ESTRO 2024 - Abstract Book

S4730

Physics - Optimisation, algorithms and applications for ion beam treatment planning

ESTR0 2024

Figure 2: Left: the effect of different RBE models on SHArc(12C) optimization for the twelve metastases case in Figure 1right. Right: dose averaged LET for SHArc(12C) of the same case.

Contemporary RBE models (mMKM, LEM IV) indicate better dose sparing for SHArc( 12 C) compared to the clinically employed model (LEM I) that has known deficiencies (Figure 2 left). As a further advantage, SHArc( 12 C) elevated LETd levels in the target beyond 100keV/μm, which enables to overcome tumor hypoxia (Figure 2 right). Target dose homogeneity was improved for SHArc when compared to HA-VMAT and SPArc plans, which could not achieve the desired dosimetric goal without significant overdose in the target. Further dose sparing was achieved with bespoke non-coplanar arc plans (HyperSHArc), indicating promising potential for specific exclusion of sensitive areas and organs at risk.

Conclusion:

Leveraging the most recent developments in the particle arc community, this work for the first time enables versatile SPArc and SHArc treatment planning for up to twelve simultaneously optimized targets. SPArc and SHArc plans yielded great potential for SISRS of multiple brain metastases. Depending on the number of lesions and RBE model employed, particle arcs achieved similar or improved dose quality compared to HA-VMAT. The developed infrastructure in both clinical and research platforms allows to push the boundary of particle arc optimization, while keeping a direct route to future clinical translation. This work therefore paves the way to advanced options for multi met SISRS with ion beams and opens new research opportunities for the growing field of particle arc therapy.

Keywords: particle arc, multi-metastases, radiosurgery

References:

[1] Palmer et al “Single-Isocenter Multitarget Stereotactic Radiosurgery Is Safe and Effective in the Treatment of Multiple Brain Metastases” Adv Radiat Oncol. 2020 Jan-Feb; 5(1): 70–76.

[2] Mein et al. “Particle Arc Therapy: status and potential” Submitted to and in review by Radiotherapy & Oncology.