Absorbed‐dose images and depth‐dose profiles have been measured in a tissue‐equivalent phantom exposed to an epithermal neutron beam designed for neutron capture therapy. The spatial distribution of absorbed dose has been measured by means of gel dosimeters, imaged with optical analysis. From differential measurements with gels having different isotopic composition, the contributions of all the components of the neutron field have been separated. This separation is important, owing to the different biological effectiveness of the various kinds of emitted radiation. The doses coming from the reactions1H(n,&ggr;)2H and14N(n,p)14C and the fast‐neutron dose have been imaged. Moreover, a volume simulating a tumour with accumulation of10B and/or157Gd has been incorporated in the phantom and the doses due to the reactions with such isotopes have been imaged and profiled too. The results have been compared with those obtained with other experimental techniques and the agreement is very satisfactory. © 2003 American Institute of Physics