private static void RegisterMappings()
{
    // Doctors - to DTO
    Mapper.CreateMap<Model.Doctor, DTO.Doctor>()
          .ForMember(dest => dest.Patients, opt => opt.Ignore());

    // Doctors - from DTO
    Mapper.CreateMap<DTO.Doctor, Models.Doctor>()
          .ForMember(dest => dest.FullName,
                     opt => opt.MapFrom(
                                src => src.FirstName + " " + src.LastName)
                            );
}