Comparison of Prescribed from Delivered Dose to Cancer of Cervix Patients Treated by Theratron Equinox 80 cm Source-to-Axis Distance (SAD) Technique at Ocean Road Cancer Institute in Tanzania

Abstract

The aim of the present study was to investigate deviations between prescribed from delivered dose for cervical cancer patients treated at Ocean Road Cancer Institute using Equinox 80 Tele-cobalt machine. In this work, anterior-posterior (AP) and posterior anterior (PA) fields using Source-to-Axis Distance (SAD) technique was used. Measurements of entrance doses were taken using calibrated diode detector in three groups of patients. In group 1, only 15 patients out of 31 curative intent patients received doses lower than ± 5% of 2 Gy as compared to the prescribed dose. In group 2, 1 measurement was done for 9 patients who received palliative single dose of 10 Gy and 2 patients out of 9 received doses within the range of ± 5% of the prescribed dose. In group 3, 1 daily measurement was done for 12 patients who were prescribed a curative dose of 50 Gy in 25 fractions. The maximum observed deviation was + 25.08%, while that of minimum was – 0.59%. Since significant deviations between prescribed and delivered doses exist, there is a need to conduct another study using both patient and machine related factors to refine the problem of high dose deviations among the patients.

Keywords: Tele-cobalt machine; in-vivo dosimetry; measured and delivered dose; cervical cancer; diode detector