A study to see the duration of holding deep breath with extra oxygen vs without extra oxygen during radiotherapy in Breast cancer patients

INTERVENTION: Intervention1: voluntary DIBH with Pre‐oxygenation or PO‐vDIBH: Patients treated in Intervention Arm with voluntary DIBH with Pre‐oxygenation or PO‐vDIBH will receive 15 min PreOxygenation with 50% O2 via Venturi mask, during DIBH training sessions, CT simulation and Radiotherapy treatment. Control Intervention1: conventional voluntary DIBH or vDIBH: Patients treated in Comparator or Control Arm, with voluntary DIBH only, will NOT receive 15 min PreOxygenation with 50% O2 via Venturi mask, during DIBH training sessions, CT simulation and Radiotherapy treatment. CONDITION: Health Condition 1: C50‐C50‐ Malignant neoplasms of breast PRIMARY OUTCOME: Breath hold duration in first session of treatment between 2 arms of the studyTimepoint: At baseline i.e. on the first day of treatment SECONDARY OUTCOME: Comparison of dosimetric parameters of target volumes & organs at risk or OARs between 2 arms of the studyTimepoint: at baseline Comparison of early adverse effects between 2 arms of the studyTimepoint: baseline, after 1 month of completion of radiotherapy , after 3 months of Radiotherapy Comparison of QOL with EORTC QLQ C30 & BR25 between 2 arms of the study ; Timepoint: baseline, on completion of Radiotherapy, after 3 months of Radiotherapy Comparison of time period required for achieving Optimal Breath Hold during training ; Timepoint: I want to determine the time required for achieving this optimal breath hold during training , before treatment. INCLUSION CRITERIA: 1. Histopathologically or cytopathology proven carcinoma of breast 2. All left breast cancer patients requiring radiotherapy 3. Right breast cancer patients requiring IMRT / VMAT Radiotherapy on Pre RT evaluation e.g. IMN+, Whole axillary Radiotherapy, Implant Reconstructed breast 4. Age ‐ More than 18 years to below 70 years of age 5. Eastern Cooperative Group / ECOG Performance Status 0‐2 6. Patients willing to provide informed consent for the approval for inclusion in the study e.g. with signature or left thumb impression