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Biomedical subjects

R E Morrell

Publications and source records attributed to R E Morrell.

9 recordsLinked to original sources
PubMed2006

A mathematical model for patient skin dose assessment in cardiac catheterization procedures.

A mathematical model has been developed for the assessment of patient skin doses from cardiac catheterization procedures. This uses exposure and projection data stored in the DICOM image files. Since these contain only information about the acquisition runs, a correction is needed to estimate and include the contribution from fluoroscopy. Maximum skin doses calculated by the model were found to correlate well with those measured on Kodak EDR2 film. Three methods for including the contribution from fluoroscopy were investigated, and all successfully identified patients receiving skin doses in excess of 1 Gy. It is hoped to automate this tool for routine assessment of skin doses in our cardiac catheterization laboratories.

Cardiac Catheterization↗
PubMed2006

Kodak EDR2 film for patient skin dose assessment in cardiac catheterization procedures.

Patient skin doses were measured using Kodak EDR2 film for 20 coronary angiography (CA) and 32 percutaneous transluminal coronary angioplasty (PTCA) procedures. For CA, all skin doses were well below 1 Gy. However, 23% of PTCA patients received skin doses of 1 Gy or more. Dose-area product (DAP) was also recorded and was found to be an inadequate indicator of maximum skin dose. Practical compliance with ICRP recommendations requires a robust method for skin dosimetry that is more accurate than DAP and is applicable over a wider dose range than EDR2 film.

Angioplasty, Balloon, Coronary↗
PubMed2005

Film dosimetry for fluoroscopic procedures: potential errors.

Kodak EDR 2 film was calibrated across the range of beam qualities and exposure rates typically used in our cardiac catheterisation laboratory. Its dose-response curve was successfully modelled up to its saturation point of 1 Gy. The consistency of the film's response with film batch, time between exposure and processing processor and day-to-day variations in performance, was investigated. The effects of field size, exposure rate, beam quality and use of the dynamic wedge filter were quantified. The overall uncertainty in dose was estimated to be between -20% and +40%, at 160 mGy. This uncertainty increases as the film approaches its saturation point. In addition, some unusual artefacts were observed.

Calibration↗
PubMed2004

Barium enema: use of increased copper filtration to optimize dose and image quality.

The purpose of this study was to determine and validate the optimum copper filtration for adult double contrast barium enema examinations. Entrance surface dose rates to polymethyl methacrylate slabs and corresponding image intensifier input kermas, were measured for various added copper filters. Image contrast was assessed using a Leeds TO.10 test object. Copper filter thickness of 0.3 mm was chosen, as this reduced entrance surface dose rate by 56%, without substantially degrading image contrast due to kV and mA saturation. 20 sets of clinical films taken with each of 0.3 mm copper, 0.1 mm copper and no copper were reviewed following randomization, by a specialist gastrointestinal radiologist. Each set of digital spot and conventional films was allocated a score for each of three regions of the bowel, on a scale of 0-3 for perceived barium coating. The Kruskal-Wallis test showed no significant difference in perceived coating between the three groups (Digital spot: sigmoid colon p=0.207, splenic flexure p=0.103, hepatic flexure p=0.894. Screen-film: left colon p=0.803, right colon p=0.487, transverse colon p=0.905). All examinations but one were classified as diagnostic. The remaining one was classified indeterminate, due to poor distension of the colon. On adding 0.3 mm copper filtration, the mean dose-area product per examination was reduced by 57%, from 17.7 Gy cm(2) to 7.6 Gy cm(2). The estimated reduction in effective dose was 11%, from 3.0 mSv to 2.7 mSv. X-ray tube loading increased by 30%, but this caused no overheating with our local examination protocol and schedule. Additional filtration of 0.3 mm copper for adult double contrast barium enemas has now been implemented in routine clinical use at our hospital.

Adult↗
PubMed2000

Coarctation of the abdominal aorta and renal artery stenosis related to an umbilical artery catheter placement in a neonate.

Umbilical artery catheters have been associated with thrombotic complications, such as partial or complete occlusion in the aorta, the renal arteries, and other blood vessels. There have been few reports of the long-term consequences of either symptomatic or asymptomatic thrombi. We report a patient, now 22 years of age, born with a normal aorta, who developed hypertension at the age of 2 months after use of an umbilical artery catheter. An intravenous pylegram and nuclear renal scan were compatible with occlusion of left renal artery and of the distal aorta. At 6 months of age, the patient presented with reduced femoral pulses. Angiography demonstrated an acquired coarctation of the abdominal aorta and renal artery stenosis. An abdominal ultrasound performed at 22 years of age revealed partial obstruction of the lower abdominal aorta and marked atrophy of the left kidney. This case underlines the importance of long-term follow-up studies of infants who have undergone umbilical artery catheterizations.

Aorta, Abdominal↗
PubMed1982

Health screening of Indochinese refugee children.

The first 100 Indochinese refugee patients screened at Oakland (Calif) Children's Hospital had a remarkably high incidence of treatable infectious and parasitic diseases. The PPD skin tests were positive in 28%, and stool parasites were present in 65%. There were wide differences among the various ethnic groups in prevalence of stool parasites, anemia, and hemoglobin E trait, with a higher rate among Cambodians accounting for these differences. There were also differences in stool parasite patterns when the refugees were separated by ethnic origin. Cambodians had predominantly hookworm and Strongyloides, Laotians harbored hookworm and Trichuris, and Vietnamese were infested with Trichuris and Giardia. Malaria. Pott's disease, and congenital syphilis were among the uncommonly encountered diseases. Results of screening will vary with ethnic origin, but health screening has a high yield for all Indochinese refugees.

Adolescent↗
PubMed1982

Suprapubic aspiration associated with hematoma.

A newborn female infant who experienced an intramural bladder hematoma with upper tract obstruction secondary to a suprapubic aspiration is described. The literature is reviewed and the conservative management of this child is discussed.

Female↗
PubMed1975

An outbreak of severe pneumonia due to respiratory syncytial virus in isolated Arctic populations.

A rapidly developing outbreak of pneumonia in young infants was documented in two isolated Artic populations in May 1972. These were studied virologically, serologically and clinically. In addition to the two stricken communities, one apparently unaffected with serious clinical illness and a fourth, in which are located the major hospital and airport in the eastern Arctic, were also studied. One hundred and twenty-four patients were studied serologically and 81 respiratory and other specimens were obtained for virus isolation from 40 of these patients. Clinical records were kept of the outbreak in each area and a detailed questionnaire was filled out for 140 children and their families. Respiratory syncytial irus (RSV) was cultured from eight ill children. Electron microscopy provided the first evidence of RSV infection. A seroconversion rate of approximately 50% was seen in both affected communities as well as in the clinically unaffected one. The epidemic in the first two communities was characterized by severe pneumonia and frequent hospitalization but no cases of bronchiolitis were seen. No evidence for other causes of this outbreak could be obtained by testing for antibodies to influenza A and B, parainfluenza 1, 2 and 3, adenovirus and herpes simplex viruses. Unusual features of this epidemic of RSV infection include the high attack rate, severe morbidity, illness manifest almost exclusively as pneumonia rather than bronchiolitis and the difference between the expression of disease in different communities. Historical data and clinical observations were inadequate to explain these unusual features.

Adult↗