REBECCA Study (RadiothErapy for BrEast Cancer and CArdiotoxicity)

Inclusion Criteria: * Women treated surgically for left or right breast cancer and for who adjuvant treatment is radiotherapy with irradiation of the breast or chest wall irradiation and possibly lymph node chains, * Age between 40 and 70 years * Adjuvant Radiotherapy is helical tomotherapy performed at Institut Claudius Regaud(Toulouse, France) Exclusion Criteria: * Indication of adjuvant chemotherapy * Clinically or radiologically detectable metastasis * Personal history of coronary artery or myocardial disease * Personal history of breast cancer or other cancer requiring radiotherapy to the chest * Contraindications to injection of iodinated contrast ( for CT ) : pregnancy , renal failure, allergy. * Pregnancy, lactation * Before radiotherapy, LVEF \<50% * Before radiotherapy, longitudinal strain \> - 16 % * Before radiotherapy,longitudinal strain rate \<1% / s * Before radiotherapy, segmental wall motion abnormality * Coronary CT before radiotherapy showing that a therapeutic treatment is required