NMD-05

PET coincidence rate

R = 2 ε² g A. Geometric efficiency g times paired detection.

Reading speed

PETPET coincidence

Governing equation

R=2\varepsilon^{2} g A

$A \in \left[10, 800\right]$

where

A: Activity (MBq)
\varepsilon: Crystal efficiency (—)
g: Geometric factor (—)
R: Coincidence rate (kcps)

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

R=2\varepsilon^{2} g A

$A \in \left[10, 800\right]$

$A = 10$ $R = 64$

Along the curve

②

Domain of the variable — blue

A_{\min} = 10,\quad A_{\max} = 800

$A \in \left[10, 800\right]$

$A = 10$ $A = 10$

Along the curve

③

Response curve — green

R=2\varepsilon^{2} g A

$A \in \left[10, 800\right]$

$A = 10$ $R = 64$

Along the curve

④

Rate of change — amber

\frac{\mathrm{d}R}{\mathrm{d}A}

$A \in \left[10, 800\right]$

$A = 14.97$ $R^{\prime} = 6.4$

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-05 — PET coincidence rate) is the form associated with PET coincidence. Working symbols: $A$ , $\varepsilon$ , $g$ $\rightarrow$ $R$ . Trues, scatter and randoms share the coincidence window. NECR is the figure of merit.

Purpose

Purpose: compute

R

from

A

\varepsilon

g

in Nuclear medicine via

R=2\varepsilon^{2} g A

R = 2 ε² g A. Geometric efficiency g times paired detection. 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 = 150.000\,\mathrm{MBq}

\varepsilon = 0.200\,\mathrm{—}

g = 0.080\,\mathrm{—}

, the governing relation

R=2\varepsilon^{2} g A

yields

R = 960.00\,\mathrm{kcps}

. A ring of crystals and a positron source. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

Activity A150 MBqCrystal efficiency \varepsilon0.2 —Geometric factor g0.08 —

Outputs

Coincidence rate R960.00 kcps

Reading speed

Watch on YouTube

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Narration of this film

A ring of crystals and a positron source.

Trues, scatter and randoms share the coincidence window. NECR is the figure of merit.

Reading speed

Watch on YouTube