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parameters as administered dose, Since the units for dose of vsieair.! +o.
ure in ruysivel terms iis naicral to tes te present dases gsicenue tos
effects of radionuclides in similarterms (1.2., rads and rems). Snew be ors!
dose depends heavily upon the kinetics of uo sor phon, distribBU
Tea,
transiocation, etc., at all levels of organization from organ sy
:
much of the literature pertinent to the toxicology of radionuchdes iy aoa,
primarily to this aspect, Le, pharmacokiuetics. Space srevent, se sot
consideration of this enormous titerature here. Also in the pracuce ef mu,
medicine it is desirable to know within reasenable limits tog rau. 6 le
the target tissue and others, either to prevent undue ex; O2u7™ ta Gine
tests cr te deliver a known dose for therapy.
coos fybFr,
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—
Theclassic scherna for internal dose computation devised ‘arneis he feo Quimoy & Hine (124) and universally applied since the late dae. . 46 lL,
expanded in the intervening years (124). Rather elaborete equation + developed for photons, beta particles, point sources, surface sruvalune ..
etc. As described by Loevinger (126) a simpler, more ecnerar treat eo
desired, particularly for the practice of nuclear medicine. To accomptisn tus
group known as the “ Medical Internal Radiation Dose Committee” (M1IRT
was organized by the Society of Nuclear Medicine. Several pamphlets bs:
a
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a
a
ft
.
o4
.
been published as supriements to the Journa! of Nuclear Modicine (27a
7 i
which detail the work of this committee and its snonsers. They preset 2:
unifving principle the concept of ‘‘specific absorbed traction” (a = da Whe
{
¢ =the absorbed fraction in mass mt) which had been introduced earuer
gamma-ray dosimetry (131). The pamphlets give the schema tables of aksori+
doses, radionuclide decay schemes, and other needed infoimalion. Fou
issues will concentrate on specific substances of intcres’ in nuctear me Hie
Z|
especially radiopharraaceuticals.
The principal accomplishment of the MIRD schema its to provide a si-.
expression which covers dose from any source of activity to an. torge: for
types of radiation. It is stated to have general applicab'lity as long as reles.
geometric relations do not change with time (126). This janer ‘ anct incense
able reservation with certain isotopes. But to the extent that absorbed fract
and specific absorbed fraction are parameters of interest for oredicting hiolog
effect, and to the extent the schema give them directly, the new plan has =i.
tages. For those brought up with the Marinelli, Quimby & Laie mene...
new apovroach will seem unfamiliar and not an obvious simpliicater tL
may become clearer with use. Fortunately tne aosorned doscs cu coieind
Speke:vy shendbbh
TM rhe atsts *i Usane Vira| rat
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MIRD Scheme are steted not to Ee racically differer: from those caicul
by the older methnds (126, p. 487).
An egually important “unction of che MERE cove ot
were
}
of metabolic data and hretimes of muciiges adreriast.cc dy be Je roe,
SPP ES me ie
ceuticals, along with inJonmation op fasion such os vhomeeatoe i:
CE OEB rdae 6 tet
‘
toe
purity, stability, etc. whica might affect absorbed dase.
Greenfield & Lane (125) have contuibuted a timely and complere craps:
radioisotope dosimetry airned at both the researcrer end rhe poysncan
bop
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