In vitro measurements of radiation exposure with different modalities (computed tomography, cone beam computed tomography) for imaging the petrous bone with a pediatric anthropomorphic phantom.

Background: Various imaging modalities, such as multi-detector computed tomography (CT) and cone beam CT are commonly used in infants for the diagnosis of hearing loss and surgical planning of implantation hearing aid devices, with differing results.

Objective: We compared three different imaging modalities available in our institution, including a high-class CT scanner, a mid-class CT scanner and an angiography system with a cone beam CT option, for image quality and radiation exposure in a phantom study.

Materials And Methods: While scanning an anthropomorphic phantom imitating a 1-year-old child with vendor-provided routine protocols, organ doses, surface doses and effective doses were determined for these three modalities with thermoluminescent dosimeters.

Radiation field and dose inhomogeneities using an X-ray cabinet in radiation biology research.

Purpose: X-ray cabinets are replacing Cs/ Co sources in radiation biology research due to advantages in size, handling, and radiation protection. However, because of their different physical properties, X-ray cabinets are more susceptible to experimental influences than conventional sources. The aim of this study was to examine the variations related to the experimental setups typically used to investigate biological radiation effects with X-ray cabinets.

Dosimetry on first clinical dark-field chest radiography.

Purpose: The purpose of this study was to evaluate the dose characteristic for patient examinations at the first clinical X-ray dark-field chest radiography system and to determine whether the effective patient dose is within a clinically acceptable dose range.

Methods: A clinical setup for grating-based dark-field chest radiography was constructed and commissioned, operating at a tube voltage of 70 kVp. Thermoluminescent dosimeter (TLD) measurements were conducted using an anthropomorphic phantom modeling the reference person to obtain a conversion coefficient relating dose area product (DAP) to effective patient dose at the dark-field system.

Efficacy of high-pitch CT protocols for radiation dose reduction.

Various strategies have been developed to reduce radiation exposure of patients in CT examinations. The aim of this study was to evaluate the efficacy of high pitch in representative CT protocols examining lung embolism. We performed thermoluminescence measurements with an anthropomorphic phantom exposing it to CT algorithms for lung embolism in a 128-multislice, dual-source CT scanner: a standard CT protocol (sCT) and a CT protocol with a high pitch (+ F).

Spectral optimization of iodine-enhanced CT: Quantifying the effect of tube voltage on image quality and radiation exposure determined at an anthropomorphic phantom.

Purpose: To provide an experimental basis for spectral optimization of iodine-enhanced CT by a quantitative analysis of image quality and radiation dose characteristics consistently measured for a large variety of scan settings at an anthropomorphic phantom.

Methods: CT imaging and thermoluminescent dosimetry were performed at an anthropomorphic whole-body phantom with iodine inserts for different tube voltages (U, 70-140kV) and current-time products (Q, 60-300mAs). For all U-Q combinations, the iodine contrast (C), the noise level (N) and, from these, the contrast-to-noise ratio (CNR) of reconstructed CT images were determined and parameterized as a function of U, Q or the measured absorbed dose (D).

Dose comparison of classical 2-plane DSA and 3D rotational angiography for the assessment of intracranial aneurysms.

Introduction: The purpose of this experimental phantom study was to compare radiation doses imparted to patients undergoing classical two-plane digital subtraction angiography (2-plane DSA) and 3D rotational angiography in interventional neuroradiology.

Methods: Thermoluminescence dosimeter (TLD) measurements were performed at an anthropomorphic phantom using a digital interventional angiography system. Two-plane DSA included posterior/anterior (PA) and lateral (LAT) projections (frame-rate, 7.

Typical exposure parameters, organ doses and effective doses for endovascular aortic aneurysm repair: Comparison of Monte Carlo simulations and direct measurements with an anthropomorphic phantom.

Objectives: Radiation exposure of patients during endovascular aneurysm repair (EVAR) procedures ranks in the upper sector of medical exposure. Thus, estimation of radiation doses achieved during EVAR is of great importance.

Material And Methods: Organ doses (OD) and effective doses (ED) administered to 17 patients receiving EVAR were determined (1) from the exposure parameters by performing Monte Carlo simulations in mathematical phantoms and (2) by measurements with thermoluminescent dosimeters in a physical anthropomorphic phantom.

