Dose 2016

33

Monitor feedback/Beam energy servo

An increase in beam energy causes a rise in the dose rate in the center of the field, and vice versa. The X-ray gun servo system of an Elekta linac uses this property to detect energy changes by using the two hump plates. The difference between the two hump plates is used to produce an error signal, which gives a correction to the nominal level of gun current set by the operator.

Lower energy

Higher energy

Outer hump

Inner hump

Elekta Dosimetry System

Utrecht 2016