F & H Dosage Calculator (ca. 1958-1960)


This high quality slide rule was produced (ca. 1958-1960) by the German company Aristo and distributed under the Frieseke & Hoepfner (F&H) name. The latter company, based in Erlangen-Bruck, Germany was taken over by FAG Kugelfischer in 1980.

Although the text on the slide rule is in German, it was sold to English-speaking markets. Both the instruction manual and the cardboard case that came with our example employ English.

Some of the fundamental calculations it could perform include a determination of:

The activity of a source as a function of time.

The exposure rate at a given distance from a source of known activity.

The maximum duration of an exposure based on a predetermined limit.

The thickness of a shield required to reduce the exposure rate to a desired level.

The half-life of a radionuclide based on two measurements.


In the above image, the text in red translates to the number of half value thicknesses. "Zeit" means time (in seconds, minutes etc.), "Dosis" means dose (in uR, mR etc) and "Aktivitat" means activity.


In the image above "Dosis bzw. Emm. Wahrscheinlichet" refers to the dosage constant for a radionuclide (e.g., 8 for Ra-226). "Activitat" is the source activity (in uCi, mCi etc.). The text in red translates to number of half-value thicknesses and the number of half-lives. "Dosisleistung" means dose rate (in R/hr, mR/hr etc.). "PhotonenfluB" refers to the photon fluence rate (number of photons per square centimeter per minute)

Size: ca. 13" x 2"


Frieseke & Hoepfner. The F & H Dosage Calculator Instructions for Use. June 1958.

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Last updated: 05/10/11
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