ESTRO 2023 - Abstract Book

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ESTRO 2023

Δ D50% (IQ)

0.18 (0.21) 0.05 (0.11) 0.00 (0.17) -0.27 (0.13)

γ (1%-1 mm) (%) 99.96

99.87

100.00

100.00

iso40% Δ D50% (IQ)

0.03 (0.11) -0.13 (0.11) -0.18 (0.10) -0.31 (0.15)

γ (1%-1 mm) (%) 99.84

99.93

99.98

99.99

iso10% Δ D50% (IQ)

-0.72 (0.64) -0.75 (0.73) -0.42 (0.93) -0.28 (0.87)

γ (1%-1 mm) (%) 97.10 99.87 No significant LETd deviations were reported in the CTV; median Δ LETd and interquartile ranges for ring-dose regions show absolute differences up to 80% for very low dose regions, as depicted in figure 2. 99.95 99.54

Conclusion The introduction of NIC+TRI resulted in clinically acceptable dose deviations for all investigated treatment sites. The updated modelling of nuclear interactions and fragment spectra provided more realistic results on energy deposition and LETd maps, particularly in the medium and low dose regions. Further investigation is needed to assess the deviations with respect to the FLUKA MC code.

PO-1976 Commissioning of helium ion therapy: physics, radiobiology and clinical directions at HIT

T. Tessonnier 1 , R. Wickert 2 , J. Besuglow 3 , S. Mein 4 , S. Ecker 5 , L. Hoeltgen 2 , M. Deng 2 , T. Eichkorn 2 , T. Haberer 6 , K. Herfarth 2 , J. Debus 2 , O. Jäkel 7 , S. Harrabi 2 , A. Mairani 8 1 Heidelberger Ionenstrahl-Therapiezentrum , Medical Physics/BioPT, Heidelberg, Germany; 2 Universitätsklinikum Heidelberg, RadioOnkologie & Strahlentherapie, Heidelberg, Germany; 3 Heidelberg University Hospital (UKHD) and German Cancer Research Center (DKFZ), Clinical Cooperation Unit Radiation Oncology, National Center for Tumor Diseases (NCT), , Heidelberg, Germany; 4 Heidelberg University Hospital (UKHD) and German Cancer Research Center (DKFZ), Clinical Cooperation Unit Radiation Oncology, National Center for Tumor Diseases (NCT), Heidelberg, Germany; 5 Städttisches Klinikum Karlsruhe, Medical Physics, Heidelberg, Germany; 6 Heidelberger Ionenstrahl-Therapiezentrum, HIT, Heidelberg, Germany; 7 Heidelberger Ionenstrahl-Therapiezentrum, Medical Physics, Heidelberg, Germany; 8 Heidelberger Ionenstrahl Therapiezentrum, BioPT, Heidelberg, Germany Purpose or Objective Helium ions (4He) therapy is envisioned as a new therapeutic option for patient treatment. With its heavier mass compared to protons, 4He offer reduced lateral scattering and improved target conformity. The lower LET of 4He yields reduced RBE values and uncertainties compared to carbon ions.

Investigations for radiation physics and biology at the Heidelberg ion beam therapy center (HIT) led to academic and industry collaborations to establish clinical systems for 4He therapy.

This work provides insight into the ongoing works at HIT from TPS commissioning (physics and radiobiological modeling), in-silico studies as support for future clinical trial design and the first patient treatment/follow-ups.

Materials and Methods The TPS RayStation (RaySearch) was commissioned against experimental measurements.