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Effects of defining realistic compositions of the ocular melanoma on proton therapy.

Keshazare Sh, Masoudi SF, S Rasouli F - J Biomed Phys Eng (2014)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: MSc 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 defining realistic materials on dose deposition due to utilizing pencil beam scanning (PBS) method for proton therapy of ocular melanoma. The first model is filled 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 figured 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 sufficiency 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.

No MeSH data available.


Related in: MedlinePlus

A schematic figure of the simulated eye phantom with a tumor located at the corner of the eye. The rectangular voxels are considered for dose calculation in depth direction.
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Figure 1: A schematic figure of the simulated eye phantom with a tumor located at the corner of the eye. The rectangular voxels are considered for dose calculation in depth direction.

Mentions: In the presented work, two models are simulated as eye phantom. These phantoms consist of a sphere with 1.2 cm radius as the human eye, with a tumor located at the corner. The tumor is modeled as a segment of a sphere with radius of 1 cm. This geometry is similar to the most common choroidal uveal melanoma [20]. A schematic figure of the simulated phantom is shown in figure 1.


Effects of defining realistic compositions of the ocular melanoma on proton therapy.

Keshazare Sh, Masoudi SF, S Rasouli F - J Biomed Phys Eng (2014)

A schematic figure of the simulated eye phantom with a tumor located at the corner of the eye. The rectangular voxels are considered for dose calculation in depth direction.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4289521&req=5

Figure 1: A schematic figure of the simulated eye phantom with a tumor located at the corner of the eye. The rectangular voxels are considered for dose calculation in depth direction.
Mentions: In the presented work, two models are simulated as eye phantom. These phantoms consist of a sphere with 1.2 cm radius as the human eye, with a tumor located at the corner. The tumor is modeled as a segment of a sphere with radius of 1 cm. This geometry is similar to the most common choroidal uveal melanoma [20]. A schematic figure of the simulated phantom is shown in figure 1.

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: MSc 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 defining realistic materials on dose deposition due to utilizing pencil beam scanning (PBS) method for proton therapy of ocular melanoma. The first model is filled 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 figured 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 sufficiency 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.

No MeSH data available.


Related in: MedlinePlus