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RAD-05

KERMA

K = Ψ (μ_tr / ρ). Kinetic energy released per unit mass.

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DosimetryKERMA

Governing equation

K=Ψ(μtr/ρ)K=\Psi(\mu_{tr}/\rho)

Ψ∈[1×10−4,10]\Psi \in \left[1\times 10^{-4}, 10\right]

where

\Psi
Energy fluence (J/m²)
\mu_{tr}/\rho
Mass energy transfer (cm²/g)
K
KERMA (mGy)

The figure, part by part

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RAD-05 · dose
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①

Governing law — red

K=Ψ(μtr/ρ)K=\Psi(\mu_{tr}/\rho)

Ψ∈[1×10−4,10]\Psi \in \left[1\times 10^{-4}, 10\right]

Ψ=1×10−4\Psi = 1\times 10^{-4}K=3×10−4K = 3\times 10^{-4}

②

Domain of the variable — blue

Ψmin⁡=1×10−4,Ψmax⁡=10\Psi_{\min} = 1\times 10^{-4},\quad \Psi_{\max} = 10

Ψ∈[1×10−4,10]\Psi \in \left[1\times 10^{-4}, 10\right]

Ψ=1×10−4\Psi = 1\times 10^{-4}Ψ=1×10−4\Psi = 1\times 10^{-4}

③

Response curve — green

K=Ψ(μtr/ρ)K=\Psi(\mu_{tr}/\rho)

Ψ∈[1×10−4,10]\Psi \in \left[1\times 10^{-4}, 10\right]

Ψ=1×10−4\Psi = 1\times 10^{-4}K=3×10−4K = 3\times 10^{-4}

④

Rate of change — amber

dKdΨ\frac{\mathrm{d}K}{\mathrm{d}\Psi}

Ψ∈[1×10−4,10]\Psi \in \left[1\times 10^{-4}, 10\right]

Ψ=0.063\Psi = 0.063K′=3K^{\prime} = 3

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-05 — KERMA) is the form associated with KERMA. Working symbols: Ψ\Psi, μtr/ρ\mu_{tr}/\rho →\rightarrow KK. Under charged-particle equilibrium D ≈ K (1−g). Air kerma is the calibration quantity.

Purpose

Purpose: compute KK from Ψ\Psi, μtr/ρ\mu_{tr}/\rho in Radiation physics via K=Ψ(μtr/ρ)K=\Psi(\mu_{tr}/\rho) K = Ψ (μ_tr / ρ). Kinetic energy released per unit mass. 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=0.050 J/m2\Psi = 0.050\,\mathrm{J/m^{2}}, μtr/ρ=0.030 cm2/g\mu_{tr}/\rho = 0.030\,\mathrm{cm^{2}/g}, the governing relation K=Ψ(μtr/ρ)K=\Psi(\mu_{tr}/\rho) yields K=0.150 mGyK = 0.150\,\mathrm{mGy}. A fluence, a transfer coefficient, a kerma. Move a slider: the numbers are this situation, not a canned story.

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Outputs

  • KERMA K0.150 mGy
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RAD-05 · dose
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Narration of this film

A fluence, a transfer coefficient, a kerma.

Under charged-particle equilibrium D ≈ K (1−g). Air kerma is the calibration quantity.

Reading speed

Watch on YouTube