468-469 / 2239
•
H only reflects attenuation coefficient of
tissue to diagnostic x-ray energies
•
Electron density insufficient for protons
Need RSP and Z
Proton interactions:
• Electronic
– ionization
– excitation
• Nuclear
– Multiple Coulomb scattering, small
θ
– Elastic nuclear collision, large
θ
– Nonelastic nuclear interaction
B Schaffner. Phys. Med. Biol. 43 (1998)
Matsufuji (2003) looked at extending stoiciometric for multiple scattering
And found up to 10% errors but minimum effect on patient distributions