Comparative dosimetric study of three-dimensional conformal (3DCRT), intensity modulated radiotherapy (IMRT), and volumetric modulated arc therapy (VMAT) for treatment in pituitary adenomas.

Abstract

e13043 Background: Radiotherapy is usually delivered after surgery in pituitary adenomas. Usually stereotactic radiotherapy is used in their treatment. The studies evaluating the recent advances like IMRT, VMAT for pituitary adenomas are rare. Present study evaluates 3DCRT, IMRT, and VMAT for the treatment of pituitary adenomas. Methods: Ten patients of pituitary adenomas who were planned for post operative adjuvant radiotherapy were included. Planning CT was done with the patient supine with a customized thermoplastic cast of head on Philips wide bore CT (for 3 mm). The CT images were transferred online to the Pinnacle TPS V.8.0M. Tumor and the critical structures like brain stem and optic nerves were contoured on pinnacle. 3DCRT was planned on pinnacle. The CT images with the contoured structures were sent to Monaco TPS V.3.10.02. IMRT and VMAT were planned on Monaco. Dose: 50 Gy in 25 fractions. PTV indices analyzed: D mean, D2 (dose received by the hottest 2 percent volume), D98 (dose received by 98 percent), homogeneity index HI [(D2-D98)/D50)], and conformity index CI (PTV volume/volume of PTV covered by 95 percent isodose). Dmax and D2 (dose received by hottest 2cc) for the brain stem, right and left optic nerve PRV were evaluated. The average were calculated and compared. Statistical analysis was done by SPSS Version 14. Results: The Table shows that VMAT is better in terms of PTV indices. For the normal structures also VMAT provides the least dose. Conclusions: VMAT is superior to IMRT and both are better than 3DCRT for the radiotherapeutic treatment of pituitary adenoma. [Table: see text]