Using different sets of wedges: clinical applications, dosimetry and safety interlocks

Each accelerator is customarily supplied with one set of wedges, typically for a maximum field width of 15 cm across the wedge slope. Clinically, however, the need arises at times for larger wedged fields. Independent jaws may require wedges which are mounted at 90 degrees from a standard set, and some half-field treatment techniques may benefit from half-field wedges. To optimize treatment conditions, it is therefore desirable to have several sets of wedges available for each treatment machine. We will present clinical examples for different sets of wedges, the results of our dosimetric measurements and will discuss the required safety interlocks.