Use of 3D printing for construction of custom bolus in external beam radiotherapy

Abstract

Aim To create a patient specific mould of a treatment area for bolus fitting using a 3D printer and compare it with conventional bolus. Methods A patient with a right medial Basal Cell Carcinoma (BCC) lesion on the forehead extending to the upper nose was presented for electron external beam radiotherapy (50 Gy in 20#). A conventional custom bolus 0.5 cm thick using Aquaplast™ thermoplastic pellets was made on the treatment area. Following this, a CT simulation using 2.5 mm slice thickness was performed. DICOM image files from the CT simulation for the treatment area were processed using 3D printing software to allow for a solid plastic mould of the patient’s contour to be printed using a 3D printer. The mould was used to fashion form fitting bolus, 1cm thick, with custom lead lens shielding included. The mould and bolus were CT scanned to ensure there were no air gaps and that the lead shielding was in the correct position. Comparison of the dosimetric performance of the conventional bolus and the bolus designed on the 3D printed mould will be presented. A 6 MeV electron plan for each bolus will be performed using electron Monte Carlo algorithm. Conclusion This work has demonstrated the feasibility of the use of 3D printing to assist in the construction of patient specific bolus for the treatment of superficial lesions. The bolus created on the 3D printed mould demonstrated less air gaps which improved the dosimetric performance when compared with a conventional bolus. To create a patient specific mould of a treatment area for bolus fitting using a 3D printer and compare it with conventional bolus. A patient with a right medial Basal Cell Carcinoma (BCC) lesion on the forehead extending to the upper nose was presented for electron external beam radiotherapy (50 Gy in 20#). A conventional custom bolus 0.5 cm thick using Aquaplast™ thermoplastic pellets was made on the treatment area. Following this, a CT simulation using 2.5 mm slice thickness was performed. DICOM image files from the CT simulation for the treatment area were processed using 3D printing software to allow for a solid plastic mould of the patient’s contour to be printed using a 3D printer. The mould was used to fashion form fitting bolus, 1cm thick, with custom lead lens shielding included. The mould and bolus were CT scanned to ensure there were no air gaps and that the lead shielding was in the correct position. Comparison of the dosimetric performance of the conventional bolus and the bolus designed on the 3D printed mould will be presented. A 6 MeV electron plan for each bolus will be performed using electron Monte Carlo algorithm. This work has demonstrated the feasibility of the use of 3D printing to assist in the construction of patient specific bolus for the treatment of superficial lesions. The bolus created on the 3D printed mould demonstrated less air gaps which improved the dosimetric performance when compared with a conventional bolus.