Minimum requirements for commissioning and long-term quality assurance of Elekta multi-leaf collimator for volumetric modulated arc therapy

• Published in: Radiological physics and technology 2013-01, Vol.6 (1), p.98-106
• Main Authors: Tatsumi, Daisaku, Nakada, Ryosei, Yomoda, Akane, Ishii, Kentaro, Tsutsumi, Shinichi, Inoue, Makoto, Ichida, Takao, Hosono, Masako N., Miki, Yukio
• Format: Article
• Language: English
• Subjects: Imaging; Medical and Radiation Physics; Medicine; Medicine & Public Health; Nuclear Medicine; Quality Control; Radiology; Radiotherapy; Radiotherapy Dosage; Radiotherapy, Intensity-Modulated - instrumentation; Radiotherapy, Intensity-Modulated - standards; Time Factors
• ISSN: 1865-0333; 1865-0341
• DOI: 10.1007/s12194-012-0175-0

We have proposed minimum requirements for commissioning and long-term quality assurance (QA) of an Elekta multi-leaf collimator (MLC) for volumetric modulated arc therapy (VMAT). The MLC leaf position accuracy during VMAT delivery was evaluated with the use of three different QA test plans: (1) a leaf gap-width test between opposing leaves by measurement of the isocenter dose during constant-gap sliding-window delivery with varied dose rates, MLC leaf speeds, and gantry angles; (2) a leaf position test by picket-fence delivery with and without gantry rotation; and (3) a leaf-bank symmetry test by measurement of the field geometry with different collimator angles at a fixed gantry position. All the QA test plans were created using an ERGO++ treatment-planning system. The leaf gap-width deviation was within 0.2 mm, the leaf position deviation was within 0.5 mm, and the leaf-bank symmetry error was within 0.5 mm under all the test conditions. MLC leaf position accuracy and long-term stability were confirmed by the proposed procedures.