An independent system for real-time dynamic multileaf collimation trajectory verification using EPID

T. Fuangrod, H.C. Woodruff, Pejman Rowshanfarzad, D.J. O'Connor, R.H. Middleton, P.B. Greer

    Research output: Contribution to journalArticlepeer-review

    15 Citations (Scopus)

    Abstract

    A new tool has been developed to verify the trajectory of dynamic multileaf collimators (MLCs) used in advanced radiotherapy techniques using only the information provided by the electronic portal imaging devices (EPID) measured image frames. The prescribed leaf positions are resampled to a higher resolution in a pre-processing stage to improve the verification precision. Measured MLC positions are extracted from the EPID frames using a template matching method. A cosine similarity metric is then applied to synchronise measured and planned leaf positions for comparison. Three additional comparison functions were incorporated to ensure robust synchronisation. The MLC leaf trajectory error detection was simulated for both intensity modulated radiation therapy (IMRT) (prostate) and volumetric modulated arc therapy (VMAT) (head-and-neck) deliveries with anthropomorphic phantoms in the beam. The overall accuracy for MLC positions automatically extracted from EPID image frames was approximately 0.5 mm. The MLC leaf trajectory verification system can detect leaf position errors during IMRT and VMAT with a tolerance of 3.5 mm within 1 s. © 2014 Institute of Physics and Engineering in Medicine.
    Original languageEnglish
    Pages (from-to)61-81
    JournalPhysics in Medicine and Biology
    Volume59
    Issue number1
    Early online date12 Dec 2013
    DOIs
    Publication statusPublished - 6 Jan 2014

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