K. Haresh, Presenter: Nothing to Disclose

Ramachandran Prabhakar -null-, Abstract Co-Author: Nothing to Disclose

Goura Kishor Rath MD, Abstract Co-Author: Nothing to Disclose

M A Laviraj, Abstract Co-Author: Nothing to Disclose

D N Sharma MD, Abstract Co-Author: Nothing to Disclose

Subramani Vellaiyan, Abstract Co-Author: Nothing to Disclose

Pramod Kumar Julka, Abstract Co-Author: Nothing to Disclose

Nikhil P Joshi, Abstract Co-Author: Nothing to Disclose

Heera Puthiyeduthu, Abstract Co-Author: Nothing to Disclose

Purpose: IMRT has established as a modality to decrease the dose to normal structures allowing dose escalation. Recently there has been some interest in inverse planning in brachytherapy. In this study we tried to compare IPSA with GO in terms of target coverage and doses to OAR for ICRT in cervical cancer. Materials/methods: Ten cases of carcinoma cervix stages IIB to IIIB initially treated with External beam Radiotherapy to a dose of 50 Gy/27 Fr (midline shield after 40 Gy /22 Fr) with concurrent Cisplatin chemotherapy were enrolled in the study. The patients were supposed to receive 7Gy of HDR-ICRT X three sessions (total 21 Gy HDR). A tandem and two ovoids were inserted and CT scan was performed on PhilipsTM wide bore CT scanner with foleys catheter in situ (bladder empty). CT images were transferred to Plato SunriseTM treatment planning system. GTV, HR-CTV, IR-CTV, Bladder, Rectum and Sigmoid colon were contoured as per GEC-ESTRO-I&II recommendations. Two plans were generated:-one with IPSA and other with volume based GO. We analyzed the DVH with the endpoints :- minimal target dose D(100), Dose received by at least 90% of volume D(90), Volume treated with a least the prescribed dose V(100), Volume receiving minimum 150% of prescribed dose V(150), Volume receiving minimum 200% of prescribed dose V(200) for GTV, HR-CTV and IR-CTV. The minimum dose received by the hottest 0.1, 1 and 2 CC of the critical organs[D 0.1 cc,D 1cc,D2 cc] were used to asses dose to OAR. The conformal index (COIN) as described by Baltas et al was used to compare the plans. Comparison between the two groups was done by the Wilcoxon matched pairs test. Results: The mean D(100) values for HR-CTV were 51.7% for IPSA and 53.7% for GO respectively. Similarly the other values for HR-CTV include D(90):-90% & 94.7% ; V(100):-83.5% &92% ; V(150):-47.8%& 74%; V(200):-27.3% & 54.7% for IPSA &GO respectively. Mean D2cc for Bladder was 101% for IPSA and 132% for GO. D2cc for Rectum was 60% for IPSA and 79% for GO. COIN was 0.39 for IPSA and 0.18 for GO (p value=0.01). Conclusions: IPSA provides equivalent target coverage as GO. The hyper dose regions are more in GO than IPSA leading to dose inhomogeneity within the CTV. IPSA provides better sparing of OAR compared to GO. IPSA provide better conformity than GO.

Haresh, K, Prabhakar, R, Rath, G, Laviraj, M, Sharma, D, Vellaiyan, S, Julka, P, Joshi, N, Puthiyeduthu, H, A Dosimetric Comparison of Inverse Planning Simulated Annealing (IPSA) versus Geometric Optimization (GO) for High Dose Rate Intracavitary Brachytherapy for Cervical Cancer.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8500979.html