Robustness of Transformer-Based Fluence Map Prediction Under Clinically Realistic Perturbations

Fuente: arXiv
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Autores principales: Mgboh, Ujunwa, Sultan, Rafi Ibn, Kim, Joshua, Thind, Kundan, Zhu, Dongxiao
Formato: Preprint
Publicado: 2026
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author Mgboh, Ujunwa
Sultan, Rafi Ibn
Kim, Joshua
Thind, Kundan
Zhu, Dongxiao
author_facet Mgboh, Ujunwa
Sultan, Rafi Ibn
Kim, Joshua
Thind, Kundan
Zhu, Dongxiao
contents Learning-based fluence map prediction offers a fast alternative to iterative inverse planning in intensity-modulated radiation therapy (IMRT), but its robustness under realistic distribution shifts remains unclear. We study a two-stage transformer pipeline that maps anatomy (CT and contours) to dose and then to beamlet fluence maps. We compare fluence-stage transformer backbones with hierarchical, global, and hybrid attention, trained with a physics-informed loss enforcing energy consistency. Robustness is evaluated under geometric perturbations, radiometric noise, reduced training data, and domain shifts using a prostate IMRT dataset, with additional evaluation of the dose stage on public datasets. Results show smooth degradation under moderate perturbations but sharp failures under severe rotations and noise. Hierarchical transformers (e.g., SwinUNETR) exhibit slower growth in upper-quartile energy error, indicating improved robustness. We further show that SSIM alone fails to capture clinically relevant errors, highlighting the need for physics-informed evaluation.
format Preprint
id arxiv_https___arxiv_org_abs_2605_00904
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Robustness of Transformer-Based Fluence Map Prediction Under Clinically Realistic Perturbations
Mgboh, Ujunwa
Sultan, Rafi Ibn
Kim, Joshua
Thind, Kundan
Zhu, Dongxiao
Computer Vision and Pattern Recognition
Learning-based fluence map prediction offers a fast alternative to iterative inverse planning in intensity-modulated radiation therapy (IMRT), but its robustness under realistic distribution shifts remains unclear. We study a two-stage transformer pipeline that maps anatomy (CT and contours) to dose and then to beamlet fluence maps. We compare fluence-stage transformer backbones with hierarchical, global, and hybrid attention, trained with a physics-informed loss enforcing energy consistency. Robustness is evaluated under geometric perturbations, radiometric noise, reduced training data, and domain shifts using a prostate IMRT dataset, with additional evaluation of the dose stage on public datasets. Results show smooth degradation under moderate perturbations but sharp failures under severe rotations and noise. Hierarchical transformers (e.g., SwinUNETR) exhibit slower growth in upper-quartile energy error, indicating improved robustness. We further show that SSIM alone fails to capture clinically relevant errors, highlighting the need for physics-informed evaluation.
title Robustness of Transformer-Based Fluence Map Prediction Under Clinically Realistic Perturbations
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2605.00904