ESTRO 2024 - Abstract Book

S3738

Physics - Dose prediction, optimisation and applications of photon and electron planning

ESTRO 2024

The dose distributions at the exit of the collimators were measured, both at conventional and UHDRs, to quantify the Peak to Valley Dose Ratio (PVDR) as a function of the depth in water for all the collimator configurations. The experimental data were also successfully compared with Monte Carlo simulations performed using the EGS, the Geant4 and the Fluka codes (figure 1). Increasing the centre-to-centre implies a decrease in the valley dose, leading to higher PVDR and a larger mini-beam zone. We found that, in case of grid configuration, the dose deposition along the depth decreases and enables a higher PVDR and mini-beam zone with fixed template parameters. In vivo irradiations for target up to 5-6 mm of size could benefit from this feature. On the other hand, the planar geometry decreases the PVDR but implies a higher peak dose and deeper dose penetration. This may be promising from a clinical perspective, as the beam does not lose penetration compared to the open field and has a mini-beam component in the first few mm of depth, which could substantially reduce side effects on the skin.

Conclusion:

The work presented demonstrate the versatility of the ElectronFLASH linac which enables the study of both mini beam and FLASH effects by independently and systematically varying the fundamental spatial and temporal parameters involved in the two effects. The mini-beam and mini-beam-flash operating beams that we have realized can be used to carry out radiobiological experiments necessary to study the quantitative dependencies of the flash and mini-beam effects and the beam parameters that characterize them, and to understand their underlying radiobiological mechanisms.

Keywords: minibeams, FLASH, dosimetry

3261

Proffered Paper

1-Click Victory: Leading the ESTRO Auto-RTP Challenge with an Integrated Auto-Planning Pipeline

Carlos E Cardenas, Rex A Cardan, Joseph Harms, Eric Simiele, Richard A Popple

University of Alabama at Birmingham, Radiation Oncology, Birmingham, USA