PURPOSE: The objective of this study is to develop a method to calculate the relative dose increase when a computerized tomography scan (CT) is carried out after administration of iodinated contrast medium, with respect to the same CT scan in absence of contrast medium. METHODS: A Monte Carlo simulation in ...

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 ...

Concerns have been raised regarding the increasing radiation exposure associated with cardiac computed tomography (CT). Traditional cardiac CT imaging techniques comprise simultaneous recording of the electrocardiogram signal combined with continuous slow-pitch spiral/helical scan acquisition with a relatively high incident radiation dose. Because of the increasing number of cardiac CT studies ...

The aims of this study were to collect data relating to radiation dose delivered by multidetector CT scanning at 10 hospitals and private practices in Queensland, Australia, and to test methods for dose optimization training, including audit feedback and didactic, face-to-face, small-group teaching of optimization techniques. Ten hospital-based public and ...

Dose reduction in pediatric nuclear medicine involves many aspects of nuclear imaging. The computed tomography (CT) parameters used during the new hybrid imaging procedures, positron emission tomography (PET)/CT and single photon emission computed tomography (SPECT)/CT, involve trade-offs between image quality and effective dose. In this setting, CT may be used ...

It is imperative that responsible clinicians understand the relationship between computed tomography imaging and radiation-induced malignancy risk. As the concept of computed tomography-induced malignancy risk becomes more widespread, it is important that clinicians are well informed and are able to intelligently answer questions and concerns posed by their patients and ...

PURPOSE: To intraindividually compare a low-tube-voltage (80 kVp), high-tube-current (675 mA) computed tomographic (CT) technique with a high-tube-voltage (140 kVp) CT protocol for the detection of pancreatic tumors, image quality, and radiation dose during the pancreatic parenchymal phase. MATERIALS AND METHODS: This prospective, single-center, HIPAA-compliant study was approved by the ...

Computed tomography (CT) intrascanner and interscanner variability has not been well characterized. Thus, the purpose of this study was to examine the within-run, between-run, and between-scanner precision of physical dosimetry-related measurements collected over the course of 1 yr on three different makes and models of multidetector row CT (MDCT) scanners. ...

PURPOSE: To evaluate stand-alone performance of computer-aided detection (CAD) for colorectal polyps of 6 mm or larger at computed tomographic (CT) colonography in a large asymptomatic screening cohort. MATERIALS AND METHODS: In this retrospective, institutional review board-approved, HIPAA-compliant study, a CAD software system was applied to screening CT colonography in ...

To evaluate image quality and radiation dose for 128-detector prospective electrocardiogram (ECG)-gated computed tomography coronary angiography (CTCA) compared with a low-dose retrospective ECG-gated imaging protocol. Thirty-one and 47 patients suspected of having coronary artery disease were enrolled into groups examined using prospective and low-dose retrospective ECG-gated CT protocols respectively. All ...

High radiation dose of conventional retrospective ECG-gated coronary MDCT (multidetector computed tomography) with regular helical pitch (HP) continuous scan has disturbed wide clinical use. The purpose was to estimate the radiation dose reduction effects of FlashScan, which was a prospective ECG-gated helical scan with high HP. Coronary MDCT was performed ...

Computed tomography (CT) of the paranasal sinus is the standard diagnostic tool for a wide range of indications in mostly younger patients. This study aims to assess the image quality of CT of the sinus by using a high-pitch dual-source technique with special regard to the radiation dose. Examinations were ...

To evaluate thin-section computed tomography (CT) images of the lung reconstructed using adaptive statistical iterative reconstruction (ASIR) on standard- and reduced-dose CT. Eleven cadaveric lungs were scanned by multidetector-row CT with two different tube currents (standard dose, 400 mA; reduced dose, 10 mA). The degree of ASIR was classified into ...

We present a web-based pediatric CT dose tool that estimates effective dose based on dose length product, patient age and region of body scanned. The tool also provides an estimate of additional lifetime risk of cancer from CT exams. These estimations are based on the interpolation of factors from published ...

Increasing attention is being paid to the cancer risk conferred by imaging modalities such as computed tomography (CT). Patients with subarachnoid hemorrhage (SAH) often are critically ill and require numerous imaging studies. A nonradiating diagnostic modality, transcranial Doppler (TCD), effectively screens for cerebral vasospasm. But when TCD is not available, ...

Virtual dissection is a three-dimensional (3D) display technique for CT colonography that could potentially reduce interpretation times. With virtual dissection, the 3D model of the colon is "sliced" open along a centerline trace, rendering a 360° view of the endoluminal mucosa as a rectangular image. However, one must be familiar ...

X-ray CT measures the attenuation of polychromatic x-rays through an object of interest. The CT data acquired are the negative logarithm of the relative x-ray intensity after absorption. These data must undergo water precorrection to linearize the measured data and convert them into line integrals through the patient that can ...

