Early studies of 3D conformal accelerated partial breast irradiation (APBI) showed some toxicity risks. At Massachusetts General Hospital and Brigham and Women's Hospital, 3 out of 198 patients developed pneumonitis after receiving 36 Gy in 9 fractions. A separate study at Tufts Medical Center of 60 patients receiving 38.5 Gy in 10 fractions found 8% developed grade 3-4 fibrosis, 25% experienced fat necrosis, and 1 each had pericarditis and a rib fracture. 18% also had fair or poor cosmetic results.