ESTRO 2024 - Abstract Book

S3361

Physics - Detectors, dose measurement and phantoms

ESTRO 2024

Higher doses for both prints and gel boluses were measured in the build-up region for the unflattened radiation beams, with difference up to 7 percentage points at the surface of the phantom. Although the properties of the materials were very similar, the results obtained for materials with different hardnesses showed noticeable differences. For both materials, the highest dose on the phantom surface was measured for prints with 10 mm thickness and 60% infill, exceeding respectively 94.9% and 96.8% of the maximum dose for FF for FFF beams. Results for 1 mm depth were 96.8% and 98.3% and at 2 mm – 98.1% and 99.1% for FF and FFF, respectively. For none of the prints, the obtained PDDs were equal to the curve measured for the 10 mm thick gel bolus (with doses at the surface over 97.5% and 99.5%). The correlation between print parameters and dose level in the build-up area was consistent for both materials. With highest values for 10 mm/60% samples, the doses were gradually reduced for print thickness of 5 mm and 100% infill, and 5 mm and 60% respectively. The results for a material with a hardness of 93 in Shore A scale and parameters of 5 mm/60% were comparable to those obtained for a gel sheet bolus of the same 5 mm thickness (within 1%). Agreement between measurements and treatment planning system calculations for all data was within 1%. Print repeatability verification showed a high level of agreement between prints, with more than 98% of evaluated dose points meeting the criteria of local percentage dose difference: ≤ 0.8% for 93 Shore A filament and ≤ 0.7% for 40 Shore D filament.

Conclusion:

The properties of examined materials have shown the potential for their use to produce personalized flexible boluses tailored to a patient's complex anatomy. PDDs measurements gave satisfactory results, similar to those obtained for 5 mm gel sheet boluses used in daily practice. Moreover, the dosimetric properties of the prints varied significantly with the chosen printing parameters, indicating that they can be modified according to the individual needs of a single patient.

The study also showed that the process of producing such boluses is relatively simple and can be considered high reproducible.

Keywords: 3D printing,personalized bolus,flexible filaments

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Digital Poster

Development of level III radiotherapy dosimetry audit system using 3D PRESAGE dosimeter

Ahmad Taufek Abdul Rahman 1,2 , Hafiz Mohd Zin 3 , Muhammad Zamir Mohyedin 1

1 Universiti Teknologi MARA, Faculty of Applied Sciences, Shah Alam, Malaysia. 2 Universiti Teknologi MARA, Institute of Science, Shah Alam, Malaysia. 3 Universiti Sains Malaysia, Advanced Medical & Dental Institute, Kuala Batas, Malaysia