A Study of Diffusing Alpha Radiation Therapy for Patients With Breast Carcinoma in Frail or Elderly Patients.

Inclusion Criteria: * Histologically confirmed invasive breast tumor with no involvement of skin within 12 months. * Tumor size ≤ 4 centimeters in the longest diameter. * Tumor is not deemed as resectable with radical surgery or the patient does not wish to go through surgery * De-novo or recurrent lesions. * Single lesion per quadrant per subject. * Targeted lesion must be technically amenable for complete coverage (including margins) by the DaRT seeds. * Interstitial implant indication validated by multidisciplinary team. * ECOG Performance Status ≤3. * Life expectancy ≥12 months. * Women Age ≥65 or younger if unfit for standard of care. * Willing and have the ability to provide signed Informed Consent. * Blood tests values: * Leucocytes ≥3000mm3, * Absolute neutrophil count ≥1500mm3, * Platelets ≥100,000 mm3, * Total bilirubin ≤ 1.5xULN, * AST, SGOT, SGPT ≤2.5xULN, If Alkaline Phosphatase ≤ 4xULN, then transaminases are normal. * Creatinine ≤ 2.0xULN. * INR or Prothrombin time ≤1.5xULN Exclusion Criteria: * T4 category with skin involvement. * Ductal carcinoma in situ. * Inflammatory breast carcinoma. * Longest tumor diameter \>4 cm. * Patients with prior radiation to the same area within the past 6 months. * Has a known additional malignancy that is progressing or requires active treatment. * Patients undergoing immunosuppressive and/or systemic corticosteroid treatment except for steroid inhalations for treatment of asthma or lung disease * Subjects not willing to sign an informed consent.