This term is used interchangeably at RERF with the terms “mean organ dose” or “dose.” It is defined as the energy absorbed in a specific organ divided by its mass, i.e., the average energy absorbed per unit mass. This quantity is expressed in gray or its submultiples. The organ-dose calculation allows for effects of external shielding and shielding provided by other tissues (see GD Kerr, “Organ dose estimates for the Japanese atomic-bomb survivors,” Health Phys 37:487-508, 1979.)