Estimated probability of engraftment to WBC count of 1,000/μL for patients receiving 1,332 cGy (n = 46) and 1,500 cGy (n = 26) of TBI. Patients receiving the higher TBI dose experienced earlier engraftment with an estimated probability of engraftment by 32 days of 0.90 compared with 0.86 in patients receiving 1,332 cGy (P = .003). Data are derived from first transplants only.