Exhibit Hall | Forum 5
Purpose: To develop a motion-enabled, dual-modal(MR/CT), and anthropomorphic lung/liver phantom for imaging technique and motion management solution testing.
Methods: To address the challenges of enabling deformable breathing motion in a MR environment, an anthropomorphic phantom was created in proportion to a real patient’s anatomy (external body housing ribs, sternum, spine, lungs and liver) using 3D-printing and casting techniques. A pneumatic-driven mechanism was designed and connected to the phantom to simulate various breathing patterns and motion. It was built with a Raspberry Pi-controlled air pump system to generate airflow in-and-out of the 3D-printed lungs to mimic breathing. Due to the presence of the ribs, sternum and spine, the lung expansion is constrained towards inferior and partially-anterior directions to mimic real patient breathing motion, with coordinated diaphragm(liver) movement. The pneumatic-driven design allows the air pumps and electronics to be placed outside of the high magnetic field, and connected to the phantom via an air tube to drive customizable and reproducible motion through an external computer. We developed a streamlined workflow to efficiently fabricate the phantom, which includes, A) anatomy segmentation from patient-specific CT/MR images; B) 3D-printing the segmented anatomies or molds of the anatomies, together with the body contour, using a Stereolithography 3D-printer; and C) casting different body parts and assembling the phantom.
Results: The motion phantom was scanned using a CT simulator, a MR simulator, and a MR-LINAC for qualitative and quantitative study. The connecting air tube was routed through the room conduit to connect the air pump to the phantom. Under different testing scenarios, the phantom shows accurate Hounsfield units and desirable T1/T2 contrasts. The motion amplitude precision and reproducibility were within 1 mm.
Conclusion: Our workflow allows patient-specific anthropomorphic phantom fabrication. It simulates realistic and MR-compatible deformable breathing motion for various MR/CT imaging and image-guide radiotherapy studies.
Funding Support, Disclosures, and Conflict of Interest: The research was supported by grants from the National Institutes of Health (R01CA258987, R01CA240808).