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Biomedical subjects

W Huda

Publications and source records attributed to W Huda.

At least 73 records · Page 4Linked to original sources
PubMed1989

Patient doses from computed tomography in Manitoba from 1977 to 1987.

The number of patients undergoing computed tomographic (CT) examinations in the province of Manitoba is reported for the period 1977-1987. The annual patient throughput has increased from 4.2 per 10(3) population in 1978 to 18.2 per 10(3) population in 1987. Over the same period, the per capita population dose from CT has increased from 4.2 to 81.0 microSv. This substantial rise has occurred because of an increase in patient throughput, higher radiation doses associated with modern CT scanners and an increasing proportion of (higher dose) body CT studies. The mean patient dose on a second generation (EMI 5005) scanner was about 1.4 mSv, whereas the corresponding doses on third generation scanners operating in Manitoba were 3.9 mSv (GE 9800) and 5.6 mSv (Siemens DRH).

Humans↗
PubMed1989

Radiation doses in extracorporeal shock wave lithotripsy.

Patients undergoing lithotripsy on the Siemens Lithostar system are exposed to radiation in three modes: film radiography, electronic radiography and fluoroscopy. Radiation exposure techniques (kVp, field size, number of exposures and projection) were recorded for the first 125 patients undergoing treatment on a recently installed Lithostar unit at a Winnipeg hospital. These data were then used in conjunction with phantom-based radiation dose measurements to calculate entrance skin dose and total energy imparted for each patient. Values of 142 mGy and 53 mJ, respectively, were found. In the case of energy imparted, 20% of the total arose from film radiography, 30% from electronic radiography and the remaining 50% from fluoroscopy. The estimated effective dose-equivalent, HE, to the average patient undergoing lithotripsy was 0.75 mSv. This corresponds to an estimated radiation risk for the induction of fatal cancers and genetic defects (in the first two generations of offspring) of between 5 and 11 per million.

Fluoroscopy↗
PubMed1989

Costs and benefits of low-osmolality contrast agents in radiology.

We have examined the costs and benefits associated with the introduction of low-osmolality contrast agents into general radiology. The result is a cost of $2,000,000 to save a life and $100,000 to save a year-of-life if it is assumed that these agents are ten times safer than conventional contrast agents in terms of fatality rates. These values are comparable to the costs of saving a life, and a year-of-life, associated with radiation protection practice, but appear to be over an order of magnitude higher than the corresponding costs in contexts such as mammography screening programs. Cost-benefit analysis provides a useful insight into medical decision making when available resources are limited. It raises the important question of whether society at large is allocating sufficient resources to health care.

Adolescent↗
PubMed1989

Irradiation of volunteers in nuclear medicine.

The preliminary assessment of many radiopharmaceuticals is often carried out with the help of "normal volunteers". These volunteers are drawn from the general public, are fully informed of the procedure to be performed and its attendant risks, and in many cases are compensated financially for their trouble. The cooperation of such people is of vital importance to the full understanding of the normal kinetics and metabolism of many new radiopharmaceuticals. The restrictions on the choice of normal volunteers, and the radiation dose limits which must be observed are not explicitly defined in any of the current guidelines, and in this paper we propose a rationale, based upon available information, which sets acceptable limits for volunteers, and provides a framework within which scientists and physicians can work.

Adult↗
PubMed1988

Lack of radiographic evidence of interstitial pulmonary edema after maximal exercise in normal subjects.

Recent physiologic studies have indirectly suggested that interstitial pulmonary edema may develop at maximal exercise in normal humans at sea level. Therefore, we compared chest radiographs taken before and immediately after incremental exercise to maximum in 5 healthy young subjects. We looked for evidence of redistribution of pulmonary blood flow, pulmonary venous distension, loss of sharp definition of pulmonary vascular markings, hilar blurring, Kerley's A, B, or C lines, peribronchial or perivascular cuffing, widening of fissures, pleural effusion, and diffuse opacity. We also quantitated radiographic density in 6 areas of the film in each subject. There was no radiographic change to suggest an increase in lung water in any lung zone in any of the subjects. Given the documented sensitivity of chest radiography in this respect, we conclude that any increase in extravascular lung water during exercise must be trivial.

Adult↗
PubMed1988

Chernobyl--the radiological impact on Canada.

