A simple ionisation method for determining the tube voltage and total filtration of three phase X-ray units

A simple ionisation method for estimating tube voltage and total filtration is described. The technique is evaluated on twelve 3-phase X-ray sets in-service and is shown to produce determinations of kVp to within +or-10% (<8 kV) and total filtration to within +or-20%. HPA guidelines suggest that discrepancies of 5-10 kV between the real and set tube voltages be brought to the attention of the user and discrepancies of greater than 10 kV be referred to the manufacturer. It is also suggested that tube total filtrations be estimated to within +or-25%. Thus it is thought that this method has a place in quality assurance programs as a guideline to generator calibration.