The
transition froa low- to high-level cadtution exposure {3s depisctiec
{in Flgure 3.
increase
This is for cell lethality only.
in the quaatal response as a function of uv,
Because of nultinie hits and
steaply beginning in
cells
of
hote the (tnitial linear
have
Che
transiticn zone,
been killed as
the organs,
fail and die,
and
and
interactive procyusses,
one enters
therefore,
so
the HLE razion.
At
this point,
the organisas, at a given value of
now a single agent,
statistics of Ph in the LLE region,
methodology applies.
Again,
that with HLE the focus
to evaluate
given dose D.
the curve rises rcatter
that a lacge fracticn of crzar
the energy carried
fonizing radlations, can span the entire gamut,
is adequate
the LLE resaloa.
ranging
UL, wil.
This
iy
fron the acctdsat
into the HLE region
in waich [a
the largest difference between the two resions
is on the individual, and the single parameter =
the probability of
the quantal
response at any
‘ith LLE, on the other hand, each pointe on the curve showa
represents an entire population of cells, and
the interesct focuses on isw
many in that popusation will be serfously injured or killed.
variables,
song
the fraction will increase to unity as D increases.
olot demonstrates clearly
is
in
the number of cells hit,
the distribution of
Here
chre
hit sizes, ana an
HSEF, are required.
CISCUSSION
The
above-presenated
differs drastically from
cell
dose
approach
to
that presently used.
radiation
ris. evaluation
Cell populations and
the
energy deposited in each cell replace the organ and organ dose concepts.
=
Ph and statistical mechanics apprvuach to evaluate cell-charged particle
interactions,
LET in
replaces
the Md approach currently used.
tissues ts abandoned
the single cell.
{a favor of use of
ean values of
the HSEF to evaluate risa ts
CGbject-oridnted shysical quantities
that are closely
related to cell damage replace the more remote field quantities.
distributions of cells,
the HSEF and
quantally responding cells
The approach,
consistent and logical
the associated discribution of
replace “linear,
in principle, appears
than is
Thus
non-threshold” relationshizs.
to be far more coherent, internally
the present system that must englcy varisus
factors and various versions of “dose equivalent” to permit it to be
operable at all.
16
500TH bS