JPH02238450A - Shutter structure for radiographing device - Google Patents

Abstract

PURPOSE:To make the movement good and to improve a control performance by forming a shutter member out of members whose radiation transmittivity are different in the moving direction of the shutter member and performing a position control by working the driving force of a shutter driving device on the side where the part faced to the aperture of the shutter member are sandwitched. CONSTITUTION:A shutter blade 10 is constituted of members 10a and 10b whose radiation transmittivity are different, which are connected in the moving direction. And a tension spring 11 is worked on one end of the shutter blade 10, and a wire 15 which is guided through a guide pulley 14 attached on the pulley 13 of the rotary shaft of a pulse motor 12, the part of the actuator of the shutter driving device, is connected on the other end. By working the force on both ends of the shutter member 10, the position control can be performed with the balance. Thus, the good movement can be obtained and the control performance can be much more improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a shutter structure for exposure compensation in a radiation (generally X-ray) photographic device.

Conventional technology> Conventionally, in radiographic imaging devices, a fan beam as a radiation beam is generated by providing a slit as an opening on the irradiation side of a radiation source and moving this slit in a direction perpendicular to the longitudinal direction of the slit. The fan beam is generated and the object is irradiated with the fan beam, and an image is taken and recorded on an imaging surface such as a screen/film provided behind the object.

However, in chest X-ray examinations, for example, objects have very large anatomical thickness variations (ie, differences in x-ray absorption between the lung field and other parts) and therefore exhibit very large x-ray attenuation variations. As a result, in addition to the narrow exposure range of X-ray film, etc., the images representing these inspections are only partially exposed properly and most of the areas are overexposed or underexposed. Therefore, a significant loss of X-ray information (decreased diagnostic value) occurs.

Therefore, in order to compensate for exposure, a shutter consisting of a plurality of shutter members (shutter blades) arranged in the longitudinal direction of the slit and movable in a direction across the slit can be provided to adjust the amount of transmitted radiation in each part of the slit. On the other hand, a detector for detecting the dose of each part on the image plane and a shutter driving device for driving each blade of the shutter based on the signal from this detector are provided (Japanese Patent Laid-Open No. 60-253198). (Refer to Japanese Patent Application Laid-Open No. 62-129034).

Problems to be Solved by the Invention However, in such conventional radiographic imaging devices, the shutter blade is slidable in the direction across the slit and is pushed in and pulled out by a wire from one end. The structure is complicated, as it is necessary to guide the wire through a tube, and there are problems in that the wire does not move well due to its lack of rigidity, resulting in poor controllability.

SUMMARY OF THE INVENTION In view of these conventional problems, it is an object of the present invention to provide a shutter structure for a radiographic imaging apparatus that has good movement and better controllability.

<Means for Solving the Problems> For this reason, the present invention provides an aperture that is provided on the irradiation side of a radiation source and generates a radiation beam, and a shutter member that is movable in a direction across the aperture and adjusts the transmitted dose. and a radiographic imaging apparatus comprising: a detector that detects the dose on a Q imaging surface behind an object to which a radiation beam is irradiated; and a shutter drive device that drives the shutter member based on a signal from the detector; The shutter member is formed of a member having different radiation transmittance in its moving direction, and the position is controlled by applying the driving force of the shutter driving device to the side of the shank member that faces the opening. This is what I did.

<Function> In the above shutter structure, force is applied to both ends of the shutter member and the position can be controlled in a balanced manner, resulting in better movement and more appropriate control, and the rigidity of the drive member is also reduced. It is not necessary and the structure becomes simpler.

Examples> Examples of the present invention will be described below. Referring to FIG. 1, by providing a vertically elongated slit 2 as an opening on the irradiation side of a radiation source (generally an X-ray tube) l and moving this slit 2 in the horizontal direction, a fan beam as a radiation beam It is designed to generate FB.

Further, the slit 2 is provided with a shutter 3 that moves together with the slit 2. This shank 3 consists of a plurality of shutter blades IO as shutter members arranged in the longitudinal direction of the slit 2 and movable in the direction across the slint 2, so that the amount of transmitted radiation in each part of the slit 2 can be adjusted. .

The fan beam FB is irradiated onto the object (human body) 4,
An image is captured and recorded in accordance with the transmitted dose on an image plane 5 such as a screen/film provided behind the object 4. In the case of screens/films, radiation is irradiated onto the phosphor layer (phosphor screen) and converted into visible light.
This visible light is exposed to a film coated with a silver salt photosensitive material. However, the present invention is not limited to this, and image information may be accumulated using a stimulable phosphor detector, scanned and retrieved by a semiconductor laser, and this digital image information may be stored in an external memory so that it can be reproduced on a CRT. It may be a method etc.

Additionally, a detector 6 detects the dose of each part on the most image plane 5, and a shutter drive device (control unit and actuator) 7 drives each blade 10 of the shutter 3 based on the signal from the detector 6.
and.

As a result, the detector 6 detects the dose of each part on the line irradiated with the fan beam FB, and the shutter drive device 7 drives each blade 10 of the shutter 3 so that the dose of each part is within a substantially constant range. to adjust the transmitted dose.

Here, as a configuration according to the present invention, each shutter blade 10 of the shutter 3 is configured as shown in FIG.

