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Program Information

Manufacturing Cost Effective Heterogeneous Phantoms for Use in Proton Therapy

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J Pruett

J Pruett*, Y Chen, S Ahmad, D Johnson, University of Oklahoma Health Sciences Center, Oklahoma City, OK


SU-F-T-171 (Sunday, July 31, 2016) 3:00 PM - 6:00 PM Room: Exhibit Hall

To study the feasibility of 3D printing cost effective heterogeneous phantoms for use in proton therapy treatment planning quality assurance.

A desktop 3D printer was utilized to create a series of 2 cm x 2 cm x 4 cm PLA plastic blocks of varying fill materials and hexagonal fill pattern. The blocks were than tested when filled with air, polyurethane foam, paraffin, silicone, and caulk of calcium carbonate –acrylic polymer blend. The blocks were evaluated with a “GE Lightspeed” 16 slice CT scanner and average CT# of the materials’ centers evaluated. Blocks were then placed into a custom aperture fitted to a Mevion Proton system to determine the relative stopping power of each. Scans were performed in water tank with Marcus type parallel plate chamber under a beam with a range of 15 cm and modulation of 2 cm. Shifts in range occurring relative to the 80% distal edge of the open SOBP were evaluated.

The CT#s of the blocks were plotted against their measured relative stopping power. This curve was compared to that which is in clinical use. While the trend agrees generally, specific differences between the relative stopping powers were as great as 10%.

We have demonstrated that it is possible to utilize different cost effective materials in the manufacturing of phantoms for use in proton therapy. While different materials may provide better agreement to established calibration curves, a custom curve specific to the materials used may be utilized to accurately predict proton treatment dose distributions.

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