Output factors at the surface for treatment cones and lead cut-outs have been measured for a Pantak Therapax SXT 150 superficial therapy unit with x-ray beam qualities from 1 to 13 mm A1 HVL. A variety of phantom materials and two ionisation chambers were tested for their suitability in output factor and percentage depth dose measurement. Solid water proved a useful water-equivalent phantom material with discrepancies between measurements in water and solid water less than 2.3% for percentage depth dose and less than 0.6% for output factors. Larger measurement discrepancies were found for Plastic Water and Perspex. A PTW Markus chamber was found to compare well with a NE 2532/3 low energy chamber in percentage depth dose measurement, but discrepancies arose between the chambers in output factor measurements, up to 5% for small field sizes. Measurements indicated that the Markus chamber had an energy dependent response in the kilovoltage range, which could account for the discrepancy in output factor measurement.

Quality assurance of external-beam treatment-planning systems is recommended, and this can be partly achieved with predefined type tests. The beam data and test geometries of IAEA TECDOC 1540 have been used to test the analytical anisotropic algorithm (AAA) and pencil-beam convolution (PBC) algorithm of the Varian Eclipse treatment planning system. Beam models were created in Eclipse for 6 MV, 10 MV and 18 MV from the available beam data. Twelve test geometries were re-created in Eclipse, and the differences between Eclipse dose calculations and dose measurements were recorded. The AAA algorithm generally performed better than the PBC algorithm for the 12 tests, but both algorithms did not meet predefined tolerances for asymmetric wedge fields. An in-house monitor unit check program based on collimator and phantom scatter factors with tissue-phantom ratios was also tested and its calculations were found to agree with measurements to within 3.2% for on-axis points.