The measurement of inherent filtration in diagnostic x-ray tubes and the effect of target angle on x-ray quality.

Abstract

Abstract Radiation protection recommendations give requirements for nitration of X-ray tubes, and to conform with these it is necessary to know the inherent filtration. Methods described for its determination and the discrepancies in the results given by reputable authors are discussed. Output measurements given in handbooks of standard data may be misleading if compared with such data for tubes for which the inherent filtration is in doubt. The importance of the correct effective kV at which measurements are made is discussed. The target angle of the tube has an important effect in altering X-ray quality. If the same target angle is not used for both calibration and measurements, discrepancies can result which can easily lead to an erroneous value of inherent filtration of between 0·25 and 0·5 mm of aluminium equivalent. A procedure is described using our copper reference number method which enables calibration curves to be obtained so that the inherent or total filtration of an X-ray tube may simply be ...