Dosimetric reliability of thermoluminescent phosphors (TLD-too).

The dosimetric reliability of TLD-100 has been studied in view of the fact that these TLDs are extensively used for patient dosimetry in the case of irregular fields and where patient's contour creates special problems. TLDs have also been used in intercavitary dosimetry (e.g. esophagus and rectum) and in some cases of dosimetric comparison of radiation output. However, it appears that these TLDs are unsuitable for most practical dosimetry due to poor reproducibility and system error. It is found that the same TLD-chip gives widely divergent readings for the same exposure even when correction for the system error is made. The composite uncertainty under the best experimental conditions is about +/-3.5%.