The purpose of this study is to investigate the potential use of Ir-192 as the source for real time imaging during HDR (High Dose Rate) brachytherapy treatment. Phantom measurement was performed to determine outside of the body dose. Monte Carlo code, EGSnrcMP egs_inprz, was used for the simulation to calculate the outside of the body x-ray signal for CT reconstruction. Matlab code was develope...

In x-ray computed tomography (CT), the most common parameter used to estimate and minimize patient dose is the CT dose index (CTDI). The CTDI is a volume-averaged measure that is used in situations where the table is incremented in conjunction with the tube rotation. Variants of the CTDI correct for averaging across the field of view and for adjacent beam overlaps or gaps. CTDI is usually measu...

Organ dose is the absorbed radiation energy from ionizing radiation to an organ, divided by the organ mass. Organ doses of a patient cannot be measured directly in the patient, but their determination requires dose measurements in anthropomorphic patient models i.e. phantoms or Monte Carlo simulations. Monte Carlo simulations can be performed for example by using computational phantoms or patie...

Introduction: Computed tomography (CT) has numerous applications in clinical procedures but its main problem is its high radiation dose to the patients compared to other imaging modalities using x-ray. CT delivers approximately high doses to the nearby tissues due to the scattering effect, fan beam (beam divergence) and limited collimator efficiency. The radiation dose from multi-slice scanners...

X-ray breast computed tomography (breast CT) was developed by some research groups to overcome the limitations of mammography. Breast CT is expected to be an effective diagnostic tool because it can generate threedimensional images of a breast. However, the spatial resolution of the existing system is not satisfactory for identifying microcalcifications within the breast. The purpose of this st...

There has been a rapid increase in the population dose from medical radiation within the last 20 years, particularly due to the increase in CT usage. Currently, about 65 million adult and 5 million pediatric CT exams are being performed in the US each year. CT-related x-ray doses are small, but very much larger than for most conventional radiological examinations. CT-related x-ray doses are lar...

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  ...

The potential value of screening for lung cancer with low-dose CT scans is currently a topic of much research and debate. This article reviews the existing trials of lung cancer screening, using chest x-ray and low-dose CT scan. Potential harms of screening, including overdiagnosis and radiation exposure, are addressed. Practical difficulties of organizing a screening program in Canada include ...

Tube current (mA) is one of the key technical scanning parameters for adjusting radiation dose in CT. To optimize radiation dose in CT, users can adjust mA either with manually selected mA values or with the application of automatic exposure control (AEC). The latter technique refers to automatic adaptation of mA on the basis of userspecified image quality and x-ray attenuation characteristics ...