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Radiotherapy Bunker Shielding Calculations and Recommendations for Structural Design for High Energy Photon Facilities |
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PP: 201-208 |
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doi:10.18576/jrna/080302
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Author(s) |
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Md. Motiur Rahman,
Md. Fajle Rabby,
Rubel Ahmed,
Mahmuda Akter,
AKM A Habib,
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Abstract |
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| This study was conducted to calculate and design the bunker shielding for LINAC with a 15MV photon facility. Shielding against neutrons should also be considered for LINACs operating in and above 10MV because of the production of photo-neutrons (ɣ, n) in the accelerator head. Boron-paint and PVC (Polyvinyl Chloride) boards were used along with the thick concrete wall of bunkers for neutron protection and interior design at TMSS Cancer Center, Bogura, Bangladesh. High-density polyethylene sheets were also used for neutron shielding at the entrance door. The maze wall is thicker at its beginning (door location) and thins gradually towards the end in the LINAC bunker design. The maze wall has nearly one foot slanting on the outside. The maze wall length should not be less than 5 meters in such cases. To preserve a concrete density of roughly 2350 kg/m3 in the calculation, which complies with BAERA regulations, we aim to mix the primary materials in 1:2:4 ratios (1kg cement: 2kg sand: 4kg stone chips). The water-to-cement ratio was kept between 0.5 and 0.55 to achieve the desired density. However, due to poor mixing and water-to-cement ratios, we could not manufacture Concrete with a 2300-2400 kg/m3 density. In that case, 10% more Concrete was added to increase the wall and ceiling thickness to prevent radiation leakage for further safety. After installing the LINAC, the radiation leakage data were collected. The results of this study are practically feasible, verified by the radiation survey. All the leakage data are very much lower than the internationally permissible limits. According to this study, the shielding strategy has efficiently taken all the possible measures and can be a straight direction for any physicist. |
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