NMD-10

Branching emission rate

Ṅγ = A Y. Photon (or particle) rate from yield Y.

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DecayBranching ratio

Governing equation

\dot N_\gamma=A\,Y

$A \in \left[1, 2000\right]$

where

A: Activity (MBq)
Y: Yield per decay (—)
\dot N_\gamma: Emission rate (10^6/s)

The figure, part by part

Each numbered marker wears the color of its card. Hover a card to light the marker. Tap a marker to jump to that card. The slider walks a red point along the curve; Animate drawing traces it like a pen.

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①

Governing law — red

\dot N_\gamma=A\,Y

$A \in \left[1, 2000\right]$

$A = 1$ $\dot N_\gamma = 0.885$

Along the curve

②

Domain of the variable — blue

A_{\min} = 1,\quad A_{\max} = 2000

$A \in \left[1, 2000\right]$

$A = 1$ $A = 1$

Along the curve

③

Response curve — green

\dot N_\gamma=A\,Y

$A \in \left[1, 2000\right]$

$A = 1$ $\dot N_\gamma = 0.885$

Along the curve

④

Rate of change — amber

\frac{\mathrm{d}\dot N_\gamma}{\mathrm{d}A}

$A \in \left[1, 2000\right]$

$A = 13.57$ $\dot N_\gamma^{\prime} = 0.885$

Along the curve

Lecture brief

Historical brief

MIRD schema, in-vivo decay, uptake fractions and PET coincidence turned unsealed sources into organ dose. The sheets compute activity, residence and well-counter geometry. This sheet (NMD-10 — Branching emission rate) is the form associated with Branching ratio. Working symbols: $A$ , $Y$ $\rightarrow$ $\dot N_\gamma$ . Tc-99m Y(140 keV) ≈ 0.885. I-131 Y(364 keV) ≈ 0.81. Branching is per decay, not per second of clock time.

Purpose

Purpose: compute

\dot N_\gamma

from

A

Y

in Nuclear medicine via

\dot N_\gamma=A\,Y

Ṅγ = A Y. Photon (or particle) rate from yield Y. Use it when a real nuclear medicine question must be answered in SI before a code check.

Live realistic example

In symbols

Live case. Given

A = 370.000\,\mathrm{MBq}

Y = 0.885\,\mathrm{—}

, the governing relation

\dot N_\gamma=A\,Y

yields

\dot N_\gamma = 327.45\,\mathrm{10^6/s}

. A decay scheme with a labelled branch. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

Activity A370 MBqYield per decay Y0.885 —

Outputs

Emission rate \dot N_\gamma327.45 10^6/s

Reading speed

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Narration of this film

A decay scheme with a labelled branch.

Tc-99m Y(140 keV) ≈ 0.885. I-131 Y(364 keV) ≈ 0.81. Branching is per decay, not per second of clock time.

Reading speed

Watch on YouTube