NMD-17

Energy-window width

W% = 100 ΔE / E0. Photopeak window as a percent of E0.

Reading speed

SpectroscopyEnergy window

Governing equation

W_{\%}=100\,\Delta E/E_0

$\Delta E \in \left[4, 80\right]$

where

\Delta E: Full window ΔE (keV)
E_0: Photopeak energy (keV)
W: Window percent (%)

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

W_{\%}=100\,\Delta E/E_0

$\Delta E \in \left[4, 80\right]$

$\Delta E = 4$ $W = 2.857$

Along the curve

②

Domain of the variable — blue

\Delta E_{\min} = 4,\quad \Delta E_{\max} = 80

$\Delta E \in \left[4, 80\right]$

$\Delta E = 4$ $\Delta E = 4$

Along the curve

③

Response curve — green

W_{\%}=100\,\Delta E/E_0

$\Delta E \in \left[4, 80\right]$

$\Delta E = 4$ $W = 2.857$

Along the curve

④

Rate of change — amber

\frac{\mathrm{d}W}{\mathrm{d}\Delta E}

$\Delta E \in \left[4, 80\right]$

$\Delta E = 4.478$ $W^{\prime} = 0.714$

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-17 — Energy-window width) is the form associated with Energy window. Working symbols: $\Delta E$ , $E_0$ $\rightarrow$ $W$ . A 20 % window on 140 keV is ±14 keV. Narrower windows cut scatter and also cut photopeak counts.

Purpose

Purpose: compute

W

from

\Delta E

E_0

in Nuclear medicine via

W_{\%}=100\,\Delta E/E_0

W% = 100 ΔE / E0. Photopeak window as a percent of E0. 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

\Delta E = 28.000\,\mathrm{keV}

E_0 = 140.000\,\mathrm{keV}

, the governing relation

W_{\%}=100\,\Delta E/E_0

yields

W = 20.00\,\mathrm{%}

. A photopeak and a pair of energy cursors. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

Full window ΔE \Delta E28 keVPhotopeak energy E_0140 keV

Outputs

Window percent W20.00 %

Reading speed

Watch on YouTube

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Narration of this film

A photopeak and a pair of energy cursors.

A 20 % window on 140 keV is ±14 keV. Narrower windows cut scatter and also cut photopeak counts.

Reading speed

Watch on YouTube