Click here to


Are you sure ?

Yes, do it No, cancel

Clinical Implementation of Plan Transformation: A Process Description

H Afsharpour1,2*, M Nielsen1, K Bozzo1, R Sankreacha1,2, (1) Department of Radiation-Oncology, Credit Valley Hospital, Mississauga, ON, Canada, (2) Department of Radiation-Oncology, University of Toronto, Toronto, ON, Canada


(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose: To report on the clinical implementation of “plan transformation”. Using plan transformation we aim to use full departmental capacity to disperse patients from Varian units with Millennium MLC (ML) to machines with High Definition MLC (HD), when the former goes down for repair.

Methods: Our center is equipped with four ML and two HD MLC Varian units. When there is a delay on a ML linac due to a machine breakdown, plan transformation is used to transfer patients from ML to HD units. An in-house developed API script automatically identifies eligible plans on a given day from Aria that are non-VMAT plans with collimator size <21.6 cm. After a preliminary review of the transformation by the physicist, planners initiate the transformation process. During this operation, the MLC pattern for every field is exported outside of Eclipse and is transformed to a HD MLC using a C# script. The converted MLCs are imported back into the patient’s plan and the plan is recalculated without any further change.

Results: On a given day, more than 25% of appointments on all ML units were eligible for transformation. The majority of eligible plans were breast tangent and boost. The difference between the original and the transformed plan is usually not-clinically significant. Plan transformation process saves time to planners and made the plans versatile and mobile among different units. Plan transformation is faster than a replan and takes less than a quarter the time required for a replan which represents a huge time gain for our planners.

Conclusion: Transformation helps relieve the burden on the department and on patients from a machine breakdown and helps to reduce patient cancellations due to workload issues.


Transformation, Treatment Planning, Linear Accelerator


Leadership: Operations

Contact Email