Fig. 1.
(a) The room layout and dimensions simulated in this study. The 3.65 m high room with the 55 cm thick concrete ceiling was simulated. Additionally, 110 cm concrete bulk simulated on top of the linac head in linac rotation direction for shielding the upper space from the primary radiation while the linac irradiates below the patient. The bulk performs as primary barrier with thickness of 1.65 m. (b) Axial view of the prostate and the treatment plan by which a patient is treated and our MC simulation was carried out. Isodoses curves can be seen in the plan provided by CorePlan TPS and used field sizes (two fields of 8 × 8 cm2 and two fields of 7 × 8 cm2) applied for simulations. Isocenter relative dose was shown in red color as 100.6%.