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A Novel 3D Printed Phantom for 4D PET/CT Imaging and SIB Radiotherapy Verification

D Soultan

D Soultan1*, J Murphy2 , B Gill3 , V Moiseenko4 , L Cervino5 , (1) University of California-San Diego, San Diego State University, La Jolla, CA, (2) University of California,San Diego, La Jolla, California, (3) British Columbia Cancer Agency, Windsor, ON, (4) University of California, San Diego, La Jolla, CA, (5) University of California, San Diego, La Jolla, CA


WE-AB-204-3 (Wednesday, July 15, 2015) 7:30 AM - 9:30 AM Room: 204

Purpose: To construct and test a 3D printed phantom designed to mimic variable PET tracer uptake seen in lung tumor volumes. To assess segmentation accuracy of sub-volumes of the phantom following 4D PET/CT scanning with ideal and patient-specific respiratory motion. To plan, deliver and verify delivery of PET-driven, gated, simultaneous integrated boost (SIB) radiotherapy plans.

Methods: A set of phantoms and inserts were designed and manufactured for a realistic representation of lung cancer gated radiotherapy steps from 4D PET/CT scanning to dose delivery. A cylindrical phantom (40x 120 mm) holds inserts for PET/CT scanning. The novel 3D printed insert dedicated to 4D PET/CT mimics high PET tracer uptake in the core and lower uptake in the periphery. This insert is a variable density porous cylinder (22.12x70 mm), ABS-P430 thermoplastic, 3D printed by uPrint SE Plus with inner void volume (5.5x42 mm). The square pores (1.8x1.8 mm2 each) fill 50% of outer volume, resulting in a 2:1 SUV ratio of PET-tracer in the void volume with respect to porous volume. A matching in size cylindrical phantom is dedicated to validate gated radiotherapy. It contains eight peripheral holes matching the location of the porous part of the 3D printed insert, and one central hole. These holes accommodate adaptors for Farmer-type ion chamber and cells vials.

Results: End-to-end test were performed from 4D PET/CT scanning to transferring data to the planning system and target volume delineation. 4D PET/CT scans were acquired of the phantom with different respiratory motion patterns and gating windows. A measured 2:1 18F-FDG SUV ratio between inner void and outer volume matched the 3D printed design.

Conclusion: The novel 3D printed phantom mimics variable PET tracer uptake typical of tumors. Obtained 4D PET/CT scans are suitable for segmentation, treatment planning and delivery in SIB gated treatments of NSCLC.

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