Inclusion Criteria: 

• Age ≥ 18 years.
• Histological confirmation of breast cancer. 
• Clinical Stage T1-T4 N0-3 M0. 
• ECOG Performance Status (PS) 0 to 2. 
• Able and willing to provide IRB-approved study specific written informed consent.
• Able to complete all mandatory tests listed in section 4.0.
• Willing to return to enrolling institution for follow-up (during the active monitoring phase of the study).
• Indications for radiotherapy for breast cancer.
• In case of discrepancies or equivocal findings, the final ruling for Eligibility will be determined by the principal investigator.

Exclusion Criteria:

• Medical contraindication to receipt of radiotherapy.
• Severe active co-morbid systemic illnesses or other severe concurrent disease which, in the judgment of the investigator, would make the patient inappropriate for entry into this study or interfere significantly with the proper assessment of safety and toxicity of the prescribed regimens.
• Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements or providing informed consent in the judgment of the principal investigator.
• Active systemic lupus or scleroderma. 
• Pregnancy. 
• Women of childbearing potential who are unwilling to employ adequate contraception.
• Prior receipt of ipsilateral breast or chest wall radiation. 
• Recurrent breast cancer.
• In case of discrepancies or equivocal findings the final ruling for eligibility will be determined by the principal investigator.

Eligibility last updated 8/26/22. Questions regarding updates should be directed to the study team contact.