نتایج جستجو برای: kilovoltage

تعداد نتایج: 427  

Journal: :Physics in medicine and biology 2006
Clifton David Fuller Charles R Thomas Scott Schwartz Nanalei Golden Joe Ting Adrian Wong Deniz Erdogmus Todd J Scarbrough

Several measurement techniques have been developed to address the capability for target volume reduction via target localization in image-guided radiotherapy; among these have been ultrasound (US) and fiducial marker (FM) software-assisted localization. In order to assess interchangeability between methods, US and FM localization were compared using established techniques for determination of a...

Journal: :Physics in medicine and biology 2009
G Poludniowski P M Evans S Webb

Monte Carlo simulation is the gold standard method for modelling scattering processes in medical x-ray imaging. General-purpose Monte Carlo codes, however, typically use the independent atom approximation (IAA). This is known to be inaccurate for Rayleigh scattering, for many materials, in the forward direction. This work addresses whether the IAA is sufficient for the typical modelling tasks i...

2012
James C L Chow

This study investigated radiation dose variations in pre-clinical irradiation due to the photon beam energy and presence of tissue heterogeneity. Based on the same mouse computed tomography image dataset, three phantoms namely, heterogeneous, homogeneous and bone homogeneous were used. These phantoms were generated by overriding the relative electron density of no voxel (heterogeneous), all vox...

2011
Poonam Yadav Velayudham Ramasubramanian Bhudatt R. Paliwal

BACKGROUND We have analyzed the stability of CT to density curve of kilovoltage cone-beam computerized tomography (kV CBCT) imaging modality over the period of six months. We also, investigated the viability of using image value to density table (IVDT) generated at different time, for adaptive radiotherapy treatment planning. The consequences of target volume change and the efficacy of kV CBCT ...

2006
Timothy Fox Calvin Huntzinger Peter Johnstone Tomi Ogunleye Eric Elder

Image-guided radiation therapy delivery may be used to assess the position of the tumor and anatomical structures within the body as opposed to relying on external marks. The purpose of this manuscript is to evaluate the performance of the image registration software for automatically detecting and repositioning a 3D offset of a phantom using a kilovoltage onboard imaging system. Verification t...

Journal: :AJNR. American journal of neuroradiology 2012
R Gnannt A Winklehner R Goetti B Schmidt S Kollias H Alkadhi

BACKGROUND AND PURPOSE CT protocols should aim for radiation doses being as low as reasonably achievable. The purpose of our study was to assess the image quality and radiation dose of neck CT at a tube potential of 70 kVp. MATERIALS AND METHODS Twenty patients (7 female, mean age 51.4 years, age range 19-81 years) underwent contrast-enhanced 64-section CT of the neck at 70 kVp (ATCM, effecti...

2014
Kihong Son Seungryong Cho Jin Sung Kim Youngyih Han Sang Gyu Ju Doo Ho Choi

Image-guided techniques for radiation therapy have improved the precision of radiation delivery by sparing normal tissues. Cone-beam computed tomography (CBCT) has emerged as a key technique for patient positioning and target localization in radiotherapy. Here, we investigated the imaging radiation dose delivered to radiosensitive organs of a patient during CBCT scan. The 4D extended cardiac-to...

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