热释光剂量仪测量体模植入125I粒子源的剂量学参数可行性

目的 探讨应用热释光剂量仪在体模中测量植入¹²⁵I粒子源(型号Sinko BT-125-1)的剂量学参数可行性。方法 将测量体模进行改进使其可适用于剂量学测量。根据AAPM TG43建议测量的参数包括剂量率常数Λ、径向剂量函数g_L(r)和各向异性函数F (r, θ)等,所测数据与文献中其他构造相似的¹²⁵I粒子源数据进行比较。结果 ¹²⁵I粒子源的Λ为0.928cGyh^－1U^－1。所测得的g_L(r)范围为径向距离在1.0~10.0 cm内所对应的值。F (r,θ)范围为角度在0°~90°内所对应的值。与型号Amersham 6711¹²⁵I粒子源相比,二者g_L(r)值的最大差异为9.6%。二者F (r=2 cm, θ=0)值的差异为10.2%。应用此体模进行测量总的不确定度<6.0%。

Experimental determination of dosimetry parameters for Sinko 125I seed source using thermolumine-scent dosimeter

Objective To study the dosimetry parameters of ¹²⁵I seed source (type Sinko BT-125-1) with thermoluminescent dosimeter (TLD) in the phantom. Methods The new type of phantom was modified to suit to measurement of a common type of ¹²⁵I seed source. The AAPM TG43 protocol recommended measurements of dose-rate constant (Λ), radial dose function (g_L(r)), and anisotropy function (F (r,θ)) have been performed in the phantom with TLD. Results The Λ was 0.928 cGyh^－1U^－1. The g_L(r) was determined at different radial distances r ranging from 1.0 to 10.0 cm with an interval of 1.0 cm;and F (r,θ) at angles from 0° to 90° in 10° increments. The g_L(r) of ¹²⁵I seed source showed a difference of 9.6% at the most in comparison to the corresponding values of ¹²⁵I seed source (type Amersham 6711). The difference in F(2 cm,θ) of ¹²⁵I seed source and Amersham 6711 was up to 10.2% near the source end. With the phantom the combined standard uncertainty in the whole measurement was less than 6.0%. Conclusions The experimental results exhibit fairly small measurement uncertainties and good self-consistency. It′s feasible to measure the dosimetry characters of permanent implant seeds in the modified phantom.