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

• Published in: Radiological physics and technology Vol. 16; no. 2; pp. 319 - 324
• Main Authors: Inaniwa, Taku, Weichert, Emely, Masuda, Takamitsu, Tanaka, Sodai, Matsufuji, Naruhiro, Kanematsu, Nobuyuki
• Format: Journal Article
• Language: English
• Published: Singapore Springer Nature Singapore 01.06.2023; Springer Nature B.V
• Subjects: Carbon; Carbon - therapeutic use; Computed tomography; Helium; Helium - therapeutic use; Humans; Imaging; Ion beams; Medical and Radiation Physics; Medicine; Medicine & Public Health; Neon; Neon - therapeutic use; Nuclear Medicine; Oxygen; Oxygen - therapeutic use; Particle energy; Proton beams; Proton Therapy; Radiation therapy; Radiology; Radiotherapy; Radiotherapy Planning, Computer-Assisted; Range errors; Soft tissues; Stopping power; Technical Note; Therapy; Tissues; Water; Stopping-power ratio; Treatment planning; Range estimation; Charged-particle therapy
• ISSN: 1865-0333; 1865-0341; 1865-0341
• DOI: 10.1007/s12194-023-00721-6

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% in the SPRs of soft tissues, whereas they led to a decrease of up to 1.9% in the SPRs of bone tissues compared with the current clinical settings. For 44 proton beams planned for 15 randomly sampled patients, the mean water-equivalent target depth change was − 0.2 mm with a standard deviation of 0.2 mm. The maximum change was − 0.6 mm, which we consider to be insignificant in clinical practice.