Radiation-induced Vascular Damage and the Impact on the Treatment Outcome of Stereotactic Body Radiotherapy.

Abstract

The aim of this study was to investigate radiation-induced tumour vascular damage and its impact thereof on the outcome of stereotactic body radiotherapy (SBRT). Vessel densities in animal tumours before and after a single dose of 20 Gy were quantified and used as input for simulations of three-dimensional tumours with heterogeneous oxygenation. SBRT treatments of the modelled tumours in 1-8 fractions were simulated. The impact of vessel collapse on the outcome of SBRT was investigated by calculating tumour control probability (TCP) and the dose required to obtain a TCP of 50% (D50). A radiation-induced increase of acute hypoxia in tumours during SBRT treatment could be simulated based on the experimental data. The D50 values for these tumours were higher than for the simulated tumours without vessel collapse. The vascular changes after high doses of radiation could compromise the outcome of SBRT by increasing tumour hypoxia.