~Qe
partial shicldins of a postion of the body will greatly increase the emount of
radiation that can be tolerated.
Many of the phenomena that have been deseribed
for irradiation of portions of the body can be produced only by amounts of radiation that are greatly in excess of the amount of radiation that will ki11 one
hundred per cent of the animals.
For example, many of the characteristic histo-
logic Lesions of the gastrointestinal
tract produced by local irradiation do not
develop with amounts of radinticn that produce a 100% mortality when the entire
body is uniformly and sinultaoncously irradiated.
blood is particularly altered.
The response of the peripheral
In oa general sense, 300 r in a sinsle dose to the
entire body will give the same henatolecic response as more than 600 r to the
entire skeletal ascas when the abdomen ia shicided.
These preliminary rccmarks
express the opinion of the authors in emphasizing the futility of comparing hemae
tologic responses unless the dcosese factors, Location end amount of tissue injured
are accurately knowa,
Total absorption of radiation energy as measured by the
groan, roentgen is not satisfactory cithor, because the distribution of the absorbed
energy throughout the body, in part, determines the response to the total energy
aboorbed (see chapter by Bond et al.).
Therefore, the remarks in this chapter will
be largely limited to the effects on the blood produced by evenly distributed,
penetrating, ionizing radiations
of the same type to the whole body of animals.
This type of experiment can bercntity duplicated.
However, it must be appreciated
that these conditions may not approximate the conditions of radiation during an
atenic bomb explosion.
For example, there may be considerable shielding. of various
portions of the body by concrete and structural steel after detonatica of an atomic
bozb over an urban crea.
Regardless of that fact, this type of laboratory study
affords a starting point for study ef radiation phenomena of the whole animal that
whl serve as a point from which one can begin to extrapolate to man.
This dis-
cussion further will be generally limited to the sublethal and zero to 100 per cent
lethal range.