基于30mA管电流低剂量呼吸门控PET/CT扫描条件的建立讨论  

Low-dose respiratory-gated PET/CT： based on 30 mA tube current

作　　者：武萍[1] 李思进[1] 张艳兰[1] 郝新忠[1] 秦志星[1] 鄢敏[1] 程鹏亮[1] 武志芳[1] 

机构地区：[1]山西医科大学第一医院核医学科,太原030001

出　　处：《国际放射医学核医学杂志》2013年第5期257-261,共5页International Journal of Radiation Medicine and Nuclear Medicine

基　　金：山西省科技攻关项目（20120321028-03）

摘　　要：目的 通过改善呼吸门控PET/CT（RG PET/CT）的扫描参数（如管电流、呼吸时相数目、呼吸周期等）,拟建立一个低辐射剂量且图像质量适于临床的扫描条件.方法 对26例有18F-FDG摄取的肺结节患者行1个床位的低剂量RG PET/CT（30 mA,1 min/时相）,评估其辐射剂量,并对比其与常规PET/CT（120mA,2min/床位）的图像质量（如均匀性、噪声、视觉评价）的差别.此外,通过模拟不同呼吸周期探讨其与辐射剂量间的关系.结果 1个PET床位的低剂量RG PET/CT的有效吸收剂量可降至4.88～7.69mSv[平均（5.68±0.83） mSv],且其PET图像信噪比与常规剂量时相比无明显差异,低剂量CT图像的均匀性在可接受范围（＜5 HU）,噪声较高,视觉评价肺结节特性在某些时相优于常规剂量CT.受检者的呼吸周期与辐射剂量呈正相关.结论 基于30 mA管电流、6个呼吸时相、1 min/时相、平静呼吸下的RG PET/CT的图像质量能满足肺结节特性观测及肿瘤放疗生物靶区勾画等临床应用,且辐射剂量大幅减低.Objective To establish a low-dose but image-comparable respiratory-gated PET/CT （RG PET/CT） protocol based on 30 mA tube current plus other improved scanning parameters,such as the tube current,the number of respiratory phase and length of breathing cycle.Methods Twenty-six patients with 18F-FDG-intaking lung nodules underwent one-bed standard-dose PET/CT（120 mA,2 min/bed）and lowdose RG PET/CT （30 mA,6 respiratory phases,1min/phase）.The radiation dose and image quality were analyzed subsequently with signal to noise ratio （SNR）for PET and the homogeneity,noise level for CT in the water phantom respectively.Otherwise the CT images were both visual evaluated by two experienced doctors.In addition,different respiratory cycle was simulated to observe its relation with radiation dose.Results The effective dose of low-dose RG PET/CT was 4.88～7.69 mSv [mean （5.68±0.83） mSv].The PET SNR showed no significance between groups.The homogeneity of 30 mA is good （＜ 5 HU）,although noise level was high,the visual character like lobulation,speculation of lung nodule was superior in some respiratory phases.The radiation dose was positively correlated with respiratory cycle.Conclusions The performance of low-dose RG PET/CT was comparable to those of standard-dose PET/CT based on a protocol with 30 mA tube current,6 respiratory phases and breathing state of eupnoea.It produced a much lower radiation exposure and the image quality was enough for clinical use such as delineation of tumor active target,characterization and staging of lung nodules,etc.

关 键 词：辐射剂量 正电子发射断层显像术 体层摄影术 X线计算机 呼吸门控 

分 类 号：R817[医药卫生—影像医学与核医学] R814.42[医药卫生—放射医学]