Premium
Monte Carlo calculations of dose distributions around 32 P and 198 Au stents for intravascular brachytherapy
Author(s) -
Reynaert N.,
Verhaegen F.,
Taeymans Y.,
Van Eijkeren M.,
Thierens H.
Publication year - 1999
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.598644
Subject(s) - stent , monte carlo method , brachytherapy , dosimetry , nuclear medicine , percentage depth dose curve , absorbed dose , materials science , restenosis , biomedical engineering , physics , radiology , medicine , ionization chamber , radiation therapy , mathematics , ion , statistics , quantum mechanics , ionization
3D dose distributions are calculated for a32 P impregnated stent and a198 Au stent for intravascular brachytherapy with the EGS4 Monte Carlo simulation code. The stents were modeled as a combination of eight helicoidal struts. This allowed investigation of the effect of the stent geometry and the electron absorption in the strut material on the dose distributions. Absorbed dose to water was calculated at radial distances ranging from 50 μm to 5 mm from the stent surface. The dose distributions around the stents are compared to the dose distribution around an intravascular brachytherapy192 Ir source, also calculated with the EGS4 Monte Carlo code. The dose profiles near the struts show hot spots. At 50 μm distance a peak to valley ratio of 3 for32 P and 6 for198 Au in the dose distribution is obtained. For both the isotopes the inhomogeneities decrease with distance and at a radial depth of 350 μm the effect becomes negligible. The calculations showed the importance of the effect of the absorption in the stent material as this leads to a dose decrease to 67% for the198 Au stent and to 77% for32 P near the stent at a distance of 2 mm from the stent axis. It is concluded that from the dosimetric point of view, the198 Au stent is inferior to the32 P stent and the192 Ir source. Application of the198 Au stent in clinical practice requires further investigation of the importance of the adventitia in the restenosis process, and the tolerance dose of the intima.