2-CAT: 2-concentric arc technique

We used conventional three-dimensional (3D) planning software and blocking to design a radiation dose distribution in the shape of a hollow sphere. The technique, known as 2-CAT, employs arcing beams with blocking of the center of the field, along with partial transmission blocking of the poles of the portal. The central core can subsequently be irradiated to deliver a relatively even dose to the entire volume. The technique differs from conventional planning in that the central portion of the tumor, while surrounded, is not included in the initial treatment volume. The clinical usefulness of the method will require future testing, as the technique has not yet been clinically proven.