The impact of increased Al filtration on x-ray tube loading and image quality in diagnostic radiology

Previous work has shown that for nine common radiographic projections (AP abdomen, AP cervical spine, LAT cervical spine, PA chest, LAT chest, AP hip, AP lumbar spine, LAT lumber spine, and AP pelvis) increasing the total x-ray tube filtration from 2.5 mm Al equivalent (the regulatory minimum for general diagnostic radiology) to 4.0 mm Al equivalent, reduces the average effective dose and average skin entrance dose by 9% and 16%, respectively, using a 400 speed screen-film system. In this study, the effects of this filtration increase on x-ray tube loading and image quality were assessed. For the above projections and filtration increase, mean absolute and percentage increases in tube loading were 2.9 mAs and 15%, respectively, for a constant film density and fixed kVp. Tube current (mA) increases of 25% (a worst case) resulted in no statistically significant loss in focal spot resolution due to blooming for both large (1.2 mm) and small (0.6 mm) focal spot sizes, except at high mA low kVp techniques. The latter losses were below 10%, and when the image receptor blur was incorporated, the total system spatial resolution losses were on the order of one-quarter to one-half these values for typical clinical geometries. Radiographs of a contrast phantom taken with 2.5 and 4.0 mm total Al equivalent x-ray tube filtration were compared at 60, 70, 81, 90, 102, and 121 kVp. No statistically significant changes were observed with regard to (1) test object conspicuity as reported by three observers, (2) image contrast, as measured using a densitometer with a 3 mm aperture (+/-0.0017 OD, 95% confidence level), and (3) pixel value image noise, image contrast-to-noise ratios, and image signal-to-noise ratios, as measured using a scanning densitometer with a 12-bit acquisition depth and 85 micron pixel size (+/-2.5%, +/-3.1%, and +/-2.5%, 95% confidence levels, respectively). These results, combined with the linear no-threshold model for radiation risk and the ALARA principle, suggest that general radiography should be carried out using a minimum of 4.0 mm total Al equivalent filtration.     

Trends in bloodborne pathogen exposure and follow-up at an urban teaching hospital: 1987 to 1997

Health care workers (HCWs) risk occupational exposure to bloodborne pathogens. Effective postexposure treatment and testing depend on compliance with follow-up, but compliance rates are poorly understood. We examined trends in exposure and follow-up at a large teaching hospital after interventions to improve compliance. We reviewed exposures from October 1987 to September 1988 (group 1) and July 1996 to June 1997 (group 2). Data were analyzed for HCW demographics, source patient characteristics, and follow-up outcomes. We found that group 2 source patient serologic data were obtained more often. Group 1 source patients were more likely to be positive for the human immunodeficiency virus (HIV). Group 2 HCWs were more likely to be immune to hepatitis B virus, to agree to HIV testing, and to comply with follow-up. Follow-up rates remained suboptimal, even after high-risk exposures. Non-licensed HCWs were less likely to accept postexposure testing than physicians or nurses in group 2. General and targeted interventions to improve compliance and follow-up are still needed.     

Relationship between the chest radiograph, regional lung function studies, exercise tolerance, and clinical condition in cystic fibrosis

This study evaluated the accuracy of the interpretation of the chest film in delineating localised abnormalities of ventilation and perfusion, as well as the overall severity of airways obstruction, exercise tolerance, and clinical condition in children with cystic fibrosis. Radiographic findings in various regions of the chest film were compared with the functional values obtained with regional lung function tests which evaluated the arrival and disappearance of boluses of radioactive nitrogen given by inhalation and infusion. While the more severely affected areas on the chest radiograph were found to correlate with similar regions on the lung function tests, as did overall scores, errors occurred in some cases if the x-ray film alone was used as a judge of regional physiological derangement. In addition the degree of airways obstruction, the exercise tolerance on a cycle ergometer, and clinical grading, each correlated significantly with the radiographic score. We conclude that the chest radiograph is a good indicator of the overall severity of the lung disease and that it correlates well with exercise tolerance and clinical condition in cystic fibrosis.     

