毫安秒对SPECT/CT检查中辐射剂量和影像质量影响的研究

A study on influence of milliampere-second on radiation dose and image quality in SPECT/CT examinations

目的在保证影像质量的前提下,为降低SPECT/CT检查中CT部分受检者的辐射剂量提供参考依据。方法使用西门子公司SymbiaT2型SPECT/CT,固定管电压130 kV,螺距2.0,分别在100 mAs、130 mAs、160 mAs、190 mAs和230 mAs的条件下测量容积CT剂量指数(CTDI_(vol)),扫描Catphan 600型和Catphan 500型CT性能检测模体,分析扫描图像,得到各个条件下CT影像质量指标。结果 CTDI_(vol)随管电流时间积(mAs)的升高而线性升高,mAs的改变对高对比分辨力,CT值和CT值的线性指标无影响,低对比可探测能力、均匀性和噪声值指标随mAs的升高而降低。结论 SPECT/CT中的CT辐射剂量随mAs的升高而升高,影像质量随着mAs的升高而提高,由于mAs对高对比分辨力无影响,在进行特定部位的扫描时可选择适当降低mAs,实现在保证影像质量的前提下降低受检者的辐射剂量。

Objective To provide a reference basi for reducing radiationdose of some CT in SPECT/CT examinations while ensuring quality of image.Methods By using SymbiaT2 of Siemens SPECT/CT,fixed tube voltage 130 kV and pitch 2.0,the volume CT dose index(CTDIvol)was measuredwhile Model of Catphan 600 was scanned under the condition of 100 mAs、130 mAs、160 mAs、190 mAs and 230 mAs,respectively.The quality indexes of CT images under various conditions are obtained by analyzing the scanned images.Results CTDIvol increased linearly with the milliampere second.the change of mA second has no effect on the high contrast resolution,the CT value and the linear index of the CT value,and the low contrast detectability,the uniformity and the noise value index decrease with the increase of milliampere-second.Conclusion The image quality of SPECT/CT image and radiation dose of CT in SPECT/CT increases with the increase of milliampere-second.While milliampere-second has no effect on the high contrast resolution,the radiation dose couldbe decreased appropriately under the guarantee of the quality of the image in specific conditions.