With the increasing use of intensity-modulated radiation therapy (IMRT) for the treatment of head and neck cancer, radiation oncologists are expected to have an in-depth knowledge of the computed tomographic (CT) and magnetic resonance (MR) imaging anatomy of this region to be able to accurately characterize tumor extent and define ...

The purpose of this study was to reduce the cumulative radiation exposure from CT of patients with aneurysmal subarachnoid hemorrhage. Baseline data on 30 patients with aneurysmal subarachnoid hemorrhage were collected retrospectively for all CT examinations of the head performed throughout the hospital course. Radiation exposure estimates were obtained by ...

We compared stair-step artifacts and radiation dose between prospective electrocardiography (ECG)-gated coronary computed tomography angiography (prospective CCTA) and retrospective CCTA using 64-detector CT and determined the optimal padding time (PT) for prospective CCTA. We retrospectively evaluated 183 patients [mean heart rate (HR) <65 beats/min, maximum HR instability <5 beats/min] who ...

PURPOSE: Crank torque (CT) application and rate of CT development (RCTD) are important considerations in sprint cycling. The stiffness of the musculotendinous unit is related to the isometric rate of torque development (RTD); however, this relationship has yet to be examined in sprint cycling. METHODS: Maximal isometric torque (MIT) and ...

The objective of this article is to describe the experience of the National CT Colonography Trial with radiologist training and qualification testing at CT colonography (CTC) and to correlate this experience with subsequent performance in a prospective screening study. Ten inexperienced radiologists participated in a 1-day educational course, during which ...

Computed tomographic colonography (CTC) has been reported to be as effective as optical colonoscopy in the detection of significant adenomas. However, there are widely conflicting performance data in relation to detection of flat neoplasia. This article describes the potential and limitations of CTC and computer-aided diagnosis in the detection of ...

Micro-CT provides non-invasive anatomic evaluation of small animals. Serial micro-CT measurements are, however, hampered by the severity of ionizing radiation doses cumulating over the total period of follow-up. The dose levels may be sufficient to influence experimental outcomes such as animal survival or tumor growth. This study was designed to ...

PURPOSE: Development and verification of peak signal-to-noise ratio (SNR(P)) equations for determining optimum CT scanning and scoring parameters for a new automated coronary calcium scoring program (N-vivo). Experimental evaluation of the new program for scoring small calcium hydroxyapatite (CaHA) microspheres with small voxel CT images. METHODS: Theoretical SNR(P) equations were ...

OBJECTIVES: In dual energy (DE) computed tomography (CT), spectral shaping by additional filtration of the high energy spectrum can theoretically improve dual energy contrast. The aim of this in vitro study was to examine the influence of an additional tin filter for the differentiation of human urinary calculi by dual ...

To determine whether the display of computer-aided detection (CAD) marks on individual polyps on both the supine and prone scans leads to improved polyp detection by radiologists compared to the display of CAD marks on individual polyps on either the supine or the prone scan, but not both. The acquisition ...

The recent technical development of multidetector CT (MDCT) has contributed to a substantial increase in its diagnostic applications and accuracy in children. A major drawback of MDCT is the use of ionising radiation with the risk of inducing secondary cancer. Therefore, justification and optimisation of paediatric MDCT is of great ...

We present a method of estimating effective doses in cardiac CT that accounts for selected techniques (kV mAs(-1)), anatomical location of the scan and patient size. A CT dosimetry spreadsheet (ImPACT CT Patient Dosimetry Calculator) was used to estimate effective doses (E) using ICRP 103 weighting factors for a 70 ...

X-ray differential phase contrast imaging methods, including projection imaging and the corresponding computed tomography (CT), have been implemented using a Talbot interferometer and either a synchrotron beam line or a low brilliance x-ray source generated by a stationary-anode x-ray tube. From small-angle scattering events which occur as an x-ray propagates ...

Computed tomography (CT) has been recognised as the most widely used imaging technique in both adults and children, owing to technological developments, especially with the recent innovations in multislice CT. This has resulted in an increase in the use of CT examinations in children younger than 15 years of age ...

PURPOSE: When CT examinations are conducted with automatic mA modulation (z-axis modulation), the tube current (mA) may vary from one CT slice to next, i.e., mA is no longer a fixed constant. Hence, patient dose calculation is no longer a straightforward process. The purpose of this article is to show ...

PURPOSE: To evaluate the image quality of both standard- and reduced-dose computed tomography (CT) by comparing multidetector CT with garnet-based detectors with multidetector CT with conventional detectors. MATERIALS AND METHODS: The study was approved by the internal ethics review board. Informed consent was obtained. Eleven cadaveric lungs inflated and fixed ...

OBJECTIVE: Concerns have been raised about the radiation exposure of coronary CT angiography (CTA). Recently, a prospective ECG-triggered sequential coronary CTA technique was developed to reduce exposure to ionizing radiation. The purpose of this analysis was to determine the impact of a sequential scanning technique on image quality and radiation ...

