Why are dose constraints from EBRT not directly transferable to radiopharmaceutical therapy (RPT)?

Invited Speaker Dr. Tahir Yusufaly (April 23, 2024); Faculty Member at Johns Hopkins University Department of Radiology. Chapter breakdowns:
0:00 Introduction
1:30 Dose distribution in RPT vs. External Beam Radiotherapy (EBRT)
8:42 Brief overview of EBRT radiobiology
27:06 Efforts towards a more universal Biologically Effective Dose (BED)
39:24 Efforts towards a more universal normal tissue complication probability (NTCP)
49:44 Summary and future outlook (computational nuclear oncology)
54:09 Summary