On 26 April 1986, an accident at a Ukrainian nuclear reactor at Chernobyl triggered the release of large quantities of fission products into the atmosphere. After 7 May 1986 measurable quantities of ruthenium-103, iodine-131, cesium-134, and cesium-137 were detected in environmental sampling carried out in all regions of Canada. Maximum airborne concentrations for each radionuclide were of the order of a few mBq.m-3 and contaminated milk samples on average contained less than 1Bq.L-1 of iodine-131 and cesium-137. The mean value of the effective dose equivalent for an adult Canadian in the two months following the accident is calculated to be 0.28 microSv. As this total radiation dose is about 10(-33) of the dose from natural background during the same period, the resultant radiological detriment is concluded to be negligible.

Accidents↗
PubMed1987

CT quality control.

A daily quality control (QC) protocol for a GE 9800 computed tomography (CT) scanner is described which quantitatively assesses system noise, an index of high contrast resolution, and the reproducibility of CT numbers for four phantom materials. The mean values and variation for each QC parameter under normal operating conditions have been determined, and their use in assessing CT scanner performance is discussed.

Quality Control↗
PubMed1979

X-ray emission analysis of human plasma by proton excitation of thick samples in air.

Thick plasma samples have been irradiated in air by 2.3 MeV protons for trace elemental analysis by proton-induced X-ray emission spectroscopy. Accurate calibration curves were obtained for Fe, Zn and Sr and detection limits in dry plasma were estimated to be 0.08 PPM for Fe, 0.065 PPM for Zn and 0.12 PPM for Sr. Low temperature ashing of these samples improved the detection limits by a factor of 3 but reduced the precision and resulted in loss of bromine from the plasma. Mass absorption coefficients for low energy X-rays in dry plasma were measured and X-ray attenuation in the sample was found to prevent the detection of trace elements with Z less than 26. The method was used to determine Sr in plasma from a patient with bone disease, the Sr being a non-radioactive bone-seeking tracer element. The results, which were in the 3--13 PPM range, were in good general agreement with the analysis of the same samples by flame photometry.

Air↗
PubMedDate not supplied

Picture archiving and communications systems (PACS).

Although there has been a recent increase in interest in picture archiving and communications systems (PACS) topics, little has been published to assist the non-technical person in understanding the complexities of the technologies required for a PACS implementation. This issue of Current Problems in Radiology defines each PACS component and explains why each is important in a system design. PACS installations at the University of Florida are used as examples to tie the concepts together. The infrastructure required for PACS consists of the information system interfaces, networks, and databases. Information system interfaces guarantee consistent patient data across all platforms and reduce labor requirements by eliminating duplicate data entry. Data networks move information from the originating location to users around the hospital, clinic, campus, city, or world. In the PACS environment, the data consist of patient and study information as well as images and information about these images. Databases organize the data from multiple sources into a coherent package that can be queried for many different purposes, such as retrieving images, reviewing patient and study information, studying practice statistics, and performing outcomes analysis. PACS components consist of acquisition nodes, archives, and output devices. Acquisition nodes may include "digital modalities" such as CT, MRI, nuclear medicine, and computed radiography (CR), along with devices to convert from analog to digital, such as digitizers and frame grabbers. Options for archives are discussed along with configuration schemes. Output devices include both hard copy (film and paper prints) and soft copy (workstations for display and diagnosis). Finally, a description of the PACS installations at the University of Florida is presented, with comments on some of the difficulties and complexities encountered. A discussion of the cost and benefits of PACS is included, along with a forecast of the future of PACS.

Computer Systems↗
PubMedDate not supplied

Comparison of dynamic and spiral CT for imaging the glottic larynx.

OBJECTIVE: Our goal was to prospectively compare dynamic CT (DCT) and spiral CT (SCT) for evaluating patients with suspected abnormalities of the glottic region and correlate the observed differences between the two techniques with phantom measurements. MATERIALS AND METHODS: Thirty-one patients suspected of having laryngeal abnormalities underwent DCT and SCT. The studies were evaluated by two head and neck radiologists for lesion detection, visualization of the paraglottic fat planes (PGFPs), motion artifact, respiratory misregistration, and overall image quality. Slice sensitivity profile (SSP) and image noise were measured for DCT and SCT for the imaging parameters used in this study. RESULTS: Artifacts due to motion and respiratory misregistration were reduced with SCT compared with DCT. Laryngeal abnormalities and the adjacent PGFPs were better visualized with DCT than SCT. With use of similar imaging parameters, SSP and image noise were both increased with SCT compared with DCT. CONCLUSION: SCT produces high quality images of the larynx with less motion and respiratory misregistration artifacts than DCT. DCT allows better visualization of lesions and subtle anatomic features of the glottic region. SCT may substitute for DCT in laryngeal imaging.

Adult↗