IMRT 2018

Measuring transmission • Transmission varies midleaf, interleaf • and at rounded leaf end • Measure by film/EPID • Some TPS only allows one value

Transmission through rounded end

Midleaf and interleaf transmission. Profile through iso-centre Transmission is ratio between open field and field blocked by MLC

4 3 2 1

LoSasso MedPhys 30,2003. Physical and dosimetric aspects of a multileaf collimation system used in the dynamic mode for implementing intensity modulated radiotherapy