Medical Physics Seminar – Monday, March 16, 2015
Advanced Radiochromic Film Methodologies for Quantitative Dosimetry of Small and Nonstandard Fields
Benjamin Rosen (student of Dr. Larry DeWerd)
Research Assistant, Dept of Medical Physics, UW-School of Medicine & Public Health, Madison, WI - USA
Radiotherapy treatments with small and nonstandard fields are increasing in use as collimation and targeting become more advanced, which spare normal tissues while increasing tumor dose. However, dosimetry of small and nonstandard fields is more difficult than that of conventional fields due to loss of lateral charged-particle equilibrium, tight measurement setup requirements, and the volume-averaging effect of one-dimensional dosimeters. This work aims to create new two-dimensional dosimetry protocols using radiochromic film in conjunction with novel readout and analysis methodologies. Specifically, a point-by-point precision densitometer and a microdosimetric model of radiochromic film response are characterized for their ability to provide accurate dosimetry based on the underlying physics of the radiochromic mechanism.