| 摘要 |
<p>The primary collimator for a radiotherapy apparatus can be made up of several layers, each comprising several apertures, and each layer being moveable so as to select a specific aperture to build up the primary collimator shape. In this way, the shape of the primary collimator can be tailored and/or the beam filters incorporated into the primary collimator assembly. This saves space in the radiation head whilst also allowing filters to be easily interchanged.</p> |
