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Proceedings Paper

Light fluence dosimetry in lung-simulating cavities
Author(s): Timothy C. Zhu; Michele M. Kim; Jonah Padawer; Andreea Dimofte; Mary Potasek; Karl Beeson; Evgueni Parilov
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Paper Abstract

Accurate light dosimery is critical to ensure consistent outcome for pleural photodynamic therapy (pPDT). Ellipsoid shaped cavities with different sizes surrounded by turbid medium are used to simulate the intracavity lung geometry. An isotropic light source is introduced and surrounded by turbid media. Direct measurements of light fluence rate were compared to Monte Carlo simulated values on the surface of the cavities for various optical properties. The primary component of the light was determined by measurements performed in air in the same geometry. The scattered component was found by submerging the air-filled cavity in scattering media (Intralipid) and absorbent media (ink). The light source was located centrally with the azimuthal angle, but placed in two locations (vertically centered and 2 cm below the center) for measurements. Light fluence rate was measured using isotropic detectors placed at various angles on the ellipsoid surface. The measurements and simulations show that the scattered dose is uniform along the surface of the intracavity ellipsoid geometries in turbid media. One can express the light fluence rate empirically as φ =4S/As*Rd/(1- Rd), where Rd is the diffuse reflectance, As is the surface area, and S is the source power. The measurements agree with this empirical formula to within an uncertainty of 10% for the range of optical properties studied. GPU voxel-based Monte-Carlo simulation is performed to compare with measured results. This empirical formula can be applied to arbitrary geometries, such as the pleural or intraperitoneal cavity.

Paper Details

Date Published: 5 March 2018
PDF: 7 pages
Proc. SPIE 10476, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XXVII, 104760F (5 March 2018); doi: 10.1117/12.2291355
Show Author Affiliations
Timothy C. Zhu, The Univ. of Pennsylvania Health System (United States)
Michele M. Kim, The Univ. of Pennsylvania Health System (United States)
Jonah Padawer, The Univ. of Pennsylvania Health System (United States)
Andreea Dimofte, The Univ. of Pennsylvania Health System (United States)
Mary Potasek, Simphotek Inc. (United States)
Karl Beeson, Simphotek Inc. (United States)
Evgueni Parilov, Simphotek Inc. (United States)


Published in SPIE Proceedings Vol. 10476:
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XXVII
David H. Kessel; Tayyaba Hasan, Editor(s)

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