Stopping-power Ratio of Body Tissues with Updated Effective Energies and Elemental I Values for Treatment Planning of Proton Therapy and Ion Beam Therapy with Helium, Carbon, Oxygen, and Neon Ions.

The stopping-power ratio (SPR) of body tissues relative to water depends on the particle energy and mean excitation energy (I value) of the tissues. Effective energies to minimize the range error in proton therapy and ion beam therapy with helium, carbon, oxygen, and neon ions and elemental I values have been updated in recent studies. We investigated the effects of these updates on SPR estimation for computed tomography-based treatment planning. The updates led to an increase of up to 0.5