<qa>  What is the flow of ibritumomab tiuxePatients undergo gamma camera imaging at 2-24 hours and 48-72 hours after the injection of IDEC-In2B8 to observe the flow of ibritumomab tiuxetan. If the flow is deemed safe, then patients receive yttrium Y 90 ibritumomab tiuxetan IV over 10 minutes on day 7. 