Exploring the impact of filament density on the responsiveness of 3D-Printed bolus materials for high-energy photon radiotherapy

Background

3D-printed boluses in radiation therapy receive consideration for their ability to enhance treatment precision and patient comfort. Yet, thorough validation of 3D-printed boluses using various validation procedures and statistical analysis is missing. This study aims to determine the effectiveness of using 3D-printed boluses in radiation therapy.

Method

The CT Hounsfield Unit (HU) profiles of the 3D-printed materials were compared to those of the commercial bolus using the Eclipse Treatment Planning System (TPS) unit. Furthermore, absolute dose measurements were carried out to assess the efficacy of the 3D-printed samples by using concordance correlation coefficient to assess the agreement between 3D materials and the commercial bolus.

Results

The average HU profiles of 3D-printed materials were: −144.53 (ABS), −124.40 (ASA), 9.55 (PLA-P), −140.79 (Polycarbonate), −68.58 (PLA-S), and −113.159 (PET-G), respectively. PDD scans showed that air gaps between the bolus and surface shifted the maximum dose depth. Whereas dosimetry has shown that ASA and Polycarbonate are different in attenuation from other tested filaments. This limitation could affect their performance in specific applications within radiation therapy. The final analysis, using the TPS-generated datasets to assess the area under the dose curve in the build-up zone of each 3D-bolus, excluded ABS.

Conclusions

The results from PDD scans and dose assessments offer compelling proof that 3D-printed boluses are effective for delivering surface dosage and are like commercially available boluses. Moreover, specific materials showed a statistically significant improvement in delivering the dose. The results highlight the capability of 3D-printed boluses to enhance the effectiveness of radiation therapy.