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A Monte Carlo Study for Photoneutron Dose Estimations around the High-Energy Linacs.

Mohammadi N, Miri-Hakimabad SH, Rafat-Motavalli L - J Biomed Phys Eng (2014)

Bottom Line: The results of dose calculations at the isocenter and maze showed that photoneutron dose decreases as the function of distance from the isocenter and increases with increasing the distance from the entrance maze.It is concluded that the simplified model of linac head is a useful and reliable method in dosimetry calculations.Calculations illustrated that the photoneutron dose is not negligible and duo to its harmful biological effects on body, it should be considered in the treatment plans.

View Article: PubMed Central - PubMed

Affiliation: Physics Department, Faculty of Sciences, Ferdowsi University of Mashhad, Iran.

ABSTRACT

Background: High-energy linear accelerator (linac) is a valuable tool and the most commonly used device for external beam radiation treatments in cancer patients. In the linac head, high-energy photons with energies above the threshold of (γ,n) interaction produce photoneutrons. These photoneutrons deliver the extra dose to the patients undergoing radiation treatment and increase the risk of secondary cancer.

Objective: In this study, a simplified model of the linac head was simulated and photoneutron dose equivalent was calculated at the isocenter and maze in the sphere detector. In addition, the absorbed and equivalent dose of photoneutron were estimated in the some organs of the phantom.

Methods: The simulations were made using the Monte Carlo code. The ICRP reference adult male voxel phantom was used as the human body model for dosimetry calculations.

Results: The results of dose calculations at the isocenter and maze showed that photoneutron dose decreases as the function of distance from the isocenter and increases with increasing the distance from the entrance maze.

Conclusion: It is concluded that the simplified model of linac head is a useful and reliable method in dosimetry calculations. Calculations illustrated that the photoneutron dose is not negligible and duo to its harmful biological effects on body, it should be considered in the treatment plans.

No MeSH data available.


Related in: MedlinePlus

The x-y plan of simulated treatment room
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Figure 3: The x-y plan of simulated treatment room

Mentions: Simulation of the treatment room was based on Imam Reza hospital of Mashhad city in Iran. The thicknesses of the walls of treatment room and maze were considered 140 cm and 165 cm, respectively, which were made of standard concrete with a density of 2.23 gr.cm-3. The isocenter was located at a height of 114 cm from the floor and the distance between the source and the isocenter was about 100 cm. The schematic view of the treatment room was shown in the figure 3.


A Monte Carlo Study for Photoneutron Dose Estimations around the High-Energy Linacs.

Mohammadi N, Miri-Hakimabad SH, Rafat-Motavalli L - J Biomed Phys Eng (2014)

The x-y plan of simulated treatment room
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4289520&req=5

Figure 3: The x-y plan of simulated treatment room
Mentions: Simulation of the treatment room was based on Imam Reza hospital of Mashhad city in Iran. The thicknesses of the walls of treatment room and maze were considered 140 cm and 165 cm, respectively, which were made of standard concrete with a density of 2.23 gr.cm-3. The isocenter was located at a height of 114 cm from the floor and the distance between the source and the isocenter was about 100 cm. The schematic view of the treatment room was shown in the figure 3.

Bottom Line: The results of dose calculations at the isocenter and maze showed that photoneutron dose decreases as the function of distance from the isocenter and increases with increasing the distance from the entrance maze.It is concluded that the simplified model of linac head is a useful and reliable method in dosimetry calculations.Calculations illustrated that the photoneutron dose is not negligible and duo to its harmful biological effects on body, it should be considered in the treatment plans.

View Article: PubMed Central - PubMed

Affiliation: Physics Department, Faculty of Sciences, Ferdowsi University of Mashhad, Iran.

ABSTRACT

Background: High-energy linear accelerator (linac) is a valuable tool and the most commonly used device for external beam radiation treatments in cancer patients. In the linac head, high-energy photons with energies above the threshold of (γ,n) interaction produce photoneutrons. These photoneutrons deliver the extra dose to the patients undergoing radiation treatment and increase the risk of secondary cancer.

Objective: In this study, a simplified model of the linac head was simulated and photoneutron dose equivalent was calculated at the isocenter and maze in the sphere detector. In addition, the absorbed and equivalent dose of photoneutron were estimated in the some organs of the phantom.

Methods: The simulations were made using the Monte Carlo code. The ICRP reference adult male voxel phantom was used as the human body model for dosimetry calculations.

Results: The results of dose calculations at the isocenter and maze showed that photoneutron dose decreases as the function of distance from the isocenter and increases with increasing the distance from the entrance maze.

Conclusion: It is concluded that the simplified model of linac head is a useful and reliable method in dosimetry calculations. Calculations illustrated that the photoneutron dose is not negligible and duo to its harmful biological effects on body, it should be considered in the treatment plans.

No MeSH data available.


Related in: MedlinePlus