Water equivalent properties of materials commonly used in proton dosimetry

► Depth-dose profile of proton beams in dosimetric materials is simulated by the SEICS code. ► The targets studied are liquid water, PMMA, polystyrene (PS), graphite, Al, Cu, Ti and Au. ► The water equivalent ratio is obtained from the simulated depth-dose distributions. ► PS and PMMA present depth-dose characteristics analogous to liquid water. ► PS and PMMA are well suited for use as phantom of liquid water in dosimetric measurements.