Considerations for MR-linac bunker shielding design

Purpose. To show the considerations followed for MR-linac in shielding design for the first MR-linac in Mexico following the national clinical necessities. Method. The National Council on Radiation Protection and Measurements (NCRP) 151 recommendations were followed for the shielding design for primary and secondary barriers and the door design. The calculations were made considering the clinical demands in the country, that is, intensity modulated (IMRT) and 3D conformal radiotherapy (3DC-RT) in 80%–20% proportion. Results. The values obtained in the level survey fully comply with the limits established by the national regulatory authority and with those recommended by the International Commission on Radiological Protection (ICRP) for public and occupational exposures. Conclusion. It is remarkable that the workload may increase or that the doses per patient may increase considering occupancy factors, which would allow the introduction of hypofractionated techniques with the same number of patients considered in this work without the need to make modifications in the bunker design.