Comparative analysis of Volumetric Modulated Arc Radiotherapy (VMAT) versus Intensity Modulated Radiotherapy (IMRT) Using the TG119 Tests

Abstract

Volumetric Modulated Arc Therapy (VMAT) is a radiother-apy modality that optimizes more parameters than intensity modulated radiotherapy (IMRT), therefore it is necessary to have a higher level of quality control of equipment and specific treatment plans for patients.

The aim of this paper was to perform a comprehensive comparison of VMAT and IMRT through a set of test developed by the Task Group 119, to show the differences between both dosimetry plans and evaluation of these delivery plans carried out at Hope International Radiotherapy Center, Guatemala.

The treatment plans were generated on Varian RapidArc and IMRT optimizer, and delivered with a Clinac 2300CD linear accelerator provided with a Millenium MLC, also from Varian. All were delivered to a cilindrical phantom, VMAT and IMRT plans. The readings on the detector array are compared with doses interpolated to 1mm grid on ArcCheck geometry based on the exported matrix dose from the Eclipse treatment plan.

The IMRT plans were optimized to achieve the plan goal on each test, using the gantry angles and recommendation according to the TG-119. In a conservative way, we created the VMAT plans to achieve the plans goal, using 2 arcs with Multitarget and Prostate and 3 arcs with Head & Neck, C-Shape and C-Shape Hard, this taking in account the way to create our clinical plans delivered to patients.