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RAD-22

Dose from energy fluence

D = Ψ (μ_en / ρ). Collision kerma under CPE equals absorbed dose.

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DosimetryMass energy absorption

Governing equation

D=Ψ(μen/ρ)D=\Psi(\mu_{en}/\rho)

where

\Psi
Energy fluence (J/m²)
\mu_{en}/\rho
Mass energy absorption (cm²/g)
D
Dose (mGy)

Lecture brief

Historical brief

Beer attenuation, Compton (1923), Klein–Nishina, Bragg–Gray cavity and KERMA are the transport of photons and charged particles in matter. The sheets compute fluence, kerma and stopping. This sheet (RAD-22 — Dose from energy fluence) is the form associated with Mass energy absorption. Working symbols: Ψ\Psi, μen/ρ\mu_{en}/\rho →\rightarrow DD. μ_en = μ_tr (1−g). The radiative fraction g is small in tissue below ~10 MeV.

Purpose

Purpose: compute DD from Ψ\Psi, μen/ρ\mu_{en}/\rho in Radiation physics via D=Ψ(μen/ρ)D=\Psi(\mu_{en}/\rho) D = Ψ (μ_en / ρ). Collision kerma under CPE equals absorbed dose. Use it when a real radiation physics question must be answered in SI before a code check.

Live realistic example

In symbols

Live case. Given Ψ=0.100 J/m2\Psi = 0.100\,\mathrm{J/m^{2}}, μen/ρ=0.030 cm2/g\mu_{en}/\rho = 0.030\,\mathrm{cm^{2}/g}, the governing relation D=Ψ(μen/ρ)D=\Psi(\mu_{en}/\rho) yields D=0.300 mGyD = 0.300\,\mathrm{mGy}. A fluence, an absorption coefficient, a dose. Move a slider: the numbers are this situation, not a canned story.

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Outputs

  • Dose D0.300 mGy
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RAD-22 · dose
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Narration of this film

A fluence, an absorption coefficient, a dose.

μ_en = μ_tr (1−g). The radiative fraction g is small in tissue below ~10 MeV.

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