Click here to


Are you sure ?

Yes, do it No, cancel

Enabling Patient Transfer From Millennium to HD MLC Varian Units; Feasibility Study of a Novel Workaround

H Afsharpour*, R Kaiyum, M Nielsen, K Bozzo, R Sankreacha, Peel Regional Cancer Center, Trillium Health Partners, Mississauga, ON


(Monday, 7/15/2019) 3:45 PM - 4:15 PM

Room: Exhibit Hall | Forum 7

Purpose: Patient transferability between linacs is an important feature in a busy clinic. It reduces stress on staff, anxiety in patients, and operational costs for the department in case of machine breakdowns or workflow issues. Currently, no plan transfer is possible from Millennium (ML) to high definition (HD) MLC Varian units. The objective of this work is to explore a methodology to enable those transfers without the need to replan while keeping the same plan quality. We will call this process “plan transformation� rather than a plan transfer.

Methods: Static or manually segmented fields with Y jaws ≤ 22cm are eligible for plan transformation. The MLC pattern for each field is exported outside of Eclipse. An in-house program is used to convert those patterns from ML to HD. The new MLC patterns are re-imported to Eclipse while the MUs are kept untouched. Although ML and HD are different in design, their dosimetric properties remain reasonably comparable for those type of plans. Still to avoid any uncertainties, transformed plans are recalculated and summed in Eclipse enabling the user to ensure about plan quality and integrity.

Results: A large number of plans including tangent breast, breast boosts and medium sized field palliative plans are eligible to be transformed from ML to HD MLC. The delivery and integrity of plan transformation process was examined at treatment units and showed to be feasible and safe. Contrary to a replan which is long and resource extensive, plan transformation takes only 10 minutes or less depending on the plan.

Conclusion: Our results show that the plan transformation is feasible and a better alternative to replanning in order to divert the high load of our Millennium MLC units to HD MLC units, if needed. Currently, we are working towards automating the entire process inside Eclipse using API.


MLC, Treatment Planning, Dose


TH- External beam- photons: treatment planning/virtual clinical studies

Contact Email