两种放射源活度校准方法对比

目的:研究两种放射源活度的校准方法的差异,讨论其在临床实践中的适用性。方法:通过两种不同的源校准方法测量4颗MicroSelectron Ir-192源。第一种方法用卫生行业标准（WS262-2017）提供的设置（300 V偏压）,在井型电离室的最大灵敏位置测量电荷,用WS262-2017中提供的公式计算放射源活度。第二种方法用井型电离室厂家提供的设置（400 V偏压）,在井型电离室的最大灵敏位置测量电荷,用厂家提供的公式计算放射源活度。对比两种方法的测量结果与理论计算值的偏差。结果:根据WS262-2017和厂家提供的方法测得放射源活度分别为AW和Ap,AW与Ap之间的最小偏差为0.64%,最大偏差为-3.03%;与理论计算值AT相比,AW与AT之间的最小偏差为-0.21%,最大偏差为2.60%;Ap与AT之间的最小偏差为-0.34%,最大偏差为4.13%。结论:根据WS262-2017和PTW方法测得的结果具有较好的一致性。【关键词】后装近距离;井型电离室;放射源活度校准;铱;剂量计算

Comparison of two kinds of calibration methods for the activity of radioactive sources

Abstract: Objective To study the differences between two kinds of calibration methods for the activity of radioactive sources, and discuss their applicabilities in clinical practice. Methods Four MicroSelectron Ir-192 sources were measured using two different calibration methods. In the first method, the electric charge at the most sensitive position of the well-type ionization chamber was measured at the setting (300 V bias) provided by the industry standard?f hygiene (WS262-2017), and the activity of radioactive sources was measured using the formula provided by WS262-2017. In the second method, the electric charge at the most sensitive position of the well-type ionization chamber was measured at 400 V bias which was the setting provided by the manufacturer of the well-type ionization chamber, and the activity of radioactive sources was measured using the formula provided by the manufacturer. The deviation between the measured results and the theoretically calculated values was compared. Results According to the methods separately provided by WS262-2017 and the manufacturer, the activity of radioactive sources was AW and AP, respectively. The minimum deviation between AW and AP was 0.64%, and the maximum deviation was -3.03%. The minimum and maximum deviations between AW and the theoretically calculated result AT was -0.21% and 2.60%, respectively and the minimum and maximum deviations between AP and AT was -0.34% and 4.13%, respectively. Conclusion The results measured by the methods provided by WS262-2017 and the manufacturer are in good agreement.