Reassessing lead protective garment assessment using ICRP 103 tissue weighting factors

Lead protective garments worn by medical staff in the presence of x-rays develop defects over time. This work proposes a novel method of assessing the protective efficacy of the garments as defects develop. The proposed method applies updated radiobiology data from ICRP 103. 

This work applied the As Low As Reasonably Achievable (ALARA) principle to devise a formula through which a maximum allowed defect area in lead protective garments can be calculated. This formula depends on the cross-sectional areas (A) and ICRP 103 tissue weighting factors (w_t) of the most radiosensitive and overlapping organs protected by the garment, the maximum allowed additional effective dose to the garment wearer due to the defects (d), and the unattenuated absorbed dose at the surface of the garment (D). The maximum allowed defect areas are separated into three regions: above the waist, below the waist, and thyroid. To be conservative, it was assumed that D = 50 mGy yr^-1, and d = 0.3 mSv yr^-1. Also conservatively, transmission was assumed to be 0%, as employing a non-zero transmission factor would increase the maximum allowed defect area. 

Maximum allowed defect areas were as follows: 370 mm²for above the waist, 37 mm²for below the waist, and 279 mm²for the thyroid. These can be compared to commonly published values which are 670 mm²for an apron, 15 mm²over the gonads, and 11-20 mm²for the thyroid.

The proposed method for lead protective garment assessment is highly adaptable as values can be adjusted as radiobiology data are updated, and as values such as radiation dose limits vary across jurisdictions. Future works will include collection of data for unattenuated dose to apron (D) as it varies across professions, so that garments may be allowed different defect areas if relegated to individuals of specific professions.

Time trends of technology mediated communication with friends among bullied and not bullied children in four Nordic countries between 2001 and 2010

BACKGROUND

Friends are important in childhood and adolescence, especially to bullied children. Technology mediated communication (TMC) could be used both to develop and maintain friendship. The present study examined (1) trends in the use of TMC with friends between 2001 and 2010; (2) possible differences between bullied and not bullied children and (3) differences between children with few close friends and children with several close friends.

METHODS

Data were obtained from three waves of the serial cross-sectional Health Behaviour in School-Aged Children survey conducted in Denmark, Finland, Iceland and Sweden during 2001/2002, 2005/2006 and 2009/2010. The total sample consisted of 65 953 children aged 11, 13 and 15.

RESULTS

Two trends were observed. The first trend showed an increased use of TMC in all countries. Children that were not bullied and/or had several close friends had increased their use of TMC with friends from 2001 to 2010. The second trend was applicable only for bullied children with few close friends; they had not as other children increased their use of TMC and thus remained at the same levels as in 2001/2002.

CONCLUSIONS

Bullied children with few close friends were excluded from communication forums that usually allow children to maintain and develop friendships. This is a concern because friends are important during childhood and adolescence, especially for bullied children.

Multicentre prospective study of fascial closure rate after open abdomen with vacuum and mesh-mediated fascial traction

BACKGROUND

Damage control surgery and temporary open abdomen (OA) have been adopted widely, in both trauma and non-trauma situations. Several techniques for temporary abdominal closure have been developed. The main objective of this study was to evaluate the fascial closure rate in patients after vacuum-assisted wound closure and mesh-mediated fascial traction (VAWCM) for long-term OA treatment, and to describe complications.

METHODS

This prospective study included all patients who received VAWCM treatment between 2006 and 2009 at four hospitals. Patients with anticipated OA treatment for fewer than 5 days and those with non-midline incisions were excluded.

RESULTS

Among 151 patients treated with an OA, 111 received VAWCM treatment. Median age was 68 years. Median OA treatment time was 14 days. Main disease aetiologies were vascular (45 patients), visceral surgical disease (57) and trauma (9). The fascial closure rate was 76·6 per cent in intention-to-treat analysis and 89 per cent in per-protocol analysis. Eight patients developed an intestinal fistula, of whom seven had intestinal ischaemia. Intestinal fistula was an independent factor associated with failure of fascial closure (odds ratio (OR) 8·55, 95 per cent confidence interval 1·47 to 49·72; P = 0·017). The in-hospital mortality rate was 29·7 per cent. Age (OR 1·21, 1·02 to 1·43; P = 0·027) and failure of fascial closure (OR 44·50, 1·13 to 1748·52; P = 0·043) were independently associated with in-hospital mortality.

