Abstract
Almost every known effect of ionizing radiation on matter, whether it be physical, chemical or biological, has been suggested as a basis for dosimetry, especially if the matter is (or can be made) dosimetrically tissue-equivalent. The latest candidate for attention is the magnetic resonance effect, the dosimetric application of which has been pioneered by British, American and Swedish workers (Gore et al. 1984, Appleby et al. 1987, Olsson et al. 1989). The method has a number of interesting features, though it may be unfamiliar to many regular practitioners of clinical dosimetry. The author gives an introductory review intended to place the new method in the broad context of radiotherapy dosimetry.