Characterization of spectral changes with measurement geometry and magnetic field strength in light guides used for scintillation dosimetry.

Characterization of spectral changes with measurement geometry and magnetic field strength in light guides used for scintillation dosimetry.
Phys Med Biol. 2020 Apr 20;:
Authors: Simiele EA, Kapsch RP, Ankerhold U, Culberson WS, DeWerd LA
Abstract
The purpose of this work was to characterize the stem-effect signal and the Cerenkov light ratio (CLR) in various light guides as functions of measurement geometry and magnetic field strength. Two PMMA-, two silica-, and one polystyrene-based light guides were considered in this work. Spectra measurements were performed as functions of depth, fiber-beam angle, and magnetic field strength using an optical spectrometer. All measurements were performed using a clinical linear accelerator at a nominal photon beam energy of 6MV. Depths ranging from 1cm to 10cm, fiber-beam angles ranging from 90degrees to 30degrees, and magnetic field strengths ranging from 0T to ±1.40T were investigated. The CLR was calculated from each spectrum by taking the ratio of the integral signal between 400nm and 500nm to the integral signal between 500nm and 600nm. A maximum increase of 80.5% in the stem-effect signal was observed in the magnetic field. Variations in spectral shape and, consequently, the CLR were observed for all of the fibers as functions of magnetic field strength and measurement geometry, particularly for wavelengths less than 400nm. The plastic fibers exhibited decreases in the CLR as a function o...

Source: Physics in Medicine and Biology - April 19, 2020 Category: Physics Authors: Simiele EA, Kapsch RP, Ankerhold U, Culberson WS, DeWerd LA Tags: Phys Med Biol Source Type: research