Combining inter-observer variability, range and setup uncertainty in a variance-based sensitivity analysis for proton therapy

Abstract

Margin concepts in proton therapy aim to ensure full dose coverage of the clinical target volume (CTV) in presence of setup and range uncertainty. Due to inter-observer variability (IOV), the CTV itself is uncertain. We present a framework to evaluate the combined impact of IOV, setup and range uncertainty in a variance-based sensitivity analysis (SA). For ten patients with skull base meningioma, the mean calculation time to perform the SA including 1.6 × 10 4 dose recalculations was 59 min. For two patients in this dataset, IOV had a relevant impact on the estimated CTV D 95% uncertainty.

Towards an integral clinical proton dose prediction uncertainty by considering delineation variation

“…While for prostate cancer-and brain tumor patients the variation is on the level of or exceeding patient setup-up errors [15], the target expansion varies greatly in the heterogeneous head and neck region, ranging from 0 to 15 mm between treatment centers [16]. The presented work by Hofmaier et al [17], published in this virtual special issue of physics highlight papers from the recent ESTRO 2021 conference, quantitatively assesses the impact on calculated dose of IOV in target delineation in combination with uncertainties in patient setup and range prediction. The work utilizes a Monte-Carlo variance-based sensitivity analysis framework [18] for error combination, where input parameters are sampled from assumed uncertainty distributions as well as from a set of delineations to quantify their influence on dose calculation and consequently dose/volume parameters.…”

A review of the clinical introduction of 4D particle therapy research concepts

“…Classification of motion patterns into different types (cyclical, continuous drift, erratic and unpredictable) and time scales (from inter- to intrafraction) automatically raises the question of which movements can and should be compensated for in 4D radiotherapy. In addition to the motion-induced uncertainties, setup and range uncertainties, anatomy and tumour changes must also be considered when developing 4D PT treatment concepts [14] , [15] .…”

Interobserver Variability Prediction of Primary Gross Tumor in a Patient with Non-Small Cell Lung Cancer

“…Examples include intensity-modulated particle therapy (IMPT) [ 8 , 9 , 10 ] and ultrahigh-dose-rate (FLASH) radiotherapy [ 11 , 12 , 13 ]. Therefore, the importance of the effects of interobserver variability (IOV) of the gross tumor volume (GTV) on target volume coverage has recently been emphasized [ 14 ], as it can lead to an undesirable dose in OARs, which may lead to tumor recurrence [ 15 , 16 ].…”