Author: Sarah E. Holler, Daniel Johnson 👨🔬
Affiliation: Department of Radiation Oncology, University of Kansas Medical Center 🌍
Purpose: As the technological availability of modern clinical infrastructure increases in resource-restricted regions of the world, the needs to maintain quality standards of practice need not be hampered by phantom cost or availability. Within this work we design and test fully 3D printable kV and MV imaging phantoms.
Methods: Utilizing an off-the shelf FDM 3D printer, a modular imaging QA/QC phantom is designed to test image resolution, scaling, geometric accuracy, and contrast resolution for analysis via PyLinac, an open- source software for automated QA within Radiotherapy. Tissue equivalent PLA plastic, as well as Bronze and Steel powder infused PLAs are utilized to create highly attenuating regions within the phantom. Resolution testing sections are achieved via varying infill percentages while varying layer thickness is used to establish gradients for contrast testing. Image testing was performed on an Edge platform Varian linear accelerator.
Results: kV and MV images for varying techniques are collected to optimize the imaging modality best used to establish a baseline. A cross comparison against commercially available phantoms within PyLinac can be used to establish MTF curves for the in-house phantom. While bronze PLA based modules are adequate for kV testing, MV systems benefit from steel infused PLA modules of increased thickness. While cost-prohibitive, a tungsten-infused PLA designed for shielding applications is also available for use.
Conclusion: With a total printed material cost below $10USD, this work demonstrated the feasibility of using a fully 3D printed imaging phantom in a fully automated QA process incorporating open-source software. The future availability of 3D printing plastics infused with high-Z materials may allow even further customization and cost effectiveness.