99Tcm-MDP全身骨显像受检者外照射剂量的研究

目的 研究99Tcm-亚甲基二膦酸盐（MDP）全身骨显像受检者对非核医学科人员的外照射剂量，以有效减少非受检者的受照辐射剂量。 方法 选取 2018年8月至2019年1月在中国科学技术大学附属第一医院行99Tcm-MDP全身骨显像的51例受检者进行回顾性研究，其中男性26例、女性25例，年龄22~91（62.23±13.36）岁。所有受检者注射925 MBq 99Tcm-MDP后，根据饮水1000 mL后0.5 h内有无排尿分为排尿组（n=39）和未排尿组（n=12），检测注射药物后0.5、1、2、3、4、6 h时受检者腹部和头部水平距离0.5、1、2、4、6 m处的辐射剂量当量率和累积剂量当量。2组间比较采用两独立样本的Mann-Whitney U检验，多次测量的不同时间、不同距离辐射剂量当量率的比较采用重复测量方差分析，配对样本采用非参数Wilcoxon检验。 结果 排尿组受检者在腹部水平距离0.5、1、2、4、6 m处的辐射剂量当量率均低于未排尿组（40.29±4.67）μSv/h对（77.29±10.71）μSv/h、（15.22±1.64）μSv/h对（29.48±4.56）μSv/h、（4.15±0.47）μSv/h对（7.45±1.07）μSv/h、（1.32±0.10）μSv/h对（2.63±0.31）μSv/h、（0.45±0.05）μSv/h对（0.78±0.15）μSv/h]，且差异均有统计学意义（Z=5.148~5.251，均P<0.001）。排尿组受检者腹部和头部的辐射剂量当量率均随着时间和距离的增加而迅速降低，且差异有统计学意义（F=3105.426~5397.675，均P<0.001）；排尿组受检者的辐射剂量当量率随着药物注射后时间的延长而显著下降。与排尿组受检者腹部水平距离0.5 m处6 h的累积剂量当量（148.51±13.83）μSv]相比，1 m处6 h的累积剂量当量（55.85±5.22）μSv]显著下降，且差异有统计学意义（Z=5.610，P<0.001）；与排尿组受检者头部水平距离0.5 m处6 h的累积剂量当量（132.74±12.95）μSv]相比，1 m处6 h的累积剂量当量（49.88±4.72）μSv]显著下降，且差异有统计学意义（Z=5.438，P<0.001）；排尿组受检者的累积剂量当量随着照射时间的延长而增加、随着距离的增加而减少。 结论 99Tcm-MDP全身骨显像对于非核医学科人员的照射剂量远远小于国内、国际法律规定限值（个人年有效剂量当量≤1 mSv），与注射药物后3 h的受检者距离1 m以上即可避免大部分额外辐射。

External exposure dose of 99Tcm-MDP from subjects awaiting whole-body bone scan

Objective To analyze the radiation-exposure dose of non-nuclear medical staff from patients who had undergone 99Tcm-MDP administration for whole-body bone scan. Methods From August 2018 to January 2019, 51 subjects who had undergone whole-body bone scan in our department were selected. The subjects were injected with 925 MBq 99Tcm-MDP and had drunk 1000 mL of water. They were divided into two groups, namely, micturition and non-micturition groups within 0.5 h. The equivalent dose rates of external radiation 0.5, 1, 2, 4, and 6 m away from the head or abdomen of the subject were measured at 0.5, 1, 2, 3, 4, and 6 h after 99Tcm-MDP injection and water drinking by using an χ, γ dosimeter. The Mann-Whitney U test of two independent samples was used to compare two groups. Repeated-measurement ANOVA was used to compare different times and distances of multiple measurements. The nonparametric Wilcoxon Z test was used for paired samples. Results The radiation equivalent dose rates of 0.5, 1, 2, 4, and 6 m in the urination group were significantly lower than those in the non-urination group (40.29±4.67) μSv/h vs. (77.29±10.71) μSv/h, (15.22±1.64) μSv/h vs. (29.48±4.56) μSv/h, (4.15±0.47) μSv/h vs. (7.45±1.07) μSv/h, (1.32±0.10) μSv/h vs. (2.63±0.31) μSv/h, (0.45±0.05) μSv/h vs. (0.78±0.15) μSv/h], and the differences were statistically significant (Z=5.197, 5.148, 5.251, 5.199, and 5.202, respectively; all P<0.001). The radiation equivalent dose rates of the abdominal or head level in the urination group decreased rapidly with prolonged time (F=5397.675 and 4834.512, respectively; both P<0.001) and with increased distance (F=3459.712 and 3105.426, respectively; both P<0.001), and the differences were statistically significant. Meanwhile, the cumulative equivalent dose increased with prolonged time and decreased distance. Compared with the 6 h cumulative dose equivalent (148.51±13.83) μSV at 0.5 m of abdominal horizontal distance in urination group, the 6 h cumulative dose equivalent (55.85±5.22) μSV at 1 m of abdominal horizontal distance in urination group decreased significantly (Z=5.610, P<0.001). Compared with the 6 h cumulative dose equivalent (132.74±12.95) μSV at 0.5 m of head horizontal distance in urination group, the 6 h cumulative dose equivalent (49.88±4.72) μSV at 1 m of head horizontal distance in urination group decreased significantly (Z=5.438, P<0.001). The cumulative dose equivalent in urination group increased with the extension of irradiation time and decreased with the increase of distance. Conclusion The external exposure dose of 99Tcm-MDP from patients awaiting whole-body bone scan was far less than the limitation (≤1 mSv/year per individual) set by domestic and international legal rules for non-nuclear medical staff. Most of the exposure risks of non-nuclear medicine staff to 99Tcm-MDP from patients could be avoided by staying more than 1 m from the patient 3 h after injection.