ABSTRACT
In 1994, Brada and Laing described the Royal Marsden Hospital experience using stereotactic radiotherapy for brain tumors. The multileaf collimator (MLC) provides beam shaping for modern C-arm linacs and is used to shape the aperture for three-dimensional conformal radiation therapy and dynamic conformal arc therapy and to produce beam modulation for intensity modulated radiation therapy and modulated arc therapy. Modulated arc therapy (MAT) is a rotational technique in which the multileaf collimator aperture shape varies with gantry angle. In most modern applications, the dose rate and gantry speed also vary. MAT differs from conformal arc therapy in that the aperture shapes and weights are inverse planned to meet dosimetric objectives, rather than conforming to the target shape at all gantry angles. By reducing the learning barriers, knowledge-based systems will facilitate the dissemination of hypofractionated stereotactic radiotherapy into more centers, fulfilling the prediction of Brada and Laing that stereotactic radiotherapy will become a routine tool in the radiotherapy armamentarium.
