Room: AAPM ePoster Library
An early indicator of radiation induced skin reactions would be a valuable tool for mitigating skin toxicity in radiation therapy patients. Based on previous mouse studies, a tomographic reconstruction of skin effusivity using a flash pulsed thermal imaging system could be used for early detection, but translation of the technique to human subjects requires additional development.
Due to the finite speed of heat propagation, one can calculate the thermal properties of materials at depth based on the decay of surface temperature after impulse heating. A pulsed thermal imaging system has been employed using two flash lamps and an infrared camera. Vinyl tape with measured thermal properties was used as a fiducial and effusivity values of a custom 3D printed imaging phantom to assess image quality were performed. The phantom was water filled to provide contrast for the imaging test.
The thermal effusivity of vinyl tape was first calibrated using the known value of water (1588 W s¹/² /(m² °K)). Calculated values of tape effusivity were found to be 590±7.5 W s¹/² /(m² °K). Effusivity profiles were taken of a 3D printed phantom with a measured effusivity of 450±20 W s¹/² /(m² °K). After effusivity reconstruction of the water filled phantom, bar patterns were analyzed and a modulation transfer function calculated. The best limiting spatial resolution of 5.9 lines / cm producing 10% modulation is achieved at a depth of 0.67mm beneath the vinyl tape.
We have validated the precision and repeatability of the measurement apparatus in a previous study and the imaging quality in this study, allowing detection of effusivity changes which may manifest as a precursor to skin toxicities grade 2 or higher.
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