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...

PURPOSE To compare computed tomography (CT) number measurement consistency under different beam hardening conditions in phantom experiment between dual-energy spectral CT and conventional CT imaging. MATERIALS AND METHODS A phantom with 8 cells in periphery region and 1 cell in central region were used. The 8 conditioning tubes in the periphery region were filled with 1 of the 3 iodine soluti...

Introduction: Recently, the use of nanoparticles has increased for many purpose in medicine. One of these is using the nano particles in shields structure to protect sensitive organs such as breast which placed inside the field of chest CT scan and receives high dose. The aim of this study was the use of nano Bi2O3 to making shield for protection breast in chest CT examination ...

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...

Introduction: Quality assurance in Computed tomography (CT) centers in developing countries are largely hindered by the unavailability of CT phantoms. The development of a local CT phantom for the measurement of organ radiation absorbed dose is therefore requisite. Material and Methods: Local CT phantoms were designed to meet the standard criteria of 32 cm diameter for body, 16 cm diameter for...

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...

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...

The purpose of this study was to investigate quantitatively by measurement and modeling the variations in CT number distributions of mobile targets in cone-beam CT (CBCT) imaging. CBCT images were acquired for three targets manufactured from homogenous water-equivalent gel that was inserted into a commercial mobile thorax phantom. The phantom moved with a controlled cyclic motion in one-dimensi...

PURPOSE With the development of RT treatment planning systems that use the relationship between CT number and Electron Density (ED), rather than the Linear Attenuation Coefficient (LAC) of a given material, a number of authors have pointed out the divergence between the linearity of CT numbers vs. LAC in the diagnostic range compared to the relationship between the CT number and ED. This paper ...