The dose distribution around the edges of an improved 32P source for endovascular brachytherapy: A Monte Carlo study

J. Lehmann, K. M. Forster, C. M. Ma, A. L. Boyer

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Endovascular brachytherapy has proven to be an effective tool in the reduction of restenosis following balloon angioplasty for coronary heart disease, while the range of optimal doses and precise target tissue are still unknown. However, over-dosing has been associated with increased thrombogenicity and permanent damage to vessel walls. Under-dosing has been found to stimulate neointima formation, causing restenosis. It has been suggested that restenosis near the edges (edge effect) of the intervention may be caused by the dose falloff towards near the source ends. Monte Carlo code EGS4 was used to calculate the dose distribution around the ends of a Guidant 32P source. At the ends of the source the 100% isodose curve was found to bend back toward the source starting at about 3 mm from the end of the active source (prescription to 2mm radius). The 80% isodose line crossed the prescription line 1 mm from the source ends. Further calculations predicted an improvement can be achieved by changing the specific activity within 1 mm of the ends of the source. A four-fold increase in specific activity in 0.5 mm segments at the ends of the source, followed by a 0.5 mm gap between the ends and the middle part of the source, kept the 100% isodose line at the prescription distance to within 0.5 mm of the active length of the source without any over-dosing. With five times the activity in the terminal segments, a "full length source" is achieved, involving a small over-dosing.

Original languageEnglish (US)
Title of host publicationAnnual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings
EditorsJ.D. Enderle
Pages2679-2681
Number of pages3
Volume4
StatePublished - 2000
Externally publishedYes
Event22nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society - Chicago, IL, United States
Duration: Jul 23 2000Jul 28 2000

Other

Other22nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society
CountryUnited States
CityChicago, IL
Period7/23/007/28/00

Keywords

  • P
  • Dose distribution
  • Edge effect
  • EGS4 Monte Carlo
  • Endovascular brachytherapy

ASJC Scopus subject areas

  • Bioengineering

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  • Cite this

    Lehmann, J., Forster, K. M., Ma, C. M., & Boyer, A. L. (2000). The dose distribution around the edges of an improved 32P source for endovascular brachytherapy: A Monte Carlo study. In J. D. Enderle (Ed.), Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings (Vol. 4, pp. 2679-2681)