DE1940983C3 - Double exposure lock for an x-ray target device - Google Patents

Description

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The invention relates to a double exposure barrier for an X-ray target device in which the film format is divided into fields of different sizes by means of various diaphragms that can be inserted into the beam path Mntividable by means of a cassette control ■ are exposed one after the other.

These are target devices from DT-AS 10 40 362 and the DT-AS 11 09 512 known, in which after exposing part of the film (if an aperture in the Beam path is pushed) the cassette is automatically moved so that the next exposure a not yet exposed part of the film or the cassette containing the film enters the beam path, and for which a renewed exposure is no longer possible is possible when the entire film format has been exposed. With one of these devices, each is a recording field composed of one or more sub-fields, and it has lamps to display the exposure status of the sub-fields.

With these target devices, double exposures cannot occur if the apertures are not changed during a series of exposures.

However, it is relatively common in clinical practice. that the examiner for the first Recording uses an esophageal diaphragm, which divides the cassette format in width, z. B. halved, then further x-rayed in order to then insert a compression tube, which the cassette format in the Width and height halved. When you first take a picture with the esophageal diaphragm, the left half of the Exposed film in the cassette When inserting the compression tube, the cassette is shifted so that as if a compression tube had been inserted from the start, so that with the second exposure the right upper quarter of the film is exposed. In the third exposure, also made with a compression tube, the lower left quarter was angry of the film moved into the beam path, which was taken with the first exposure together with the upper left Quarter of the film was exposed; so in this way there could be double exposures when the examiner is not paying attention.

The invention is based on the object of avoiding such double seals.

You could solve this problem by means of a lock that prevents a diaphragm from being replaced as long as a partially exposed cartridge is in the target device. Then, however, could be a film format can only be divided equally; a subdivision in which the first image with an esophageal diaphragm in the left half and two further images with a compression tube in the right Half of the film format would not be possible.

According to the invention, the task is also solved for the production of such recordings in a device of the type mentioned in that the double exposure lock is a coding device that is controlled by the Format of the inserted film, the inserted aperture and the number of images already exposed dependent code signals assigned to the exposure field to be exposed generated, a memory that stores the code signals assigned to the already exposed exposure fields, and has a comparison circuit which compares the code signals assigned to the exposure field to be exposed with the stored code signals assigned to the already exposed exposure fields and in the event a correspondence of the code signals of the exposure field to be exposed with the code signals of the already exposed exposure fields emits a blocking signal preventing the exposure of the respective exposure field approaching the exposure.

The invention is explained below with reference to an embodiment shown in the drawing.

The drawing shows the block diagram of a double exposure barrier according to the invention. A logic network 1 is provided, which, for example, in binary-coded form signals for the Film or cassette format, the inserted aperture and the number of images already exposed are linked.

In an X-ray target device, the film formats are generally 13 × 18 cm, 18 × 24 cm, 24 × 30 cm

(portrait or landscape) as well as the film format 35 χ 35 cm These dimensions can be determined in a known manner by sensors that register whether the Cassette format in width and height exceeds certain predeterminable values, and can in the form of a coded signal with three binary digits (e.g. Code 101 can have the format 18 χ 24 cm across denote) are fed to the linking network.

In a similar way, signals are generated which are assigned to the inserted diaphragm, which the Film format divided into several exposure fields to be exposed one after the other. In general, only uses three different apertures in an X-ray target device:

One esophageal diaphragm that halves the recording field in width, another esophageal diaphragm that that Recording field divided in width into three parts and a compression tube that divides the recording format in height and width. The B'enden can if necessary, the format of the inserted cassette can be adapted, like the one in the German utility model 18 01045 is described. These three apertures can be represented by a signal with two binary digits be coded (e.g. O can mean the compression tube).

The number of exposure fields already exposed on the film can also be easily determined and the Linking network can be entered in binary code.

A signal then appears at the output of the linking network that will be used for the next recording is assigned to the exposure field. For example, if a film of size 18 χ 24 cm and a Compression tube of size 9 χ 12 cm are inserted and already two receptacles of size 9 χ 12 cm a signal appears which is fed to the lower left recording field; this The exposure field should, if possible, be exposed for the next exposure.

The signal is in a comparison circuit 2 with the already exposed stored in a memory 3 Signals assigned to recording fields are compared. The comparison circuit, the linking network as well as the memory can be realized from commercially available logic circuits; on their structure should therefore not be discussed in more detail at this point.

If there is a match, i. H. if the exposure field to be exposed is completely or partially with the already covers exposed recording fields, an output signal, e.g. B. a flashing light, triggered and the exposure prevents this recording field. If there is no match, the recording can be triggered, the signal for the exposure field that has just been exposed is transferred to the memory.

