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A Novel Method to Automate the Optimization of Multileaf Collimator Transmission and Dosimetric Leaf Gap Parameters for Eclipse Treatment Planning System

D DiCostanzo* and A Ayan*, The Ohio State University, Columbus, OH


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

Room: AAPM ePoster Library

To develop a novel and automated optimization process for the MLC transmission and dosimetric leaf gap (DLG) parameters for Eclipse® Treatment Planning System, utilizing the Eclipse Scripting Application Programming Interface (ESAPI) in order to identify the optimal values for TrueBeam® linacs equipped with either a standard 120-leaf or a high-definition 120-leaf MLC system.

In a non-clinical Eclipse environment, seven energy and MLC combinations (6X SD, 6X HD, 6FFF SD, 6FFF HD, 10X SD, 10FFF HD, 15X SD) were commissioned. The DLG was set to 0.001mm in RT Administration, with no values set in Beam Configuration for the volume dose algorithm specific DLG and transmission. The transmission values were manually varied from 0.01% to 2.50% by 0.25% increments. A variety of clinical and geometric plans were calculated with preset monitor units programmatically using ESAPI after changing physical MLC positions (0mm to 2.5mm in 0.05mm increments) simulating varying different DLG values (N=38097).

The plans were measured on TrueBeam® linacs with a Sun Nuclear MapCHECK®2. Gamma analysis was performed utilizing software developed in-house, which was validated using published resources. Each plan was evaluated with gamma criteria of 1%/1mm and 2%/2mm. An optimization program was developed to search the DLG/transmission/GammaPassIndex phase space for the DLG/transmission pair that maximizes the agreement between the calculated and measured dose planes for all plans.

The solution space for transmission and DLG pairs was adequately sampled to evaluate for optimal values. In addition, a programmatic gamma evaluation of the calculated solution space to measured plans removes a trial-and-error search to identify the optimal DLG and transmission values for energy and MLC type combinations.

A novel automated methodology using ESAPI was developed to perform a comprehensive search for DLG/Transmission value pairs which optimizes the agreement between the calculated and measure Eclipse treatment plans.


Commissioning, MLC, Modeling


TH- External Beam- Photons: Development (new technology and techniques)

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