ICRU Report 47, is the third report in the series treating determination of dose equivalent. The first two reports of the series, ICRU Report 39, Determination of Dose Equivalents from External Radiation Sources, and ICRU Report 43, Determination of Dose Equivalents from External Radiation Sources – Part II, provided the grounds for the Commission’s selection of the quantities and the basis for their definition. ICRU Report 47 gives guidance on the design, calibration and use of instruments required to implement the recommended system of dose determination. Covered in the report are principles of measurement, operational quantities, characteristics of instruments, calibrations and the impact of new operational quantities on the design of future instrumentation. Among the instruments characterized are ionization chambers, proportional counters, Geiger-MÃ¼ller counters, scintillation detectors, semiconductor detectors, photographic films, thermoluminescent dosimeters, thermally stimulated exoelectron emission detectors and photoluminescent detectors. An appendix provides conversion factors for dose equivalent quantities.