ABSTRACT
Aim: Electron, photon or proton beams are used in radiotherapy for cancer
treatment while each one may be used depending on depth and the location of
tumor and normal tissues around the treatment target as well as economic issues. Materials and Methods: In this research, dose distribution by proton was
measured by film dosimetry in nasal cavity Plexiglas phantom and Monte Carlo
simulation. Then the DVH of treatment target and the posterior of treatment
target of different beams were compared. The energies of electron, photon and
proton were 9 MeV, 6 MV, and maximum 65 MeV, respectively. Due to a depth of
3.5 cm of CTV (Clinical Target Volume), Modulation Range was between 0 - 3.5 cm
and SOBP (Spread-out Bragg Peak) was between 0 - 65 MeV. Results: Comparing the obtained DVH values, 95% dose coverage of target
volume for electron, photon, proton and Photon-Electron beams were 88%, 98%,
98%, and 95%, respectively. However, doses above 40% that reached outside the
target were 50%, 82%, 5%, and 44%, respectively. Conclusions: The
results demonstrate the superiority of proton therapy in nasal cancer due to
its better target volume coverage and the less amount of the dose reaching
outside the target that is because of dose discharge in a small area and
significant dose fall-off after Bragg peak.