Comprehensive quality assurance for the delivery of intensity modulated radiotherapy with a multileaf collimator used in the dynamic mode

Abstract

The delivery of intensity modulated radiation therapy ͑IMRT͒ using dynamic multileaf collimation ͑DMLC͒ accounts for about 40% of all treatments on eight multileaf collimator ͑MLC͒-equipped linacs currently at the central and satellite facilities of the Memorial Sloan Kettering Cancer Center ͑MSKCC͒. These numbers have been steadily growing for the past 6 years. Treatment with IMRT has been used for a variety of cancers, including tumors of the prostate, head and neck, breast, paraspinal regions, and brain. To ensure that patients are treated in an accurate, efficient, and safe manner, we have developed a comprehensive QA program including mechanical quality assurance, which monitors known potential weaknesses in the MLC device itself, and verification of patientspecific treatments, to confirm the reliability of new software and to identify errors introduced through human interaction with individual patient's plans. This paper presents the reasoning, methodology, and results for mechanical, dosimetric, and electronic tests that are conducted at MSKCC.

Verification of dynamic and segmental IMRT delivery by dynamic log file analysis

“…Routine QA is required to ensure the MLC is operating properly and that the data in the DynaLog files is accurate. Guidelines for routine MLC QA have been previously reported 14 . The validity of the data in the DynaLog files is dependent on the accurate readout of the leaf positions.…”

Comparing measurement‐derived (3DVH) and machine log file‐derived dose reconstruction methods for VMAT QA in patient geometries

“…The difference in analysis using these two methods will be primarily due to sensitivity of ArcCHECK on plan delivery errors, measurement uncertainty related to ArcCHECK device, and the difference in dose reconstruction algorithms between the two methods. This study is of significance because many institutions rely on machine log files for their patient‐specific QA 9 , 10 . Schreibman et al (2) have also used machine log file‐based methodology for patient specific QA for VMAT delivery.…”

Application of AAPM TG 119 to volumetric arc therapy (VMAT)

“…Clinical advantages and comparison with present techniques for different sites have been reported 4 , 6 . To commission and QA the delivery system, Ling et al (7) proposed benchmark tests based upon the principles addressed by LoSasso et al (8) for dynamic IMRT QA. A guidance document (9) for IMRT commissioning and guidelines for IMRT commissioning have recently been published (10) by AAPM Task Group (TG) 119.…”