Determination of absorbed dose in electron beams using parallel-plane ionization chambers

Abstract

OBJECTIVE: The objective of this paper was to establish a procedure for the determination of calibration factors and absorbed doses in electron beams. MATERIALS AND METHODS: An irradiator with a 60Co source and a linear accelerator Varian, Clinac 2100C, with photon and electron beams, were utilized. Thimble type and parallel-plane ionization chambers were tested. RESULTS: The measurement systems showed very good results in the preliminary tests (response stability and leakage current). The ionization chambers used for electron beam dosimetry were calibrated using four different methods. For the determination of absorbed dose, three methodologies recommended by the International Atomic Energy Agency were applied. Concordant results were obtained in almost all cases. CONCLUSION: The majority of the ionization chambers tested showed good results according to the established international limits.

Absorbed dose; Ionization chambers; Electron beams; Calibration of instruments