Abstract：Objective To investigate MRI localization the accuracy and correct the deviation for gamma knife treatment. Methds With 25-point-matrix tank, the deviation of MRI localization and its regularities could be identified after the comparison between the coordinates of MRI localization and the ones which have already been verified by CT within the deviation of 0.5 mm. Then the original MRI coordinates will be corrected by the acquired mean deviation and the geometric distortion of images. Afterwards the corrected coordinates will be compared with the standard ones and finally validated by exposure film. ResultsThere are no significant deviations on x-and z-axis after measurement in three hospitals, y-axis, however, bears deviation of (1.94±0.45) mm for hospital A,(－2.22±0.29) mm for hospital B,(－1.25±0.21) mm for hospital C,respectively. Furthermore there also exists geometric distortion of 1% on y-axis in hospital A. The corrected coordinates on y-axis (yc) will be calculated from the formula:Yc=(Y－M)+GD (Y0－Y)(Y:the original coordinates on y-axis, M:the mean of deviation on y-axis, GD:the geometric distortion,Y0:the coordinate on y-axis of the central point among the 25-point matrix).Once completed, the corrected coordinates of MRI localization is of no significant difference with the standard coordinates verified by CT. Even the deviation of focal spot on validation film is within 0.5 mm. Conclusions The 25-point-matrix tank in the multi-point measurement of the accuracy and the correction of deviation for gamma knife treatment is feasible to determine whether MRI can be utilized in the localization for head gamma knife treatment.
Li Shengyuan,Li Xiaoyang,Yan Zheng et al. Detection and correction of the accuracy of gamma knife treatment positioned by MRI[J]. Chinese Journal of Radiation Oncology, 2014, 23(6): 535-539.
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