phosphors exhibit stimulated luminescence depending on the
It is called a stimulable phosphor. A system that uses this stimulable phosphor to obtain an electrical signal representing a radiation image of a subject is also known. This system first records radiographic image information of a subject such as a human body on a stimulable phosphor sheet, and then 2nds this stimulable phosphor sheet with excitation light such as a laser beam.
This method generates stimulated luminescence light by scanning dimensionally, and photoelectrically reads the resulting stimulated luminescence light with a photodetector to obtain an image signal (Japanese Patent Application Laid-open Nos. 12429-1982 and 56-1983).
11395 etc.).

By the way, as mentioned above, it is possible to irradiate the radiation that has passed through the object onto an X-ray photographic film, stimulable phosphor sheet, etc. and record the radiation image of the object there, or to use an image intensifier or the like. When radiographic images are taken using radiographic images, the influence of scattered rays scattered by the subject becomes a problem. Therefore, various attempts have been made to remove these scattered rays to photograph (record) radiographic images. For example, in Japanese Patent Application Laid-open No. 149043/1986, an object is scanned with linear radiation passing through a slit, and the linear radiation transmitted through the object is passed through another slit to be incident on radiation detection means. , a so-called slit exposure type radiation image forming method is disclosed.

[0005]

However, since the conventional radiographic image capturing apparatus described above has a structure in which two slit plates arranged in parallel are moved in a straight line, it is difficult to move the slits at high speed. Therefore, when using this conventional device, it takes time to capture one radiographic image.
It has been recognized that it is difficult to increase the photographic processing capacity, and furthermore, there are problems in that the subject moves during the photographing process and the photographing process often fails.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a radiographic image capturing apparatus capable of capturing radiographic images at high speed using a slit exposure method.

[0007]

[Means for Solving the Problems] A radiographic imaging device according to the present invention has: ◆ a radiation source that emits radiation; and ◆ a plurality of slits extending in the central axis direction on the circumferential surface, and the radiation source is housed inside. , a radiation-absorbing first cylinder rotatably held around the central axis, and ◆ having a plurality of slits extending in the direction of the central axis on the circumferential surface, these slits forming the first cylinder with the subject in between; A second radiation-absorbing cylinder is arranged to face parallel to the slit of the cylinder and is rotatably held around the central axis; a driving means for synchronously rotating the surfaces of which both pass through the radiation source; The device is characterized in that it is comprised of a radiation detection means.

[0008] As the radiation detecting means, the above-mentioned stimulable phosphor sheet or X-ray photographic film can be used. Furthermore, this radiation detection means can also be comprised of, for example, a fluorescent screen and a photodetector that detects the fluorescence emitted by the fluorescent screen that has been irradiated with radiation.

[0009]

[Operation and Effects of the Invention] In the above configuration, by rotating the two cylinders as described above, the linear radiation passing through the slit of the first cylinder scans the object,
The linear radiation that has passed through the object passes through the slit of the second cylinder and enters the radiation detection means. At this time, most of the scattered radiation scattered by the object is absorbed by the portions of the second cylinder other than the slits, so that only the direct radiation that has passed through the slits of both cylinders is detected by the radiation detection means. In this way, a radiation image is photographed using the slit exposure method.

[0010] Since the cylinder as described above can be easily rotated at high speed, high-speed scanning of linear radiation becomes possible. Therefore, this radiographic imaging device can shorten the time required for imaging and improve imaging processing capacity compared to conventional equipment that uses the slit exposure method. Therefore, it is less likely that a photographing failure will occur.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below based on embodiments shown in the drawings. 1 and 2 show a radiation image capturing apparatus according to a first embodiment of the present invention. This device is configured to capture (record) and read radiation images, and Figure 1 shows the state at the start of image recording, and Figure 2 shows the state at the end of image reading. There is.

[0012] This device includes a device body 1, an imaging table 11 placed above the device body 1, a radiation source 12 such as an X-ray source placed above it, and this radiation source 12 housed inside. a second cylinder 14 disposed outside the first cylinder 13 and housing the photographing table 11 therein;
It consists of a driving means that rotates these cylinders 13 and 14 integrally. On the other hand, a stimulable phosphor sheet 2 serving as radiation detection means is fixedly held inside the apparatus main body 1 at a position below the imaging table 11. Storable phosphor sheet 2
is a stimulable phosphor layer 2B on a radiotransparent support 2A.
It is formed by the formation of In addition, the above-mentioned photographing stand 11 is also
It is radiolucent.

