Whole-body counting

In health physics, whole-body counting refers to the measurement of radioactivity within the human body.

Radioactive decay may give rise to gamma radiation which cannot escape the body due to being absorbed or other interaction whereby it can lose energy; so account must be taken of this in any measurement analysis.

A whole-body counter is calibrated with a device known as a "phantom" containing a known distribution and known activity of radioactive material.

The BOMAB phantom consists of 10 high-density polyethylene containers and is used to calibrate in vivo counting systems that are designed to measure the radionuclides that emit high energy photons (200 keV < E < 3 MeV).

Because many different types of phantoms had been used to calibrate in vivo counting systems, the importance of establishing standard specifications for phantoms was emphasized at the 1990 international meeting of in vivo counting professionals held at the National Institute of Standards and Technology (NIST).

Such systems are designed to measure radionuclides that emit high-energy photons and that are assumed to be homogeneously distributed in the body.

The amount of naturally occurring radioactive potassium present in all humans is also easily detectable.

In 1950, Leonidas D. Marinelli developed and applied a low-level gamma-ray whole body counter to measure people who had been injected with radium in the early 1920s and 1930s, contaminated by exposure to atomic explosions, and by accidental exposures in industry and medicine[4][5] The sensitive methods of dosimetry and spectrometry Marinelli developed obtained the total content of natural potassium in the human body.