Victoreen X-Ray Filters (1936)
This is a set of five X-ray filters manufactured by the Victoreen Instrument Company. Three are copper, two are aluminum.
These types of filters were positioned between the X-ray tube and the patient. More specifically, they were placed between the X-ray tube and the unit's diaphragm. Their purpose was to alter the effective energy (quality) of the X-ray beam. For example, if the deeper portions of the body were to be exposed, low energy X-rays would be undesirable since they would simply result in a dose to the outer tissues of the patient's body without exposing the deeper tissues being treated.
The use of a filter in an X-ray beam increases the effective energy of the X-rays, and the higher the atomic number of the filter, the higher the effective X-ray energy. Sometimes different filters were used in combination. When that was done, the filter with the higher atomic number (e.g., Cu) was placed closest to the X-ray tube while the lower atomic numbered material was placed on the patient's side. Of course, the use of filtration also reduced the intensity of the X-rays, but this could be compensated for by increasing the tube current.
The calibration curves that came with the filters are dated December 22, 1936.
Size: The copper filters are 5 3/8" x 6 1/4"—two are 0.5 mm thick and the other is 0.25 mm thick. One aluminum filter is 6 1/4" x 6 1/4" and 1 mm thick, while the other is 4 1/4" x 6" and 1 mm thick.