Deutsches Krebsforschungszentrum (DKFZ)
Clinical Cooperation Unit Translational Radiation Oncology

Author Of 1 Presentation

ULTRA-HIGH DOSE RATE (FLASH) CARBON ION IRRADIATION: FIRST IN VITRO AND IN VIVO RESULTS

Session Type
FLASH Modalities Track (Oral Presentations)
Date
Thu, 02.12.2021
Session Time
11:00 - 12:00
Room
Hall C
Lecture Time
11:10 - 11:20

Abstract

Background and Aims

In this work, we present the results of first in vitro and in vivo studies for carbon ion beams irradiation that aim to investigate the biological effects delivered at ultra-high dose rate (FLASH).

Methods

The Heidelberg Ion-Beam Therapy Center (HIT) synchrotron, after technical adaptions, can reliably extract 5×108 12C ions within approximately 150 ms. This yields a dose of 7.5 Gy (homogeneity of ±5%) in a volume of at least 8 mm in diameter and a corresponding dose rate of 40-70 Gy s-1. Additionally, similar beam application but at 8 times higher beam intensity could be recently performed at GSI for carbon FLASH irradiations in mice models (Dose: 12-18 Gy, Dose-rate 60-100 Gy s-1).

Results

For the in vitro experiments a clonogenic survival assay and residual γH2AX foci analysis have been performed. The results of the survival assay demonstrate a significant FLASH sparing effect which is strongly oxygenation-dependent and is mostly pronounced at the concentration of 0.5% O2 but absent at 0% and 21% O2 (fig 1). The γH2AX results shows reduction in the residual foci signal at 1% O2.

The GSI in vivo irradiations of mice models could be successfully performed in the plateau and in the SOBP region (fig 2). The SIS18 synchrotron enables treatment of target volumes of typically 20 cm3 with 15 Gy in 150 ms. Larger volumes seem to be possible.

fig1.png

fig2.png

Conclusions

The in vitro experiments confirm FLASH sparing effect at low oxygen concentrations. The pre-clinical results from the very recent mice model experiments are currently under evaluation.

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