Share Email Print
cover

Journal of Medical Imaging

Calculation of the entrance skin dose distribution for fluoroscopically guided interventions using a pencil beam backscatter model
Format Member Price Non-Member Price
PDF $20.00 $25.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

Radiation backscattered from the patient can contribute substantially to skin dose in fluoroscopically guided interventions (FGIs). The distribution of backscatter is not spatially uniform, and use of a single backscatter factor cannot provide an accurate determination of skin dose. This study evaluates a method to determine the backscatter spatial distribution through convolution of a backscatter-to-primary (BP) point spread function (PSFn). The PSFn is derived for a pencil beam using EGSnrc Monte Carlo software and is convolved with primary distributions using a dose-tracking system. The backscatter distribution calculated using the convolution method is validated with Monte Carlo-derived distributions for three different size “uniform” fields and with XR-QA2 Gafchromic film for nonuniform x-ray fields obtained using region-of-interest (ROI) attenuators and compensation filters, both with homogenous poly-methyl methacrylate and nonhomogenous head phantoms. The BP ratios inside uniform fields were calculated within ± 2 % of that determined using EGSnrc. For shaped fields, the BP ratio in the unattenuated ROI was calculated within ± 3 % of that measured with film; in the beam-attenuated periphery, agreement was within ± 17 % , due to the larger uncertainty of the dose-response curve of the film in the low-dose region. This backscatter PSFn convolution method is much faster than performing full-field Monte Carlo calculations and provides improved accuracy in skin dose distribution determination for FGI procedures.

Paper Details

Date Published: 14 June 2017
PDF: 10 pages
J. Med. Imag. 4(3) 031203 doi: 10.1117/1.JMI.4.3.031203
Published in: Journal of Medical Imaging Volume 4, Issue 3
Show Author Affiliations
Sarath Vijayan, Univ. at Buffalo (United States)
Toshiba Stroke and Vascular Research Ctr. (United States)
Zhenyu Xiong, Univ. at Buffalo (United States)
Toshiba Stroke and Vascular Research Ctr. (United States)
Stephen Rudin, Univ. at Buffalo (United States)
Toshiba Stroke and Vascular Research Ctr. (United States)
Daniel R. Bednarek, Univ. at Buffalo (United States)
Toshiba Stroke and Vascular Research Ctr. (United States)


© SPIE. Terms of Use
Back to Top