Figure 3. Out‐of‐field PD/MU in the phantom at depths of 1, 5, and 10 cm for the $27.4\times 27.4\hspace{0.17em}{\text{cm}}^2$ field size, and at depths of 1 and 10 cm for the $27.4\times 27.4\hspace{0.17em}{\text{cm}}^2$ field size.