Comparison of dosimetry calibration factors at the NRCC and the NIST. National Research Council of Canada. National Institute of Standards and Technology

In early 1998, three transfer ionization chambers were used to compare the air-kerma and absorbed-dose-to-water calibration factors measured by the National Research Council of Canada (NRCC) and the National Institute of Standards and Technology (NIST). The ratios between the NRCC and NIST calibration factors are 0.9950 and 1.0061 in the case of the absorbed-dose-to-water and air-kerma standards, respectively. In the case of the standard of absorbed dose to water, the combined uncertainty of the ratio between the standards of the two laboratories is about 0.6% and consequently, the observed difference of 0.5% is not significant at the one sigma level. In the case of the standard of air kerma, the combined uncertainty of the ratio between the standards of the two laboratories is about 0.4%, and so the observed difference of 0.61% is significant at the one sigma level. However, this discrepancy is due to the known differences in the methods of assessing the wall correction factor at the two laboratories. Taking into account changes implemented in the standards that form the basis of the calibrations, the present results are consistent with those of the previous comparison done in 1990/91. As a direct result of these differences in the calibration factors, changing from an air-kerma based protocol following TG-21 to an absorbed-dose-to-water based protocol following TG-51, would alter the relationship between clinical dosimetry in Canada and the United States by about 1%. For clinical reference dosimetry, the change from TG-21 to TG-51 could result in an increase of up to 2% depending upon the ion chamber used, the details of the protocol followed and the source of traceability, either NRCC or NIST.     

Bone mineral density as a marker of cumulative endogenous estrogen exposure: Relationship to background genetic risk of psychotic disorder

BackgroundAlterations in bone mineral density (BMD) in patients with psychotic disorder may reflect the effect of treatment (disease effect observed in patients but not their siblings) or, as an intermediate marker of cumulative endogenous estrogen exposure, alterations in the neuroprotective effect of estrogen in the brain (vulnerability effect observed in patients and siblings).MethodsDual X-ray absorptiometry (DEXA) scans were acquired in 62 patients with a psychotic disorder, 67 non-psychotic siblings of patients with a psychotic disorder, and 48 controls. BMD (g/cm²), Z-scores and T-scores were measured in the lumbar spine and proximal femur. Associations between group and BMD were investigated with multilevel random regression analyses. Group × sex interactions and effects of antipsychotic medication (AP) on BMD were examined.ResultsGroup was not associated with BMD outcome measures, although patients had consistently lower BMD measures compared to both siblings and controls. There were no significant group × sex interactions, but stratified analyses showed that BMD measures in female patients were significantly lower in comparison to female controls and siblings (e.g. total femoral BMD, P vs. C: B = ? 0.100, p = 0.010; P vs. S: B = ? 0.104, p = 0.008). After excluding female patients who used prolactin-raising AP, the effect was attenuated (e.g. total femoral BMD, P vs. C: B = ? 0.073, p = 0.072; P vs. S: B = ? 0.085, p = 0.051). In men, there were no significant BMD differences between patients and controls.ConclusionFamilial risk of psychotic disorder was not associated with BMD. Instead, decreased BMD in the femur may reflect treatment effects or non-familial risk associated with low cumulative endogenous estrogen levels in women.     

Severe Autoimmune Hemolytic Anemia Associated with IgM Warm Autoantibodies Directed against Determinants on or Associated with Glycophorin A

Background and objectives: Autoimmune hemolytic anemia (AIHA) is rarely caused by IgM warm autoantibodies, and is sometimes difficult to diagnose. We describe three patients with severe AIHA caused by IgM warm autoantibodies; in two of the three, the hemolysis was fatal. Materials and methods: Conventional hematologic and serologic procedures were used. Results: The IgM autoantibodies in all three cases were directed against determinants on or associated with glycophorin A (En^a, Wr^b, and Pr). The IgM autoantibodies had unusual serological characteristics, in that the agglutinins were detected or greatly enhanced only by the presence of albumin or a low pH, and/or the agglutinins reacted optimally at 20–30°C. Conclusions: IgM warm autoantibodies directed at determinants on or associated with glycophorin A appear to cause severe (often fatal) hemolytic anemia.     

Practical guide for pediatric pulmonologists on imaging management of pediatric patients with COVID‐19

Understanding of coronavirus disease 2019 is rapidly evolving with new articles on the subject daily. This flood of articles can be overwhelming for busy practicing clinicians looking for key pieces of information that can be applied in daily practice. This review article synthesizes the reported imaging findings in pediatric Coronavirus disease 2019 (COVID‐19) across the literature, offers imaging differential diagnostic considerations and useful radiographic features to help differentiate these entities from COVID‐19, and provides recommendations for requesting imaging studies to evaluate suspected cases of pediatric COVID‐19.     

A new evaluation method for upper extremity dexterity of patients with hemiparesis after stroke: the 10-second tests

We developed a new, sensitive evaluation method for upper extremity dexterity in patients with hemiparesis after stroke. This evaluation method consists of three types of test: the Finger Individual Movement Test, Hand Pronation and Supination Test, and Finger Tapping Test. In each test, the number of movements that can be performed during a 10-s period is measured. Data obtained by these 10-s tests were compared with those obtained by the Nine-Hole Peg Test (NHPT), and the usefulness of this new method was evaluated. In patients with hemiparesis after stroke, three types of 10-s test and NHPT were performed for the upper extremities on both the affected and unaffected sides. Simple correlation analysis and multiple regression analysis of data obtained by the three types of test and NHPT were performed using the affected/unaffected ratios. Twenty patients participated (54-85 years; 0.23-43.83 months after stroke) with mild upper extremity hemiparesis. Significant correlations exist between Finger Individual Movement Test and NHPT data (r=-0.584, P=0.0068) and between Hand Pronation and Supination Test and NHPT data (r=-0.707, P=0.0005). The multiple regression analysis model using the three types of 10-s test as explanatory variables was significant (P=0.0025) and explained 52.4% of the NHPT results. A significant association was observed between NHPT and the 10-s tests. The 10-s tests require no special examination instruments and can be readily performed in a short period. This evaluation method consisting of the 10-s tests can be a new clinical parameter of dexterity in patients with hemiparesis after stroke.