基于三维傅里叶变换的胸腹表面测量

摘要

This paper proposes a 3D Fourier transform measurement method for thoraco-abdominal surface.It has important applications in the 3D measurement of the motion of human thoraco-abdomi-nal surface for accurate radiotherapy in the medical field.The method combines 3D Fourier fringe a-nalysis(3D-FFA)with triple-frequency temporal phase unwrapping.It uses three primary colors that include three cosine fringe patterns with different frequencies to generate a composite pattern,and can achieve the corresponding 3D measurement of the thoracic and abdominal surface by capturing one im-age.Taking the dynamic fringe pattern sequence as a 3D volume,the wrapped phase can be extracted using 3D Fourier transform combined with a 3D Gaussian filter.The proposed method shows a root mean square(RMS)error less than 0.005 rad for the wrapped phase without interference,a peak-val-ley(PV)value error less than 0.015 rad,and an anti-interference ability higher than that of the 2D Fourier fringe analysis(2D-FFA)method and other thoracic and abdominal surface 3D-FFA methods.A new triple-frequency temporal phase unw rapping method is used for unw rapping the w rapped phase,and show s an absolute phase error less than the w rapped phase error under limited conditions. Theoretical analysis and experimental results show that the proposed method can achieve 3D dynamic measurement of human thoraco-abdominal surface.%鉴于人体胸腹表面三维运动测量在精确放疗等医学领域中的重要应用背景,提出一种三维傅里叶条纹分析与三频时间相位展开相结合的三维傅里叶变换胸腹表面测量方法.投射一幅不同频率三原色余弦条纹组成的图案,每采集一幅图像就能实现相应时刻胸腹表面的三维形状测量;将动态条纹图像序列作为一个三维序列整体,通过三维傅里叶变换并结合三维高斯滤波器提取折叠相位.无干扰时其均方根误差不超过0.005 rad,峰谷值误差不超过0.015 rad,其抗干扰能力高于二维傅里叶条纹分析和其他胸腹表面三维傅里叶条纹分析方法;通过三频时间相位展开方法进行折叠相位展开,在限定条件下绝对相位的误差不超过折叠相位的误差.理论分析和实验结果表明,本文方法能实现人体胸腹表面的三维动态测量.