OBJECTIVE: To accurately compare the radiation dose between prospectively gated cardiac multidetector CT (with and without iterative reconstruction) and diagnostic invasive coronary angiography using the latest International Commission on Radiological Protection 103 (ICRP) tissue weightings. DESIGN, SETTING AND PATIENTS: A retrospective analysis of consecutive patients presenting to a university teaching ...

OBJECTIVE: New generation Dual Source computed tomography (CT) scanners offer different x-ray spectra for Dual Energy imaging. Yet, an objective, manufacturer independent verification of the dose required for the different spectral combinations is lacking. The aim of this study was to assess dose and image noise of 2 different Dual ...

Polyp size is a critical biomarker for clinical management. Larger polyps have a greater likelihood of being or of becoming an adenocarcinoma. To balance the referral rate for polypectomy against the risk of leaving potential cancers in situ, sizes of 6 and 10 mm are increasingly being discussed as critical ...

PURPOSE: The superior radiation dose efficiency of a newly implemented differential phase contrast CT imaging method compared to the conventional absorption CT method is demonstrated. METHODS: A differential phase contrast CT imaging method has recently been implemented using conventional x-ray sources with a grating interferometer consisting of three gratings. This ...

This study was carried out to assess the annual per capita effective dose from medical diagnostic procedures using computed tomography (CT) in Canada. Relevant data concerning the nature and the frequency of various diagnostic CT examinations were obtained from the reports on Medical Imaging in Canada and Diagnostic Services in ...

PURPOSE: To determine the equivalence of radiation therapy treatment planning and delivery for various imaging options on helical tomotherapy. METHODS: Seven treatment plans using identical anatomy and planning parameters were created based on the following CT studies: Standard kilovoltage CT (kVCT); 2, 4, and 6 mm spacing megavoltage CT (MVCT); ...

RATIONALE AND OBJECTIVES: The use of breast computed tomography (CT) has been limited by radiation hazard and image quality. The objective of this study was to compare radiation doses and image quality for different 64-channel multidetector row CT (MDCT) parameters, and to potentially provide optimal CT parameters for breast imaging. ...

The National Lung Screening Trial includes 33 participating institutions that performed 75,133 lung cancer screening CT examinations for 26,724 subjects during 2002-2007. For trial quality assurance reasons, CT radiation dose measurement data were collected from all MDCT scanners used in the trial. A total of 247 measurements on 96 MDCT ...

The relationship between patient cross-sectional area and both volume CT dose index (CTDI) and dose length product was explored for abdominal CT in vivo, using a 16 multidetector row CT (MDCT) scanner with automatic exposure control. During a year-long retrospective survey of patients with MDCT for symptoms of abdominal sepsis, ...

This article describes a common methodology and measurement technique, encompassing both conventional (helical and axial) CT scanning using phantom translation and cone beam (or narrow fan beam) CT scans about a stationary phantom. Cone beam CT systems having beam widths along the z-axis wide enough to cover a significant anatomical ...

Since computed tomography (CT) was introduced about 40 y ago, its use has continuously grown, resulting in the increase of the CT dose. Therefore, an awareness of the CT dose and its potential complications has led to the development of several dose-reduction strategies. One of the strategies is automatic exposure ...

CT colonography without bowel preparation is a safer and better-tolerated alternative to full laxation protocols, but comparative sensitivity and specificity are potentially reduced. Uptake of (18)F-FDG by colonic neoplasia is well described, and combining PET with nonlaxative CT colonography could improve accuracy. The purpose was to prospectively test the technical ...

PURPOSE: To evaluate the performance of computed tomography (CT) systems of various designs as a source of electron density (rho(el)) data for treatment planning of radiation therapy. MATERIAL AND METHODS: Dependence of CT numbers on relative electron density of tissue-equivalent materials (HU-rho(el) relationship) was measured for several general-purpose CT systems ...

PURPOSE: In proton therapy, uncertainty in the location of the distal dose edge can lead to cautious treatment plans that reduce the dosimetric advantage of protons. After radiation exposure, vertebral bone marrow undergoes fatty replacement that is visible on magnetic resonance imaging (MRI). This presents an exciting opportunity to observe ...

The aim of this study was to investigate the dose response relationship of dicentrics in human lymphocytes after CT scans at tube voltages of 80 and 140 kV. Blood samples from a healthy donor placed in tissue equivalent abdomen phantoms of standard, pediatric and adipose sizes were exposed at dose ...

BACKGROUND: Conventional computed tomography angiography (CTA) is time consuming, user-dependent and has poor image quality in skull base region. This study assessed the feasibility of a new method, dual energy CTA for depicting the cerebral artery. METHODS: Phantom scan was done with head CTA sequences on dual source CT and ...