RPR-16

Lead thickness from TVL

x = TVL log10(1/B). Lead (or concrete) needed for transmission B.

Reading speed

ShieldingLead thickness

Governing equation

x=\mathrm{TVL}\,\log_{10}(1/B)

$B \in \left[1\times 10^{-6}, 0.5\right]$

where

TVL: Tenth-value layer (mm)
B: Required transmission (—)
x: Shield thickness (mm)
n: Number of TVLs (—)

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

x=\mathrm{TVL}\,\log_{10}(1/B)

$B \in \left[1\times 10^{-6}, 0.5\right]$

$B = 1\times 10^{-6}$ $x = 72$

Along the curve

②

Domain of the variable — blue

B_{\min} = 1\times 10^{-6},\quad B_{\max} = 0.5

$B \in \left[1\times 10^{-6}, 0.5\right]$

$B = 1\times 10^{-6}$ $B = 1\times 10^{-6}$

Along the curve

③

Response curve — green

x=\mathrm{TVL}\,\log_{10}(1/B)

$B \in \left[1\times 10^{-6}, 0.5\right]$

$B = 1\times 10^{-6}$ $x = 72$

Along the curve

④

Rate of change — amber

\frac{\mathrm{d}x}{\mathrm{d}B}

$B \in \left[1\times 10^{-6}, 0.5\right]$

$B = 0.003$ $x^{\prime} = -7247.9$

Along the curve

Lecture brief

Historical brief

Inverse-square, half-value layer, ICRP weighting and ALARA are the protection craft since the 1920s commissions. The lab computes transmission, equivalent dose and a shielding snapshot. This sheet (RPR-16 — Lead thickness from TVL) is the form associated with Lead thickness. Working symbols: $TVL$ , $B$ $\rightarrow$ $x$ , $n$ . First TVL is larger than equilibrium TVL. Diagnostic lead: ~0.3–0.5 mm HVL at 80 kV; linac concrete: tens of cm.

Purpose

Purpose: compute

x

n

from

TVL

B

in Radiation protection via

x=\mathrm{TVL}\,\log_{10}(1/B)

x = TVL log10(1/B). Lead (or concrete) needed for transmission B. Use it when a real radiation protection question must be answered in SI before a code check.

Live realistic example

In symbols

Live case. Given

TVL = 12.000\,\mathrm{mm}

B = 0.010\,\mathrm{—}

, the governing relation

x=\mathrm{TVL}\,\log_{10}(1/B)

yields

x = 24.00\,\mathrm{mm}

n = 2.00\,\mathrm{—}

. A required B and a stack of tenth-value sheets. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

Tenth-value layer TVL12 mmRequired transmission B0.01 —

Outputs

Shield thickness x24.00 mm
Number of TVLs n2.00 —

Reading speed

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Narration of this film

A required B and a stack of tenth-value sheets.

First TVL is larger than equilibrium TVL. Diagnostic lead: ~0.3–0.5 mm HVL at 80 kV; linac concrete: tens of cm.

Reading speed

Watch on YouTube