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Dosimetry of a W‐188/Re‐188 beta line source for endovascular brachytherapy
Author(s) -
Häfeli Urs O.,
Roberts William K.,
Meier Dominik S.,
Ciezki Jay P.,
Pauer Gayle J.,
Lee Eric J.,
Weinhous Martin S.
Publication year - 2000
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 - 10.1118/1.598928
Subject(s) - dosimetry , brachytherapy , nuclear medicine , monte carlo method , materials science , neutron source , radioactive source , radiochemistry , neutron , physics , nuclear physics , medicine , optics , chemistry , radiology , radiation therapy , mathematics , statistics , detector
Purpose : The objective was to determine the dosimetry of a potential endovascular brachytherapy source consisting of a coiled tungsten wire mounted on the distal end of a drive wire and neutron‐activated to contain the parent–daughter nuclides tungsten‐188 ( 188 W ) and rhenium‐188 ( 188 Re ) .Methods : A coiled tungsten wire 40 mm in length was neutron‐activated by double‐neutron capture for 78 hours at1.9 × 10 15 h / cm 2/ s to contain 925 MBq (25 mCi) of188 W / 188 Re in equilibrium. The dose‐fall off from this source was determined using three independent methods: (a) Thermoluminescence dosimetry with small LiF‐100 rods, (b) Gafchromic film dosimetry, and (c) Bang gel dosimetry. In addition, a Monte Carlo simulation was performed to compute the beta‐dose. Results : Each of the three measurement methods recorded similar values for the dose fall‐off within the distances useful for endovascular brachytherapy. The Monte Carlo calculations closely approximated the measured results in the treatment range between 1 and 3 mm and may thus be useful for evaluating changing geometries in the development of catheters and source setups. A 2 min restenosis treatment delivering 20 Gy at a radius of 2 mm would require a source of 1384.8 MBq/cm (37.4 mCi/cm). Conclusions : The dose distribution from a188 W / 188 Re source is similar to that of a90 Y ‐source. An added advantage of the188 W / 188 Re source is that it can be used for at least two months and still provides fast treatment times because of the parent isotope's half‐life of 69 days. The additional gamma emission from the source is too small to impose a serious radiological hazard. The high atomic number and density of the source material allows direct fluoroscopic imaging without additional markers.