Three-dimensional printer use in the Australian and New Zealand radiation therapy setting.

INTRODUCTION: This cross-sectional survey aimed to collect data from radiation therapy departments around Australia and New Zealand to establish a baseline of 3D printer and product use. METHODS: Each department in Australia and New Zealand was contacted to determine the most appropriate person to answer the survey. A Microsoft Forms link to the survey was sent to the individual. The survey contained 47 questions in relation to what 3D printing device departments had (if any), how it was being utilised, and what 3D printed products were in use. RESULTS: A total of 112 departments completed the survey (100% response rate), with 22.3% reporting 3D printer ownership, and thirty-four departments (30.4%) outsourcing 3D printed products. The primary use of 3D printers was bolus production (60.9%). Public departments represented 84% of printer ownership, while private departments were the greatest users of outsourced 3D printed products (91.4%). 3D Slicer was the most common software used for Digital Imaging and Communications in Medicine (DICOM) file conversion (42.3%), while polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS) were the most common filaments in use, 46% and 14%, respectively. CONCLUSION: This research established a baseline for 3D printer and product use within the Australian and New Zealand radiotherapy setting.

Comparison of 3D printed nose bolus to traditional wax bolus for cost-effectiveness, volumetric accuracy and dosimetric effect.

INTRODUCTION: Three-dimensional printing technology has the potential to streamline custom bolus production in radiotherapy. This study evaluates the volumetric, dosimetric and cost differences between traditional wax and 3D printed versions of nose bolus. METHOD: Nose plaster impressions from 24 volunteers were CT scanned and planned. Planned virtual bolus was manufactured in wax and created in 3D print (100% and 18% shell infill density) for comparison. To compare volume variations and dosimetry, each constructed bolus was CT scanned and a plan replicating the reference plan fields generated. Bolus manufacture time and material costs were analysed. RESULTS: Mean volume differences between the virtual bolus (VB) and wax, and the VB and 18% and 100% 3D shells were -3.05 ± 11.06 cm3 , -1.03 ± 8.09 cm3 and 1.31 ± 2.63 cm3 , respectively. While there was no significant difference for the point and mean doses between the 100% 3D shell filled with water and the VB plans (P> 0.05), the intraclass coefficients for these dose metrics for the 100% 3D shell filled with wax compared to VB doses (0.69-0.96) were higher than those for the 18% and 100% 3D shell filled with water and the wax (0.48-0.88). Average costs for staff time and materials were higher for the wax ($138.54 and $20.49, respectively) compared with the 3D shell prints ($10.58 and $13.87, respectively). CONCLUSION: Three-dimensional printed bolus replicated the VB geometry with less cost for manufacture than wax bolus. When shells are printed with 100% infill density, 3D bolus dosimetrically replicates the reference plan.

PLA as a suitable 3D printing thermoplastic for use in external beam radiotherapy.

The purpose of this paper is to investigate the tissue equivalence and radiological properties of Polylactic Acid (PLA) to determine if this material is suitable for use as a 3D printing thermoplastic for radiotherapy applications. Profiles and percentage depth-dose measurements (PDDs) were analysed for photon and electron modalities with PLA samples (~ 1.25 g/cm3) to determine material dosimeteric characteristics. Beam profiles and PDDs from treatment planning system (TPS) simulations, water tank measurements and radiochromic film measurements were compared. Tissue equivalence was determined through CT scanning several PLA samples and measuring the Hounsfield units (HUs) to determine relative electron density (RED), mass density and mass attenuation, these results were compared to several commercial tissue phantoms with varying properties. Geometric accuracy was tested by comparing digitally planned dimensions to physical and CT image measurements. Finally, resistance to radiation damage was tested by exposing PLA samples to several thousand monitor units (MUs) over several weeks and inspecting for damage. It was determined that PLA is a safe and effective thermoplastic for use as a patient specific bolus for both electron and photon treatment modalities. The material properties have been characterised and can be accurately modelled in the MONACO TPS.