Study of Dosimetric Characteristics of Clinical Electron Beams Collimated by Square Applicators using Plane-Parallel Ionization Chambers

Abstract

Introduction: High-energy clinical electron beams are frequently used in external beam radiation therapy of superficial tumors. The present study aimed to assess the dosimetric characteristics of the electron beams of energies 4 – 15 MeV from Elekta Synergy platform linear accelerator incorporated by Elekta Medical Systems, Crawley, UK. In this study, the key parameters of central axis percent depth dose distribution and beam profile are measured and calibrated using national AERB, Mumbai, and International ICRP protocols.

Materials and Methods: The measurements were done for the square field applicators of sizes 6×6, 10×10, 14×14, 20×20 and, 25×25 cm2 using a reference dosimetry system comprising a PTW-Freiburg parallel plate ionization chamber. The measurements are performed at a source to the surface distance (SSD) of 100 cm and dose rate of 100 MU/Second with the water phantom.

Results: The measurements performed are analyzed using a radiation field analyzer (RFA) under AERB Mumbai protocols. The results for the measurements for square field applicators are in good agreement with the reference values of PDD and beam profile measured with micro-silicon detectors and also within the stated uncertainties.

Conclusions: The results so obtained confirm the reliability of central axis PDD distribution and beam profile of the clinical electron beams collimated by square field applicators in the treatment of superficial tumors.