Dosimetric Comparison of Target Volume, Heart and Left Lung in Post Mastectomy Radiotherapy (RT) of Left Sided Breast Cancer by Free Breathing (FB) Versus Deep Inspiration Breath Hold (DIBH) Technique

Participants will be trained for 2-3 days for obtaining the desired breathing cycle by trained technologists. No extra equipment will be needed. At first, they will be assured and asked to relax. Then instructed to breath in and out twice followed by a slow, deep breath in to a comfortable higher level than normal and to hold it for at least 20 seconds then again breath normally. Once they are ready with expected breath holding, simulation will be done. Treatment will also be given in this breath holding position.

Patient will be advised for free breathing during simulation and treatment.