As shown in detail in FIG.
One end of the cylinder 14 is fixed to a rotating disk 15, and the first cylinder 13 is also fixed to the rotating disk 15 with its center axis aligned with the center axis of the second cylinder 14. The first cylinder 13 has a circumferential surface 13b made of a radiation-absorbing material such as lead, and this circumferential surface 13b is provided with a plurality of (24 in this example) slits 13a extending in the central axis direction. Second
The cylinder 14 also has a circumferential surface 14b made of a radiation-absorbing material, and this circumferential surface 14b is provided with a plurality of (24 slits) 14a extending in the direction of the central axis. These slits are one slit 13a of the first cylinder 13.
A plane passing through one slit 14a of the second cylinder 14 passes through the focal point of the radiation source 12.

The center of the rotating disk 15 is fixed to a rotating shaft (not shown), and both cylinders 13 and 14 are held rotatably about this rotating shaft (that is, around the cylinder center axis). The rotating shaft is connected to a drive unit 16 that includes a motor, power transmission gears, and the like. Therefore, when this drive unit 16 operates, both cylinders 13, 14
rotate around their central axes. As described above, in this embodiment, the rotary disk 15 and the drive unit 16 constitute a drive means for rotating both cylinders 13 and 14 while keeping them in a predetermined positional relationship.

On the other hand, below the stimulable phosphor sheet 2, there is provided a reading/erasing unit 4 in which an image reading means 20 and an erasing means 30 are placed close to each other and are housed integrally in the housing 3. . This reading/erasing unit 4 can reciprocate while facing the sheet 2 between the right end position (first position) shown by a solid line in FIG. 1 and the left end position (second position) shown by a solid line in FIG. It becomes. In this example, the first
The moving path in the direction of arrow A from the position to the second position is the outward path, and the moving path in the direction of arrow A' from the second position to the first position is the backward path. The unit moving means 40 for reciprocating the reading/erasing unit 4 includes, for example, a screw rod 41 extending in the moving direction of the unit 4, a unit support portion 42 screwed to the screw rod 41, and a gear 43 fixed to the screw rod 41. , a gear 44 that meshes with this gear 43, a pulse motor 45 that rotates this gear 44 in both forward and reverse directions, and means (not shown) for guiding and holding the unit 4 so as to be movable in a direction parallel to the screw rod 41. , the gear 44 by the pulse motor 45,
By rotating the screw rod 41 via the screw rod 43, the unit support part 42 is screwed back and forth, and the unit 4 is moved back and forth.

When a subject 19 is placed on the photographing table 11 of the photographing section 10, the drive unit 16 is activated and both cylinders 13 and 14 rotate about their central axes. At the same time, the radiation source 12 is activated. As a result, the object 19 is scanned by the linear radiation 18 that has passed through the slit 13a, and the scattered rays scattered by the object 19 are blocked by the portion of the second cylinder 14 other than the slit, so that almost all the slits 13a, 14a The stimulable phosphor sheet 2 is exposed to radiation only by the direct radiation that has passed through. In this way, the transmitted radiation image of the subject 19 is accumulated and recorded on the phosphor layer 2B of the sheet 2.

As mentioned above, in this device, both cylinders 1
3 and 14 are rotated to record a radiographic image of the subject 19 on the stimulable phosphor sheet 2 using the slit exposure method, eliminating the influence of scattered radiation scattered by the subject 19, resulting in less noise. It becomes possible to record high-quality radiation images.

Since the cylinders 13 and 14 described above can be easily rotated at high speed, a radiation image can be recorded on the sheet 2 in a short time. As a result, it is possible to improve the photographing processing capacity, and it is less likely that the subject 19 will move during slit exposure and fail in photographing. Furthermore, in this embodiment, the stimulable phosphor sheet 2 is irradiated with multiple lines of linear radiation at the same time, so compared to the case where the stimulable phosphor sheet 2 is irradiated with a single line of linear radiation. For example, even if both cylinders 13 and 14 are rotated at a higher speed, the necessary amount of radiation irradiation to the sheet 2 can be ensured, and the above-mentioned effects can therefore be obtained more markedly.

When the slit exposure described above is completed,
The sheet 2 is read by the image reading means 20 in the unit 4.
The image information stored and recorded is read out. The image reading means 20 includes an excitation light source 21 such as a semiconductor laser, a condenser lens 22 provided in the optical path of the excitation light 21A emitted from the excitation light source, and an excitation light 21A that has passed through the condenser lens 22 as shown in FIG. Excitation light scanning means includes a rotating polygon mirror 23, which is an optical deflector that main scans the sheet 2 by deflecting it in a direction intersecting the plane of the paper, an fθ lens 22f, and mirrors 24a, 24b, and 24c that change the optical path of the excitation light 21A. The excitation light scanning means causes the excitation light 21A to repeatedly main-scan the sheet 2 in a direction perpendicular to the paper surface.

