ABSTRACT
This study is the first regional investigation in Najran, Saudi Arabia aimed at investigating radiation dose and image quality of computed tomography (CT) examinations. The survey data was collected from five scanners in four hospitals. For all CT scanners, a correction factor was calculated to measure the weighted computed tomography dose index (CTDIw) using standard dosimetry phantoms. The CTDIw were reported in this study and compared with other countries. It was found that most CTDIw values were close to the European reference levels and in line with the results of similar surveys in the other parts of world. Concerning image quality, 80 % of the scanners were found to be in compliance with the relative international guidelines for all the examined parameters.
Subject(s)
Phantoms, Imaging , Radiation Dosage , Tomography, X-Ray Computed/instrumentation , Tomography, X-Ray Computed/methods , Adult , Child , Humans , Models, Biological , Quality Control , Saudi Arabia , Tomography, X-Ray Computed/standardsABSTRACT
The entrance skin dose (ESD) of chest X-ray examinations for AP and PA projections of paediatric patients at Maternity and Children Hospital in Najran, Saudi Arabia have been obtained using DoseCal software. The majority of the results obtained show low measured ESD for chest X-ray examinations. The mean of ESD for the AP projection was found to be 37.5, 40.5, 41.3, and 52.3 µ Gy for age groups 0-1, >1-5, >5-10, and >10-15 years respectively. However, the ESD for PA projection was found to be 50.7 and 56.7 µ Gy for age groups >5-10, and >10-15 years respectively.
Subject(s)
Body Burden , Radiation Dosage , Radiography, Thoracic/statistics & numerical data , Radiometry/statistics & numerical data , Adolescent , Age Distribution , Child , Child, Preschool , Female , Humans , Infant , Infant, Newborn , Male , Saudi Arabia/epidemiology , Sex DistributionABSTRACT
PURPOSE: To determine if moderate numbers of low fluence, 193-nm excimer laser pulses modify or damage the corneal stroma. METHODS: The corneal epithelium of fresh bovine eyes was scraped off and the exposed stroma was irradiated with 200 low fluence laser pulses from an argon fluoride excimer laser. This process was performed on five eyes each at two laser fluences, 10 mJ/cm2 and 30 mJ/cm2. The ten irradiated and three control (unirradiated) corneas were sectioned and studied by electron microscopy. The maximum and minimum thickness of the anterior layer of randomly oriented collagen fibers was measured using electron microscopy. RESULTS: The mean maximum thickness of the anterior randomly oriented layer of collagen was 1.23 +/- 0.45 microm in the control corneas, 0.67 +/- 0.32 microm in the corneas irradiated at 10 mJ/cm2, and 0.10 +/- 0.12 microm in the corneas irradiated at 30 mJ/cm2. The mean thickness of corneal stroma removed was 0.7 microm at a fluence of 10 mJ/cm2 and 1.1 microm at a fluence of 30 mJ/cm2. A thin, electron-dense pseudomembrane was present at both fluences. CONCLUSION: We report removal of bovine corneal stroma at 10 mJ/cm2--below the previously reported ablation threshold of 20 mJ/cm2.
Subject(s)
Corneal Stroma/surgery , Corneal Stroma/ultrastructure , Photorefractive Keratectomy/methods , Animals , Cattle , Collagen/ultrastructure , Lasers, ExcimerABSTRACT
OBJECTIVE: To evaluate Erythrocyte Sedimentation Rate in children with sickle cell disease. METHODS: Erythrocyte Sedimentation Rate was performed in 95 children with sickle cell disease during the period from December 1992 to June 1999. Patients were classified into 4 groups. Patients in the steady state (group 1), painful crisis (group 2), mild infection (group 3) and moderate/severe infection (group 4). Comparison between the groups was performed using ANOVA and ANCOVA. RESULTS: There were 55 males (58%) and 40 females (42%) with a mean age of 79.1 months. The mean Erythrocyte Sedimentation Rate values for the various groups were as follows: Group 1 (n=10); mean Erythrocyte Sedimentation Rate is 5 mm/hr (+/-4.6) and was significantly the lowest (p<0.05), group 2 (n=44); mean Erythrocyte Sedimentation Rate is 25.8 mm/hr (+/-16.3), group 3 (n=18); mean Erythrocyte Sedimentation Rate is 28.1 mm/hr (+/-25.8), while group 4 (n=23); mean Erythrocyte Sedimentation Rate is 99.2 mm/hr (+/-33.5) and was significantly the highest (p<0.05). Two cut-off values for the Erythrocyte Sedimentation Rate (> or = 30 mm/hr then > or = 50 mm/hr) were considered to evaluate their specificity and sensitivity for moderate/severe infection. CONCLUSION: Although the Erythrocyte Sedimentation Rate is low in sickle cell disease, it does increase during painful crisis and infection and it is a useful indicator of moderate/severe infection.
