Physical validation of UF‐RIPSA: A rapid in‐clinic peak skin dose mapping algorithm for fluoroscopically guided interventions

Abstract 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 (OSLDs) and tissue‐equivalent phantoms. Methods The OSLDs used in this study were InLightTM Nanodot dosimeters by Landauer, Inc. The OSLDs 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 OSLDs was then modeled using Monte Carlo techniques to derive correction factors between free‐in‐air exposures and more complex irradiation geometries. A grid of OSLDs 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 OSLDs 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.

[1]  E G Yukihara,et al.  Optically stimulated luminescence (OSL) dosimetry in medicine , 2008, Physics in medicine and biology.

[2]  Teresa Wu,et al.  Validation and initial clinical use of automatic peak skin dose localization with fluoroscopic and interventional procedures. , 2013, Radiology.

[3]  Stephen Rudin,et al.  Verification of the performance accuracy of a real-time skin-dose tracking system for interventional fluoroscopic procedures , 2011, Medical Imaging.

[4]  S Rudin,et al.  A tracking system to calculate patient skin dose in real-time during neurointerventional procedures using a biplane x-ray imaging system. , 2016, Medical physics.

[5]  Stephen Balter,et al.  A hybrid phantom system for patient skin and organ dosimetry in fluoroscopically guided interventions , 2017, Medical physics.

[6]  J. Valentin.  Basic anatomical and physiological data for use in radiological protection: reference values , 2002, Annals of the ICRP.

[7]  Cynthia H McCollough,et al.  A method to generate equivalent energy spectra and filtration models based on measurement for multidetector CT Monte Carlo dosimetry simulations. , 2009, Medical physics.

[8]  Mahadevappa Mahesh,et al.  Radiation Dose Management for Fluoroscopically Guided Interventional Medical Procedures , 2012 .

[9]  Stephen Balter,et al.  Skin dose mapping for fluoroscopically guided interventions. , 2011, Medical physics.

[10]  J H Siewerdsen,et al.  Spektr: a computational tool for x-ray spectral analysis and imaging system optimization. , 2004, Medical physics.

[11]  J. Boone,et al.  An accurate method for computer-generating tungsten anode x-ray spectra from 30 to 140 kV. , 1997, Medical physics.

[12]  Daniel E. Hyer,et al.  Construction of anthropomorphic phantoms for use in dosimetry studies , 2009, Journal of applied clinical medical physics.

[13]  Stephen Balter,et al.  Fluoroscopically guided interventional procedures: a review of radiation effects on patients' skin and hair. , 2010, Radiology.

[14]  CHARACTERIZATION OF A COMMERCIALLY-AVAILABLE, OPTICALLY-STIMULATED LUMINESCENT DOSIMETRY SYSTEM FOR USE IN COMPUTED TOMOGRAPHY , 2011, Health physics.