On the other hand, as the unit 4 is conveyed at a constant speed in the direction of arrow A by the unit moving means 40, the scanning position of the excitation light 21A is moved in the direction of arrow A to perform sub-scanning, and the sheet 2 is irradiated with excitation light 21A over almost the entire surface thereof. From the excitation light irradiation location of the sheet 2, stimulated luminescence light is generated in an amount corresponding to the accumulated and recorded image information, and this stimulated luminescence light is detected by the photoelectric reading means of the image reading means 20.

The photoelectric reading means in this device includes a long photomultiplier (photomultiplier tube) 25 extending in the main scanning direction over the length of the main scanning line, and a light receiving surface of the photomultiplier 25. A filter 27 is provided to cut the excitation light 21A reflected from the sheet surface from entering the photomultiplier 25 and selectively transmits only the stimulated luminescence light, and the filter 27 is provided at It consists of a light guide 26 that is attached to the end face and condenses the stimulated luminescence light well, and a mirror 29 that reflects the stimulated luminescence light emitted on the opposite side of the light guide 26 to the light guide 26 side. The elongated photo multiplier 25 is disclosed in detail in, for example, Japanese Patent Laid-Open No. 16666/1983, and receives stimulated luminescence light incident through the light guide 26 and generates electricity according to the amount of light. Outputs signal S. When recording and reading of the image information is thus completed, the reading/erasing unit 4 has moved to the second position as shown by the broken line in FIG.

The output signal S of the photomultiplier 25 described above is suitably amplified, subjected to image processing (signal processing) such as gradation processing, and then sent to an image reproducing device such as a CRT display device or an optical scanning recording device. , if a radiation image is reproduced based on the signal S, a high-quality radiation image with a high S/N ratio can be obtained by removing the influence of scattered radiation.

When the reading of the image information is completed, the reading/erasing unit 4 moves from the second position to the first position as shown in FIG.
The sheet 2 is transported in the direction of arrow A' to the position shown in FIG. For example, the erasing means 30 includes an erasing light source 31 such as a fluorescent lamp extending in the main scanning direction, and this erasing light source 31.
It is provided with a reflecting plate 32 that reflects the light directed downward among the light emitted from the sheet toward the surface side of the sheet. Furthermore, in this embodiment, since the erasing light source 31 is always turned on, when recording and reading images, the erasing light source 31 is placed above the erasing light source 31 to block the erasing light as shown in FIG. As shown in FIG. 2, a movable shutter 33 is provided above the photomultiplier 25 to expose the erasing light source 31. Note that if the erasing light source 31 is turned on only during erasing and turned off at other times, the movable shutter 33 may not be particularly provided.

The erasing light source 31 illuminates the entire surface of the sheet 2 as the unit 4 moves in the direction of arrow A'. The erasing light source 31 mainly emits light in the excitation wavelength range of the sheet 2, and the radiation energy remaining on the sheet 2 after reading the image is irradiated with such light to the sheet 2. released from. The sheet 2 that has been erased is again in a state where new recording can be made by the photographing section 10, and the reading and erasing unit 4 is returned to the first position again.

Next, a second embodiment of the present invention will be described with reference to FIG. Note that in FIG. 4, elements equivalent to those in FIGS. 1 and 2 are given the same numbers, and explanations thereof will be omitted (the same applies hereinafter).

In this device, the first cylinder 13 is fixed to a rotating disk 15A, and this rotating disk 15A is rotated in the direction of arrow Q by a drive unit 16A. A radiation source 12 is arranged inside this first cylinder 13 . On the other hand, the second cylinder 14 has its circumferential surface 14b facing the subject 19.
It is disposed at a position facing the circumferential surface 13b of the first cylinder 13 with . This second cylinder 14 is a rotating disk 15
This rotary disk 15B is fixed to the drive unit 16
B rotates in the direction of arrow T. The stimulable phosphor sheet 2 is held within the second cylinder 14 in a state facing the radiation source 12 .