Radiation protection issues in dynamic contrast-enhanced (perfusion) computed tomography.

Dynamic contrast-enhanced (DCE) CT studies are increasingly used in both medical care and clinical trials to improve diagnosis and therapy management of the most common life-threatening diseases: stroke, coronary artery disease and cancer. It is thus the aim of this review to briefly summarize the current knowledge on deterministic and stochastic radiation effects relevant for patient protection, to present the essential concepts for determining radiation doses and risks associated with DCE-CT studies as well as representative results, and to discuss relevant aspects to be considered in the process of justification and optimization of these studies. For three default DCE-CT protocols implemented at a latest-generation CT system for cerebral, myocardial and cancer perfusion imaging, absorbed doses were measured by thermoluminescent dosimeters at an anthropomorphic body phantom and compared with thresholds for harmful (deterministic) tissue reactions.

Radiation exposure of patients undergoing whole-body FDG-PET/CT examinations: an update pursuant to the new ICRP recommendations.

Aim: Reinvestigation of the radiation exposure of patients undergoing whole-body [18F]FDG-PET/CT examinations pursuant to the revised recommendations of the ICRP.

Methods: Conversion coefficients for equivalent organ doses were determined for realistic anthropomorphic phantoms of reference persons. Based on these data, conversion coefficients for the effective dose were calculated using the revised tissue-weighting factors that account for the different radiation susceptibilities of organs and tissues, and the redefinition of the group 'remainder tissues'.

Dose and image quality of cone-beam computed tomography as compared with conventional multislice computed tomography in abdominal imaging.

Objectives: Recent technical developments have facilitated the application of cone-beam computed tomography (CBCT) for interventional and intraoperative imaging. The aim of this study was to compare the radiation doses and image quality in CBCT with those of conventional multislice spiral computed tomography (MSCT) for abdominal and genitourinary imaging.

Methods: Different CBCT and MSCT protocols for imaging soft tissues and hard-contrast objects at different dose levels were investigated in this study.

Radiation exposure in perfusion CT of the brain.

Objective: This study aimed to show the simulation of the radiation exposure of the brain during perfusion measurements multi-detector-CT.

Material And Methods: The effective dose and different organ doses were measured with thermoluminescent dosimeters in an Alderson-Rando phantom and compared with the data of a simulation program (CT-Expo V1.6) for varying scan protocols with different tube voltages (in kilovolts) and constant parameters for tube current (270 mAs), scan length (28.

Cumulative radiation exposure and cancer risk of patients with ischemic heart diseases from diagnostic and therapeutic imaging procedures.

Objectives: To present a detailed analysis of the cumulative radiation exposure and cancer risk of patients with ischemic heart diseases (IHD) from diagnostic and therapeutic imaging.

Methods: For 1219 IHD patients, personal and examination data were retrieved from the information systems of a university hospital. For each patient, cumulative organ doses and the corresponding effective dose (E) resulting from all imaging procedures performed within 3 months before and 12 months after the date of the diagnosis were calculated.

Radiation dose at coronary CT angiography: second-generation dual-source CT versus single-source 64-MDCT and first-generation dual-source CT.

Objective: The purpose of this study was to assess the radiation doses of different coronary CTA (CTA) protocols: second-generation dual-source 128-MDCT, first-generation dual-source 64-MDCT, and single-source 64-MDCT.

Materials And Methods: Thermoluminescent dosimetry was used to determine scanner-specific dose coefficients for standard coronary CTA of an anthropomorphic phantom. These coefficients were used to estimate the effective doses (EDs) of retrospectively gated, prospectively triggered, and prospectively triggered high pitch coronary CTA performed at 100 and 120 kV.

Dynamic contrast-enhanced CT studies: balancing patient exposure and image noise.

Objectives: To establish the essential basis for balancing the dose versus noise trade-off in dynamic contrast-enhanced (DCE) CT by means of a phantom study.

Materials And Methods: Measurements were performed at a 64-section dual-source system, using the default protocols for DCE imaging (40 scans) of the trunk (current-time product per scan, 100 mAs; voltage, 120 kVp; pixel size, 0.9 × 0.

Dual energy CT of the chest: how about the dose?

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 Energy CT settings with reference to a standard chest scan and to compare image noise and contrast to noise ratios (CNR).

Dose reduction by automatic exposure control in multidetector computed tomography: comparison between measurement and calculation.

