This International Standard specifies the requirements for reference beta radiations produced by radionuclide sources to be used for the calibration of protection level dosemeters and doseratemeters", and for the determination of their response as a function of beta energy. It gives the characteristics of radionuclides which have been used to produce reference beta radiations, gives examples of suitable source constructions and describes methods for the measurement of the residual maximum beta energy and the absorbed dose r?te" at a depth of 7 mgcm-2 in a semi-infinite tissue-equivalent medium. The energy range involved lies between 66 keV*** and 3,6 MeV and the absorbed dose r?tes are in the range from about 10nGy-h-i (1 mradh-1) toatleast 10Gyh-i (103 rad-h-i).
This International Standard proposes two series of beta reference radiations from which the radiation necessary for determining the characteristics (calibration and energy response) of an instrument shall be selected.
Series 1 reference radiations are produced by radionuclide sources used with beam flattening filters designed to give uniform dose r?tes ?ver a large area at a specified distance. The proposed sources of 9°Sr + 90Y, 2MTI and 147Pm produce maximum dose r?tes of approximately 5 mGy-h 1 (0,5radh-i).
Series 2 reference radiations are produced without the use of beam flattening filters which allows a range of source-to-
calibration plane distances to be used. Close to the sources only relatively small areas of uniform dose r?te are produced but this Series has the advantage of extending the energy and dose r?te ranges beyond those of Series 1. The radionuclides used are those of Series 1 with the addition of the radionuclides 14C and 106Ru + 106Rh; these sources produce dose r?tes of upto 10 Gyh-i (103 radh-i).