Figure 2. Example External Beam Radiation Fields and Low-dose-rate Brachytherapy.

Anteroposterior (A) and right lateral (B) fields (two of four opposed fields) are shown with multi-leaf collimation shielding of organs at-risk for normal tissue toxicity. Anterior fluoroscopic projection of a low-dose-rate tandem-ovoid applicator is depicted for an intracavitary brachytherapy of an advanced stage cervical cancer (C). Dummy sources are positioned in the tandem-ovoid device. A graduated marker is positioned in the rectum. A Foley catheter balloon is shown filled with radiopaque fluid (7 ml). Anteroposterior (D) and right lateral (E) half-beam projections are provided as part of an extended four-field arrangement for the treatment of cervical cancer with disease-proven para-aortic lymph node involvement. A matched, half-beam anteroposterior extended treatment field is shown (F). An opposed posteroanterior would also be used.