水模型鉴定PET-CT同机融合图像配准误差

本文是应用水模型模拟PET-CT实际检查检测同机融合图像的配准误差。首先制备含59.2 MBq氟18]-氟代脱氧葡萄糖的水模型,静置80 min,采集2D PET图像20 min,然后经形态学处理与阈值法得水的CT与PET图像,把两组图像的质心位置经线性回归方程拟合,求配准误差。并用Alignment软件测量CT与PET成像系统配准误差4次。得出水PET图像质心较CT图像在X轴偏移(0.011×层数+0.63)mm;在Y轴质心偏移(0.022×层数+1.35)mm,PET图像须经平移且X轴须旋转(0.06±0.07)、Y轴旋转(0.01±0.08)才能与CT图像配准。所以检查床的负载与分布不影响本PET/CT仪系统的配准校正,测量坐标轴旋转角度的随机误差易使PET与CT配准产生偏差。

Registered error between PET and CT images confirmed by a water model

The registered error between PET and CT imaging system was confirmed by a water model simulating clinical cases.A barrel of 6750 mL was filled with 59.2 MBq 18F]-FDG and scanned after 80 min by 2 dimension model PET/CT.The CT images were used to attenuate the PET images.The CT/PET images were obtained by image morphological processing analyses without barrel wall.The relationship of the water image centroids of CT and PET images was established by linear regression analysis,and the registered error between PET and CT image could be computed one slice by one slice.The alignment program was done 4 times following the protocol given by GE Healthcare.Compared with centroids of water CT images,centroids of PET images were shifted to X-axis(0.011slice+0.63) mm,to Y-axis(0.022×slice+1.35) mm.To match CT images,PET images should be translated along X-axis(2.69±0.15) mm,Y-axis(0.43±0.11) mm,Z-axis(0.86±0.23) mm,and X-axis be rotated by(0.06±0.07),Y-axis by(0.01±0.08),and Z-axis by(0.11±0.07).So,the systematic registered error was not affected by load and its distribution.By finding the registered error between PET and CT images for coordinate rotation random error,the water model could confirm the registered results of PET-CT system corrected by Alignment parameters.