MDCB Formulas + Memorization Questions
with Complete Solutions
a source is leaking if ____ or more is detected 0.005 µCi
electron depth (cm) @ 90% isodose per energy ~E(MeV)÷4
electron depth (cm) @ 80% isodose per energy ~E(MeV)÷3
electron depth (cm) @ 10% isodose per energy ~E(MeV)÷2 - 0.5cm
maximum range of electrons per energy ~E(MeV)÷2
secular equilibrium's A(D)/A(P) = ? =1
transient equilibrium's A(D)/A(P) = ? = λ(D)÷[λ(D) - λ(P)]
half life of Cs-137 30 years
,half life of Ra-226 1600 years
half life of Co-60 5.26 years
half life of I-127 60 days
half life of Pd-103 17 days
half life of Ir-192 74 days
decay method of Ra-226 alpha decay
decay method of Cs-137 beta minus decay
decay method of Ir-192 electron capture, beta minus decay
,decay method of Au-192 beta minus decay
decay method of I-125 electron capture
decay method of Pd-103 electron capture
decay method of R-222 alpha decay
decay method of I-131 beta minus decay
decay method of Co-60 beta minus decay
exposure rate (gamma) constant for Ra-226 8.25 R·cm²/mg·hr
(in equilibrium with daughter products and filtered by 0.5 mm Pt)
exposure rate (gamma) constant for Cs-137 3.26 R·cm²/mCi·hr
, brachytherapy: exposure rate and dose rate (formulas) exposure rate = Γ · A/d², where
A = activity, d = distance from the source
dose rate = Sk · ∧ · G(r,θ) · F(r) · g(θ), where
Sk = air kerma strength
∧ = dose-rate constant
G(r,θ) = geometry factor
F(r) = anisotropy factor
g(θ) = radial dose function
brachytherapy: total dose for permanent implant, for temporary implant (formulas)
permanent implant total dose
D(total) = (initial dose rate)(mean life), where
mean life = t(avg) = 1.44(half life) = 1/λ, where
λ = decay constant
temporary implant total dose
D(total) = (inital dose rate)(mean life)[1-exp(-t/{mean life})]
with Complete Solutions
a source is leaking if ____ or more is detected 0.005 µCi
electron depth (cm) @ 90% isodose per energy ~E(MeV)÷4
electron depth (cm) @ 80% isodose per energy ~E(MeV)÷3
electron depth (cm) @ 10% isodose per energy ~E(MeV)÷2 - 0.5cm
maximum range of electrons per energy ~E(MeV)÷2
secular equilibrium's A(D)/A(P) = ? =1
transient equilibrium's A(D)/A(P) = ? = λ(D)÷[λ(D) - λ(P)]
half life of Cs-137 30 years
,half life of Ra-226 1600 years
half life of Co-60 5.26 years
half life of I-127 60 days
half life of Pd-103 17 days
half life of Ir-192 74 days
decay method of Ra-226 alpha decay
decay method of Cs-137 beta minus decay
decay method of Ir-192 electron capture, beta minus decay
,decay method of Au-192 beta minus decay
decay method of I-125 electron capture
decay method of Pd-103 electron capture
decay method of R-222 alpha decay
decay method of I-131 beta minus decay
decay method of Co-60 beta minus decay
exposure rate (gamma) constant for Ra-226 8.25 R·cm²/mg·hr
(in equilibrium with daughter products and filtered by 0.5 mm Pt)
exposure rate (gamma) constant for Cs-137 3.26 R·cm²/mCi·hr
, brachytherapy: exposure rate and dose rate (formulas) exposure rate = Γ · A/d², where
A = activity, d = distance from the source
dose rate = Sk · ∧ · G(r,θ) · F(r) · g(θ), where
Sk = air kerma strength
∧ = dose-rate constant
G(r,θ) = geometry factor
F(r) = anisotropy factor
g(θ) = radial dose function
brachytherapy: total dose for permanent implant, for temporary implant (formulas)
permanent implant total dose
D(total) = (initial dose rate)(mean life), where
mean life = t(avg) = 1.44(half life) = 1/λ, where
λ = decay constant
temporary implant total dose
D(total) = (inital dose rate)(mean life)[1-exp(-t/{mean life})]
