ESTRO 2025 - Abstract Book

S36

Invited Speaker

ESTRO 2025

level. One proposal is to reconstruct the 3D dose distribution from the PG information, another is to condense the PG information to a classification of a relevant change (either binary yes/no or multi-class also differentiating the source of error). Yet another approach, called spot boosting, not yet clinically applied, proposes to boost the dose for a limited number of PBS spots and to irradiate those spots first, to selectively use them for PG range verification at those selected spot locations (Tian et al. 2020). In the presentation, an overview of all clinical applications of PGTV will be given, with a clear focus on the results of an observational study at OncoRay in Dresden using a PGI slit camera system, in which more than 450 clinical treatment deliveries have been monitored and retrospectively evaluated. The classification approach has been successfully tested and validated on this clinically acquired PGI data for H&N and prostate treatments (Berthold et al. 2023; Pietsch et al. 2023). The additional margin reduction potential due to additional PGI information has been assessed (Bertschi et al. 2023) and currently the first interventional clinical application within a prospective study is in preparation.

Berthold et al., 2023, “Detectability of Anatomical Changes with Prompt-Gamma Imaging: First Systematic Evaluation of Clinical Application during Prostate-Cancer Proton Therapy,” IJROBP 117, 718-729.

Bertschi et al. 2023. „Potential margin reduction in prostate cancer proton therapy with prompt gamma imaging for online treatment verification”. phiRO 26, 100447.

Richter et al., 2016, “First Clinical Application of a Prompt Gamma Based in Vivo Proton Range Verification System,” Radiother. Oncol. 118, 232–237.

Stichelhaut, F, and Jongen, Y, 2003, “Verification of the Proton Beam Position in the Patient by the Detection of Prompt Gamma-Rays Emission,” 39th Meet. PTCOG 16.

Tian et al. 2020, “A New Treatment Planning Approach Accounting for Prompt Gamma Range Verification and Interfractional Anatomical Changes,” PMB 65, 095005.

Pietsch et al. 2023, “Automatic Detection and Classification of Treatment Deviations in Proton Therapy from Realistically Simulated Prompt Gamma Imaging Data,” Med. Phys. 50, 506–517.

Verburg et al. 2020, “First-In-Human Use of Prompt Gamma-Ray Spectroscopy for Proton Range Verification,” Med. Phys. 57, e292.

Xie et al., 2017, “Prompt Gamma Imaging for In Vivo Range Verification of Pencil Beam Scanning Proton Therapy,” IJROBP 99, 210–218.

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Speaker Abstracts What's required to make TV a clinical product? Julien Smeets Proton Therapy R&D, Ion Beam Applications SA, Louvain-la-Neuve, Belgium

Abstract:

In-vivo treatment verification (TV) of proton therapy is already effective in research investigations and has yet to become routine, clinical use. The last presentation of this symposium will address the status of three requirements to make any of these technologies a clinical product.