A brief look at absorbed dose measurements in the 60Co field

The main quantity of interest in radiotherapy is absorbed dose to water. For years, its determination has been obtained by indirect methods with an accuracy of 1 to 2%. A brief summary is given of the work undertaken by the national standardizing laboratories and the BIPM, to obtain better accuracy. Several methods are now available (calorimetry, ionometry, etc.) and the agreement between them is better than 1%.