Table of Contents
Journal of Radiotherapy
Volume 2014, Article ID 325057, 5 pages
Research Article

Pretreatment Patient Specific Quality Assurance and Gamma Index Variation Study in Gantry Dependent EPID Positions for IMRT Prostate Treatments

1Department of Physics, Noorul Islam Centre for Higher Education, Kumaracoil, Thuckalay, Kanyakumari District, Tamil Nadu 629 180, India
2Department of Radiation Therapy, HCG-Dr. Balabhai Nanavati Hospital, Vile Parle, Mumbai, Maharsahtra 400 056, India
3Department of Physics, University of Calicut, Thenhipalam, Kerala 673635, India
4INFN and Department of Physics, University of Turin, Via P. Giuria, 10125 Turin, Italy
5Department of Radiation Therapy, K.S Hegde Medical Academy, Nitte University, Deralakatte, Mangalore, Karnataka 575018, India

Received 30 November 2013; Accepted 29 January 2014; Published 5 March 2014

Academic Editor: Tibor Major

Copyright © 2014 Siji Cyriac et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Pretreatment quality assurance (QA) is a major concern in complex radiation therapy treatment plans like intensity modulated radiation therapy (IMRT). Present study considers the variations in gamma index for gantry dependent pretreatment verification and commonly practiced zero gantry angle verifications for ten prostate IMRT plans using two commercial medical linear accelerators (Varian 2300 CD, Varian Clinac iX). Two verification plans (the one with all fields at the actual treatment angles and one with all fields merged to 0 degree gantry angles) for all the patients were generated to obtain dose fluence mapping using amorphous silicon electronic portal imaging device (EPID). The gamma index was found depend on gantry angles but the difference between zero and the nonzero treatment angles is in the confidence level for clinical acceptance. The acceptance criteria of gamma method were always satisfied in both cases for two machines and are stable enough to execute the patient specific pretreatment quality assurance at 0 degree gantry angle for prostate IMRTs, where limited number of gantry angles are used.