Enclosure 1 Comparison of Spiers and ICRP Models for Dose from Pu to Red Marrow and Endosteal Cells 1. Ratio of Bone Marrow to Endosteal Cell Dose A. Spiers (References 1,2,3). In Spiers method the dose is calculated to a tissue filled cavity and is referred to as Do. The dose in bone, DB, is then related to DO by the ratio of the mass stopping powers of bone and tissue. Thus DO SB/ST From geometry consideration and deposition and energy loss characteristic for alpha emitters, the doses to red marrow, DM, and endosteal cells, DS, may be calculated by applying appropriate factors to DB. 239 Pu are: ‘M= The factors for 0.26 DB DS = 3.11 DB Thus, the ratio between the red marrow dose and endosteal cell dose is: 3.11 =% 12. 0.26 B. ICRP (ICRP 30, Supplement to Part 1) From ICRP-30, Supplement to Part 1 page 414 and 415, are listed the committed Dose Equivalent unit activity. (C.D.E. ) in target organs or tissues per intake of The ratio of these C.D.E. for bone surface cells and bone marrow provides the necessary comparison for the ICRP model to Spiers model. -7 Thus, for f, = 1.0 x 10-4, the red marrow CDE is 1.6 x 10 Sv/Bq and the bone surface CDE is 2.1 x 10-6 Sv/Ba. and endosteal cell dose is: The ratio between the red marrow dose 2.1 x 10 -6 1.6x 10-7 2 =,3