Schaart Dennis R, Bos Adrie J J, Winkelman August J M, Clarijs Martijn C
Nucletron BV, Veenendaal, The Netherlands.
Phys Med Biol. 2002 Oct 21;47(20):3605-27. doi: 10.1088/0031-9155/47/20/304.
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.
利用一种新型超薄型LiF:Mg,Cu,P热释光探测器（TLD），在聚甲基丙烯酸甲酯（PMMA）模体中测量了已知活度的188W/188Re原型β粒子线源的径向深度剂量分布。该血管内近距离治疗源的测量径向剂量函数与MCNP4C蒙特卡罗模拟结果吻合良好，模拟结果表明，在距源轴径向距离1毫米至5毫米之间，188Re对剂量的贡献≥99%。TLD使用90Sr/90Yβ二级标准进行校准。使用解析方法和蒙特卡罗方法计算了几个校正因子，并对测量不确定度进行了分析。由于它部分由随机效应产生的不确定度分量决定，重复测量会产生较低的不确定度。在径向距离2毫米处，绝对剂量的扩展不确定度对于1次、2次、3次和5次测量分别为11%、10%、9%和8%。在对源的不均匀性进行校正后，在径向距离2毫米处每单位源活度的测量剂量率等于(1.53±0.16) Gy min(-1) GBq(-1)（2σ），与MCNP4C模拟预测的值(1.45±0.01) Gy min(-1) GBq(-1)（2σ）一致。
