The Journal of Trauma: Injury, Infection, and Critical Care: September 1989 - Volume 29 Issue 9 p 1301

CT dose optimization is typically guided by pixel noise or contrast-to-noise ratio that does not delineate low contrast details adequately. We utilized the statistically defined detectability to study its relationship and lesion size in abdominal CT. A realistically shaped medium sized abdomen phantom was customized contain a cylindrical void of 4 cm diameter. The filled with (1% 2%) insert containing six groups targets ranging from 1.2 mm 7 size. Helical scans were performed using Siemens...

Some digital radiography (DR) detectors and software allow for remote download of exam statistics, including image reject status, body part, projection, exposure index (EI). The ability to have automated data collection from multiple DR units is conducive a quality control (QC) program monitoring institutional radiographic exposures. We implemented such QC with the goal identify outliers in machine radiation output opportunities improvement dose levels. studied records four greater detail on...

Optimizing CT protocols is challenging in the presence of automatic dose modulation because index (CTDI

To quantify the trade-offs of dose and image quality among pre-loaded automatic exposure control (AEC) options in digital mammography, two AEC tables from Hologic Selenia mammography system were compared: default "table 0" 1". Realistically-shaped phantoms consisting tissue-equivalent material various thicknesses (4.5 cm-7 cm) imaged to obtain a figure merit (FOM), squared contrast-to-noise ratio per mean glandular dose. relate results pathological findings evaluate overall performance,...

For CT dose optimization, one needs to address two important questions. The first is how various lesion-specific detection tasks demand different patient doses for the same patient. second variation of size requires lesion task. In this study, we attempted find quantitative solutions these questions by utilizing a wide range abdomen phantoms.A simplified model with monochromatic fan beam passing through bowtie-filter and an elliptical object was proposed. relates minimum detectable contrast...

Purpose: Grids are often not used in mobile chest radiography, and when used, they have a low ratio inaccurately aligned. Recently, radiography automatic grid alignment system (MRAGA) was developed that accurately automatically aligns the focal spot with grid. The objective of this study is to investigate high‐ratio tradeoffs at fixed patient dose lies on axis Methods: phantoms (medium large) were modifications ANSI (American National Standards Institute) phantom consisted layers Lucite™,...

Presents our initial results in comparing three algorithms for autonomous robotic mapping using two types of laser scanner data. The compared are the Markov localization approach S. Thrun et al. (1998), F. Lu and E. Milios's (1997) iterative dual correspondence algorithm, C. Touzet's (2000) model-free landmark extraction algorithm. data utilized AccuRange from Acuity SICK scanner. We compare these terms quality mapped results, computational requirements, sensitivity to odometry errors. While...

The Ramsey number $r(G)$ of a graph $G$ is the minimum $N$ such that any red-blue colouring edges $K_N$ contains monochromatic copy $G$. Pavez-Signé, Piga and Sanhueza-Matamala proved for function $n\leq f(n) \leq r(K_n)$, there sequence connected graphs $(G_n)_{n\in \mathbb{N}}$ with $|V(G_n)|=n$ $r(G_n)=\Theta(f(n))$ conjectured $G_n$ can additionally have arbitrarily large connectivity. In this note we prove their conjecture.

Introduction. The methods used in the microscopical examination of inorganic materials may be grouped into two classes, those involving a flat, generally polished, surface by reflected light and which transparent section is examined transmitted light. development these largely due to work H. C. Sorby who, grinding polishing pieces steel examining structure prepared surfaces, founded science metallography, who also, investigating microscopically sections rocks ground sufficiently thin...

82Rb cardiac PET is largely used to study myocardial perfusion with function and calculate blood flow (MBF) coronary reserve or reserve. Although the dosing activity of determined by patient weight, infusion volume concentration varies age generator. We sought predict needed bolus help evaluate accuracy MBF findings. Methods: Data were collected from deidentified tickets an generator, including instantaneous eluted rate. The times reach 4 levels-740, 1,110, 1,480, 1,665 MBq (20, 30, 40, 45...

Purpose: Recent concerns about accumulated radiation dose and collective risk prompted a check of the software reported CT index (CTDI Vol ) dose‐length‐product (DLP) Philips Brilliance scanners. The CTDI DLP were measured for comparison with values using high‐resolution chest protocol (commonly used COPD). Method Materials: A 40‐slice scanner was protocol, which has technique 120 kVp 200 mAs/slice, detector collimation 2×0.625 mm, reconstructed scan thickness 1.25 table increment 10 mm....

Abstract The performance of three digital detectors was measured at two exposure index (EI) levels in terms the effect on features borderline detectability. null hypothesis that there would be no statistically significant difference CNR marginally visible a baseline‐ (2.2 µGy) and reduced dose (1.4 images. experiment used phantom composed an aluminum contrast‐recovery plate, with varying diameters hole depths, which placed between detector/grid 5–20 cm Lucite. Exposures were made using kVp...

Purpose: It is of practical use to obtain the dose for a specified low contrast lesion detectability and given ASIR fraction before scan. To achieve goal, we investigated relationship minimum required blending in abdominal CT scans. Methods: A realistically shaped abdomen phantom (CIRS TE-07) with an embedded vertebral bone rod was utilized. Helical scans were performed on GE 750 HD at two levels 8 mGy 18 mGy. The images reconstructed using different fractions (0–100%). noise images,...

Purpose: To investigate the noise details in ASIR reconstructed images with regard to location and signal dependency distribution normality abdominal CT scans. Methods: A realistically shaped abdomen phantom (CIRS TE-07). The was customized allow for insert of a low contrast module 700 QA). Helical scans (120 kV, pitch 1.375, thickness 5 mm) were performed on GE 750 HD at two dose levels 8 mGy 18 mGy. using different fractions (0–100%). images, obtained subtraction from adjacent slices,...

Purpose: To develop a standard set of target exposure index (TEI) values to be applied Agfa Computed Radiography (CR) readers in accordance with International Electrotechnical Committee 62494‐1 (ed. 1.0). Methods: A large data cohort was collected from six USAF Medical Treatment Facilities that exclusively use CR Readers. Dose monitoring statistics were each reader. The analyzed based on anatomic region, view, and processing speed class. specific metric, logarithmic mean (LGM), converted...

Purpose: It is possible to measure the patient surface dose non‐invasively using radiolucent dosimeters. However, size specific weighted remains unknown. We attempted study relationship as varies in abdominal CT. Methods: Seven abdomen phantoms (CIRS TE series) simulating patients from an infant a large adult were used. Size doses measured with 100 mm CT chamber under axial scans Siemens Sensation 64 (mCT) and GE 750 HD. The scanner settings 120 kVp, 200 mAs fully opened collimations....

Purpose: Adaptive statistical iterative reconstruction (ASIR) is often used for noise reduction. However, it may not be clear whether the reduction uniform across different spatial scales. As this important lesion detection, we attempted to quantify dependency on scales under ASIR blending fractions. Methods: An abdomen phantom (CIRS TE‐07) simulating medium sized patient was used. The contains a cylindrical void of 4 cm diameter, filled with an insert containing six groups targets (1% and...