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Brachytherapy Source Strength
Only the reference air kerma rate (RAKR)
K
R
is a quantity that is traceable
to a standards laboratory (i.e., NMI or PSDL)
RAKR defined as kerma rate to air @ 1 meter
in vacuo
, corrected for attenuation/scatter
RAKR defined on the source transverse-plane for photons with E > δ
δ threshold is dependent on source calibration protocol
RAKR has units Gy/s, also Gy/h or μGy/s (unit conversion - convenience)
mg Ra, mgRaEq, mCi (apparent activity), Bq
are not traceable quantities
Obsolete units: mg Ra, mgRaEq, mCi (apparent activity), Bq