A method for generating intensity-modulated radiation therapy fields for small animal irradiators utilizing
Suk W Yoon1,2, Jacob Kodra2, Devin A Miles3
1Department of Radiation Oncology, Perelman School of Medicine of the University of Pennsylvania, Perelman Center for Advanced Medicine, Philadelphia, PA, 19104, USA.
Medical Physics
|April 14, 2020
Summary
This study demonstrates the feasibility of using 3D-printed molds filled with sodium iodide powder to create radiation compensators for small animal intensity-modulated radiation therapy (IMRT). This novel method achieves high spatial resolution and accurate dose delivery for precise small animal radiation treatments.
Area of Science:
- Medical Physics
- Radiation Oncology
- Biomedical Engineering
Background:
- Intensity-modulated radiation therapy (IMRT) requires precise dose shaping.
- Small animal radiation research necessitates high-resolution treatment techniques.
- Traditional compensator fabrication can be complex and time-consuming.
Purpose of the Study:
- To investigate the feasibility of using fused deposition modeling (FDM) 3D printing for creating radiation compensators.
- To develop a novel method using 3D-printed molds filled with sodium iodide (NaI) powder for small animal IMRT.
- To achieve high spatial resolution (~1 mm) for small animal radiation treatments.
Main Methods:
- Adapted Computational Environment for Radiotherapy Research (CERR) software to simulate the XRAD-225Cx irradiator.
- Designed and 3D printed polylactic acid (PLA) molds for compensators with a resolution of 1.25 x 1.25 mm².
- Filled molds with sodium iodide (NaI) powder and evaluated compensator reproducibility using Radiochromic EBT2 film.
- Performed gamma analysis comparing delivered 2D dose distributions to calculated doses.
Main Results:
- Achieved good reproducibility in 3D-printed compensator manufacture with a mean error of ±0.024 Gy and relative dose error of ±4.2%.
- Demonstrated a maximum radiation blocking efficiency of 91.5% within a 13.8 mm compensator height limit.
- Eight out of nine IMRT fields showed >90% pass rate in gamma analysis (5%/0.5 mm tolerances), with one field showing lower pass rates attributed to fabrication errors.
Conclusions:
- Confirmed the feasibility of high spatial resolution IMRT for small animals using 3D-printed compensator shells filled with NaI powder.
- Highlighted the advantages of 3D printing PLA molds for geometric accuracy and NaI powder for balanced attenuation.
- Showcased the capability of achieving 1.25 mm resolution IMRT fields with significant fluence modulation and ±4.2% relative dose accuracy.
