An investigation of correlation between external surrogate signal and internal motion according to respiratory irregularity

Abstract

Our study investigated the impact of irregular respiration on correlation between surrogate respiratory signal and internal organ motion in 4DCT. Based on the proposed quantitative index of respiratory irregularity, the study cases were divided into two: the case with regular breathing and the case with irregular breathing. By groups, internal organ movements were measured from 4CT images, and correlation between external surrogate signal and internal organ motion was analyzed. The results showed that the correlation with internal organ motion was obviously deteriorated in the case with irregular breathing, rather than the case with regular breathing. As observed that the irregular respiration may lead to such errors on gating interval up to 20% either phase or amplitude level, it would be necessary to employ the respiratory guidance and feedback system that can minimize the respiratory irregularity.