[en] A technique is described for treating inguinal nodes when using radiotherapy in the control of pelvic malignancies. A posterior photon field treats the pelvis. A wider anterior photon field treats pelvis and inguinal nodes. An anterior photon boost to nodes is delivered using asymmetric collimator jaws moved across center line. Advantages of this technique include simplicity of setup and treatment (a single isocenter is retained, and no transmission block is needed), minimal dose inhomogeneity, reduced dose to femoral necks reducing the risk of femoral fracture, low risk of nodal underdose, and elimination of dosimetric difficulties inherent in electron beam boosts