specified in 10CFR33.100, Schedule A, Column I; and the Type C license
permits maximum activities of by-product material specified in
10CFR33.100, Schedule A, Column II, which are an order of magnitude less
than those in the Type B license.
In the Type A license, a radiation safety committee and a radiation safety
officer are required to implement and monitor all aspects of radiation safety
in the use and disposal of by-product material. Such licenses are mainly
offered to large medical institutions with previous experience that are
engaged in medical research, and in diagnostic and therapeutic uses of by-
product material. Individual users are authorized by the radiation safety
committee to conduct specific protocols using by-product materials.
The Type B specific license requires a radiation safety officer, but no radi-
ation safety committee, to implement and monitor all radiation safety reg-
ulations. The Type C specific license requires neither the radiation safety
officer nor the committee, but a definite statement that the by-product
material will be used by the licensee or by persons under his direct super-
vision who has the training specified in 10CFR33.15.
In all cases of specific licenses, an application must be filed to the NRC
using the NRC Form 313 with all information related to the possession, use,
and disposal of by-product materials.
Radiation Protection
Rules and regulations pertaining to radiation protection set by the NRC
are contained in 10CFR20. Because it is beyond the scope of this book to
include the entire 10CFR20, only the relevant highlights are included.
Definition of Terms
Several terms related to absorbed dose as defined in the 10CFR20 are given
here.
Committed dose equivalent (HT,50) is the dose equivalent to organs or tissues
of reference (T) that will be received from an intake of radioactive mate-
rial by an individual during the 50-year period following the intake.
Deep-dose equivalent (Hd), which applies to the external whole-body expo-
sure, is the dose equivalent at a tissue depth of 1 cm (1000 mg/cm^2 ).
Shallow-dose equivalent (Hs), which applies to the external exposure of the
skin or an extremity, is the dose equivalent at a tissue depth of 0.007 cm
(7 mg/cm^2 ) averaged over an area of 1 cm^2.
Tissue weighting factor (WT) for an organ or tissue is the proportion of the
risk of stochastic effects resulting from irradiation of that organ or tissue
to the total risk of stochastic effects when the total body is irradiated
uniformly.
Radiation Protection 271