Novel application of 3D printing in brachytherapy using MED610 3D printed insert for I-125 ROPES eye plaque

The purpose of this study was to evaluate if MED610 3D printed material can be used as a surrogate for acrylic in the manufacturing of a replacement insert used in an eye plaque brachytherapy applicator. Measurement of the dose distributions from a standard acrylic insert were compared with dose obtained from MED610 3D printed replica using GafChromic^® EBT3 films. The study used a 15 mm Radiation Oncology Physics and Engineering Services, Australia (ROPES) type eye plaque applicator loaded with I-125 (model 6711) seeds. GafChromic^® EBT3 films were placed in a solid water phantom and dose distributions were measured three-dimensionally both along and perpendicular to a loaded ROPES eye plaque's central axis (CAX). Each measurement was performed with the stainless steel plaque backing attached to the eye plaque, to assess the variability of the dose distributions between the acrylic and MED 610 insert. Results of dose along the central axis were compared between acrylic and MED610 insert and the results found agreement within 1.5 %. Off-axis profiles were also compared between the acrylic insert and MED610 and were found to agree to within 7 % in the central 15 mm width centred on CAX at depths ranging from z = 2 mm to z = 8 mm in 2 mm increments. The aim of this investigation was to verify the consistency between doses profiles over a range of clinically relevant depths for a 15 mm loaded ROPES plaque using acrylic versus MED610 material. The results show an agreement between experimental measurements given the film uncertainty of 7 %.