Dosimetry of a W-188/Re-188 beta line source for endovascular brachytherapy.
OBJECTIVE
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 (188W) and rhenium-188 (188Re).


METHODS
A coiled tungsten wire 40 mm in length was neutron-activated by double-neutron capture for 78 hours at 1.9 x 10(15) h/cm2/s to contain 925 MBq (25 mCi) of 188W/188Re 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 a 188W/188Re source is similar to that of a 90Y-source. An added advantage of the 188W/188Re 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.
Häfeli
U O
UO
Cleveland Clinic Foundation, Radiation Oncology Department, Ohio 44195, USA. hafeliu@ccf.org
Roberts
W K
WK
Meier
D S
DS
Ciezki
J P
JP
Pauer
G J
GJ
Lee
E J
EJ
Weinhous
M S
MS
D001610:Beta Particles; D001918:Brachytherapy / Q000295:instrumentation / Q000379:methods*; D004583:Electrons; D004730:Endothelium, Vascular / Q000528:radiation effects*; D005373:Film Dosimetry / Q000295:instrumentation / Q000379:methods; D005459:Fluorides / Q000737:chemistry; D005782:Gels; D018020:Lithium Compounds / Q000737:chemistry; D009010:Monte Carlo Method; D011108:Polymers; D011868:Radioisotopes / Q000627:therapeutic use*; D011874:Radiometry / Q000379:methods*; D012211:Rhenium / Q000627:therapeutic use*; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation / Q000379:methods*; D014414:Tungsten / Q000627:therapeutic use*
C106521:BANG polymer gel; D005782:Gels; D018020:Lithium Compounds; D011108:Polymers; D011868:Radioisotopes; C027651:lithium fluoride; D012211:Rhenium; D005459:Fluorides; D014414:Tungsten