The sensitivity of gamma index analysis to detect multileaf collimator (MLC) positioning errors

What is it about?

Due to the increased degree of modulation and complexity of VMAT plans, it is necessary to have a pre-treatment patient-specific quality assurance (QA) program. The gamma index is commonly used to quantitatively compare two dose distributions. In this study we investigated the sensitivity of single- and multi-gamma criteria techniques to detect MLC positioning errors using the Varian TrueBeam Electronic Portal Imaging DeviceTM (EPID) dosimetry and the ArcCHECKTM device. The Varian TrueBeam EPID dosimetry shows a higher sensitivity in detecting MLC positioning errors compared to the ArcCHECK regardless of using the single- or the multi-gamma criteria techniques. Higher sensitivity was observed using the multi-gamma criteria technique compared to the single-criterion technique when using the EPID.

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