Transition in occupational radiation exposure monitoring methods in diagnostic and interventional radiology

Radiation exposure monitoring is a traditional keystone of occupational radiation safety measures in medical imaging. The aim of this study was to review the data on occupational exposures in a large central university hospital radiology organisation and propose changes in the radiation worker categories and methods of exposure monitoring. An additional objective was to evaluate the development of electronic personal dosimeters and their potential in the digitised radiology environment. The personal equivalent dose of 267 radiation workers (116 radiologists and 151 radiographers) was monitored using personal dosimeters during the years 2006-2010. Accumulated exposure monitoring results exceeding the registration threshold were observed in the personal dosimeters of 73 workers (59 radiologists' doses ranged from 0.1 to 45.1 mSv; 14 radiographers' doses ranged from 0.1 to 1.3 mSv). The accumulated personal equivalent doses are generally very small, only a few angiography radiologists have doses >10 mSv per 5 y. The typical effective doses are <10 μSv y(-1) and the highest value was 0.3 mSv (single interventional radiologist). A revised categorisation of radiation workers based on the working profile of the radiologist and observed accumulated doses is justified. Occupational monitoring can be implemented mostly with group dosimeters. An active real-time dosimetry system is warranted to support radiation protection strategy where optimisation aspects, including improving working methods, are essential.     

Investigation of the Pentathiepin Functionality as an Inhibitor of Feline Immunodeficiency Virus (FIV) via a Potential Zinc Ejection Mechanism,as a Model for HIV Infection

A small diverse library of pentathiepin derivatives were prepared to evaluate their efficacy against the nucleocapsid protein function of the feline immunodeficiency virus (FIV) as a model for HIV, using an in vitro cell culture approach. This study led to the development of nanomolar active compounds with low toxicity.     

Personal radiation doses in PET/CT facility: measurements vs. calculations

The estimation of shielding requirement of a new positron emission tomography (PET) facility is essential. Because of penetrating annihilation photons, not only radiation safety in the vicinity of patients should be considered, but also rooms adjacent to uptake and imaging rooms should be taken into account. Before installing a PET/CT camera to nuclear medicine facilities of Helsinki University Central Hospital (HUCH), a typical PET imaging day was simulated using phantoms. Phantoms were filled with 300 +/- 36 MBq of (18)F isotope and dose rates were measured at 12 central locations in the laboratory. In addition to measurements, dose rates were also calculated using guidelines of AAPM Task Group 108. The relationship between the measured and calculated dose rates was found to be good and statistically significant, using Pearson's correlation test. The evaluated monthly doses were compared with personal dosemeter readings. AAPM's report gives practical tools for evaluation of radiation shielding. Calculations can be carried out successfully for existing hospital complexes too. However, calculations should be carried out carefully, because especially doors, windows and partitions can easily cause underestimation of shielding requirements as shown in this work.     

Examination of factors determining fault in two-vehicle motorcycle crashes

Motorcycle crashes frequently involve a combination of high-risk behaviors by the motorcyclist or the other crash-involved driver. Such behaviors may include riding or driving without appropriate licensure or while under the influence of alcohol, as well as deciding not to use a safety device such as a helmet or safety belt. Given that these factors frequently occur in combination with one another, it is difficult to untangle the specific effects of individual factors leading up to the crash outcome. This study assesses how various rider-, driver-, and other crash-specific factors contribute to at-fault status in two-vehicle motorcycle crashes, as well as how these same factors affect the propensity for other high-risk behaviors. Furthermore, the interrelationships among fault status and these other behaviors are also examined using a multivariate probit model. This model is developed using police-reported crash data for the years 2006–2010 from the State of Ohio. The results show that younger motorcyclists are more likely to be at-fault in the event of a collision, as are riders who are under the influence of alcohol, riding without insurance, or not wearing a helmet. Similarly, motorcyclists were less likely to be at-fault when the other driver was of younger age or was driving under the influence of alcohol, without insurance, or not wearing their safety belt. Crash-involved parties who engaged in one high-risk behavior were more likely to engage in other such behaviors, as well, and this finding was consistent for both motorcyclists and drivers. The results of this study suggest that educational and enforcement strategies aimed at addressing any one of these behaviors are likely to have tangential impacts on the other behaviors, as well.     

Traumatic inferior vena caval injuries

Twenty-three cases of inferior vena caval injury (1.4% of all operatively managed abdominal injuries) are reviewed. The caval injury presented as free haemorrhage in 15 cases and as a retroperitoneal haematoma in eight. The site of vena caval injury was at or above the level of the renal veins in 14 cases (61%). Successful lateral suture repair was achieved in 18 cases (78%). The overall mortality rate was 39%. Factors positively associated with survival were stab wound, presentation as retroperitoneal haematoma, infrarenal injury, low Abdominal Trauma Index score and small peroperative blood loss. Concomitant injury to the abdominal aorta, liver or kidney worsened the prognosis. The crucial factor in management of inferior vena caval injuries is rapid and effective control of bleeding, whether from the caval or associated injuries.     

Integral equation formulation for scatter density problem

Integral equation formulation for the problem of finding a circularly symmetric scatter density (SD) around the mobile is deduced, and the SD is computed assuming that the distribution of angle-of-arrival (AoA) in the base station is known. The corresponding integral equation is solved by using the spline collocation method. Thus, instead of fitting a priori selected SD to estimated AoA distribution, the SD is solved based on AoA characteristics.     

Fast direct solution of the Helmholtz equation with a perfectly matched layer or an absorbing boundary condition

We consider the efficient numerical solution of the Helmholtz equation in a rectangular domain with a perfectly matched layer (PML) or an absorbing boundary condition (ABC). Standard bilinear (trilinear) finite‐element discretization on an orthogonal mesh leads to a separable system of linear equations for which we describe a cyclic reduction‐type fast direct solver. We present numerical studies to estimate the reflection of waves caused by an absorbing boundary and a PML, and we optimize certain parameters of the layer to minimize the reflection. Copyright © 2003 John Wiley & Sons, Ltd.     

Left ventricular function in children with the Marfan syndrome

Aortic dilatation and heart valve lesions are common in the Marfan syndrome but whether primary alterations occur in left ventricular (LV) function has not been studied hitherto. LV size, mass and systolic as well as diastolic function were studied by M-mode and Doppler echocardiography and cine magnetic resonance imaging in 22 Marfan children aged 3.0-15.4 years and in 22 age-matched healthy children. No child had significant valve disease. Heart rate and systolic blood pressure were comparable in the groups but diastolic blood pressure was higher in the controls (67 +/- 7 mmHg vs 62 +/- 8 mmHg, P = 0.030). No statistically significant differences were found in LV size, mass or systolic function. The Marfan children had slower LV peak diameter lengthening rates (106 +/- 27 mm.s-1 vs 132 +/- 29 mm.s-1, P = 0.004), prolonged relaxation times (155 +/- 22 ms vs 140 +/- 19 ms, P = 0.023), slower deceleration of the early transmitral velocity (580 +/- 144 cm.s-1 vs 720 +/- 160 cm.s-2, P = 0.006), and smaller early-to-late peak velocity ratios (1.99 +/- 0.40 vs 2.29 +/- 0.46, P = 0.031). These data indicate that LV early diastolic function (relaxation) is impaired in the Marfan syndrome. Weakened elastic recoil due to the underlying connective tissue abnormality may best explain this novel observation.