Cone Beam Breast CT for Breast Cancer Screening

Inclusion Criteria: Screening Group: * Female sex of any ethnicity * Age 40 years or older * Scheduled for a routine screening mammography exam within 4 weeks. Diagnostic Group: * Female sex of any ethnicity * Age 30 years or older * Have an abnormality detected by Breast Self Exam (BSE), or Clinical Breast Exam (CBE), or have an abnormality detected by an imaging modality. * Will undergo diagnostic mammography, prior to breast biopsy (if needed). Exclusion Criteria: * Pregnancy * Lactation * Unknown pregnancy status AND * has refused pregnancy testing and * has refused to sign a pregnancy test waiver * Women who are unable or unwilling to understand or to provide informed consent * Women with physical limitations that may prohibit resting prone on the exam table, such as, but not limited to: frozen shoulder, recent heart surgery, pace maker. * Women who are unable to tolerate study constraints. * Women who have received radiation treatments to the thorax or breast area for malignant and nonmalignant conditions, such as (but not limited to): * Treatment for enlarged thymus gland as an infant * Irradiation for benign breast conditions, including breast inflammation after giving birth * Treatment for Hodgkin's disease * Women who have participated in a prior breast clinical trial that gave additional radiation dose, such as an additional mammogram. * Women who have received large numbers of diagnostic x-ray examinations for monitoring of disease such as (but not limited to): * Tuberculosis * Severe scoliosis Additional exclusion criteria due to machine limitations * Patient's body weight is over the limit of the scanner table (440 lbs. or 200kg)