摘要
目的探讨PET/CT不同管电压下的CT加权剂量指数测量及其对图像质量的影响。方法在管电压分别为140、120、100、80 k V等条件下,使用PET/CT系统对Catphan~?500 CT的性能模体和CT剂量模体进行扫描。测量CT图像的相关性能,同时测量和计算不同管电压下CT加权剂量指数(CT Dose Index of weighted,CTDIw)以及给定螺距下的CT容积剂量指数(CT Dose Index of volume,CTDIvol)。结果管电压不影响CT图像的高对比度分辨力,但是随着管电压的增加,CT图像的低对比度分辨力、CTDIvol、CT图像的均匀性和噪声性能等均随之增加。对比度在0.30%、0.50%和1.00%时低对比度分辨力随管电压的增大而增大;CT图像的均匀性也随着管电压的升高而变优,其中在120~140 k V之间变化幅度较小,而在80~100 k V时变化幅度较大;其中CTDIvol的增加呈线性规律增加,而性能提高则呈非线性规律。结论随着管电压的降低,PET/CT检查中的CT剂量也会降低,并且在CT剂量超过一定值时,适当降低CT剂量不会影响CT图像的质量。
Objective To investigate the CT weighted dose index measurement and its influence on the image quality of PET/CT under different tube voltage.Methods In the tube respectively voltage of140,120,100,80kV and other conditions,we used PET/CT system to scan the simulate performance of the body and the CT dose phantom body of Catphan?500CT.The related characters of the CT image were measured.Meanwhile,the CT dose index of weighted(CTDIw)under different tube voltage and the CT dose index of volume(CTDIvol)under given pitches were measured and calculated.Results The high contrast resolution of the CT images were not affected by the tube voltage.However,with the increase of the tube voltage,the low contrast resolution of the CT images,CTDIvol,the uniform and noise performance of the CT images were increased.When in low contrast resolution of0.30%,0.50%and1.00%,the contrast of the images increased with the increasing of the tube voltage.The CT image uniformity also increased with the increasing of tube voltage.The changes was in a small range when the tube voltage was in120～140kV and the changes was in a bigger range in80～100kV.The CTDIvol increased linearly with the increasing of the tube voltage,while improving performance was nonlinear rules.Conclusion With the reduction of tube voltage,the CT dose of PET/CT is also reduced,and the appropriate dose of CT dose not affect the quality of CT image when the CT dose is more than a certain value.
作者
钟承双
徐谢生
ZHONG Cheng-shuang;XU Xie-sheng(Department of Equipment, Maoming Hospital of Traditional Chinese Medicine,Maoming Guangdong 525000, China)
出处
《中国医疗设备》
2017年第5期105-107,共3页
China Medical Devices
