Dose–volume histogram and dose–surface histogram analysis for skin reactions to carbon ion radiotherapy for bone and soft tissue sarcoma

Background and purposeTo evaluate the usefulness of the dose–volume histogram (DVH) and dose–surface histogram (DSH) as clinically relevant and available parameters that helped to identify bone and soft tissue sarcoma patients at risk of developing late skin reactions, including ulceration, when treated with carbon ion radiotherapy.Materials and methodsThirty-five patients with bone and soft tissue sarcoma treated with carbon ion beams were studied. The clinical skin reactions were evaluated. Some pretreatment variables were compared with the grade of late skin reactions.ResultsAverage DVH and DSH were established in accordance with the grading of the skin reactions. Prescribed dose, the difference in depths between the skin surface and the proximal extent of the tumor, and some DVH/DSH parameters were correlated with late skin reaction (≧≧grade 3) according to univariate analysis. Furthermore, the area irradiated with over 60 GyE (S60 > 20 cm2) on DSH was the most important factor by multivariate analysis.ConclusionsThe area irradiated with over 60 GyE (S60 > 20 cm2) on DSH was found to be a parameter for use as a predictor of late skin reactions.