Reliability of clinical port films for measuring dose inhomogeneities in radiotherapy for head and neck tumours.

Weltens, C; van Dam, J; Leunens, G; Dutreix, A; van der Schueren, E · Radiother Oncol · 1994

other · Level V

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Abstract

Reproducibility and reliability of film dosimetry are evaluated in clinical circumstances. Optical densities were read on 82 routinely taken verification films of Ear-Nose-Throat (ENT) treatment fields and corrected with the sensitometric curve to obtain relative dose values. Off-axis ratios measured on 10 successive films of one specific field were compared with each other and show a good reproducibility (s = 1.7%). Reliability was assessed by comparing 82 off-axis ratios obtained on the films with off-axis ratios obtained by simultaneously performed diode measurements. Only small relative differences were detected (mean = 1.1%, s = 3.0).

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