Dosimetric Comparison of Optimized and Non-optimized Plans In Intracavitary Brachytherapy Using international Commission On Radiation Units and Measurements (ICRU) 89.

Abstract

IntroductionThe study aimed at evaluating the effect on the target coverage and dosimetric parameters of organs-at-risks (OARs) in optimized plans as compared to non-optimized plans normalized at point A.Materials and MethodsIt is a retrospective study of 21 cervical cancer patients of stage II and stage III who underwent high dose rate (HDR) intracavitary brachytherapy (ICBT) following external beam radiotherapy. For the study, two treatment plans were created for each application using computed tomography (CT) images. The non-optimized plans were normalized at point A and the other plans were optimized in such a way that 90% volume of HR-CTV should receive the prescription dose. Dose volume histograms were used to compare D5cc, D2cc, D1cc, and D0.1cc (minimum doses received by 5cc, 2cc, 1cc and 0.1cc most irradiated volumes, respectively) for organs-at-risks (OARs) namely bladder, rectum, sigmoid and small bowel, and D90% ,D50% , D98%,D100% ,D95% coverage of HR-CTV between non-optimized and optimized plans. RESULTS HR-CTV coverage was improved for 80% of the patients and bladder and rectum dose was reduced by 9.85% and 8.75% respectively in optimized plans as compared to the non-optimized plans normalized at point A. Reduction of about 8.95% and 9.75% in sigmoid and bowel doses respectively in optimized plans was observed.CONCLUSION Optimized plans resulted in better OARs sparing and satisfactory target coverage as compared to non-optimized plan normalized at point A.KEYWORDS: ICRU 89, HR-CTV, Dosimetric comparison , Brachytherapy , Optimized plans, Non-optimized plans.