The radial depth-dose distribution of a 188W/188Re beta line source measured with novel, ultra-thin TLDs in a PMMA phantom: comparison with Monte Carlo simulations.
The radial depth-dose distribution of a prototype 188W/188Re beta particle line source of known activity has been measured in a PMMA phantom, using a novel, ultra-thin type of LiF:Mg,Cu,P thermoluminescent detector (TLD). The measured radial dose function of this intravascular brachytherapy source agrees well with MCNP4C Monte Carlo simulations, which indicate that 188Re accounts for > or = 99% of the dose between 1 mm and 5 mm radial distance from the source axis. The TLDs were calibrated using a 90Sr/90Y beta secondary standard. Several correction factors are calculated using analytical and Monte Carlo methods. An analysis of the measurement uncertainty is made. Since it is partly determined by components of uncertainty arising from random effects, repeated measurements yield a lower uncertainty. The expanded uncertainty in the absolute dose at 2 mm radial distance equals 11%, 10%, 9% and 8% for 1, 2, 3 and 5 measurements, respectively. After a correction for source non-uniformity, the measured dose rate per unit source activity at 2 mm radial distance equals (1.53 +/- 0.16) Gy min(-1) GBq(-1) (2sigma), in agreement with the value of (1.45 +/- 0.01) Gy min(-1) GBq(-1) (2sigma) predicted by the MCNP4C simulations.
Schaart
Dennis R
DR
Nucletron BV, Veenendaal, The Netherlands. schaart@iri.tudelft.nl
Bos
Adrie J J
AJ
Winkelman
August J M
AJ
Clarijs
Martijn C
MC
D001610:Beta Particles / Q000627:therapeutic use; D001918:Brachytherapy / Q000295:instrumentation* / Q000379:methods; D003198:Computer Simulation; D004867:Equipment Design; D019544:Equipment Failure Analysis / Q000379:methods; D009010:Monte Carlo Method; D009532:Nickel; D019047:Phantoms, Imaging; D010865:Pilot Projects; D019904:Polymethyl Methacrylate; D011829:Radiation Dosage; D011868:Radioisotopes / Q000627:therapeutic use*; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012211:Rhenium / Q000627:therapeutic use; D012680:Sensitivity and Specificity; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation* / Q000379:methods; D014025:Titanium; D014414:Tungsten / Q000627:therapeutic use
D011868:Radioisotopes; C040654:titanium nickelide; D012211:Rhenium; D009532:Nickel; D019904:Polymethyl Methacrylate; D014025:Titanium; D014414:Tungsten