A hybrid-type female computational model was constructed by combining the tomographic voxel model of the ATOM adult female physical phantom with the mathematical organ models of the MIRD5 stylized phantom. The constructed model has 13 internal organs: 5 organs from the ATOM phantom and the other 8 organs from the MIRD5 phantom. The model was employed in Monte Carlo dose calculations with MCNPX to calculate organ doses, and the calculated values were compared with the values of Regina for reference external irradiation conditions.