The aim of this study was to investigate the potential of dose reduction in multidetector computed tomography (MDCT) by current-modulated automatic exposure control (AEC) and to test the reliability of the dose estimation by the conventional CT dosimetry program CT-EXPO, when an average tube current is used. Phantom measurements were performed at a CT system with 64 detector rows for four representative examination protocols, each without and with current-modulated AEC. Organ and effective doses were measured by thermoluminescence dosimeters (TLD) at an anthropomorphic Alderson phantom and compared with those given by the calculation with CT-EXPO.

Radiation exposures of cancer patients from medical X-rays: how relevant are they for individual patients and population exposure?

X-ray procedures have a substantial impact not only on patient care but also on man-made radiation exposure. Since a reliable risk-benefit analysis of medical X-rays can only be performed for diagnosis-related groups of patients, we determined specific exposure data for patients with the ten most common types of cancer. For all patients with the considered cancers undergoing medical X-ray procedures in a maximum-care hospital between 2000 and 2005, patient- and examination-specific data were retrieved from the hospital/radiology information system.

[Cross-sectional imaging in dentomaxillofacial diagnostics: dose comparison of dental MSCT and NewTom 9000 DVT].

Purpose: For nonsuperimposed and three-dimensional imaging of jaws and teeth, multislice computer tomography (MSCT) can be performed, or alternatively digital volume tomography as a cone beam technique can be applied. The radiation dose of both procedures should be evaluated with different methods of dose assessment.

Materials And Methods: A 4-row MSCT (Volume Zoom Siemens) and a cone beam CT (NewTom QR-DVT 9000) were compared regarding the radiation exposure of the patient during a dental examination.

Radiation exposure of patients undergoing whole-body dual-modality 18F-FDG PET/CT examinations.

Unlabelled: We investigated radiation exposure of patients undergoing whole-body 18F-FDG PET/CT examinations at 4 hospitals equipped with different tomographs.

Methods: Patient doses were estimated by using established dose coefficients for 18F-FDG and from thermoluminescent measurements performed on an anthropomorphic whole-body phantom.

Results: The most relevant difference between the protocols examined was the incorporation of CT as part of the combined PET/CT examination: Separate low-dose CT scans were acquired at 2 hospitals for attenuation correction of emission data in addition to a contrast-enhanced CT scan for diagnostic evaluation, whereas, at the other sites, contrast-enhanced CT scans were used for both purposes.

[Low-dose spiral CT of the lung in the follow-up of non-malignant lung disease].

Purpose: To assess image quality of chest CT with an 80 to 90 percent dose reduction in follow-up studies of patients with lung disease, dose and image quality of a low-dose protocol was investigated.

Materials And Methods: A follow-up low-dose CT (ND-CT, 120 kV, 10 mAs/slice, 3 mm slice thickness) was performed on 35 patients with non-malignant lung disease and compared with the initial standard dose CT (= SD-CT, 100 mAs/slice, 3 or 5 mm slice thickness). The dose was measured by thermo-luminescence in an Alderson phantom.

Assessment of a theoretical formalism for dose estimation in CT: an anthropomorphic phantom study.

Dose assessment in computed tomography (CT) is challenging due to the vast variety of CT scanners and imaging protocols in use. In the present study, the accurateness of a theoretical formalism implemented in the PC program CT-EXPO for dose calculation was evaluated by means of phantom measurements. Phantom measurements were performed with four 1-slice, four 4-slice and two 16-slice spiral CT scanners.

Radiation exposure in multi-slice versus single-slice spiral CT: results of a nationwide survey.

Multi-slice (MS) technology increases the efficacy of CT procedures and offers new promising applications. The expanding use of MSCT, however, may result in an increase in both frequency of procedures and levels of patient exposure. It was, therefore, the aim of this study to gain an overview of MSCT examinations conducted in Germany in 2001.

[Assessment of the effective dose for routine protocols in conventional CT, electron beam CT and coronary angiography].

Purpose: To compare the effective dose applied by sequential CT (SEQ), spiral CT (SCT), electron beam CT (EBT) and coronary angiography for investigations of the chest, abdomen and the heart.

Methods: The Alderson Phantom was used to compare the effective dose for all modalities. In addition, the effective dose for conventional CT (SEQ and SCT) was estimated with a mathematical phantom.