Apparatus for taking X-ray pictures of a standing human typically include two vertically-extending rails on which a cassette holder is movable to various positions at which the cassette holder can be locked. This permits the X-ray plate to be positioned at various height to accommodate people of different heights and to permit various parts of the body to be X-rayed.
A sheet of X-ray film is placed into a rigid picture-frame-like cassette which holds the X-ray plate flat and facilitates handling of the X-ray plate.
In practice, a device called a grid is normally positioned in the cassette holder immediately in front of the cassette. The grid typically includes a great number of very small baffles resembling the slats of a venetian blind, but far more delicate because they are formed of very thin sheets of lead. These very small and fragile strips serve to prevent stray X-radiation from entering the cassette, particularly at directions inclined to a normal to the plate.
Typically, the cassette holder includes a lower lip on which the lower edges of the cassette and of the grid are supported, and typically the upper edges of the cassette and of the grid are secured to the cassette holder by a clamp, which may be spring-loaded.
Once the cassette and the grid have been thus mounted in the cassette holder, they cannot be freely rotated with respect to the holder. After having thus mounted the cassette in the holder, the operator checks to make sure the picture will include all of the desired portions of the patient's body. Typically, the X-ray plate is rectangular in shape, and it is not unusual for the operator to decide that better coverage can be obtained by rotating the X-ray plate 90 degrees.
When the operator finds it necessary to reorient the plate, he must release the cassette and grid from the cassette holder, manually turn them 90 degrees, and then reinsert the cassette and grid once again into the cassette holder.
It occasionally happens that during this reorientation operation, the technician accidentally drops the expensive and fragile grid, and the grid is thereby destroyed. Such a grid might typically cost on the order of $600 today.
Thus, there exists a need for a simple and relatively inexpensive apparatus that can be used to prevent the grid from being dropped.