The study purpose was to develop and validate a quality assurance test for CT automatic exposure control (AEC) systems based on a set of nested polymethylmethacrylate CTDI phantoms. The test phantom was created by offsetting the 16 cm head phantom within the 32 cm body annulus, thus creating a three part phantom. This was scanned at all acceptance, routine, and some nonroutine quality assurance...

background:  this study presents patient specific and organ dose estimation in computed tomography (ct) imaging of thorax directly from patient ct image using monte carlo simulation.  patient's ct image is considered as the patient specific phantom and the best representative of patient physical index in order to calculate specific organ dose. materials and methods: egsnrc /beamnrc monte c...

BACKGROUND The most commonly used form of reporting doses in multislice computed tomography involves a CT dose index per slice and dose-length product for the whole series. The purpose of this study was to analyze the actual dose distribution in routine chest CT examination protocols using an antropomorphic phantom. MATERIAL/METHODS We included in the analysis readings from a phantom filled w...

Image guided radiation therapy solutions based on megavoltage computed tomography (MVCT) involve the extension of electronic portal imaging devices (EPIDs) from their traditional role of weekly localization imaging and planar dose mapping to volumetric imaging for 3D setup and dose verification. To sustain the potential advantages of MVCT, EPIDs are required to provide improved levels of portal...

BACKGROUND Radiation exposure has been a hot point in research field of computed tomography (CT). Recently, automated tube current modulation (ATCM) has emerged as an important technique to reduce radiation exposure. Many studies have shown that the difference in scout view would affect modulation. This prospective randomized controlled study is aimed to investigate the impact of an additional ...

introduction: in 2000, the unscear reported that ct constitutes 5% of all the medical x-ray  examinations and it contributes 34% of the resultant collective dose worldwide. children are more  sensitive to the ionizing radiations than adults. so, routine quality control tests are expected to be  carried out periodically on the ct scanners. the aim of this research was to estimate the effective  ...

objective: the aim of this study was to evaluate the influences of reconstruction and attenuation correction on the differences in the radioactivity distributions in 123i brain spect obtained by the hybrid spect/ct device. methods: we used the 3-dimensional (3d) brain phantom, which imitates the precise structure of gray mater, white matter and bone regions. it was filled with 123i solution (20...

PURPOSE The purpose of this study is to compare digital radiography systems using the metric effective detective quantum efficiency (eDQE), which better reflects digital radiography imaging system performance under clinical operating conditions, in comparison with conventional metrics such as modulation transfer function (MTF), normalized noise power spectra (NNPS), and detective quantum effici...

Background:  This study presents patient specific and organ dose estimation in computed tomography (CT) imaging of thorax directly from patient CT image using Monte Carlo simulation.  Patient's CT image is considered as the patient specific phantom and the best representative of patient physical index in order to calculate specific organ dose. Materials and Methods: EGSnrc /BEAMnr...

Introduction: Nowadays, the demand for CT-scan is increased, and this issue has become a critical subject in radiation protection, because of the risk of cancer especially for children. The quality assurance of CT images is a necessary factor that can effect on children dose. The CT dose index is an important dosimetry index in CT-Scan dosimetry. The purpose of this study is t...