  Respiratory-gated radiation therapy (RGRT) has been used to minimize the dose
to normal tissue in lung-cancer radiotherapy. The present research aims to
improve the regularity of respiration in RGRT using a video coached respiration
guiding system. In the study, 16 patients with lung cancer were evaluated. The
respiration signals of the patients were measured by a real-time position
management (RPM) Respiratory Gating System (Varian, USA) and the patients were
trained using the video coached respiration guiding system. The patients
performed free breathing and guided breathing, and the respiratory cycles were
acquired for ~5 min. Then, Microsoft Excel 2010 software was used to calculate
the mean and standard deviation for each phase. The standard deviation was
computed in order to analyze the improvement in the respiratory regularity with
respect to the period and displacement. The standard deviation of the guided
breathing decreased to 65.14% in the inhale peak and 71.04% in the exhale peak
compared with the values for the free breathing of patient 6. It was found that
the standard deviation of the respiratory cycle was decreased using the
respiratory guiding system. 2 The respiratory regularity was significantly
improved using the video coached respiration guiding system. Therefore, the
system is useful for improving the accuracy and efficiency of RGRT.
