Measurement of thoraco-abdominal surface using 3D Fourier transform

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-abdominal surface for accurate radiotherapy in the medical field. The method combines 3D Fourier fringe analysis (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 image. 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-valley (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 unwrapping method is used for unwrapping the wrapped phase, and shows an absolute phase error less than the wrapped 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. © 2018, Science Press. All right reserved.