Absorbed ionizing particles differentially effect first and second acquiring circuit stages configured to respectively generate first and second acquisition signals. Each acquisition signal has a characteristic that is variable as a function of an amount of absorbed ionizing particles. A measuring circuit generates, on the basis of the first and second acquisition signals, a relative parameter indicative of a relationship between the variable characteristics. A computation of a total ionizing dose is made using a 1st- or 2nd-degree polynomial relationship in the relative parameter.