Original Research Article
Year: 2017 | Month: Aug | Volume: 7 | Issue: 8 | Pages: 102-109
Dosimetric Advantage of VMAT Technique in Bone Marrow Sparing Than IMRT in Treatment of Cervical Cancer
Jayapalan Krishnan1,2, Jayarama Shetty2, Suresh Rao1, Sanath Hegde1, Shambhavi1
1Department of Radiation Oncology, Mangalore Institute of Oncology, Mangalore, India.
2Department of Radiation Oncology, K.S.Hegde Medical Academy, Mangalore, India.
Corresponding Author: Jayapalan Krishnan
Aim: Aim of this study was to compare bone marrow (BM) sparing at different dose and volume level of two state of the art technique VMAT and IMRT in the treatment of Ca.Cervix.
Methods and Materials: 20 patients with carcinoma of cervix were selected and each patient was simulated in head first supine position using a thermoplastic mask and/or vaclock. Computed tomographic images with a thickness of 3 mm were acquired with state of full bladder condition. The prescribed dose was 50 Gy in 25 equal fractions for 5weeks concurrently chemotherapy with cisplatin from second week of radiotherapy was administered. Two set of plans, one set of VMAT and another set of IMRT were generated and optimized with similar planning objectives to each patient. Dose of all plans of both techniques was calculated for 6MV photon using AAA with calculation grid size of 2.5mm. Dosimetric score of both techniques plans were evaluated and compared using student ‘t’ test at 5% significant level.
Results: All of the patients in this study received VMAT technique treatment. The all patient VMAT plan satisfied with better DVH scoring, technical parameters as well as better Unified Dosimetry Index score. Both techniques achieved good target coverage. Moreover, CN(95%) (p=0.001) and V107% (p=0.006) of target were significantly better with VMAT. Bone marrow dose was significantly lesser(P<0.001) with VMAT than IMRT at the same time, with out compromise, the sparing of other OARs also was achieved.
Conclusion: In the treatment of cervical cancer, the VMAT technique can be delivered highly conformal dose to the target with better OARs sparing. It helps to reduce hematological toxicity by reducing the bone marrow irradiation dose and volume to avoid the treatment gap due. The un-interruption treatment helps to be continued chemoradiotherapy with out delay to achieve better tumor control.
Key words:VMAT, IMRT, Bone marrow, Cervical cancer.