ESTRO course Dose Modelling and Verification 2017
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
T Knöös
Warsaw 2017
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