Detectors for measurement of microdosimetric quantities

Microdosimetric quantities have been used for assessing the radiation quality of hadron therapy fields since long. They are stochastic quantities whose distributions depend on the fluctuations of energy deposition in cellular and/or sub-cellular structures. The present work overviews the detectors which are used mainly for assessing the radiation quality of hadron therapy fields (protons and carbon ions), discussing their advantages and limitations based on the author’s experience. The microdosimeters which are described and discussed herein are, in particular, tissue-equivalent proportional counters (TEPCs), gas detectors based on gas-electron multiplication (GEMs), silicon and diamond detectors.