Author: Reza Farjam, Russell K Hales, Seth Jayawardane, Todd R. McNutt, Mohammad Rezaee, Ehsan Tajikmansoury, K. Ranh Voong 👨🔬
Affiliation: Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Johns Hopkins University, Department of Biomedical Engineering, Johns Hopkins School of Medicine 🌍
Purpose: This study presents a novel cost-effective customizable 3D-printed phantom developed for end-to-end treatment verification and image-quality assessment for thoracic applications.
Methods: The torso anatomy is simulated using a computer-aided design (CAD) model to include fat,muscle,lung(air), and bony tissue as the main tissue components within the thorax. The thoracic phantom, 20×39.5×25cm³,is 3D-printed using Acrylonitrile-styrene-acrylate (ASA), Polylactic-acid (PLA)-80%, Polylactic-acid (PLA)-15% and Bone Modeling Filament(SimuBone) to simulate the muscle,fat,lung, and bony-tissues, respectively. A CT scan study was conducted to validate the density of each material as proper substitute for each tissue component within the thorax. The lung tissue is 3D-printed with three-different densities and patterns simulating the varying tissue density in different lobes of the lung. The phantom has potential to include lesions of various sizes in different areas of the lung. Each lesion includes inserts to place Gafchromic film or TLD dosimeters for dose measurement and verification. The varying density and pattern within each area of lung provides delicate architecture for image quality assessment and verification.
Results: The 3D-printed phantom components, optimized by adjusting printing settings such as infill (15%to100%) and filament type, demonstrated highly acceptable Hounsfield Units(HU) value ranging from -1004 to 1500 representing all tissue types within the thorax. Minor deviations in HU values were observed for bone tissue but remained within the clinically acceptable range. The phantom’s geometric accuracy and imaging properties were consistent with the intended design. Dose measurements using the phantom is expected to closely match treatment planning criteria with 5% uncertainties to be within acceptable limits.
Conclusion: Our newly developed 3D-printed thoracic phantom provides a cost-effective customizable solution for dosimetric verification and image-quality assessment and can be tailored to address various needs within an institution with the main application in quality assurance of emerging radiotherapy techniques and imaging device, ensuring improved treatment quality and safety.