In addition, the exposure status of the inserted film cassette can be displayed. A light panel 4, which is subdivided into different subfields a to h , is used for this purpose in such a way that each possible recording field corresponds to such a subfield or a combination of several subfields. For example, if the width is divided into three, the second shot is shot at the combination of subfields b, c, f and g ; accordingly, the code signal for this recording field is made up of the code signal for subfields b. c, f and g together. Each subfield can be illuminated by two different colored lamps (e.g. red and white). The red lamps indicate that the red-lit sub-fields have already been illuminated, while the white lamps indicate that the white sub-fields will be exposed for the next exposure. The simultaneous lighting up of a red and a white lamp in a partial field indicates that an already exposed partial field would be exposed for the next exposure.

The red lamps, which indicate the pictures already exposed, are taken from the output of the memory controlled and the white lamps from the linking network; accordingly the connection between the lamps and the memory or the linking network from a corresponding number of Cables.

The way in which the schematic representation of the film with all exposure options takes place with the described display field can be done with television broadcasts a similar picture on a subfield of the television picture - e.g. B. in the part of the screen that is in the usual Image converter mode is not used - be displayed.

The operation of the double exposure lock in the individually explained.

Before the first exposure, in which an esophageal diaphragm halving the width of the film format is inserted, the signal for the exposure field to be exposed is formed, which is composed of the code signals for the subfields a, b, e and / and the corresponding white ones Lights are switched on. After the exposure has been triggered, this signal is transferred to the memory, the white lamps in subfields a, b, e and f are extinguished and the red lamps in these subfields are switched on instead.

When the compression tube is used, the film format is halved in width and in height and a signal is generated which is assigned to the recording field intended for the next exposure, ie subfields c and d, and is indicated by the white lamps in these fields. There is no correlation between the already exposed subfields a, b, e and fund the exposing sub-fields c and d, and the recording can be started. Then the code signals for subfields c and d are also transferred to the memory so that the corresponding red lamps light up.

With the third exposure (with compression tube) the film cassette would be moved into the beam path in such a way that the lower left exposure field would be exposed. The code signal for the (already exposed) subfields e and f is generated in the linking network and compared with the memory content (subfields a to f) , whereby the agreement is found and the triggering of the third exposure is prevented. In this case, the surveyor has to take an empty exposure in which no radiation falls on the film, after which the free lower right quarter of the film is available for the next exposure.

Cie empty recording can be omitted if the comparison circuit 2 is coupled to the cassette controller so that, if there is a match, the The cassette is moved to the left or, if that does not work, upwards until a right or the still unexposed recording field below has been found.

When the lower right subfield h is reached, the film is completely exposed, so that the film cassette is produced.

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.excepted and the memory and the illuminated panel; can be erased.

Since different film formats (e.g. 18>: 24 cm or! 4 χ 30 cm) can be used, the coating of one or more subfields (e.g. e and f) shows the absolute dimensions, but only the relative, represent dimensions of a recording field related to the respective recording format or the subdivision of the film format. The absolute dimensions can optionally be indicated by separate lamps which are each assigned to a specific film format.

1 sheet of drawings

Claims (4)

Patent claims: 1. Double exposure lock for an X-ray target device in which the film format is different Apertures that can be pushed into the beam path can be subdivided into receiving fields of different sizes which are sequentially exposed by means of a cassette control, characterized in that the double exposure lock is a Coding device (t), which depends on the format of the inserted film, the inserted aperture and the number of already exposed exposures dependent, the exposure field to be exposed associated code signals generated, a memory (3), the stores the code signals assigned to the already exposed exposure fields and has a comparison circuit (2) which stores the code signals assigned to the exposure field to be exposed with the stored code signals assigned to the already exposed recording fields and, if they match, the Code signals of the exposure field to be exposed with the code signals of the exposure fields that have already been exposed. would take approaching recording field emits preventing blocking signal. 2. Double exposure lock according to claim 1 for an X-ray target device, in which the corresponding possible subdivisions, each recording field is composed of one or more sub-fields is, characterized in that a code signal is assigned to each subfield. 3. Double exposure lock according to claim 2 with the subfields associated lamps for display the exposure state of the subfields, characterized in that the lamps from the coding device (1) and from the output of the memory (3) are controlled. 4. double exposure lock according to claim 1, characterized in that the comparison circuit (2) influences the cassette control so that when the code signals of the recording field to be exposed match the code signals of the exposure fields already exposed, the cassette is shifted until a possibly still unexposed exposure field comes into the beam path.