Shallow Dose Correction Factor - Panasonic PT-DZ12000U Operating Instructions Manual

Shallow Dose Correction Factor

In accordance with 10CFR20 and 10CFR835 deep dose
equivalent shall be used for posting of radiation areas.
Shallow dose equivalent shall be reported separate from deep
dose equivalent. Deep dose equivalent is the sum of the
gamma and neutron deep dose equivalents. Shallow dose
includes low-energy photons and charged particles such as
betas, positrons, and protons. Alpha particles are not
included in shallow dose.
The following applies to vented air ionization chambers with a
2
window density thickness of 7 mg/cm and a moveable shield
2
with a density thickness of 1,000 mg/cm .
Determining the need to report a shallow dose;
If the Open Shield Reading divided by the Closed Shield
Reading is equal to or greater than 1.2, then perform a
shallow dose survey.
Calculate the shallow dose rate using this equation;
(Open Shield Reading - Closed Shield Reading) x CF
Obtain the CF (Correction Factor) from experimental or
published data for the specific detector and radiation
source(s).
Typical correction factors for betas range between 2 and 5
(multipliers).
Typical correction factors for low energy photons range
between 0.1 and 1 (multipliers).
Low energy photons that penetrate the closed shield of the ion
chamber and produce a response in the instrument are part of
the "deep" dose.