病人皮肤剂量监测仪在放射治疗的临床应用  

Application of patient skin dosimeter in radiotherapy:a preclinical assessment

作　　者：董晓庆[1] 林清[1] 胡杰[1] 黄亮[2] 张佳斐 陆春花[1] 岳堃[3] 

机构地区：[1]同济大学附属第十人民医院肿瘤放射治疗科,上海200072 [2]同济大学附属第十人民医院医疗设备和材料管理处,上海200072 [3]上海交通大学医学院附属第九人民医院(北院)放疗科,上海201999

出　　处：《中国医学物理学杂志》2017年第4期363-370,共8页Chinese Journal of Medical Physics

基　　金：院内攀登人才计划项目

摘　　要：目的:对病人皮肤剂量监测仪(PSD)进行放射治疗临床前性能测试及评价。方法:在标准定标条件下(SSD=100cm,照射野10 cm×10 cm),通过PTW剂量仪、0.6 cc电离室和水箱测量将加速器各档X线和电子线定标到最大剂量点处100MU对应为100 c Gy。以6 MV X射线为射线源,在加速器分别开机100和200 MU条件下,对PSD进行重复性测量并根据贝塞尔公式计算重复性指数S。在6 MV、6 MeV、9 MeV、12 MeV、15 MeV条件下,对PSD进行线性检测并建立剂量与PSD读数的线性关系,通过最小二乘法拟合线性方程。以6 MV X射线为射线源,测量有无PSD探头时,组织不同深度吸收剂量的差异并测得PDD曲线。结果:经PSD重复性计算,在100和200 MU条件下,对于黑探头,重复性指数分别为0.029%、0.025%;对于红探头,重复性指数分别为0.040%、0.043%。对于PSD的线性偏差,在15 MeV条件下,黑探头和红探头线性偏差分别为1.08%、1.10%,其余各挡能量的线性偏差均小于1.00%。在6 MV、6 MeV、9 MeV、12 MeV、15 MeV条件下,对PSD两个探头,均拟合得出线性方程,方便PSD读数转化为实际剂量。比较有无PSD探头组织不同深度吸收剂量以及PDD曲线的差异,当加PSD探头后,最大剂量点往组织表面迁移,最大剂量点约在组织深度1.1 cm处。加PSD探头后,最大剂量深度处前,组织吸收剂量有所增加;最大剂量深度处后,组织吸收剂量有所减少。其中,对于黑探头和红探头,在组织表面加探头后组织吸收剂量分别增加39.76%、43.77%;在0.5 cm深度处吸收剂量分别增加4.62%、4.91%;在3.0 cm处剂量分别减少0.92%、1.09%。由于该探头尺寸是0.4 cm×1.5 cm×1.5 cm,对于临床射野大小而言,实际剂量影响很小。结论:PSD的各项性能指标均满足国际国内通用标准,并且PSD对病人真实剂量影响很小,可以用于放射治疗临床病人皮肤测量。Objective To evaluate the pertbnnance of patient skin dosimeter （PSD） for potential clinical application in radiotherapy. Methods Under the condition of standard calibration （SSD=100 cm with a radiation field of 10 cm× 10 cm） and using the PTW dosimeter, 0.6 cc ionization chamber, and the water tank, the X-ray and electron beam at each level of the accelerator was calibrated to the maximum dose point of 100 MU （corresponding to 100 cGy）. With 6 MV X-ray as the radiation source, the repeatability of PSD was assessed at the levels of 100 MU and 200 MU of the accelerator, and the repeatability index S was calculated according to the Bessel formula. At the energy levels of 6 MV, 6 MeV, 9 MeV, 12 MeV, and 15 MeV, the linearity of the PSD was measured to establish a linear relationship between the dose and PSD readings, and the linear equations were fitted using the least squares method. The differences in the absorbed dose at different tissue depths and the PDD curves were measured with 6 MV X-ray as the radiation source either in the presence or absence of the PSD probes. Results At 100 MU and 200 MU, the repeatability index of the black probe was 0.029% and 0.025%, and that of the red probe was 0.040% and 0.043%, respectively. At the energy level of 15 MeV, the linear deviations of PSD were 1.08% and 1.10% for the black probe and the red probe,respectively, and the linear deviations were less than 1.00% at other energy levels. At the energy levels of 6 MV, 6 MeV, 9 MeV, l 2 MeV, and 15 MeV, the linear equations were fitted to translate the PSD readings into the actual dose. Measurement of the absorbed dose and PDD curves showed that in the presence of the PSD probe, the maximum dose point shifted toward the tissue suH＇ace to the tissue depth of 1.1 cm; the absorbed dose at the depth before the maximum dose point increased and that alter the maximum dose point decreased. For the black and red probe, the absorbed doses increased by 39.76% and 43.77% at the tissue surface and by 4.62% and 4.91% at the de

关 键 词：病人皮肤剂量监测仪 直线加速器 放射治疗 剂量 

分 类 号：R730.55[医药卫生—肿瘤] R811.1[医药卫生—临床医学]