Hepatic scintigraphy in management of infants and children with liver disease

Scintiscans of liver and spleen using technetium 99m sulphur colloid in 15 infants with extrahepatic biliary atresia and 11 infants with severe obstructive jaundice (7 with genetic deficiency of alpha 1-antitrypsin) showed similar hepatic size, pattern of isotope uptake, and splenic abnormality with no distinguishing features. In 37 older children with a variety of liver disorders, the scan was invaluable in showing filling defects in five instances. Selenomethionine was taken up not only by the two filling defects due to hepatoblastoma but also in a haemangioendothelioma. In the remaining patiens liver scanning confirmed hepatic abnormality and the necessity for more specific invasive diagnostic investigations.     

The effect of phenobarbital on asphyxia in the newborn monkey.

This study characterizes the circulatory changes associated with asphyxia in the newborn monkey and examines the effect of phenobarbital on asphyxia. The time to last gasp and duration of total asphyxia as well as heart rate at the start of resuscitation were the same in the phenobarbital-treated and untreated infants. Initial cardiac output was the same in both groups; there was a profound drop in cardiac output with asphyxia which was the same in both groups. Organs which preferentially receive a greater percentage of cardiac output during asphyxia are heart, total brain, and adrenal glands. Organs receiving a decreased percentage of cardiac output during asphyxia are kidneys, liver, and gastrointestinal tract. Cerebral hemisphere flow as a percentage of cardiac output is maintained during asphyxia, whereas paleoencephalon flow as a percentage of cardiac output increases significantly. These data confirm the circulatory redistribution of cardiac output in response to asphyxia described previously in the monkey fetus. The treated infants did not show the prolongation of time to last gasp reported in the monkey fetus; the dose of phenobarbital we used, although adequate to produce sedation, may have been too low to demonstrate the protective effect.     

Consequences of pulmonary inflations (sighs) on cerebral haemodynamics in neonates ventilated by high-frequency oscillation

High-frequency oscillation (HFO) is a technique frequently used in neonatal resuscitation, but which has yet to be evaluated. The use of intrathoracic pressures may have an effect on the cerebral circulation of immature neonates. The aim of this study was to examine the variations in cerebral blood velocity and oxygenation during brief pulmonary inflations (sighs), by focusing on alveolar recruitment. In this prospective study performed in 13 intubated and ventilated neonates (alpha = 5%; 1-beta = 80%), mean blood velocity and Doppler Resistance Index were measured, and variations in chromophores concentrations were evaluated by near infrared spectroscopy. Brief inflations at 4 cm H2O above the mean regulated intra-thoracic pressure did not cause any variation in the parameters measured. An explanation for this discordance with animal studies may be the level of pressure chosen, which could be more appropriate for the pulmonary compliance of neonates.     

The prognostic value of intraepithelial and stromal CD3‐, CD117‐ and CD138‐positive cells in non‐small cell lung carcinoma

Al‐Shibli K, Al‐Saad S, Andersen S, Donnem T, Bremnes RM, Busund L‐T. The prognostic value of intraepithelial and stromal CD3‐, CD117‐ and CD138‐positive cells in non‐small cell lung carcinoma. APMIS 2010; 118: 371–82. The major value of prognostic markers in potentially curable non‐small cell lung carcinoma (NSCLC) should be to guide therapy after surgical treatment. Although tumor‐infiltrating T lymphocytes and plasma cells have been documented in NSCLC, a clear association with clinical outcome, especially for the stromal component, has not been well established. The aim of this study was to elucidate the prognostic significance of these cells/markers in the epithelial and stromal compartments of NSCLC. Tissue microarrays from 335 resected, stage I‐IIIA, NSCLC were constructed by duplicate cores from viable neoplastic epithelial and stromal areas. Immunohistochemistry was used to evaluate the infiltration of CD3⁺, CD117⁺ as well as CD138⁺ cells in epithelial and stromal areas. In univariate analyses, increasing numbers of stromal CD3⁺ (p = 0.001) and epithelial CD3⁺ cells (p = 0.004) correlated significantly with an improved disease‐specific survival. No such relation was noted with CD3⁺ or CD117⁺ cells. In the multivariate analysis, stromal CD3⁺ cells was an independent prognostic factor for disease‐specific survival (HR 1.925, CI 1.21–3.04, p = 0.005). Increased presence of the pan T‐cell marker, CD3, which is an independent factor, correlates with improved clinical outcome in NSCLC. This prognostic impact of T cells is clearer in the tumor stroma. Neither plasma cells nor mast cells were prognostic indicators in our cohort.