B. Blad et al., THE INFLUENCE OF THE MAGNETRON FREQUENCY, THE SERVO SETTINGS AND THE GANTRY ANGLE ON THE FLATNESS AND THE DOSE CALIBRATION OF A LINEAR-ACCELERATOR, Journal of medical engineering & technology, 22(4), 1998, pp. 185-188
For the Philips SL75/5, we have noticed that the performance of the be
am (e.g. the hump) varies with the settings of the magnetron frequency
and the gantry angle. This study investigated these changes and the o
ptimum magnetron frequency setting was determined. The relation betwee
n the relative absorbed dose measured by the accelerator and the relat
ive absorbed dose measured for different amounts of the hump in the ce
ntre of the beam was found. Results from a model and from measured val
ues were compared. The beam was studied for different gantry angles an
d for different adjustments of the beam servo systems. The profiles ob
tained showed some variations, but were reduced when optimal adjustmen
ts of the servos were performed.