Retrospective Dosimetric analysis of Bone marrow sparing vs non bone marrow sparing Image Guided Volumetric Modulated Arc Therapy in intact Carcinoma Cervix patients

ABSTRACT   Aim: Aim of this study was to compare dosimetric parameters of  bone marrow (BM) and non bone marrow sparing with  state of the art technique image guided volumetric modulated arc therapy in the treatment of Carcinoma Cervix.   Methods and Materials: The retrospective Dosimetric study was  conducted on 10  consecutive patients of  biopsy-proven invasive cervical cancer attending the outpatient department of Geetanjali cancer centre. For treatment planning, patients were scanned on a GE Optima-520, 16 slice fan-beam CT (FBCT) scanner with 2.5 mm slice thickness in the supine position on a customized vacuum cushion with simulation tattoos and alignment lasers. All the simulation scans were taken after following a bladder and bowel preparation protocol, aimed at an empty rectum and full bladder, starting prior to the initial planning scan and continuing throughout the treatment. The prescribed dose to PTV was 50Gy in 25 fractions (2Gy/fraction) and from second week of radiotherapy 50mg/m2/week cisplatin chemotherapy was administered for five weeks. Two sets of plans were generated for all the 10 patients using Volumetric Arc Radiotherapy (VMAT) in Monaco  v 5.11.02(Elekta, Crawley, UK) treatment planning system. Keeping all constraints in mind planning optimization was performed with no compromise in coverage of PTV.   Results: In the present study V5, V10, V20, V30 were all significantly lower in BMS-IG/VMAT plan . Maximum significance was noted at V20. Value of V40   is lower in BM-IG/VMAT plan, but statistically not significant.   Conclusion: Treatment of  carcinoma cervix is restricted as a result of toxicity of the surrounding normal structures and HT.  HT could be significantly reduced by bone marrow sparing, which could be aided by IGRT/VMAT. This modality could allow completion of treatment with prescribed dose and concurrent chemotherapy in allotted stipulated time.  More prospective randomized control trials are needed, to prove its efficacy.   key words: bone marrow sparing, hematological toxicity, Image Guidance/Volumetric Modulated Arc Therapy