Linked Life Data

8455503

Source:http://linkedlifedata.com/resource/pubmed/id/8455503

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1993-4-19
pubmed:abstractText
The influence of tissue and applicator heterogeneities on brachytherapy dose distributions is not well understood, despite widespread use of shielded applicators in intracavitary therapy. Heterogeneity correction factors (HCF) have been measured using a silicon diode detector arising from bounded heterogeneities consisting of lead, steel, titanium, silver, aluminum, and air cylinders near brachytherapy sources of 125I, 137Cs, and 192Ir. In addition, transverse-axis dose distributions for the three sources in homogeneous water were measured for distances of 0.2 to 16.0 cm. For each point of measurement, relative diode readings were simulated by a Monte Carlo photon transport code utilizing accurate models of the source internal structure, the experimental measure geometry and the source-strength calibration geometry. Comparison of measured and calculated HCF's reveals excellent agreement (1%-3% average) over a wide range of materials, diameters, and thicknesses. In addition, Monte Carlo simulation not only accurately reproduced the relative transverse-axis dose distributions in homogeneous medium, but was able to predict the variation of diode response with photon energy with an accuracy of 3% over the range of 30-662 keV. Our measurements demonstrate that HCF's vary by as much as 60%-100% with distance and heterogeneity diameter for a fixed thickness. Finally, silicon diode measurements of HCF (denied as reading with heterogeneity/reading in homogeneous medium) is shown to lead to errors of 5%-30% for 137Cs and 192Ir sources in the presence of high-atomic number shielding materials. This paper concludes, that Monte Carlo simulation is a powerful, convenient and accurate tool for investigating the long-neglected area of brachytherapy heterogeneity corrections.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0094-2405
pubmed:author
pubmed:issnType
Print
pubmed:volume
20
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
209-22
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:articleTitle
Comparison of calculated and measured heterogeneity correction factors for 125I, 137Cs, and 192Ir brachytherapy sources near localized heterogeneities.
pubmed:affiliation
Radiation Oncology Center, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S.