Hadron therapy uses ion beams for irradiation of cancerous tissue taking advantage of the highly localized dose deposition in the target tumor. For a correct estimation of dose deposited in tissue surrounding the target it is necessary to consider also the contribution of energetic sec-ondary radiation generated by primary ions. It was already experimentally demonstrated that this contribution can be measured using the semiconductor pixel detector Timepix (256256 pixels with 55mm pitch) visualizing traces of secondary particles. The resolving power of the detec-tor enables the differentiation of traces of different types of particles. In this work we studied the possibilities of determination of different types of secondary particles in correlation with their flight direction. Such identification allows correct assignment of dose for each type of particle. The distribution of secondary particles was compared to Monte Carlo simulations. Measurements were performed with a PMMA target irradiated with a therapeutic carbon beam at the Heidelberg Ion-Beam Therapy Center (HIT)