Intensity Modulated Radiation Therapy with volumetric modulation (VMAT)

IMRT (Intensity Modulated Radiation Therapy) is the latest radiotherapy technique for high dose treatment of complex shaped tumors or neoplasm close to sensitive organs at risk. VMAT (Volumetric Modulated Arc Therapy) is next generation arc therapy technique which performs uninterrupted arc(s) around the patient, dramatically speeding treatment delivery and reducing treatment times to those required for “conventional” radiation therapy. Beam modulation is obtained by continuous changes in collimator morphology on the basis of target shape and in dose rate during gantry rotation around the patient. Since November 2010, in our institution, 257 patients were treated with VMAT. Plan evaluation was performed using Homogeneity and Conformity Index and a phantom (Delta 4) to control correspondence between calculated and delivered dose. In our experience VMAT provides to dose distributions comparable with most of other IMRT systems, but with a dramatic shortening of delivery time with considerable advantages in terms of treatment reproducibility (reduction of intrafraction movement of the patient), radioprotection and organization of LINAC spaces.