Institute of Radiation Physics, University Hospital and University of Lausanne, Rue du Grand-Prd 1, CH-1007 Lausanne, Switzerland.
Med Phys. 2011 Jul;38(7):4073-80. doi: 10.1118/1.3596528.
In nuclear medicine, the activity of a radionuclide is measured with a radionuclide calibrator that often has a calibration coefficient independent of the container type and filling.
To determine the effect of the container on the accuracy of measuring the activity injected into a patient, The authors simulated a commercial radionuclide calibrator and 18 container types most typically used in clinical practice. The instrument sensitivity was computed for various container thicknesses and filling levels. Monoenergetic photons and electrons as well as seven common radionuclides were considered.
The quality of the simulation with gamma-emitting sources was validated by an agreement with measurements better than 4% in five selected radionuclides. The results show that the measured activity can vary by more than a factor of 2 depending on the type of container. The filling level and the thickness of the container wall only have a marginal effect for radionuclides of high energy but could induce differences up to 4%.
The authors conclude that radionuclide calibrators should be tailored to the uncertainty required by clinical applications. For most clinical cases, and at least for the low-energy gamma and x-ray emitters, measurements should be performed with calibration coefficients specific to the container type.
在核医学中，放射性核素的活度是用放射性核素校准器来测量的，而校准器的校准系数通常与容器类型和填充无关。
为了确定容器对测量注入患者的放射性活度的准确性的影响，作者模拟了一种商业放射性核素校准器和 18 种最常用于临床实践的容器类型。计算了不同容器厚度和填充水平下的仪器灵敏度。考虑了单能光子和电子以及七种常见的放射性核素。
用γ放射性源进行的模拟质量通过与在五个选定的放射性核素中测量值的一致性得到了验证，其误差小于 4%。结果表明，根据容器的类型，测量的活度可能会有超过两倍的变化。对于高能放射性核素，填充水平和容器壁的厚度只有很小的影响，但可能会导致高达 4%的差异。
作者得出结论，放射性核素校准器应根据临床应用所需的不确定性进行定制。对于大多数临床情况，至少对于低能量的γ射线和 X 射线发射体，应使用特定于容器类型的校准系数进行测量。
