JPS6260097B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray automatic exposure control device using an X-ray detector with a detection field display function and a selectable detection field.

As is well known, the automatic X-ray exposure control device is equipped with an X-ray detector such as a plate-shaped ion chamber that corresponds to the X-ray irradiation field (film size) in front of the X-ray film, and The X-ray device is controlled to stop X-ray exposure when the amount of X-rays required to bring the X-ray photograph to an appropriate degree of darkening has been irradiated.

In this case, some X-ray detectors use an X-ray detector having a function of specifying the X-ray detection field so that an appropriate degree of darkening can be obtained for a predetermined area in the X-ray imaging area. For example, if an ion chamber is used as an X-ray detector, a plurality of collector electrodes are provided in various shapes, sizes, and positional relationships, and the plurality of collector electrodes can be selected as appropriate. This allows the X-ray detection field to be set.

In this type of device, the selected detection field is
This is confirmed by checking the on/off status of the selection switch on the line operation desk or by display means such as a lamp.
However, when the operator positions the subject, the operator must take his eyes off the console, which causes the inconvenience of having to memorize the selected detection field and perform the positioning operation. In addition, although the position of the detection field in the imaging area is generally displayed on the X-ray detector, top plate, or its cover together with the imaging area display, if the subject is located above it, There was a problem in that it was difficult to operate the position because the operator could not see it.

The present invention has been made in light of the above circumstances, and includes operations for confirming and positioning the selected detection field by projecting the shape, size, and positional relationship corresponding to the selected detection field onto the body surface of the subject's photographed area. It is an object of the present invention to provide an X-ray automatic exposure control device having a function of displaying a selected detection field, which makes it easy to perform detection.

The configuration of an embodiment of the main part of the present invention will be described below with reference to FIG.

In Figure 1, 1 is X due to the ion chamber.
This is the main body of the line detector, and a pair of circular and rectangular collecting electrodes 1a, 1b, 1c are provided at appropriate positions on a thin insulating plate as shown in the figure. These collector electrodes 1a to 1c each have switch elements Sa, Sb,
It is connected to an automatic exposure control circuit (not shown) via Sc. Collecting electrodes 1a to 1 of this detector main body 1
A high-voltage electrode (not shown) having the same shape (size) as the detector main body 1 is provided on the side facing the surface on which c is provided, and an appropriate high-voltage voltage is applied between both electrodes to
A line detector is configured. Reference numeral 2 denotes a display mask which is arranged inside the X-ray movable diaphragm main body (not shown) in the irradiation field after the diaphragm blades (at the tip of the X-ray diaphragm), and whose main body is made up of a pair of transparent plates joined together. This mask 2 includes each collecting electrode 1a in the detector main body 1.
Projection bodies 2a, 2b, and 2c are formed that correspond similarly to the shape, size, and positional relationship of ~1c. The projectors 2a to 2c are liquid crystals that are sandwiched between a pair of transparent plates of the main body of the mask 2 via a pair of transparent electrodes, and change from a transparent state to an opaque state by applying a voltage between the pair of electrodes. It is formed in Each of the projectors 2a to 2c is connected to a control circuit, that is, a liquid crystal drive control circuit 3a, 3b, 3c that controls voltage application between a pair of electrodes that sandwich each liquid crystal. 4
is a detection field selector for selecting and setting the detection field of the X-ray detector 1, and selection switches 4a, 4b, 4b, corresponding to each collecting electrode 1a to 1c of the detector main body 1
4c. These selection switches 4a to 4c are connected to the switch elements Sa to Sc and the control circuits 3a to 3c, and provide control signals thereto. Incidentally, the automatic exposure control circuit operates on the collector electrode 1a of the detector main body 1.
The detection signal (minor current) from ~1c is introduced via switch elements Sa~Sc, and after performing current-voltage conversion, it is integrated by an integrator, and this integrated voltage is set to the reference voltage (the appropriate blackening degree). This circuit generates an X-ray cutoff signal to the X-ray controller via a comparator when a corresponding voltage (corresponding voltage) is reached.

Next, the operation of the above configuration will be explained with reference to FIG.

That is, during imaging, a desired one (switches 2a and 2b in this example) of the selection switches 4a to 4c of the detection field selector 4 is closed according to the part to be imaged (chest in this example) of the subject 5. do. As a result, the collector electrode 2 is connected via the switch elements Sa and Sb.
a, 2b are connected to an input part of an automatic exposure control circuit (not shown), and at the same time, liquid crystal drive control circuits 4a,
A voltage is applied to the liquid crystals of the projectors 2a and 2b of the mask 2 through the mask 2, and only the projectors 2a and 2b become optically opaque.

Then, if the lamp for setting the irradiation field in the X-ray aperture 7 attached to the irradiation port of the X-ray tube 6 is turned on,
Light having an irradiation field corresponding to the X-ray irradiation field is projected through the X-ray diaphragm 7 and the mask 2 at its tip. As a result, a mask as shown in the figure is placed on the X-ray tube 6 side of the imaged area of the subject 5, who is positioned in front of the chest stand 8 in which the X-ray film and X-ray detector are stored, that is, on the back body surface. Projection body 2a', 2
b′ is projected.

As described above, according to the present invention, the selected X-ray detection field is displayed as an optical shadow on the body surface of the subject to be imaged. You can easily check whether the relationship is appropriate or not. Therefore, with this improvement in operability, it is possible to prevent failures in selecting and setting the detection field or in positioning the imaging region, and as a result, it is possible to improve the functionality of this type of automatic exposure control device.

In the above embodiment, an ion chamber having a plurality of collecting electrodes was used as an X-ray detector with a selectable X-ray detection field, but an X-ray detector with a selectable other detection field may also be used. You can achieve your goals for the term. That is, it is possible to use an X-ray detector in which a plurality of semiconductor X-ray detection elements or fluorophores are arranged in a shape, size, and positional relationship corresponding to the collecting electrodes 1a to 1c in the X-ray detector main body 1. can. In this case, in the latter case, each phosphor is introduced into a photomultiplier tube through a separate light guide, or a semiconductor photoelectron such as a photodiode is installed on the opposite surface of each phosphor. This can be applied by arranging a required number of conversion elements.

It goes without saying that other modifications may be made as appropriate without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the essential parts of an automatic X-ray exposure control device according to the present invention, and FIG. 2 is an explanatory diagram showing a usage state when the automatic X-ray exposure control device in FIG. 1 is applied. It is. 1... X-ray detector main body, 1a, 1b, 1c...
Collector electrode, Sa, Sb, Sc... switch element, 2...
Display mask, 2a, 2b, 2c...projection body, 3
a, 3b, 3c...Liquid crystal drive control circuit, 4...
...Detection field selector, 4a, 4b, 4c...Selection switch.

Claims (1)

[Scope of Claims] 1. An X-ray detector in which a plurality of detection fields can be selected, and an X-ray detector that corresponds to the plurality of detection fields of the X-ray detector and forms an optically opaque state by a drive signal. an optically transparent display mask projecting with light having a plurality of projectors to obtain and having a field matching an X-ray field; and a projection providing the drive signal to the plurality of projectors of the display mask. An X-ray automatic exposure control device comprising: a body control circuit; and a detection field selector that selectively sets a detection field of the X-ray detector and provides the drive control signal to the projection body control circuit based on the selection signal. 2. The automatic X-ray exposure control device according to claim 1, characterized in that a liquid crystal is used as a projection body of the display mask.