نتایج جستجو برای: gantry angle

تعداد نتایج: 131688  

Journal: :iranian journal of radiation research 0
s. barlaz us mersin university, faculty of medicine, department of radiation oncology, mersin, turkey e. kaya pepele inonu university, faculty of medicine, department of radiation oncology, malatya, turkey

background: the purpose of this study was to investigate the various gantry angle and ssd dependencies of tld and mosfet dosimeters. materials and methods: lif (mg) tld and mosfet were used in this study. dosimeter systems were calibrated and then irradiated at various gantry angle and ssd by applying 6 mv photon energy. results: based on the results, mosfet changes were found to be in 2% range...

E. Kaya Pepele, S. Barlaz US,

Background: The purpose of this study was to investigate the various gantry angle and SSD dependencies of TLD and MOSFET dosimeters. Materials and Methods: LiF (Mg) TLD and MOSFET were used in this study. Dosimeter systems were calibrated and then irradiated at various gantry angle and SSD by applying 6 MV photon energy. Results: Based on the results, MOSFET changes were found to be in 2% range...

2014
Peter M. McCowan Daniel W. Rickey Pejman Rowshanfarzad Peter B. Greer William Ansbacher Boyd M. McCurdy

EPID images acquired in cine mode during arc therapy have inaccurate gantry angles recorded in their image headers. In this work, methods were developed to assess the accuracy of the gantry potentiometer for linear accelerators. As well, assessments of the accuracy of other, more accessible, sources of gantry angle information (i.e., treatment log files, analysis of EPID image headers) were inv...

2016
Michael P. Barnes Pejman Rowshanfarzad Peter B. Greer

In VMAT treatment delivery the ability of the linear accelerator (linac) to accurately control dose versus gantry angle is critical to delivering the plan correctly. A new VMAT test delivery was developed to specifically test the dose versus gantry angle with the full range of allowed gantry speeds and dose rates. The gantry-mounted IBA MatriXX with attached inclinometer was used in movie mode ...

2012
Pejman Rowshanfarzad Mahsheed Sabet Daryl J. O'Connor Peter M. McCowan Boyd M.C. McCurdy Peter B. Greer

The increasing popularity of intensity-modulated arc therapy (IMAT) treatments requires specifically designed linac quality assurance (QA) programs. Gantry angle is one of the parameters that has a major effect on the outcome of IMAT treatments since dose reconstruction for patient-specific QA relies on the gantry angle; therefore, it is essential to ensure its accuracy for correct delivery of ...

2015
Iori Sumida Hajime Yamaguchi Hisao Kizaki Keiko Aboshi Mari Tsujii Yuji Yamada Masashi Yagi Kazuhiko Ogawa

Pretreatment dose verification with beam-by-beam analysis for intensity-modulated radiation therapy (IMRT) is commonly performed with a gantry angle of 0° using a 2D diode detector array. Any changes in multileaf collimator (MLC) position between the actual treatment gantry angle and 0° may result in deviations from the planned dose. We evaluated the effects of MLC positioning errors between th...

2017
Todsaporn Fuangrod Peter B. Greer Benjamin J. Zwan Michael P. Barnes Joerg Lehmann

Volumetric-modulated arc therapy (VMAT) treatment delivery requires three key dynamic components; gantry rotation, dose rate modulation, and multi-leaf collimator motion, which are all simultaneously varied during the delivery. Misalignment of the gantry angle can potentially affect clinical outcome due to the steep dose gradients and complex MLC shapes involved. It is essential to develop inde...

2009
M. A. Ahmad

This paper presents the use of anti-sway angle control approaches for a two-dimensional gantry crane with disturbances effect in the dynamic system. Delayed feedback signal (DFS) and proportional-derivative (PD)-type fuzzy logic controller are the techniques used in this investigation to actively control the sway angle of the rope of gantry crane system. A nonlinear overhead gantry crane system...

2010
John P. Mullins Michael G. Herman

Mechanical flex of the gantry and mounted imaging panels leads to systematic offsets in localization image isocenter as a function of gantry angle for linear accelerator-mounted image guidance systems. Subsequently, object positions obtained from localization radiographs may be offset, resulting in greater target positioning uncertainty. While current QA procedures measure kV/MV image agreement...

2011
Stewart J. Becker

The use of non-coplanar radiation fields can potentially lead to collisions between the gantry and the couch or patient. The collisions are often not realized until the plan is finished and the fields are checked on the machine, or even later when the patient is already on the table. This paper presents an easy method of gauging if a collision is likely between the gantry and couch or patient d...

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