RapidArc Planning for Stereotactic Body Radiation Therapy (SBRT) of Liver: An Institutional Experience
Priya Jacob*, Alex Antony
Abstract
The study aims institutional experience with liver SBRT planning and evaluate the plan quality through dosimetric parameters. Thirty patients who had undergone liver SBRT treatment in our Clinic were chosen retrospectively for the study. RapidArc plans with, non-coplanar beam arrangement generated in Eclipse (16.1v) planning system for Varian TrueBeam Linac using 6MV and 6MV FFF photon. The NC- RapidArc plans were created by two to four arcs which includes non-coplanar partial arcs with couch rotation of ±20° to± 15° had an arc span of 130° to 160° and coplanar 360° full arc. Plans were analysed with various dosimetric and technical parameters. The dosimetric parameters for PTV coverage were PTV100% 94.1±2.5 and PTV95% 97.4±1.2. The Conformality Index (CI) of all plans was 0.898±0.104 on average, and the Gradient Index (GI) for non-coplanar plans was 4.315±1.214 on average. The dose-volumetric parameters for OARs are also within the acceptable consraints. The average dose to 1 cm³ (D1cc) of the spine was 465±114cGy, and that of the left kidney, 352±217cGy. The average volume of normal tissue that received a low-dose spillage of 15Gy was 820±174cc. Technically, the average monitor units (MU) for non-coplanar RapidArc plans were 2525. 2±452.The plan quality of NC- RapidArc plans was acceptable based on RTOG 1112 and QUANTEC guidelines.