Some technical problems with diagnostic radiography at 20 to 40 kVp.

Abstract

Abstract Some problems associated with low voltage (20—40 kV) radiography are described. A practically X-ray transparent light beam diaphragm has been achieved by using a mirror of aluminized Melinex 0·125 mm thick and a Melinex front cover. Some of the effects of these and other changes on the output and quality of the X-ray beam are described. Focal spot sizes of X-ray tubes of four different manufacturers have been measured under working conditions; focal spots frequently nearly double their normal size at 20—30 kV and high mA. They are smallest at high kV and low mA. Similar results have been obtained using a pinhole and a penumbra method. The penumbra method is more practical under working conditions and does not require the 0·7 correction factor recommended when using the pin-hole method. Modifications are described to the penetrameter cassette described by Ardran and Crooks (1968) which enable it to be used in the 20 kV range with an accuracy better than 1 kV. These consist of: (1) substitution of ...