The purpose of this study was to measure the multileaf collimator (MLC) transmission from the first Hi-Art II tomotherapy machine installed at the Advanced Center for Treatment, Research, and Education in Cancer (ACTREC). The MLC transmission was measured with an A1SL ion chamber and the radiographic extended dose range (EDR2) film in virtual water slabs at 1.5-cm depth with a source-to-surface...

background: inclusion of inhomogeneity corrections in intensity modulated small fields always makes conformal irradiation of lung tumor very complicated in accurate dose delivery. objective: in the present study, the performance of five algorithms via monte carlo, pencil beam, convolution, fast superposition and superposition were evaluated in lung cancer intensity modulated radiotherapy planni...

The purpose of this study was to create AAPM TG 119 benchmark plans for volumetric arc therapy (VMAT) and to compare VMAT plans with IMRT plan data. AAPM TG 119 proposes a set of test clinical cases for testing the accuracy of IMRT planning and delivery system. For these test cases, we generated two treatment plans, the first plan using 7-9 static dMLC IMRT fields and a second plan utilizing on...

INTRODUCTION Results of use of methodology for VMAT commissioning and quality assurance, utilizing both control point tests and dosimetric measurements are presented. METHODS AND MATERIALS A generalizable, phantom measurement approach is used to characterize the accuracy of the measurement system. Correction for angular response of the measurement system and inclusion of couch structures are ...

Benchmarking Flattening Filter-Free Photons for IMRT/VMAT using TG119 By Sarah Ashmeg Graduate Program in Medical Physics Duke University Date: _______________________ Approved: ___________________________ Jennifer O’Daniel, Co-Supervisor ___________________________ Fang-Fang Yin, Co-Supervisor ___________________________ Timothy Turkington An abstract of a thesis submitted in partial fulfillme...

Nasopharyngeal carcinoma is an endemic disease within specific regions in the world. Radiotherapy is the main treatment. In recent decades, intensity-modulated radiation therapy has undergone a rapid evolution. Compared with two-dimensional radiotherapy and/or three-dimensional conformal radiotherapy, evidence has shown it may improve quality of life and prognosis for patients with nasopharynge...

A new method of generating wedge-shaped dose distributions through dynamic multileaf collimator dose delivery rather than computer-controlled jaw motion is presented. The method starts with the calculation of a wedge-shaped beam profile for the desired wedge angle. The resultant wedge beam profile is then passed to the intensity-modulated radiation therapy (IMRT) leaf sequence generation algori...

PURPOSE Scattered radiation from multi-leaf collimators (MLCs) is no longer negligible for calculating in-air output ratio, Sc for small and irregular fields often used in intensity-modulated radiation therapy (IMRT). An extra-focal source model for scattered radiation from MLCs, namely MLC scatter source, has been developed to improve the accuracy of the Sc calculation. METHODS A conventiona...

The build-up dose in the megavoltage photon beams can be a limiting factor in intensity-modulated radiation therapy (IMRT) treatments. Excessive surface dose can cause patient discomfort and treatment interruptions, while underdosing may lead to tumor repopulation and local failure. Dose in the build-up region was investigated for IMRT delivery with solid brass compensator technique(compensator...