Use of a 3D printer to create a bolus for patients undergoing tele-radiotherapy

Background: This study describes the possibility of implementing three-dimensional printing technology to create a precise construction of a planned bolus, based on computed tomography information stored in the Digital Imaging and Communications in Medicine (DICOM) format file. Materials and Methods:  To create the bolus with a 3D printer, we converted data in the DICOM format to the stereolithography (STL) format. In addition, we produced a paraffin bolus that, traditionally, is manually placed directly on the patient. CT scans were acquired for both boluses, and the images were superimposed onto the patient CT scans that were used to design the bolus. The superimposition of images was performed to compare the fit of the bolus printed on a 3D printer to that of the paraffin bolus made in the traditional way. In addition, for both models, the dose distribution was simulated. To quantify the level of matching ML, special formula was used. The ML parameter had a value between 0 and 100%, where 100% indicated a perfect fit between the model and the 3D printed bolus. Results: We verified that 100% of the volume of the 3D printed bolus was located within the contour of the designed model. The ML of the bolus was 94%. For the classical paraffin bolus the ML was only 28%. Conclusion: A bolus printed on a three-dimensional printer can faithfully reproduce the structure specified in the project plan. Compared to the classical paraffin bolus, the three-dimensional printed bolus more closely matched the planned model and possessed greater material uniformity