双探头SPECT对向平面显像放射性活度定量的模型研究

Activity quantification of phantom using dual-head SPECT with two-view planar image

放射性核素体内吸收剂量估测是评价辐射危害和内照射治疗价值的重要指标。器官组织的绝对活度定量是吸收剂量估算的必要步骤。本研究采用双探头单光子发射型计算机断层显像术(Singlephotonemissioncomputedtomography,SPECT)对向测定对模拟的99Tcm源器官进行了活度定量的模型实验。结果表明:双探头SPECT对向平面显像放射性活度定量不受放射源在体模内深度的影响,并且在放射源直径≤2cm时活度定量最准确;Buijs法提供了最准确且最稳定的本底校正方法。

The absorbed radiation dose from internally deposited radionuclide is a major factor in assessing risk and therapeutic utility in nuclear medicine diagnosis or treatment. The quantification of absolute activity in vivo is necessary procedure of estimating the absorbed dose of organ or tissue. To understand accuracy in the determination of organ activity, the experiments on ^99Tc%m activity quantification were made for a body phantom using dual-head SPECT with the two-view counting technique. Accuracy in the activity quantification is credible and is not affected by depth of source organ in vivo. When diameter of the radiation source is ≤2cm, the most accurate activity quantification result can be obtained on the basis of establishing the system calibration factor and transmission factor. The use of Buij s＇s method is preferable, especially at very low source-to-background activity concentration rations.