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Program Information

Construction of An Inhomogeneous Patient Specific QA Phantom

R Halford

R Halford1*, M Snyder2 , B Loughery3 , G Baran4 , (1) Karmanos Cancer Institute, Detroit, MI, (2) Wayne State University, Detroit, MI, (3) Wayne State University, Detroit, MI, (4) Karmanos Cancer Institute, Detroit, MI


TU-C2-GePD-TT-2 (Tuesday, August 1, 2017) 10:00 AM - 10:30 AM Room: Therapy ePoster Theater

Purpose: To create an inhomogeneous phantom for patient specific QA. The phantom contains simulated ribs, lung, and a tumor and allows measurements using film and ion chambers in both the target and normal tissue.

Methods: The phantom was constructed using several different two-part urethane plastics and foam from Reynolds Advanced Materials. The ribs of the phantom were cast using Smooth-Cast 385, a two-part, mineral-filled urethane with a density of 1.6 g/cc. The lung was cast using Foam-It! 15, a two part polyurethane foam with a density of 0.24 g/cc. The body of the phantom and tumor were cast using Smooth-Cast 300, a two-part urethane with a density of 1.05 g/cc. After construction, a CT scan of the phantom was imported to Elekta Monaco 5.0 treatment planning system and the electron densities of the structures were measured.

Results: The phantom is a 12” diameter cylinder with simulated ribs, lung and tumor. The phantom allows for a planar dose distribution measurement using film. There is a hole for an ion chamber measurement in the tumor and one in normal tissue. The electron densities of the simulated body, ribs, lung and tumor are 1.015, 1.48, 0.30, and 1.015 which are representative of their real equivalents.

Conclusion: An inhomogeneous phantom for patient specific QA was designed and built. The inhomogeneous construction allows for measurements under more realistic anatomical conditions.

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