[The Gamma-Scout® Geiger counter displays radiation exposure rate µSv/h (microsievert/hour). The sievert is an internationally recognized unit that indicates the biological effect of radiation – the so-called equivalent dose. Much of contemporary literature on radiation refers to the rem (Roentgen Equivalent Man). The conversion ratio for rem to sievert is as follows:

1 rem = 0.01 Sv = 10 mSv = 10,000 µSv

1 mrem = 0.001 rem = 10 uSv

Switching the Gamma-Scout® display from sievert to rem is simple (see user guide).

Converting Bq into µSv/h:

For Cs-137 applies at a distance of 1 meter:

1 GBq = 87 µSv/h

100 MBq = 8.7 µSv/h

10 MBq = 0.87 µSv/h

1 MBq = 0.087 µSv/h


100 µSv/h = 1.23 GB GBq

10 µSv/h = 123 MBq

1 µSv/h = 12.3 MBq

0,1 µSv/h = 1.23 MBq

M = 10^6 = 1 million

G = 10^9 = 1 billion

Each material has a certain activity depending on its composition (= measurement of radioactive content), which can be presented in Bq/kg: Bq = decay per unit of time.

Conversion from Bq into µSv/h is possible only in certain specific cases when the material composition and the geometry between the material and the place of measurement are precisely known.

(Distance of the source from the measuring device, shielding of the measuring device, air or other filter between source and measuring device, the chemical form of the nuclide, the type, age and proportion of the isotope in the source …)

The relationship between Bq and µSv/h described above is thus only a very rough indication. An even more tentative indication would be: 1 GBq is equal to approx. 100 µSv/h