The microdosimetric characterization represents a useful method for the quality assessment of hadron beams [1,2]. These distributions can be measured by means of Tissue Equivalent Proportional Counters (TEPCs) . Besides, the possibility of performing dosimetry and quality assessment at the same time allows a detailed picture of the physical properties of clinical beams and permits the investigation of the effectiveness of a therapeutic treatment [1,3]. For these reasons, efforts should be made for developing experimental techniques able to measure microdosimetric distributions in hadron beams. Yet standard TEPCs cannot sustain the particle current of clinical hadron beams, while miniaturized TEPCs (miniTEPCs) are fairly complex and difficult to use . A new kind of TEPC based on a GEM structure has been recently developed. It simulates a tissue-equivalent region of a micrometer size. The new detector has been tested with photons and fast neutron beams by the LNL laboratories , before being used to perform microdosimetric measurements with 62 AMeV carbon ions at the cyclotron facility of the INFN-Laboratori Nazionali del Sud (LNS, Catania, Italy).