This is an investigator-initiated blinded, efficacious, phase III randomized clinical trial study. The study hypothesis is that the use of Surface Guided Radiation Therapy (SGRT) in combination with the Deep Inspiration Breath Hold (DIBH) technique for left breast cancer treatment can improve positioning accuracy and heart protection without any increase in radiation or adverse reactions. The primary endpoint of this study is the accuracy of the treatment location and incidence of patient coronary events/myocardial perfusion decline.
