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This paper describes modelling, application and validation of a filtration technique for a linear slot-scanning digital X-ray system to reduce radiation dose to paediatric patients while preserving diagnostic image quality. A dose prediction model was implemented, which calculates patient entrance doses using variable input parameters. Effective dose is calculated using a Monte Carlo simulation. An added filter of 1.8-mm aluminium was predicted to lower the radiation dose significantly. An objective image quality study was conducted using detective quantum efficiency (DQE). The PTW Normi 4FLU test phantom was used for quantitative assessment, showing that image contrast and spatial resolution were maintained with the proposed filter. A paediatric cadaver full-body imaging trial assessed the diagnostic quality of the images and measured the dose reduction using a 1.8-mm aluminium filter. Assessment by radiologists indicated that diagnostic quality was maintained with the added filtration, despite a reduction in DQE. A new filtration technique for full-body paediatric scanning on the Lodox Statscan has been validated, reducing entrance dose for paediatric patients by 36 % on average and effective dose by 27 % on average, while maintaining image quality.

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This paper examines the effect that a 1.8 mm aluminium filter has on paediatric patient dose and image quality for linear slot scanning radiography (LSSR). A dynamic dose prediction model for LSSR accurately predicted the dose reduction effects of added aluminium filtration. A cadaver imaging study was carried out to assess the effects of filtration on image quality. With 1.8 mm added aluminium filtration, no visible degradation to image contrast or clarity was found, and in some cases the aluminium filtration improved the image quality as judged by radiologists.

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SETTING: Paradoxical tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) is an important complication in human immunodeficiency virus type I (HIV-1) infected tuberculosis (TB) patients who start combination antiretroviral treatment (ART). Neurological manifestations occur in more than 10% of TB-IRIS cases. Apart from a few case reports, the radiological features of neurological TB-IRIS have not been described. OBJECTIVE: To describe the neuroradiological findings of patients with paradoxical neurological TB-IRIS. DESIGN: Computed tomography (CT; n = 13) and magnetic resonance imaging (n = 3) findings of 16 patients were reviewed. RESULTS: IRIS manifestations included meningitis (n = 4), intracranial space occupying lesions (SOLs, presumed tuberculomas; n = 5), meningitis and SOLs (n = 5), radiculomyelitis (n = 1) and spondylitis (n = 1). In patients with tuberculoma IRIS, we observed a high prevalence of 1) low density lesions on non-contrast-enhanced CT (all lesions), 2) multiple lesions (in 5/10 patients) and 3) perilesional oedema (17/22 lesions). In patients with meningitis, meningeal enhancement (n = 2) and hydrocephalus (n = 1) were infrequently observed. CONCLUSION: This is the first substantial series to describe the radiological features of paradoxical neurological TB-IRIS. Compared to published radiological findings of tuberculomas in HIV-1-infected patients (not receiving ART), an increased inflammatory response is suggested in tuberculoma IRIS. However, this was not observed in patients with TB meningitis IRIS.

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STUDY OBJECTIVE: The effect of ouabain on regional myocardial mechanics and corresponding regional myocardial oxygen consumption was investigated. DESIGN: Regional myocardial segment length (ultrasonic dimension crystals) and force development (miniature strain gauge) were measured. The integrated multiples of myocardial shortening by corresponding force during an averaged beat was used to express regional segment work (= area under the systolic portion of the length-force loop). External cardiac work was calculated from aortic blood pressure and cardiac output. Global and regional myocardial O2 consumption (MVO2) were evaluated at baseline and during intravenous infusion of ouabain (7 micrograms.kg-1.min-1). Regional coronary blood flow was measured with radioactive microspheres, and microspectrophotometry of frozen myocardial biopsies was used to evaluate O2 saturation in small arteries and veins. These variables were used to calculate regional myocardial MVO2. Arterial and coronary sinus O2 saturation was used to calculate global left ventricular O2 consumption. Myocardial efficiency was expressed as regional work/regional myocardial MVO2. SUBJECTS: Ten open chest anaesthetised dogs, weight about 20 kg, were used. MEASUREMENTS AND MAIN RESULTS: Ouabain increased regional myocardial segment work [from 5291(SEM 1067) to 8916(2338) mm.g-1.min-1] to a greater extent than regional myocardial MVO2 [from 6.33(0.75) to 8.54(0.75) ml O2.min-1.100 g-1]. Regional efficiency was increased from 734(78) to 1036(160) g.mm.ml O2(-1).100 g-1. External efficiency was not raised. Percent shortening was increased to a greater extent than peak force development (+76% v + 38%), possibly indicating increased myocardial compliance. The length-force loop was shifted upward and to the right. CONCLUSIONS: Ouabain increases regional efficiency of myocardial contraction.

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The concentration of radioactivity excreted in breast milk following the administration of gallium 67 to 3 patients was measured in milk samples obtained for several days after injection. Similar values were obtained from all 3 patients, with milk samples obtained approximately 120 h after administration containing 4.3-5.7 Bq/ml per MBq of 67Ga administered. These values are lower than those previously reported. The image of a child who had inadvertently been breast-fed for 48 h after administration of 67Ga to the mother showed activity in the intestines only. Our results seem to confirm recommendations by other authors that gallium scintigraphy should be avoided in nursing mothers. Should the administration of 67Ga be inevitable, breastfeeding should be discontinued, since interruption periods of approximately 2 weeks may be required to reduce the effective dose equivalent to the infant below 1 mSv. However, close contact between mother and child need not be avoided.

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