That is, the shutter blade 10 is constructed by joining members 10a and 10b having different radiation transmittances in the direction of movement thereof. Furthermore, if the width of the slit 2 is W, then the member 1
Each length w, , W2 of 0a, 10b is w. ≧w, wt
≧W.

Specifically, the member 10a is made of, for example, an acrylic plate with high radiation transmittance or an aluminum plate with medium radiation transmittance. A copper plate is used, and the member 10b is made of, for example, a lead plate with low radiation transmittance.

Alternatively, the member 10a may be an acrylic plate with high radiation transmittance, for example, and the member 10b may be an aluminum plate with medium radiation transmittance.
Use a copper plate or a lead plate with low radiation transmittance, for example.

One end of this shutter blade 10 (member 10
A tension spring 1l is applied to the other end (member 1).
A wire (or rope) 15 is attached to the pulley 3 of the rotating shaft of the pulse motor 12, which is the actuator portion of the shutter drive device 7, and guided through the guide pulley 4.

In this configuration, when the pulse motor l2 is rotated in a specific direction and the wire l5 is pulled, the shutter blade 10 moves to the right in the figure against the spring 11, and the member with high radiation transmittance in the slit 2 is moved. The proportion occupied by 10a becomes large, and the overall X-ray transmittance becomes large. On the other hand, by rotating the pulse motor 12 in the opposite direction,
When the wire 15 is loosened, the tension spring 1l moves the shutter blade 10 to the left in the figure, opening the slit 2.
The proportion of the member 10b with low radiation transmittance within the X-ray transmittance becomes large, and the overall X-ray transmittance becomes small.

In this way, the X-ray transmittance can be adjusted as desired.

In addition, in the drive mechanism for the shutter blade 10, an external force is applied to both ends of the shutter blade 10, and the position is controlled by the balance of the force, so that the force of the spring 11 is applied not only when pulling with the wire 15 but also when loosening the wire 15. is working, so the movement is extremely good.

Moreover, the rigidity of the wire 15 is not required, and it becomes possible to use a nylon wire or the like that does not interfere with radiation.

FIG. 3 shows another embodiment.

In this embodiment, members 10a and 10 having different radiation transmittances are used.
Both ends of a wire (or rope) 21 are connected to both ends of the shutter blade 10 consisting of b, forming a loop, and this loop is guided by a guide pulley 22, while being driven by a drive pulley 24 attached to a pulse motor 23 in the middle. It was designed to do so.

The wires 21 are arranged in a staggered manner, and the positions of driving parts such as the motor 23 are shifted vertically, thereby enabling a compact layout of these parts.

If necessary, a tensioner may be provided in the middle.

Another embodiment is also shown in FIG.

In this embodiment, a member 10a having a high or medium radiation transmittance is provided over the entire length of the shutter blade 10, and a member 10b having a medium or low radiation transmittance is provided over a part of the member 10a.

Similar effects can be obtained with such a device. Further, in this case, if the member 10a is of the same quality as the imaging filter normally attached to the radiation source, it can also serve as the filter.

Still another embodiment is shown in FIG. 5 or FIG. 6.

The embodiment shown in FIG. 5 shows members 10a and 1 having different radiation transmittances.
The cross-sectional shape of the shutter blade 10 made of 0b is a right triangle, and the cross-sectional shape of the shutter blade IO is an isosceles triangle, and the cross-sectional shape of the shutter blade IO is an isosceles triangle, and the cross-sectional shape of the shutter blade IO is an isosceles triangular shape, and the cross-sectional shape of the shutter blade IO is a right triangle, and the cross-sectional shape of the shutter blade IO is an isosceles triangle. It was designed to match.

In this way, the spring l1 and the wire (or rope) 15 can be shifted, which is more advantageous in terms of layout.

<Effects of the Invention> As explained above, according to the present invention, force can be applied to both ends of the shutter member to control the position in balance.
The movement is improved, the controllability is further improved, the rigidity of the driving member is not required, and the structure is simplified.

[Brief explanation of drawings]

Fig. 1 is a schematic perspective view of a radiographic imaging apparatus showing one embodiment of the present invention, Fig. 2 is an enlarged perspective view of a shutter blade, and Fig. 3 is a perspective view of a shutter blade drive mechanism showing another embodiment. , FIG. 4 is a perspective view of a shutter blade showing another embodiment, and FIGS. 5 and 6 are perspective views of a shutter blade showing other embodiments. l... Radiation source 2... Slit 2... Shutter 4... Target object 5... Imaging surface 6
...Detector 7...Shutter drive device
10... Shutter blade lQa, 10b...
- Members with different radiation transmittances 11... Tension spring 12... Pulse motor l5... Wire 21... Wire 23... Pulse motor

Claims (1)

[Claims] an aperture provided on the irradiation side of the radiation source to generate a radiation beam; a shutter member movable in a direction across the aperture to adjust the transmitted dose; and an imaging plane behind the object to which the radiation beam is irradiated. In a radiographic imaging apparatus having a detector that detects a dose and a shutter drive device that drives the shutter member based on a signal from the detector, the shutter member is formed of a member having different radiation transmittance in the direction of movement thereof. . A shutter structure in a radiographic imaging apparatus, characterized in that the shutter structure is configured to perform position control by applying a driving force of the shutter driving device to sides of the shutter member facing the opening.