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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

The created SOBP in instance depth of ocular media using the weighting factors which are optimized for water phantom (solid line), and the SOBP created in water phantom using the appropriate weighting factors for water (dashed line). See table 2.
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Figure 5: The created SOBP in instance depth of ocular media using the weighting factors which are optimized for water phantom (solid line), and the SOBP created in water phantom using the appropriate weighting factors for water (dashed line). See table 2.

Mentions: In order to show the effect of defining realistic media in delivered dose in proton therapy simulations, the weighting factors optimized for water phantom are used to create a SOBP in ocular media. This procedure is equivalent to using the weighted proton pencil beams for a patient obtained from irradiation of the beams to a water phantom. The created SOBPs are shown in figure 5. Obviously, using this method leads to disturbance the uniformity of SOBP.


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

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

The created SOBP in instance depth of ocular media using the weighting factors which are optimized for water phantom (solid line), and the SOBP created in water phantom using the appropriate weighting factors for water (dashed line). See table 2.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 5: The created SOBP in instance depth of ocular media using the weighting factors which are optimized for water phantom (solid line), and the SOBP created in water phantom using the appropriate weighting factors for water (dashed line). See table 2.
Mentions: In order to show the effect of defining realistic media in delivered dose in proton therapy simulations, the weighting factors optimized for water phantom are used to create a SOBP in ocular media. This procedure is equivalent to using the weighted proton pencil beams for a patient obtained from irradiation of the beams to a water phantom. The created SOBPs are shown in figure 5. Obviously, using this method leads to disturbance the uniformity of SOBP.

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