术前125I粒子活度检测对剂量准确性影响的价值分析
The effect of pre-operation 125I seed activity measuring on dose accuracy
目的 探讨术前检测放射性125I粒子活度,对剂量准确性影响.方法 选取河北省人民医院于2017年11月1至30日行125I粒子植入的10例患者.术前1d用井型电离室分别测量A、B公司各100颗粒子的实际活度(记为A、B组),与标定粒子活度22.2 MBq(C组)对比,并计算A、B组与C组的活度误差.首先选择22.2 MBq制定术前计划,处方剂量100 ~140 Gy,得出90%靶体积所接受的剂量(Dg0)、150%处方剂量覆盖的体积占靶体积百分率(V150)、100%处方剂量覆盖的体积占靶体积百分率(V100),然后将22.2 MBq更换为A、B组的实测平均活度,得出D90、V100、V150.比较C组与A、B组的D90、V100、V150差异.对比10例粒子植入患者采用标定活度与实测的平均活度,做术前计划时的剂量学差异分析.结果 A、B组术前1d的实际活度分别为(22.6±0.7)、(23.9±0.9)MBq,和标定活度对比,差异均有统计学意义(分别为t=5.7、P<0.05和t=19.2、P<0.05),且B组的活度误差>5%.A、B、C组的D90分别为(124.3±9.7)、(131.2±10.2)、(121.9±9.5) Gy,V150分别为58.4%±9.4%、63.7%±8.9%、56.5%±9.2%,V100分别为88.9%±5.0%、92.0%±4.1%、88.1%±5.2%.C组与A、B组的D90比较,差异均有统计学意义(分别为t=40.2、P<0.05和t=40.3、P<0.05);C组与A、B组的V150比较,差异均有统计学意义(分别为t=7.5,P<0.05和t=24.7,P <0.05);C组与A、B组的V100比较,差异均有统计学意义(分别为t=6.6、P<0.05和t=7.3、P<0.05).结论 放射性粒子的实测活度与公司标定活度有差异,可影响术前计划剂量参数.粒子植入前应严格检测活度,根据实测粒子活度制定术前计划.
更多Objective To measure the activity of 125I seed and compare the dose difference of ten patients treated with seed implantation in pre-plan with actual seed activity and calibrate activity.Method The activity of 100 seeds from company A and B was measured with a well-type ionization chamber 1 day before operation and named group A and B.The activity of two groups was compared and the error between actual and calibrate activity (22.2 MBq,group C) was calculated.Ten patients implanted with 125I seeds from November 1 st to 30 th,2017,solstice 30 were selected in Hebei General Hospital.Firstly,pre-plans were designed with 22.2 MBq,prescribed dose were 100-140 Gy.The dose parameters of 90% volume absorbed dose (D90),150% volume fraction (V150) and 100% volume fraction (V100) were calculated.Then changed 22.2 MBq to actual activity of group A and B,calculated the dose parameters above again.Then dose parameters of D90,V150,V100 in group C were compared with those in group A and B respectively.Result The actual activity 1 day before the operation was (22.6 ± 0.7) and (23.9 ± 0.9) MBq in group A and B respectively.Compared with 22.2 MBq,the difference was statistically significant (t =5.7,P < 0.05 and t =19.2,P < 0.05),and the activity error of group B was greater than 5 %.The Dg0 of group A,B and C were (124.3 ±9.7),(131.2 ± 10.2) and (121.9 ±9.5) Gy respectively.The V150 were 58.4% ±9.4%,63.7%±8.9% and 56.5% ±9.2% respectively.The V100 were 88.9% ±5.0%,92.0% ±4.1%,88.1% ± 5.2% respectively.The difference of D90 between calibrate activity (group C) and actual activity (group A and B) were statistically significant (t =40.2,P <0.05 and t =40.3,P <0.05).The difference of V150 between group C and group A and B were statistically significant (t =7.5,P < 0.05 and t =24.7,P < 0.05).The difference of V100 between group C and group A and B were statistically significant (t =6.6,P < 0.05 and t =7.3,P < 0.05).Conclusion There is difference between the actual activity and calibration activity.The difference affects the dose parameters in pre-plan.The seed activity should be measured before operation strictly and the pre-plan should be designed with the actual activity.
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