Open AccessPhysical validation of UF ‐ RIPSA : A rapid in‐clinic peak skin dose mapping algorithm for fluoroscopically guided interventions
Author(s) -
Borrego David,
Marshall Emily L.,
Tran Trung,
Siragusa Daniel A.,
Bolch Wesley E.
Publication year - 2018
Publication title -
journal of applied clinical medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.83
H-Index - 48
ISSN - 1526-9914
DOI - 10.1002/acm2.12312
Subject(s) - imaging phantom , dosimeter , monte carlo method , irradiation , materials science , nuclear medicine , dose profile , biomedical engineering , physics , medicine , dosimetry , mathematics , statistics , nuclear physics
Purpose The purpose of this study was to experimentally validate UF ‐ RIPSA , a rapid in‐clinic peak skin dose mapping algorithm developed at the University of Florida using optically stimulated luminescent dosimeters ( OSLD s) and tissue‐equivalent phantoms. Methods The OSLD s used in this study were InLight TM Nanodot dosimeters by Landauer, Inc. The OSLD s were exposed to nine different beam qualities while either free‐in‐air or on the surface of a tissue equivalent phantom. The irradiation of the OSLD s was then modeled using Monte Carlo techniques to derive correction factors between free‐in‐air exposures and more complex irradiation geometries. A grid of OSLD s on the surface of a tissue equivalent phantom was irradiated with two fluoroscopic x ray fields generated by the Siemens Artis zee bi‐plane fluoroscopic unit. The location of each OSLD within the grid was noted and its dose reading compared with UF ‐ RIPSA results. Results With the use of Monte Carlo correction factors, the OSLD 's response under complex irradiation geometries can be predicted from its free‐in‐air response. The predicted values had a percent error of −8.7% to +3.2% with a predicted value that was on average 5% below the measured value. Agreement within 9% was observed between the values of the OSLD s and RIPSA when irradiated directly on the phantom and within 14% when the beam first traverses the tabletop and pad. Conclusions The UF ‐ RIPSA only computes dose values to areas of irradiated skin determined to be directly within the x ray field since the algorithm is based upon ray tracing of the reported reference air kerma value, with subsequent corrections for air‐to‐tissue dose conversion, x ray backscatter, and table/pad attenuation. The UF ‐ RIPSA algorithm thus does not include the dose contribution of scatter radiation from adjacent fields. Despite this limitation, UF ‐ RIPSA is shown to be fairly robust when computing skin dose to patients undergoing fluoroscopically guided interventions.