Wow ! That is exactly my situation and I am so afraid of radiation because of left side as well . I am thinking about proton therapy but one doctor said it would be not beneficial to me. Still with stage 0 after lumpectomy they suggest 4 weeks of radiation . My margins were 2mm accept posterior less then 1mm. I was told radiation is needed or another lumpectomy . But now no Savy scout , no marker and doctors comment that he would need to remove much more all around ( it's like playing in the dark he said ). That didn't sound good and lost some confidence in my surgeon . Trying to get another opinion from oncology radiologist. . All the best to you ! ❤️🙏🏻