Dosimetric Impact on IMRT Plans of Altering Per Control Point Statistical Uncertainty in Monaco TPS

Abstract

Intensity-Modulated Radiation Therapy (IMRT) uses computer-controlled linear accelerators to deliver precise radiation dose to a benign or malignant tumor or specific areas within the tumor while minimizing the radiation dose to healthy tissues and organs at risk. The purpose of this study is to evaluate the dosimetric impact on IMRT plans of altering the per control point Statistical Uncertainty (SU) from 1% to 6% at intervals of 1% using Monaco Treatment Planning System (TPS) for three different diagnoses. Such as Larynx, Oesophagus, and Prostate. Per control point SU is an important factor to decide dose calculation accuracy and calculation time. In this work, 54 IMRT plans were generated altering the per control point SU as 1%, 2%, 3%, 4%, 5%, and 6% using nine patients for Larynx, Oesophagus, and Prostate. Dosimetric indices; including Conformity Index, Heterogeneity Index, Target Dose (PTV) and Organ At Risk Doses, Dose Calculation Time, Treatment Delivery Results, and Dose Volume Histogram were used to evaluate the generated 54 IMRT plans. There are no significant differences observed in all the dosimetric indices and there is an exponential relationship observed between Dose Calculation Time and per Control Point SU. For IMRT plans, we can accept per Control Point SU from 3% to 4% with reduced and acceptable dose calculation time without compromising the plan quality and deliverability.

Keywords: Radiotherapy, IMRT, dosimetric impact, Per Control Point, Statistical Uncertainty