Counts per minute dose reading. This modifies the tube characteristic so each count resulting from a particular radiation type is equivalent to a specific quantity of deposited dose. More can be found on radiation dose and dose rate at absorbed dose and equivalent dose. Disintegrations per minute (dpm) and disintegrations per second (dps) are measures of the activity of the source of radioactivity. The SI unit of radioactivity, the becquerel (Bq), is equivalent to one disintegration per second. This unit should not be confused with cps, which is the number of counts received by an instrument from the source. One dps (one dpm)
Specific activity the radionuclide is given by where "m" is mass number of the radionuclide and "N" is the Avogadro constant. Specific radioactivity "a" is defined as radioactivity per unit mass of the radionuclide: In addition, decay constant "λ" is related to the half-life "T" by the following equation: Thus, specific radioactivity can also be described by This equation is simplified by When the unit of half-life converts a year For example, specific radioactivity of radium-226 with a half-life of 1600 years is obtained by This value derived from radium 226 was defined as unit of radioactivity known as Curie (Ci). Experimentally