The goal of quality assurance (QA) for a radiation oncology medical LINAC is to maintain an acceptable level of equipment performance and reliability. The increasing complexity of Radiation Oncology equipment and treatment techniques have led to increased demands on the work load of the medical physicist. Regular testing needs to be as efficient as possible. Generally, the QA tests, as recommen...

In volumetric-modulated arc therapy (VMAT) treatment delivery perfect beam symmetry is assumed by the planning system. This study aims to test this assumption and present a method of measuring time-resolved beam symmetry measurement during a VMAT delivery that includes extreme variations of dose rate and gantry speed. The Sun Nuclear IC Profiler in gantry mount was used to measure time-resolved...

PURPOSE To investigate various issues for clinical implementation of aSi EPID panels for IMRT/VMAT QA. METHODS Six linacs are used in our clinic for EPID-based plan QA; two Varian Truebeams, two Varian 2100 series, two Elekta Infiniti series. Multiple corrections must be accounted for in the calibration of each panel for dosimetric use. Varian aSi panels are calibrated with standard dark fiel...

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...

background and purpose: this study was designed to investigate of simulation based education in achieves skills proficiency in medical radiation technologist students. methods: the students randomly were divided in two groups, a (n=25) and b (n=22) that received a routine course and simulation based education respectively. the chain of experiments was concerned to evaluate of skills proficiency...

PURPOSE MLC dynamic log files have been clinically used for quality assurance for years. The logged machine parameters and the derived beam 2D fluence maps can be compared to the ones obtained in the treatment plans in order to evaluate the accuracy and consistency of IMRT beam deliveries. In this study, we propose a computationally efficient method, called Direct 3D Fluence Calculation or D3DF...

Helical tomotherapy has been developed at the University of Wisconsin, and 'Hi-Art II' clinical machines are now commercially manufactured. At the core of each machine lies a ring-gantry-mounted short linear accelerator which generates x-rays that are collimated into a fan beam of intensity-modulated radiation by a binary multileaf, the modulation being variable with gantry angle. Patients are ...

The aim of this study is to determine the gantry angle and multileaf collimator (MLC) gap error-detection threshold of a diode helical array with an inserted micro-ionization chamber in order to use this device for the pretreatment quality assurance (QA) of intensity-modulated radiation therapy (IMRT) treatments. Implications on the dose-volume histograms (DVHs) of the patient treatments will a...

Multileaf collimator (MLC) positions should be precisely and independently mea-sured as a function of gantry angle as part of a comprehensive quality assurance (QA) program for volumetric-modulated arc therapy (VMAT). It is also ideal that such a QA program has the ability to relate MLC positional accuracy to patient-specific dosimetry in order to determine the clinical significance of any dete...