NMD-12

Resolution FWHM

FWHM = 2.355 σ. Gaussian energy or spatial width.

Reading speed

Gamma cameraFWHM

Governing equation

\mathrm{FWHM}=2.355\,\sigma

where

\sigma: Gaussian σ (mm)
FWHM: FWHM (mm)
FWTM: FWTM (mm)

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-12 — Resolution FWHM) is the form associated with FWHM. Working symbols: $\sigma$ $\rightarrow$ $FWHM$ , $FWTM$ . Intrinsic spatial FWHM of a modern camera is ~3.5–4.5 mm. Energy FWHM/E is the % resolution.

Purpose

Purpose: compute

FWHM

FWTM

from

\sigma

in Nuclear medicine via

\mathrm{FWHM}=2.355\,\sigma

FWHM = 2.355 σ. Gaussian energy or spatial width. 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

\sigma = 1.700\,\mathrm{mm}

, the governing relation

\mathrm{FWHM}=2.355\,\sigma

yields

FWHM = 4.00\,\mathrm{mm}

FWTM = 7.30\,\mathrm{mm}

. A Gaussian peak and its half-maximum width. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

Gaussian σ \sigma1.7 mm

Outputs

FWHM FWHM4.00 mm
FWTM FWTM7.30 mm

Reading speed

Watch on YouTube

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Narration of this film

A Gaussian peak and its half-maximum width.

Intrinsic spatial FWHM of a modern camera is ~3.5–4.5 mm. Energy FWHM/E is the % resolution.

Reading speed

Watch on YouTube