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

The delivery of intensity modulated radiation therapy (IMRT) using dynamic multileaf collimation (DMLC) accounts for about 40% of all treatments on eight multileaf collimator (MLC)-equipped linacs currently at the central and satellite facilities of the Memorial Sloan Kettering Cancer Center (MSKCC). 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 patient-specific treatments, to confirm the reliability of new software and to identify errors introduced through human interaction with individual patientʹs plans. This paper presents the reasoning, methodology, and results for mechanical, dosimetric, and electronic tests that are conducted at MSKCC.