Also, with the diameter of
has commonly been called a "hit".
specified as a nucleus of 8 microns in diameter,
and often simply “cell dose" have been employed.
“cell dose” will be used here
the
the TCV
term “elementary dose”
"Hit", “hit-size”, and
interchangeably.
Although it is also useful to distinguish between stochastically
iping ing
and with
.t)
substantive requirement.
is
this
to avoid confusion and not a
In other words, all else being equal, an organisa
has no physiological means of determining whether a given agent transfer
has occurred stochastically or by plan.
can
It is only because of the above-outlined capabilities of
iguous
eristic
ye between
microdosimetric methods that the substantial advantages of using the
cell dose approach can be realized,
type or energy of
to the
. be
.
to planned doses,
delivered as opposed
Thus
energy deposition.
an
The instrument ts “completely blind"
the radiation particle responsible
the number of hits and
for the given
the hit sizes are
“object-oriented” quantities, on which the extent and severity of etfect
those
the biological material is exposed.
only in
ity,
in principle,
it is unnecessary to know anything about the nature of the field in which
been
as
In other words,
resulting from radiation exposure depends.
three
it
The large advantage of this lies not
that it usually fis quite difficult practically,
“pure” of radiations,
to determine
even for the most
the field strength itn
fluences and energies of the different types of particles.
fields,
it is often essentially impossible
variables.
Even if defined,
the
terms of
In mixed
to define adequately these
they are too remote from the btological eftect
to be satisfactory for quantitative prediction purposes.
Microdosimetry in
princtple obviates any requirement for their teasurement,
The companion advantage of using microdosimetric methods
is
that,
in
permitting measurements to be made at the time of stochastic events, they
in effect turn
the abstract cisk of being dosed, and cell doses,
concrete values.
living cell
cell,
Even though it is usually not possible to desiznute whicn
is hit, or to assign any particular cell dose
it is possible
for any given exposure.
essentially all the information that one has
ans
an
lap.
to any given
to state accurately the relative numbers
at any given value of cell dose,
toxicology,
into
that were hit
Thus one has
in pharmacology and
in which the number of individuals at any given dose level is
known precisely, and from which the (fractional) number of quantal
responders can be determined.
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