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Fillable 3D Printed Hollow Sphere Sets for Resolution and Contrast Measurement in Nuclear Medicine

R Bartlett*, D Barbee , NYU Langone Health, New York, NY


(Tuesday, 7/31/2018) 9:30 AM - 10:00 AM

Room: Exhibit Hall | Forum 8

Purpose: Nuclear medicine imaging tests frequently require use of multiple hollow spheres of various size filled with radioactivity in order to measure resolution, contrast, and recovery coefficient. Certain vendor tests can require scans using identical spheres, requiring purchase of multiple sphere sets or specific spheres. Additionally, once filled for testing, spheres become unavailable for other scanners. Therefore, this work sets out to develop 3D printed, fillable spheres for resolution and contrast quality assurance tests of PET and SPECT scanners as customizable, disposable, and low-cost alternatives to those available on the market.

Methods: Hollow sphere sets were designed in 123D (Autodesk) with various stem and wall thickness configurations for inner diameter spheres of 5.0, 7.5, and 10 mm. Each sphere and stem were combined and printed as one piece with 1/4-20 threads and hollow inner diameter for filling. Spheres were 3D printed using a Makerbot Replicator 2 (Makerbot Industries) using a variety of layer thicknesses, infill and outer shells. All spheres were vacuum tested and leak tested using blue dye in a water bath.

Results: The optimal 3D printing parameters were found to be 0.1 mm layer thickness, 100% infill, 1 shell, and transparent filament. Wall thicknesses were successfully reduced to as small as 1 mm while maintaining seal. Spheres printed in 30-45 min for less than $1. MicroCT of each sphere demonstrated that sphere inner diameter was reproducible to within 0.2 mm of the desired diameter. Spheres successfully performed as well as marketed products in PET and cardiac SPECT QA testing.

Conclusion: 3D printing of hollow spheres can be an alternative to perform regulatory quality assurance tests on nuclear medicine SPECT and PET cameras. Printed spheres are inexpensive, quick to manufacture, disposable, and configurable for on-demand testing requirements.


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