Tehran University of Medical Sciences Frontiers in Biomedical Technologies 2345-5837 13 1 2026 01 20 104 116 Mohammad Ali Bijari 1- Faculty of Sciences and Modern Technologies, Graduate University of Advanced Technology, Haftbagh highway. 7631885356 Kerman, Iran Ahmad Esmaili Torshabi Faculty of Sciences and Modern Technologies, Graduate University of Advanced Technology, Haftbagh St. 7631885356 Kerman, Iran 2023 12 11 2024 05 19 Purpose: Real time motion tracking of thorax area of patient body is a main issue at various part of medical fields such as radiotherapy. Several strategies were proposed by using different monitoring hardwares. In this work a contactless method using optical camera is proposed to trace breathing motion by implementing virtual markers defined on chest area. A comprehensive algorithm has been developed to analyze the video frames and track each virtual point as real time.  Methods: In this wotk, Python program and its OpenCV library has been used for breathing motion, two dimensionally. Utilized database in this work are motion data taken from breathing motion of a real volunteer. The motion data was captured using cellphone optical camera and the gathered data was moved to in-room computer system by means of WiFi. It’s worth mentioning that 15 virutal test points were determiened using Artifical Intelligence concept of Python inside chest area. Results: Final results represent that the performance accuracy of monitoring proposed idea is acceptable. The chest area is determined automatically and will be variable for each patient, uniquely. Various normal and deep breathings was tested as real time at different respiration frequencies. As example, two dimentional motion displacements of a test point, are 4.75 and 7.15 mm for normal and deep breathing, respectively. Conclusion: The  main robusts of the proposed motion tracking method are simplicity, contactless and using virtual markers determination, while real infra-red markers are currently used clinically by locating on patient chest skin.  https://fbt.tums.ac.ir/index.php/fbt/article/view/900 https://fbt.tums.ac.ir/index.php/fbt/article/download/900/546