The purpose of this study was to implement full/half bowtie filter models in a com-mercial treatment planning system (TPS) to calculate kilovoltage (kV) cone-beam CT (CBCT) doses of Varian On-Board Imager (OBI) kV X-ray imaging system. The full/half bowtie filter models were created as compensators in Pinnacle TPS using MATLAB software. The physical profiles of both bowtie filters were imported...

In this study, the relationship between ground-glass opacity (GGO) visibility and physical detectability index in low-dose computed tomography (LDCT) for lung cancer screening was investigated. An anthropomorphic chest phantom that included synthetic GGOs with CT numbers of -630 Hounsfield units (HU; high attenuation GGO: HGGO) and -800 HU (low attenuation GGO: LGGO), and three phantoms for phy...

The variation in exposure factors and patient dose, between seven centres using identical multislice CT scanners, was investigated for six standard examinations. Dose values were compared with each other and the relevant diagnostic reference level (DRL) for each examination. The range in weighted CT dose index (CTDI(w)) values between the seven centres was small for abdominal scans and head sca...

Cardiac computed tomography (CT) dosimetry makes use of two radiation parameters: a volume CT dose index (CTDI) and a dose length product (DLP). The volume CTDI quantifies the intensity of the radiation used to perform CT examinations, whereas DLP quantifies the amount of radiation used. CTDI metrics can be converted into patient dose metrics by using dose/CTDI conversion factors. In cardiac CT...

The purpose of this study was to apply European Commission reference dose levels (EC RDLs) to routine CT examinations. The dosimetric quantities proposed in the European Guidelines (EG) for CT are weighted computed tomography dose index (CTDI(w)) for a single slice and dose-length product (DLP) for a complete examination. Patient-related data as well as technical parameters for brain, chest, ab...

Computed tomography (CT) scan of the brain is the commonest CT examination performed and had been recognized to deliver very high radiation dose to the patients. This study was aimed at evaluating the radiation dose from routine brain CT scan and to compare the dose from the protocols for brain CT. The ex-postfacto design was adopted. All the records of brain CT scan from September 2011 to Augu...

Four methodologies were evaluated for quantifying kilovoltage cone-beam computed tomography (CBCT) dose: the Cone-Beam Dose Index (CBDI), IAEA Report 5 recommended methodology (IAEA), the AAPM Task Group 111 methodology (TG111), and the current dose metric; the Computed Tomography Dose Index (CTDI) on two commercial Varian cone-beam CT imaging systems; the Clinac iX On-Board Imager (OBI); and t...

We propose that a new type of drill, alternately known as a Fast Mechanical-Access Drill, or Coiled Tubing Drill for Ice (CTDI), be developed for polar research. The proposed drill is similar in concept to the latest coiled tubing (CT) drills used for commercial oil and gas development. CT drills use a metal or advanced-composite tube to deliver fluid downhole to a hydraulic motor that drives a...

PURPOSE Positioning verification is usually performed with treatment beam (MV) portal images (PI) using an electronic portal imaging device (EPID). A new alternative is the use of a low energy photon source (kV) and an additional EPID mounted to the accelerator gantry. This system may be used for PI or--with rotating gantry--as cone-beam CT (CBCT). The dose delivered to the patient by different...

The computed tomography dose index (CTDI) measured with a 10 cm long pencil ionization chamber placed in a 14 cm long PMMA phantom is typically used to evaluate the doses delivered during CT procedure. For the new generation of CT scanners, the efficiency of this methodology is low because it excludes the contribution of radiation scattered beyond the 100 mm range of integration along z. The AA...