NMD-35

Tc-99m remaining

T½ = 6 h.

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Nuclear medicineTc-99m

Governing equation

A=A_0 2^{-t/6\\mathrm{h}}

$t \in \left[0, 24\right]$

where

A_0: A0 (MBq)
t: t (h)
A: A (MBq)

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

A=A_0 2^{-t/6\\mathrm{h}}

$t \in \left[0, 24\right]$

$t = 0$ $A = 800$

Along the curve

②

Domain of the variable — blue

t_{\min} = 0,\quad t_{\max} = 24

$t \in \left[0, 24\right]$

$t = 0$ $t = 0$

Along the curve

③

Response curve — green

A=A_0 2^{-t/6\\mathrm{h}}

$t \in \left[0, 24\right]$

$t = 0$ $A = 800$

Along the curve

④

Rate of change — amber

\frac{\mathrm{d}A}{\mathrm{d}t}

$t \in \left[0, 24\right]$

$t = 0.151$ $A^{\prime} = -90.83$

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-35 — Tc-99m remaining) is the form associated with Tc-99m. Working symbols: $A_0$ , $t$ $\rightarrow$ $A$ . T½ = 6 h.

Purpose

Purpose: compute

A

from

A_0

t

in Nuclear medicine via

A=A_0 2^{-t/6\\mathrm{h}}

T½ = 6 h. 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_0 = 800.000\,\mathrm{MBq}

t = 6.000\,\mathrm{h}

, the governing relation

A=A_0 2^{-t/6\\mathrm{h}}

yields

A = 400.0\,\mathrm{MBq}

. T½ = 6 h. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

A0 A_0800 MBqt t6 h

Outputs

A A400.0 MBq

Reading speed

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Narration of this film

T½ = 6 h.

Reading speed

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