Encrypted login | home

Program Information

Dosimetric Characterization and Comparison of the Elekta Agility and MLCi2 Multi-Leaf Collimator Heads

D Cutright

D Cutright*, M Gopalakrishnan, V Sathiaseelan, Robert H. Lurie Comprehensive Cancer Center & Department of Radiation Oncology, Northwestern University, Northwestern Memorial Hospital, Chicago, IL 60611

SU-E-T-261 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

The new Elekta Agilityâ„¢ radiation head with integrated 160 x 5mm inter-digitating tungsten-alloy leaves has been designed with leaf sides tilted to reduce overall transmission and leaf leakage. In this study, a comparison of the major dosimetric parameters of the Elekta Agilityâ„¢ 160 leaf (5mm leaf width) multi-leaf collimator (MLC) head design and the older Elekta MLCi2â„¢ 80 leaf MLC head (10mm leaf width) is presented.

Electron and photon beam data (including PDDs and profiles for various field sizes) were collected and analyzed using IBA hardware and software products for linac commissioning (i.e., IBA water tank, diodes, and OmniPro Acceptâ„¢ 7). MLC transmission and leakage was measured using gafchromic film and SunNuclear MAPcheck2â„¢.

Photon beams: Percent depth doses for 6MV and 10MV photon beams with various field sizes indicated little difference between the MLCi2â„¢ and Agilityâ„¢ heads (i.e., less than 1% difference at depths beyond dmax). Penumbra and umbra of dose profiles matched well for both energies; marginally differences were noticed on the toe-side of large wedged-fields. The average Agilityâ„¢ MLC transmission was measured to be 0.4%, nearly an order of magnitude lower than the MLCi2â„¢. Collimator scatter factors were nearly identical for small fields and reduced by as much as 1% for larger fields.
Electron beams: PDDs of electron beam energies of 6, 9, 12, 15, and 18 MeV were collected, indicating little differences between the Elekta Infinityâ„¢ with the MLCi2â„¢ and Agilityâ„¢ heads.

Analysis of the MLCi2â„¢ and Agilityâ„¢ beam data indicate little to no undesirable dosimetric differences; the largest deviation being a significant decrease in MLC transmission and leakage. These characteristics, combined with a significant increase in leaf speed, make the Elekta Agilityâ„¢ a considerable improvement over the MLCi2â„¢.

Contact Email: