Mucositis Following HSCT With Myeloablative TBI Based on GVHD Prophylaxis Regimen

Abstract

associated with high response rates and decreased rates of neurotoxicity compared with higher dose WBRT. Our treatment policy for PCL patients with residual disease following chemotherapy is whole-brain irradiation to a total dose of 23.4 Gy in 13 fractions of 1.8 Gy followed by a sequential boost up to 45-50 Gy in 25 fractions of 1.8-2 Gy to the primary site/residual tumor. We propose a new methodology in order to limit the dose to the healthy brain to the prescribed dose by using composite planning (bias dose planning). Materials/Methods: We treated two patients with PCL and residual disease after chemotherapy using our methodology. First, we prepared a "standard plan", where the WBRT dose was planned first for volumetric arc therapy (VMAT) using the Monoco TPS (Elekta), followed by the sequential boost dose plan; second, a "bias plan" where the sequential boost dose was planned first, and only thereafter the WBRT dose using the bias dose planning option with the Monaco TPS in order to have a final composite plan corresponding to the prescribed doses. Results: Treatment plans resulting from bias dose planning had a markedly reduced dose to the brain outside of the boost. The mean dose to the brain minus the boost volume was of 25.00 Gy AE 0.5 Gy (Bias plan) vs 30.00 AE 0.6 Gy (standard plan). Conclusion: Composite planning of the boost first and only thereafter planning the dose to the brain taking the boost plan into account allows a reduction of 5 Gy to the healthy brain. To our knowledge, in lymphoma treatment, the total delivered dose is important, rather than the dose per fraction. We recommend this procedure for PCL radiations that have a sequential boost.