Author/Authors :
Keshazare، Sh نويسنده MSc Student in Applied Nuclear Physics, Department of Physics, KN Toosi University of Technology, Tehran, Iran , , Masoudi، F نويسنده Associate Professor of Physics Department, Head of Nuclear Physics Group, Department of Physics, KN Toosi University of Technology, Tehran, Iran , , Rasouli، F نويسنده PhD Student in Applied Nuclear Physics, Department of Physics, KN Toosi University of Technology, Tehran, Iran ,
Abstract :
Background: Recent studies in eye plaque brachytherapy have shown a considerable difference between the dosimetric results using water phantom and a model of human eye containing realistic materials. In spite of this fact, there is a lack of simulation
studies based on such a model in proton therapy literatures. In the presented work, the
effect of utilizing an eye model with ocular media on proton therapy is investigated
using the MCNPX Monte Carlo Code.
Methods: Two different eye models are proposed to study the effect of defning realistic materials on dose deposition due to utilizing pencil beam scanning (PBS) method
for proton therapy of ocular melanoma. The frst model is flled with water, and the
second one contains the realistic materials of tumor and vitreous. Spread out Bragg
peaks (SOBP) are created to cover a typical tumor volume. Moreover, isodose curves
are fgured in order to evaluate planar variations of absorbed dose in two models.
Results: The results show that the maximum delivered dose in ocular media is
approximately 12-32% more than in water phantom. Also it is found that using the
optimized weighted beams in water phantom leads to disturbance of uniformity of
SOBP in ocular media.
Conclusion: Similar to the results reported in eye brachytherapy published papers,
considering the ocular media in simulation studies leads to a more realistic assessment
of suffciency of the designed proton beam in tissue. This effect is of special importance in creating SOBP, as well as in delivered dose in the tumor boundaries in proton
pencil beam scanning method.
