arXiv subjects

Jelte R. de Jong

Publications and source records attributed to Jelte R. de Jong.

2 recordsLinked to original sources

arXiv2026

Direct probabilistic IMPT treatment planning with setup and range errors for neuro-oncological patients

To show clinical feasibility of a previously proposed probabilistic planning approach that can precisely optimize for clinical goals with patient-specific acceptance probabilities on a neuro-oncological patient group, we compared probabilistic plans with (automated) robust plans for one patient (group A) that could achieve sufficient clinical target coverage and for four patients (group B) where target coverage had to be compromised due to organ-at-risk (OAR) dose constraints. The probabilistic approach is percentile-based and uses the fact that a (dose) percentile can be approximated as a linear combination of its expected value and standard deviation. The optimization has a nested structure: the inner optimization optimizes the beam weights for a given percentile estimate, while an outer loop iteratively updates and improves the accuracy of the percentile estimate. For every outer iteration, the optimization is warm-started from the previous iteration. Percentiles are efficiently calculated by sampling a polynomial chaos expansion of the dose-influence matrix. The patient in group A achieved cumulative OAR dose reductions (of OAR-related DVH-metrics) of 19 GyRBE, for identical target coverage. Target coverage improved for all patients in group B (the 10th percentile of $D_{99.8\%}$ increased up to 0.93 GyRBE), at the same time reaching cumulative OAR dose reductions (of OAR-related DVH-metrics) up to 33 GyRBE. Probabilistic plans were optimized in 44h to 141h. For two representative patients, eliminating warm-starting (i.e., the outer loop) from the approach reduced total optimization times to below 10h (which took originally 80h and 141h). Compared to robust optimization methods, the probabilistic approach achieves improved trade-offs between probabilistic target coverage and OAR sparing, potentially leading to better treatments.

physics.med-ph↗

arXiv2025

Probabilistic Proton Treatment Planning: a novel approach for optimizing underdosage and overdosage probabilities of target and organ structures

Treatment planning uncertainties are typically managed using margin-based or robust optimization. Margin-based methods expand the clinical target volume (CTV) to a planning target volume, generally unsuited for proton therapy. Robust optimization considers worst-case scenarios, but its quality depends on the uncertainty scenario set: excluding extremes reduces robustness, while too many make plans overly conservative. Probabilistic optimization overcomes these limits by modeling a continuous scenario distribution. We propose a novel probabilistic optimization approach that steers plans toward individualized probability levels to control CTV and organs-at-risk (OARs) under- and overdosage. Voxel-wise dose percentiles ($d$) are estimated by expected value ($E$) and standard deviation (SD) as $E[d] \pm δ\cdot SD[d]$, where $δ$ is iteratively tuned to match the target percentile given Gaussian-distributed setup (3 mm) and range (3%) uncertainties. The method involves an inner optimization of $E[d] \pm δ\cdot SD[d]$ for fixed $δ$, and an outer loop updating $δ$. Polynomial Chaos Expansion (PCE) provides accurate and efficient dose estimates during optimization. We validated the method on a spherical CTV abutted by an OAR in different directions and a horseshoe-shaped CTV surrounding a cylindrical spine. For spherical cases with similar CTV coverage, $P(D_{2\%} > 30 Gy)$ dropped by 10-15%; for matched OAR dose, $P(D_{98\%} > 57 Gy)$ increased by 67.5-71%. In spinal plans, $P(D_{98\%} > 57 Gy)$ increased by 10-15% while $P(D_{2\%} > 30 Gy)$ dropped 24-28%. Probabilistic and robust optimization times were comparable for spherical (hours) but longer for spinal cases (7.5 - 11.5 h vs. 9 - 20 min). Compared to discrete scenario-based optimization, the probabilistic method offered better OAR sparing or target coverage depending on the set priorities.

physics.med-ph↗