ANTHROPOMORPHIC PHANTOM MEASUREMENTS FOR THE VALIDATION OF A TREATMENT PLANNING SYSTEM

A series of eight irradiations of an anthropomorphic phantom has been performed as part of a programme of treatment planning system (TPS) va lidation. The 'treatment' configurations used represent a realistic cr oss section of those carried our routinely in a radiotherapy centre. T he dose distributions within the phantom were determined using 75 LiF TLD chips per irradiation and the measured dose distributions were com pared with calculations performed on a TPS for three ranges of dose gr adient. The accuracy of the technique per measurement point is estimat ed to be 3% in dose (low dose gradient) and 3 mm in position (high dos e gradient). The measurement and data analysis techniques used permit evaluation of a TPS against recently recommended criteria of acceptabi lity although it is noted that is is nor possible to isolate TPS perfo rmance from factors depending on, for example, open beam data fitting and treatment set up accuracy.