Book Description

An air ionization chamber is theoretically the ideal type of radiation dosimeter since the roentgen is defined in terms of the ionization in air. When it comes to the continuous monitoring of a large number of people for radiation exposure, however, the practical problems of handling and servicing the meters must be considered in the choice of a method for carrying out such monitoring. Dental films have been used for a long time as a means of obtaining qualitative information regarding individual exposure to x-rays and gamma rays. The blackening of a film, however, varies by such a large factor for radiations of various quantum energies that this method could not be considered satisfactory unless some means of compensation for this energy dependence of response were achieved. A good pocket dosimeter should have the following properties. (1) Response for equal exposures in roentgens should be, as far as possible, independent of the quantum energy of the radiation. (2) The range of the meter preferably should be such that doses from less than 0.1 r to 10 or 20 r should be accurately measurable. (3) The response should not be producible by agents other than the radiations to be measured. (4) It should be small and light and should permit of being handled in large numbers by technicians.