CONCLUSION

The VAWCM method provided a high fascial closure rate after long-term treatment of OA. Technique-related complications were few. No patient was left with a large planned ventral hernia.

Insights into brain microstructure from the T2 distribution

T2 weighting is particularly sensitive, but notoriously unspecific, to a wide range of brain pathologies. However, careful measurement and analysis of the T2 decay curve from brain tissue promise to provide much improved pathological specificity. In vivo T2 measurement requires accurate 180 pulses and appropriate manipulation of stimulated echoes; the most common approach is to acquire multiple echoes from a single slice. The T2 distribution, a plot of component amplitude as a function of T2, can be estimated using an algorithm capable of fitting a multi-exponential T2 decay with no a priori assumptions about the number of exponential components. T2 distributions from normal brain show peaks from myelin water, intra/extracellular water and cerebral spinal fluid; they can be used to provide estimates of total water content (total area under the T2 distribution) and myelin water fraction (MWF, fractional area under the myelin water peak), a measure believed to be related to myelin content. Experiments on bovine brain suggest that magnetization exchange between water pools plays a minor role in the T2 distribution. Different white matter structures have different MWFs. In normal white matter (NWM), MWF is not correlated with the magnetization transfer ratio (MTR) or the diffusion tensor fractional anisotropy (FA); hence it provides unique information about brain microstructure. Normal-appearing white matter (NAWM) in multiple sclerosis (MS) brain possesses a higher water content and lower MWF than controls, consistent with histopathological findings. Multiple sclerosis lesions demonstrate great heterogeneity in MWF, presumably due to varying myelin contents of these focal regions of pathology. Subjects with schizophrenia were found to have significantly reduced MWF in the minor forceps and genu of the corpus callosum when compared to controls, suggesting that reduced frontal lobe myelination plays a role in schizophrenia. In normal controls, frontal lobe myelination was positively correlated with both age and education; this result was not observed in subjects with schizophrenia. A strong correlation between MWF and the optical density from the luxol fast blue histological stain for myelin was observed in formalin-fixed brain, supporting the use of the MWF as an in vivo myelin marker.

Administration mode bias in a school survey on alcohol, tobacco and illicit drug use

School surveys have become the most common method for determining the general level of tobacco, alcohol and illicit drug use among adolescents in a large number of countries. The two most commonly applied field procedures in school surveys are teachers' and researchers' administration of questionnaires. The impact of the difference between these two modes of administration has not been determined, although it has been argued that central involvement of teachers in data collection may decrease the perceived anonymity of the survey among students, and should thus be avoided. In a split-half random sample of 3017 urban, Icelandic 16-20-year-old students, no statistically significant differences were found in reported use of licit or illicit drugs, nor in the stated willingness to be honest between these two modes of administration. These results suggest that when students return their responses in sealed envelopes, the two modes of administration produce equally valid results.

Manifest predictors of past suicide attempts in a population of Icelandic adolescents

Past suicide attempts have been found to be a major risk factor for both repeated attempts and completed suicide. The utility of this is, however, limited by the fact that the majority of all suicide attempts never come to professional attention. This paper explores the possibility of using manifest indicators to predict which individuals in a population of adolescents have attempted suicide. Using logistic regression, manifest predictors in the categories of school, leisure, peer and parent relations, consumption, and contact with suicidal behavior could identify either a quarter of the population containing three quarters of all suicide attempters or 2% of the population where two thirds of those predicted actually had attempted suicide. It is thus concluded that manifest predictors can complement psychiatric screening methods by efficiently reducing the number to be screened.

Barium findings in retrograde intussusception

Four instances of antiperistaltic intussusception are presented. These serve to depict the varied roentgen appearances in both types of intussusception on barium study and emphasize two simple interpretational principles: (1) when contrast material is administered orad to an antegrade or caudad to a retrograde intussusception, it must first enter the intussusceptum; and (2) when barium is administered orad to a retrograde or caudad to an antegrade intussusception, it must first enter the intussuscipiens. Attention is also directed to tube related intussusceptions and to potential difficulty in their identification.