The Research Of Fast Calibration Of Three Dimensional Ultrasound And Respiratory Correlation Model Based On Optical Positioning System

During radiotherapy the target will deviate from the treatment area duing to respiratory movement, which will produce big impact for precise radiotherapy. Many scholars have done much research on respiratory movement tracking,such as four dimensional CT of image guidance radiotherapy treatment, we can get tumor motion range by scanning the four-dimensional computed tomography. Because of the different density of different tissue, different imaging devices have different advantages. We used ultrasound as imaging device in the paper, it has good effect on the substantive organ and can be tracking diseased tissue dynamic.First,we developed the calibration of ultrasound based on an optical positioning system (OPS). because OPS has a widely use of clinical. As a widely use of real-time image guidance technology, OPS has high positioning accuracy, comparing to the current application of image guidance technique such as EPID,CBCT. In this paper, we first verified the precise of OPS by comparing this three techniques. The method of experimental study with OPS has obvious advantages compared with the similar guidance technology. The setup error were ±0.5mm in inferior-to-superior and left-to-right, and ±1.5mm in anterior-to-posterior.Secondly, we proposed a novelty respiratory motion tracking model based on ultrasound. In the model, we collected external data by Polaris (Northern Digital Inc) optical positioning system and the input data by B mode ultrasound. In this paper we maped the two-dimensional ultrasound image to the three-dimensional space, and we proposed a triangular pyramid model in a large sink. In this model we pasted two metal ball on the side of pyramid model. The OPS can acquire the coordinate value of the balls by NDI technique. However because of image coordinate system is not is the same coordinate with infrared coordinate. So in this paper, we mainly solved how to unified the two coordinate system which we called calibration. Hoping to improve respiration motion model based on this method.Finally, this project is hoping to build respiratory tracking model with guiding by ultrasound based on optical positioning system, which provide new direction of respiratory tracking.