The use of precision thermoluminescence dosimetry for intercomparison of absorbed dose

A technique is described for making thermoluminescence measurements on phosphor powder with a relatively high degree of precision. Factors such as the rate of fading of TL response and extent of supralinearity for TLD-700 in the therapy-dose range have been measured in relation to its use for precise absorbed dose intercomparison studies in cobalt-60 beams. The results of such a trial intercomparison of six British radiotherapy centres are given, the performance of the TLD technique being matched against that of Fricke dosemeters. Factors involved in the extension of the technique to medium-energy X-rays are discussed including the possibility of determination of beam quality by employing TLD-700 and CaSO4: Dy 'in tandem'.