IMRT 2018

IMRT dynamic delivery

Picket fence test

• •

Test of MLC position and speed

• Deviations in MLC position => dosimetric deviation • Picket fence test is a combination of • Film/EPID (relative position of individual leaves) • Ion chamber at central axis (stable output)

Leaves move synchronously with constant speed and stop four times

Gantry

MLC movement

Film

IC

LoSasso MedPhys 28,2001. Comprehensive quality assurance for the delivery of intensity modulated radiotherapy with a multileaf collimator used in the dynamic mode