ESTRO 2024 - Abstract Book

S3800

Physics - Image acquisition and processing

ESTRO 2024

Figure 1. Combined EQD2 D0.1cm 3 doses for the brainstem, spinal cord and their PRVs for the ten patients in the study, with data points overlaid in blue. Cumulative EQD2 dose constraints are displayed – 60Gy for the spinal cord PRV and 54Gy for the brainstem PRV

Conclusion:

A method has been presented to independently verify the treatment planning approach used to compensate for previous treatment in spinal cord and brainstem reirradiation cases for head and neck cancer patients. Additionally and to the best knowledge of the authors, this is the first time that this approach using iso-dose-segmented volumes for re-irradiation optimisation has been reported in the literature. The use of EQD2 dose mapping is a suitable approach for independent combined dose assessment. Quantifying dose mapping uncertainties due to registration uncertainties for cases close to the limits would help increase confidence in this approach.

Our results also indicate that few patients suffered from neurological side-effects after reirradiation. However, these results should be taken with care due to the limited sample size.

Keywords: reirradiation, spinal cord, dose mapping