3D printing of bolusClinical implementation of 3D printing in the construction of patient specific bolus for electron beam radiotherapy for non-melanoma skin cancer

Background and purposeCreating an individualized tissue equivalent material build-up (i.e. bolus) for electron beam radiation therapy is complex and highly labour-intensive. We implemented a new clinical workflow in which 3D printing technology is used to create the bolus.Material and methodsA patient-specific bolus is designed in the treatment planning system (TPS) and a shell around it is created in the TPS. The shell is printed and subsequently filled with silicone rubber to make the bolus. Before clinical implementation we performed a planning study with 11 patients to evaluate the difference in tumour coverage between the designed 3D-print bolus and the clinically delivered plan with manually created bolus. For the first 15 clinical patients a second CT scan with the 3D-print bolus was performed to verify the geometrical accuracy.ResultsThe planning study showed that the V85% of the CTV was on average 97% (3D-print) vs 88% (conventional). Geometric comparison of the 3D-print bolus to the originally contoured bolus showed a high similarity (DSC = 0.89). The dose distributions on the second CT scan with the 3D print bolus in position showed only small differences in comparison to the original planning CT scan.ConclusionsThe implemented workflow is feasible, patient friendly, safe, and results in high quality dose distributions. This new technique increases time efficiency.