International standard reference radiations and their application to the type testing of dosimetric apparatus

This report describes the use of X, γ and beta radiations for the assessment of commercial dosimetric apparatus. The International Standards Organization standard X-radiations can be produced by using filtered X-ray beams and by the excitation of fluorescent radiation. A comparison of instrument responses obtained for 20%, 30% and 50% resolution filtered beams and the fluorescent X-rays is given. Their use for the assessment of surface and depth dose equivalent rate meters, the problems of the measurement of dose rate from the radiations and of relating the standards to primary standards are also discussed. Since standardization for its own sake is unacceptable, it is important that the derived benefits should be clearly known before it is undertaken. While the benefits of standardization in radiation therapy and medical diagnosis are obvious, for radiation protection they are not always so apparent. The advantages and disadvantages of formulating standards for the calibration and assessment as well as in the specification of health physics instruments are therefore discussed and contrasted