Accurate multileaf collimator (MLC) leaf positioning plays an essential role in the effective implementation of intensity modulated radiation therapy (IMRT). This work evaluates the sensitivity of current patient-specific IMRT quality assurance (QA) procedures to minor MLC leaf positioning errors. Random errors of up to 2 mm and systematic errors of +/-1 mm and +/-2 mm in MLC leaf positions wer...

IMRT QA requires, among other tests, a time-consuming process of measuring the absorbed dose, at least to a point, in a high-dose, low-dose-gradient region. Some clinics use a technique of measuring this dose with all beams delivered at a single gantry angle (collapsed delivery), as opposed to the beams delivered at the planned gantry angle (rotated delivery). We examined, established, and opti...

The aim of this study was to investigate a novel method for verification of the dose distribution for intensity modulated radiation therapy (IMRT) patient-specific quality assurance (QA) using dynamic multi-leaf collimator (DMLC) log files (Dynalog files). Dynalog files are recorded every 50 ms by using a MLC controller during the IMRT treatment. Dynalog files contain actual MLC positional info...

The purpose of this study was to determine the reproducibility of patient-specific, intensity-modulated radiation therapy (IMRT) quality assurance (QA) results in a clinical setting. Six clinical patient plans were delivered to a variety of devices and analyses, including 1) radiographic film; 2) ion chamber; 3) 2D diode array delivered and analyzed in three different configurations (AP deliver...

The purpose of this study is to apply the principles of statistical process control (SPC) in the context of patient specific intensity-modulated radiation therapy (IMRT) QA to set clinic-specific action limits and evaluate the impact of changes to the multileaf collimator (MLC) calibrations on IMRT QA results. Ten months of IMRT QA data with 247 patient QAs collected on three beam-matched linac...

In the recent years, more and more researchers believe measurement-based quality assurance (QA) method for intensity-modulated radiotherapy (IMRT) is insensitive in detecting various types of failures.(1-3) Machine delivery log-file analysis has been proposed to be a more effective and efficient approach in verifying IMRT delivery accuracy in terms of gantry, collimator, jaws, and MLCs.(1,4-9) ...

Intensity-modulated radiation therapy (IMRT) is a complex procedure that involves the delivery of complex intensity patterns from various gantry angles. Due to the complexity of the treatment plans, the standard-of-care is to perform measurement based patient-specific quality assurance (QA). IMRT QA is traditionally done with film for relative dose in a plane and an ion chamber for absolute dos...

background: this work investigated the dosimetry limitations of the random and systematic uncertainties of sliding window (sw) intensity modulated radiation therapy (imrt). materials and methods: a varian 21ex linear accelerator, pinnacle3 treatment planning system and radiographic film dosimetry was used. the limitations of the sw were studied using beam modulation ranging from 2 to 100 mu/bea...

The purpose of this study is to determine comparability of three different planar IMRT QA techniques: patient gantry angle composite (PGAC), single gantry angle composite (SGAC), and field by field (FBF), using MapCHECK 2 device and the γ test as performance metrics; and to assess the dependency of these techniques on intensity modulation, couch attenuation, and detector position (angular depen...