Figure 2: Attenuation of treatment couch. The measurements are shown in dark blue diamond, Set Default in dark red squares, Set 1 in green triangles, Set 2 in purple squares, Set 4 in orange circle, Set 5 in yellow stripes, and Set 6 in pink stripes. The grey shape indicates the measurement setup on treatment couch and the position of the rails.

a) Diagram of the attenuation of treatment couch for 6 MVphotons, rails in middle position.

b) Diagram of the attenuation of treatment couch for 20 MVphotons, rails in middle position.

c) Diagram of the attenuation of treatment couch for 6 MVphotons, rails in external position.

d) Diagram of the attenuation of treatment couch for 20 MVphotons, rails in external position.