Figure 5. Normalized mean fetal dose, as a percentage of prescribed dose(PD), for a typical two-field tangential beam plan as a function of fetal depth within the maternal abdomen. Data are presented for various treatment plans (sMLC, 15°, 30°, 45° and 60° wedged plans) and for 6 MV and 15 MV photon energies. The gestational age is 15 weeks post-conception.