Linked Life Data

19336848

Source:http://linkedlifedata.com/resource/pubmed/id/19336848

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
8
pubmed:dateCreated
2009-4-7
pubmed:abstractText
The dosimetry of small fields as used in stereotactic radiotherapy, radiosurgery and intensity-modulated radiation therapy can be challenging and inaccurate due to partial volume averaging effects and possible disruption of charged particle equilibrium. Consequently, there exists a need for an integrating, tissue equivalent dosimeter with high spatial resolution to avoid perturbing the radiation beam and artificially broadening the measured beam penumbra. In this work, radiochromic ferrous xylenol-orange (FX) and leuco crystal violet (LCV) micelle gels were used to measure relative dose factors (RDFs), percent depth dose profiles and relative lateral beam profiles of 6 MV x-ray pencil beams of diameter 28.1, 9.8 and 4.9 mm. The pencil beams were produced via stereotactic collimators mounted on a Varian 2100 EX linear accelerator. The gels were read using optical computed tomography (CT). Data sets were compared quantitatively with dosimetric measurements made with radiographic (Kodak EDR2) and radiochromic (GAFChromic EBT) film, respectively. Using a fast cone-beam optical CT scanner (Vista), corrections for diffusion in the FX gel data yielded RDFs that were comparable to those obtained by minimally diffusing LCV gels. Considering EBT film-measured RDF data as reference, cone-beam CT-scanned LCV gel data, corrected for scattered stray light, were found to be in agreement within 0.5% and -0.6% for the 9.8 and 4.9 mm diameter fields, respectively. The validity of the scattered stray light correction was confirmed by general agreement with RDF data obtained from the same LCV gel read out with a laser CT scanner that is less prone to the acceptance of scattered stray light. Percent depth dose profiles and lateral beam profiles were found to agree within experimental error for the FX gel (corrected for diffusion), LCV gel (corrected for scattered stray light), and EBT and EDR2 films. The results from this study reveal that a three-dimensional dosimetry method utilizing optical CT-scanned radiochromic gels allows for the acquisition of a self-consistent volumetric data set in a single exposure, with sufficient spatial resolution to accurately characterize small fields.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0031-9155
pubmed:author
pubmed:issnType
Print
pubmed:day
21
pubmed:volume
54
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2463-81
pubmed:meshHeading
pubmed:year
2009
pubmed:articleTitle
Three-dimensional dosimetry of small megavoltage radiation fields using radiochromic gels and optical CT scanning.
pubmed:affiliation
Department of Physics and Engineering, London Regional Cancer Program at London Health Sciences Centre, 790 Commissioners Road East, London, Ontario N6 A 4L6, Canada. steven.babic@lhsc.on.ca
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't