a Thus from (2) ami (3), D+ eypd = 55H pqultay(t) m oeseaoeveveewe 6 (4) A(t) Equations (2) and (4), when solved, give the activity of the tissue at any tine and the total dose received. From ref (3), A(t) is of the forn y(t) = Ket - xe At with k 7 0.0205 ky = 0.00359 eeecevteeneos (5) & = time after fission, days A, = 0.0855 , = 0.554 The first term in the above ie due to the radioactive decay of T", while the second term - and a third term whieh was neglected since it is small after 3 hours - allow for the contributions from ether decay chains to the D4 actavity. (The second term also falls to a negligible amount by 4 days, but is ineluted). A(t) 4s of the form A(t) = kt” n Where k « 6170, n = 1,12 fort .&hre (Ne B. Ballon). Sinse an initial uptake is to be determined, a time t, = 305 bre is taken, at which both u(t) and A¢t) are known. Then, letting E = 0.20 Mev. m = 12 mm, he may define a quantity Ry © aaylt) , And the rateof nfaleof t) R(t) Also, ky = SB «1 eoceoveevvuevnseennseveeve (6) > BA,(t) «9 R a a a a a 2 (7) and letting Ar ¢ b = 2d, as in ref (1), there results for equation (2) TOS ARCHIVES