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Does concrete composition affect photoneutron production inside radiation therapy bunkers?
Asghar Mesbahi1, Ali-Asghar Azarpeyvand, Hamid Reza Khosravi
1Medical Physics Department, Medical School, Tabriz University of Medical Sciences, Tabriz, Iran. mesbahiiran@yahoo.com
Japanese Journal of Radiology
|December 20, 2011
Summary
Different concretes impact neutron doses in radiation therapy bunkers. High-density concretes like barytes and galena increase photoneutron doses, necessitating enhanced shielding for maze entrances.
Area of Science:
- Medical Physics
- Radiation Oncology
- Nuclear Engineering
Background:
- Radiation therapy bunkers utilize various concrete types for shielding.
- High-energy photon beams generate photoneutrons, posing a radiation hazard.
- Understanding concrete composition's effect on neutron dose is crucial for safety.
Purpose of the Study:
- To evaluate the influence of different concrete compositions on photoneutron doses.
- To assess neutron doses at the isocenter and maze entrance.
- To inform bunker design and shielding requirements.
Main Methods:
- Simulated an 18-MV photon beam and a radiation therapy bunker using MCNPX Monte Carlo code.
- Calculated photoneutron doses for various commercially available concretes.
- Analyzed neutron fluence at the isocenter and maze entrance.
Main Results:
- Barytes and galena concretes resulted in higher neutron doses to the water phantom.
- No significant difference in phantom neutron dose was observed for other concrete types.
- Neutron fluence at maze entrances varied up to 36% based on concrete atomic composition.
Conclusions:
- High-density concretes may increase neutron doses at bunker maze entrances.
- Stricter neutron shielding requirements may be needed for maze entrance doors when using high-density concretes.
- Concrete selection impacts radiation safety and shielding design in therapy bunkers.
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