DE1794974U - DEVICE FOR DETERMINING THE EXPOSURE VALUES FOR PHOTOGRAPHICAL RECORDINGS, IN PARTICULAR FOR X-RAY PHOTOS. - Google Patents

Description

Device for determining the exposure values for photographic Recordings, in particular for X-ray recordings There are devices for determination the exposure times for photographic materials are known, with scale-bearing Parts are slidably or rotatably arranged.

However, these known exposure panels or discs do not satisfy all requirements to be placed on them, in particular not for the determination of the Exposure values for X-rays. For a perfect diagnosis using a X-rays are next to that for assessment necessary correct Situation conditions are primarily necessary for the contrast and sharpness of the X-ray image Pre-condition. These requirements require clean darkroom work but above all the determination of the optimal exposure values. With modern X-ray machines the exposure value is generally given as the mAs product (milliampere-seconds), which, depending on the subject, depends on various variable factors.

Even for the experienced X-ray assistant, it is often difficult take into account all the factors influencing the uptake. For such cases a series of tools was created, either as a table or as a exposure disks used to determine the correct exposure value can be.

The innovation relates to a device for determining the exposure values for x-rays. It consists of two outer ones, fixed and one with the other connected disks and a rotatable disk disposed therebetween, wherein the outer pane with two openings (windows) for those on the inner pane located scales is provided. The two outer panes are on opposite sides Places that protrude beyond the circumference of the inner disc, connected to each other. The projections formed thereby also serve as stops for the with the inner disc performed rotary movements.

For the purpose of handling the inner disk, it is serrated or toothed on its edges. v In the example shown in the illustration guide is located on the back of the disc a table with information about the objects to be photographed, the basic numbers (G) for these objects, the optimal kV values on the half-wave and four-valve device (kV4), the optimal kV values on the three-phase device (6-valve device) (kV6), the recommended focus -Film gaps (A), the normal object thicknesses (N).

On the front of the disc are in ring-shaped gaps under 2 the kV values, "3 the X-ray machines," 4 the recording materials, "5 special recording conditions, "6 deviations from the normal Obj & H-t thickness, "7 information about the grid, "8 Information on intensifying screens, "9 Information on focus-film distances.

In the embodiment shown, through the opening 1 can be attached to the inner pane; jscale of the basic numbers one through the opening 10 the scale of the final valid mAs values can be read. The X-ray exposure disk according to the invention has the advantage over the previously used aids that it avoids any computational work. Both are omitted './ the addition necessary for logarithmic tables as' also the necessary for the so-called factor calculation common multiplications and divisions. A few practice steps are sufficient to handle the disc properly for the most important recordings that occur in practice.

To determine the mast first, proceed as follows : The subject is selected on the back of the disc and the one below G (= basic number) given inertly transferred to window no. 1 on the front.

The one for half-wave and four-valve devices below kV4 (for Three-phase devices below kVg) represents the kr-inert, which has been optimally tested in practice. This The value is set in column 2 on the front side by turning the toothed washer in the direction of the arrow as far as it will go.

Proceed in the same way for columns 3-9.

For columns 2-4 it should be noted that the direction of rotation is downwards is carried out to the stop. For columns 5-9 the direction of rotation is for the Values above the red dividing line up to the stop, for the values to be carried out under the dividing line down to the stop.

Column 6 shows the deviation from the normal object thickness in cm. The digits with the plus sign mean thicker object thicknesses than the normal values given in the table on the reverse side, those with the minus sign provided digits thinner object thicknesses. The focus- Film excesses are only guidelines that, depending on the Requirements for the recording can be changed at will. Example: A picture of the esophagus is to be taken at an angle of a 12-year-old child. Deviation from normal thickness -2 cm, addition due to the inclined mounting + 5 cm (total + 3 cm). A three-phase device (6 valves) is available. The measures to be taken are as follows: 1.) Determination of the base number for oblique esophagus = 41 2.) Transfer of the basic number to window no. 1 3.) According to Set rear table 70 kV 4.) Set single-phase current device 5.) Set SSS film 6.) Set the "Children" sector under column 5 7.) Set + 3 cm deviation from normal thickness 8.) Fine and fine grid (anti-scatter screen ) set 9.) set universal film (no rotation required) 10.) set 70 cm focus-film distance 11.) read the mAs product in window no. 10. The mAs values determined with the exposure disk are guide values for the production of well-exposed images, which in many cases no longer require any changes.

In the event of deviations, the optimal exposure values can generally be found Achieve this by making minor changes to the mAs products.

Claims (4)

Protection claims 1.) Device for determining the exposure values marked for photographic recordings, in particular for X-ray recordings by two outer fixed and interconnected discs and one in between arranged rotatable disc, with an outer disc with windows for the on the inner disc is provided with numerical values. 2.) Device for determining the exposure values according to claim 1, characterized in that the two outer discs on two opposite Places that protrude beyond the circumference of the inner disc as projections connected are. 3.) Device for determining the exposure values according to claim 1 and 2, characterized in that the projections of the outer disc act as stops serve to rotate the inner disc. 4.) Device for determining the exposure values according to claim 1-3, characterized in that the inner disc is jagged or at its edges is toothed.