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Positional radiotherapy beam dosimetry using a laser heated thermoluminescent plate
Author(s) -
Kearfott Kimberlee J.,
GrupenShemansky Melissa E.
Publication year - 1990
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.596580
Subject(s) - dosimetry , optics , laser , materials science , laser beam quality , beam (structure) , ionization chamber , thermoluminescent dosimetry , radiation , dose profile , thermoluminescent dosimeter , thermoluminescence , nuclear medicine , ionization , laser beams , optoelectronics , physics , dosimeter , luminescence , medicine , ion , quantum mechanics
A 4‐W, laser‐based system for the positional readout of thermoluminescent (TL) plates was utilized to obtain dose profiles for a Co 60radiotherapy beam. Experimentally obtained glow curves for LiF resulting from the rapid heating rates characteristic of laser heating agreed well with results predicted using a first‐order kinetic model. Excellent system linearity was obtained for sensitivity to Co 60 . The useful dynamic range for this tissue‐equivalent system could extend over 8 orders of magnitude. A minimum detectable signal of 1.2 R was estimated for the presently configured system, whose spatial resolution is limited by the laser beam diameter, 1.7 mm. Depth dose profiles for the radiotherapy beam obtained using the prototype laser TL system with a specially designed composite 2.2 cm×3.3 cm×0.254 mm LiF plate agreed to within 14% of ionization chamber measured doses.