SU‐E‐J‐143: Improvement in Accuracy of Respiratory Gated Radiation Therapy Using Respiratory Training System

Purpose: The accuracy of respiratory gated radiation therapy (RGRT) depends on the respiratory regularity because external respiratory signals are used for gating the radiation beam at particular phases. Many studies have applied a respiratory guiding system to improve the respiratory regularity. This study aims to evaluate the effect of an in‐house developed respiratory guiding system to improve the respiratory regularity for RGRT. Methods: To verify the effectiveness of this system, respiratory signals were acquired from 5 volunteers. The improvement in respiratory regularity was analyzed by comparing the standard deviations of amplitudes and periods between free and guided breathing. The reduction in residual motion at each phase was analyzed by comparing the standard deviations of sorted data within each corresponding phase bin as obtained from free and guided breathing. Results: The results indicate that the respiratory guiding system improves the respiratory regularity, and most volunteers show significantly lesser average residual motion at each phase. The average residual motion measured at phases of 40, 50, and 60%, which showed lower variation than other phases, were respectively reduced by 41, 45, and 44% during guided breathing. Conclusion: The results show that the accuracy of RGRT could be improved using the in‐house developed respiratory guiding system. Furthermore, this system should reduce artifacts caused by respiratory motion in 4D CT imaging. This program was supported by the program of Basic Atomic Energy Research Institute (BAERI) which is a part of the Nuclear R and D programs (No. 20120004886) funded by the Ministry of Education, Science and Technology (MEST) and a grant (2012‐007883) from the Mid‐career Researcher Programfunded by the Ministry of Education, Science and Technology (MEST) and Leading Foreign Research Institute Recruitment Program through the National Research Foundation of Korea(NRF)(Grant No.2009‐00420) funded by the Ministry of Education, Science & Technology (MEST) of Korea.