The drive unit 16A is driven by a drive circuit 60, and the drive unit 16B is driven by a drive circuit 61. These drive circuits 60 and 61 each control the drive unit 16A based on drive control signals SR1 and SR2 output from the synchronous drive control circuit 62.
, drives the drive unit 16B. Drive control signal SR
1, SR2 is one slit 13a of the first cylinder 13
Both cylinders 13 and 14 are rotated so that the plane passing through one slit 14a of the second cylinder 14 remains in a state passing through the focal point of the radiation source 12. In order to do this, the first cylinder 13 may be rotated at a constant speed while the second cylinder 14 may be rotated while changing its speed periodically, or vice versa. Cylinder 14
may be rotated at a constant speed, while the first cylinder 13 may be rotated while changing the speed periodically, or furthermore, both cylinders 13 and 14 may be rotated while changing the speed periodically. .

By rotating both cylinders 13 and 14 as described above, the object 19 is scanned by the linear radiation 18 that has passed through one slit 13a, and the scattered radiation from this object 19 is transferred to the second one. The slits 13a, 14 are almost blocked by the parts of the cylinder 14 other than the slits.
The stimulable phosphor sheet 2 is exposed to radiation only by the direct radiation that has passed through a. In this way, also in this case, the influence of scattered radiation scattered by the subject 19 can be eliminated, and a high-quality radiation image with little noise can be recorded.

In this embodiment, the cylinders 13 and 14 are relatively large, and the radiation source 12 is placed at a sufficient distance from the stimulable phosphor sheet 2. As a result, the linear radiation 18 that has passed through the slits 13a and 14a enters the stimulable phosphor sheet 2 in the effective scanning area W with respect to the stimulable phosphor sheet 2, with the incident angle remaining almost unchanged (always approximately 0°). It becomes incident. In this case, the cylinder 13 or 14 that is being shifted
In this case, it is sufficient to rotate the cylinder 14 or 13 at a very constant speed in accordance with the speed of the cylinder 14 or 13 which is rotated at a constant speed, making speed change rotation control relatively easy.

Since the cylinders 13 and 14 described above can also be easily rotated at high speed, a radiation image can be recorded on the sheet 2 in a short time. As a result, it is possible to improve the photographic processing capacity, and the subject 19 can be photographed during slit exposure.
It is also less likely that the camera will move and cause a failure in shooting.

Next, a third embodiment of the present invention will be described with reference to FIG. In this embodiment, compared to the second embodiment, the intervals between the slits 13a and the intervals between the slits 14a are set relatively small, and a plurality of strips (for example, 3) of linear radiation 18 are made incident on the sheet 2. In this case, linear radiation 1
The angle of incidence on the stimulable phosphor sheet 2 of 8 is as follows: cylinder 13, 1
The width of the slit 14a of the cylinder 14 is made relatively large in order to absorb this change.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing the state of the apparatus according to the first embodiment of the present invention at the time of starting image recording.

FIG. 2 is a partially cutaway front view showing the state of the first embodiment device at the end of image reading.

[Fig. 3] A perspective view showing the main parts of the device of the first embodiment.

[Figure 4
] Partially cutaway front view showing a device according to a second embodiment of the present invention

[Figure 5
] Partially cutaway front view showing a device according to a third embodiment of the present invention

[Explanation of symbols] 2 Stormative phosphor sheet 4 Reading/erasing unit 10 Imaging unit 11 Imaging table 12 Radiation source 13 First cylinder 14 Second cylinder 13a, 14a Slits 13b, 14b Cylinder circumferential surface 15, 15A, 15B Rotation Discs 16, 16A,
16B Drive unit 18 Radiation 19 Subject 20 Image reading means 21 Excitation light source 21A Excitation light 23 Rotating polygon mirror 25 Photo multiplier 26 Light guide 30 Erasing means 31 Erasing light source 40 Unit moving means 60, 61 Drive circuit 62 Synchronous drive control circuit

Claims (1)

[Claims] Claim 1: A radiation-absorbing material having a radiation source that emits radiation, and a plurality of slits extending in the direction of the central axis on the circumferential surface, housing the radiation source inside, and being held rotatably around the central axis. It has a first cylinder and a plurality of slits extending in the direction of the central axis on the circumferential surface, and these slits are arranged so as to face parallel to the slits of the first cylinder with the subject in between, and a second radiation-absorbing cylinder rotatably held by the radiation-absorbing second cylinder, and the first and second cylinders are rotated synchronously while keeping the surfaces passing through each one of the slits passing through the radiation source. A radiation image capturing apparatus comprising a driving means and a radiation detecting means for detecting linear radiation passing through a slit in the first cylinder, a subject, and a slit in the second cylinder.