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@ARTICLE{Sevilla:299491,
author = {A. C. Sevilla and G. Cabal and N. Wahl$^*$ and M. E. Puerta
and J. C. Rivera},
title = {{A} robust optimization model for intensity-modulated
radiotherapy: {C}heap-{M}inimax.},
journal = {Medical physics},
volume = {52},
number = {5},
issn = {0094-2405},
address = {Hoboken, NJ},
publisher = {Wiley},
reportid = {DKFZ-2025-00451},
pages = {3360-3376},
year = {2025},
note = {Volume 52, Issue 5 p. 3360-3376},
abstract = {Over the past three decades, the intensity-modulated
radiotherapy (IMRT) has become a standard technique,
enabling highly conformal dose distributions tailored to
specific clinical objectives. Despite these advancements,
IMRT treatment plans are significantly susceptible to
uncertainties during both the planning and delivery phases.
The most commonly used strategy to address these
uncertainties is the margin-based or planning target volume
(PTV) approach, which relies on the so-called dose cloud
approximation. However, the PTV concept has notable
limitations, particularly in complex scenarios where target
volumes are superficial or located near critical structures.
In contrast, the advent of intensity-modulated particle
therapy has driven the development of robust optimization
models, which have emerged as a promising alternative for
managing uncertainties. Among these, the worst-case scenario
or minimax strategy is the most widely employed. While
minimax can be directly applied to photon treatments, its
use in IMRT often leads to overly conservative plans or
plans that are very similar to those obtained using the
conventional margin-based PTV approach.In this work, we
present a robust optimization model particularly suitable
for photon treatments. The new approach, called
Cheap-Minimax, is a generalization of the minimax strategy
used for particle therapy and aims to improve the balance
between plan robustness and the price of robustness in terms
of dose to organs at risk (OARs), an issue particularly
pronounced in photon treatments.The c-minimax model was
implemented in the MatRad treatment planning system,
developed at the German Cancer Research Center (DKFZ). It
was applied to 20 clinical cases, comprising 5 prostate
cancer cases and 15 breast cancer cases. The results were
compared with those obtained using the conventional minimax
model and the PTV-based approach.For prostate cancer cases,
the c-minimax model maintained a robustness comparable to
the PTV approach, while achieving a $20\%$ reduction in V 40
Gy $V_{40 \, \text{Gy}}$ for the rectum and a 10\% reduction
in V 60 Gy $V_{60 \, \text{Gy}}$ for the bladder compared to
the minimax model. In breast cancer cases, the c-minimax
model improved robustness by 23.7\% relative to the PTV
approach and by 18.2\% compared to the minimax model.
Additionally, the c-minimax model reduced V 20 Gy $V_{20 \,
\text{Gy}}$ for the ipsilateral lung by 3.7\% and the mean
heart dose by 1.2 Gy (20\%) compared to minimax. Both the
c-minimax and minimax models reduced D 5 \% $D_{5\\%}$ skin
dose by 10.9 Gy (18.9\%) and 11.1 Gy (19.3\%), respectively,
compared to the PTV approach.The c-minimax model
successfully overcomes the limitations of the PTV approach
and the over-conservativeness of the minimax model,
demonstrating significant advantages in managing
uncertainties in complex cases, such as breast cancer. By
providing superior robustness compared to PTV and reducing
OAR doses relative to minimax, the model offers a flexible
and clinically feasible strategy to enhance treatment
quality. The marked reduction in high-dose regions
(hotspots) in superficial tissues and skin highlights its
potential to lower toxicity risks and improve patient
outcomes. These results provide quantitative evidence of the
practical benefits of robustness-compromise-oriented
approaches in IMRT.},
keywords = {IMRT (Other) / robust optimization (Other) / uncertainty
(Other)},
cin = {E040},
ddc = {610},
cid = {I:(DE-He78)E040-20160331},
pnm = {315 - Bildgebung und Radioonkologie (POF4-315)},
pid = {G:(DE-HGF)POF4-315},
typ = {PUB:(DE-HGF)16},
pubmed = {pmid:40012139},
doi = {DOI:10.1002/mp.17709},
url = {https://inrepo02.dkfz.de/record/299491},
}