Influencing factors of geometrical accuracy in magnetic resonance imaging for gamma knife radiosurgery / 中华放射医学与防护杂志

ABSTRACT

Objective To evaluate and improve the geometrical accuracy of the magnetic resonance imaging used for gamma knife radiosurgery localization. Methods Four common MRI scan programs were used in this study. The images were transferred to the Gamma Plan treatment planning system.Deviations between stereotactic coordinates based on MR images and real geometrical positions given by the construction of the phantom insert were evaluated for each study.The deviations were further investigated as a function of the spatial position of measured points in the investigated volume.Results The geometrical coordinate errors for axial and coronal images of the selected scan programs were all less than 1 mm.Optimal imaging procedure in terms of geometrical accuracy was observed using spin echo T1 and 3D FSPGR MRI sequences in the unit.Statistically significant differences were found in axial images amongSE T1,FSE T2,FRFSE Pd,FSPGR 3D sequences (F=1497.51,1873.63,2.87,3.00,P ＜0.05).The error increased along with the increase of the distance between node point and centricity.Conclusions The geometrical coordinate errors is related with the imaging program in M(il)l. Proper imaging programs and parameters should be selected according to the imageology character of patients' lesions when the radiosurgery is performed.