肺通气显像剂锝气体内照射吸收剂量估算

Dosimetry of Technegas in lung ventilation studies

目的估算锝气体(Technegas)肺显像内照射吸收剂量。方法 8名健康志愿者,单次吸入 Technegas(46.71±19.02)MBq 后,采用连续显像方法估算各时间点全身及肺等主要器官的放射性,并将原始数据转换为百分吸人剂量率(%ID)后拟合时间-放射性曲线,求单位累积活度。应用MIRDOSE 3.0软件,估算肺及全身各主要器官的平均吸收剂量。结果肺为平均吸收剂量最高的器官[(9.8±1.2)×10^(-2)mGy/MBq],此后依次为胃[(1.7±1.2)×10^(-2)mGy/MBq]、心脏壁[(1.2±0.17)×10^(-2)mGy/MBq]、甲状腺[(8.3±5.9)×10^(-3)mGy/MBq]、肝[(7.8±2.8)×10^(-3)mGy/MBq]和肾[(7.6±3.0)×10^(-3)mGy/MBq],全身有效剂量当量为(1.6±0.37)×10^(-2)mSv/MBq。结论虽然 Technegas 肺通气显像中受试者接受的有效剂量明显高于^(99)Tc^m-DTPA 气溶胶、^(81)Kr^m 及^(133)Xe 等肺通气显像剂,但是参考 WHO 推荐的生物医药研究中健康志愿者的年累积有效剂量限值和国际辐射防护委员会(ICRP)辐射危险分类标准(ICRP 62),该有效剂量是可以接受的低剂量。

Objective Techenegas is an ultra-fine dispersion of carbon aggregates labeled with 99^Tc^m developed for lung ventilation scanning. The purpose of this study was to investigate the dosimetry of Technegas in healthy volunteers. Methods In 8 healthy volunteers a single inhalational dose of （46.71 ± 19.02） MBq was administered. Biodistribution was assessed for up to 24 h by a gamma camera. The counts from ROIs were obtained over the critical organs. The residence of activity in each critical organ and wholebody were computed via the area under their time-activity curves. The medical internal radiation dose （MIRD） formulation was used to calculate the absorbed radiation dose for various organs. Results On average, The highest absorbed dose was received by lung [ （9.8 ± 1.2） × 10^-2 mGy/MBq] followed by stom- ach [（1.7±1.2）×10^-2 mGy/MBq], heart wall [（1.2 ±0.17） × 10^-2 mGy/MBq], thyroid [（8.3 ± 5.9） ×10^-3 mGy/MBq], liver [（7.8 ±2.8） ×10^-3 mGy/MBq] and kidney [（7.6 ±3.0） ×10^-3 mGy/ MBq]. The estimated mean effective dose was （1.6±0.37） ×10^-2 mSv/MBq. Conclusion Although the effective absorbed dose of Technegas is much higher than 99^Tc^m-DTPA aerosol, 81^Kr^m and 133^Xe, it results in an acceptable effective dose to the patient according to the recommended dose constraints of adult volunteers in biomedical research （WHO） and risk categories stated in International Commission on Radiological Protection （ICRP） 62.