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BOOKLET to Provide Basic Information Regarding Health Effects of Radiation (2nd edition)

Internal Exposure Measurement Using a Whole-body Counter

Internal Exposure Measurement Using a Whole-body Counter_Figure

A whole-body counter is a device to measure γ-rays emitted from the body. As γ-ray energy differs by radionuclide, if a specific amount of energy, for example, 1,461 keV, which is the γ-ray energy of radioactive potassium (K-40), is counted, this can be interpreted as γ-rays emitted from K-40 in the body. The γ-ray energy of Cs-137 is 662 keV.

Potassium is an essential element for a living organism and approximately 0.01% of it is radioactive. Radioactive potassium is mainly dissolved in cellular water and exists in muscles but not so much in fat cells that contain little water.

As radioactive cesium spreads all over the body, the internal dose of cesium is measured using a whole-body counter.

(Related to p.60 of Vol. 1, "Instruments for Measuring Internal Exposure")

  • Included in this reference material on March 31, 2013
  • Updated on March 31, 2016
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