METHODS
DOSI 1ETRIC EQUATIONS
Declining continuous uptake of radioactive dietary items was mathematicall: modeled for each nuclide of concern.
The following general equations were
used
t
°
-(y)+
u u,/f, - 9° (¢ K:X; e (14KDE)
eee
K.
Dt
(5 Xuma
(e ~C+Kp ES dt - ~CA+K:iy)
OF
(1)
‘ K.-Ke
Ap® =
p= earpeg
ol
.
1
zr
£
qg-a° (i Xie
X;
LCii
eeE
(e - (A+Kp)t
-(A+K. Jt
_
i]
e ~(\+K.
(dX Ki)ty)
» and
(2)
A+
~(K- +i
oi (Kirke -O+Ki) Cskg rt ¢ CAKE) 67 (Ki *)
KK
1 E
(KoA)
(K,1 +A)
E
‘
+a
°
X.1
2i Oe1 (
l-e
(A 4K;L )t
),
(3)
where
t
= time post onset of uptake, days,
A
= instantaneous fraction of atoms decaying per unit time, day”!
P° = initial atom ingestion rate, atoms day~!,
Kj = instantaneous fraction of atoms removed from compartment i by physiological
mechanisms, day7!,
Xj = compartment i deposition fraction,
¢
X; = the number of atoms in compartment i relative to the number in all compart-
ments at the onset of uptake (t=0),
U
= instantaneous urine activity concentration, Bg oe
US = subject urine excretion rate, & day~!,