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The worldwide average exposure to cosmic rays contributes to about 16% of the annual effective dose from natural radiation sources. At ground level, doses from cosmic ray exposure depend strongly on altitude, and weakly on geographical location and solar activity. With the analytical model PARMA developed by the Japan Atomic Energy Agency, annual effective doses due to cosmic ray exposure at ground level were calculated for more than 1,500 communities across Canada which cover more than 85% of the Canadian population. The annual effective doses from cosmic ray exposure in the year 2000 during solar maximum ranged from 0.27 to 0.72 mSv with the population-weighted national average of 0.30 mSv. For the year 2006 during solar minimum, the doses varied between 0.30 and 0.84 mSv, and the population-weighted national average was 0.33 mSv. Averaged over solar activity, the Canadian population-weighted average annual effective dose due to cosmic ray exposure at ground level is estimated to be 0.31 mSv.

New reconstruction algorithms allow reduction in acquisition times or the amount of injected radioactivity. We examined the impact of different corrections on low-count clinical SPECT myocardial perfusion images (MPI) and compared to ^sup 82^Rb PET/CT. We compared no corrections (NC) to attenuation correction (AC) with and without scatter correction by either a dual-energy-window (AC-DEW) or model-based (AC-ESSE) approach. All reconstructions included resolution recovery. 56 Patients were imaged using a standard rest/stress Tc-99m-tetrofosmin MPI SPECT/CT protocol with an additional half-time acquisition. A ^sup 82^Rb-rest/stress PET/CT MPI was acquired within 4 weeks. Reconstruction methods were compared using summed rest/stress/difference scores from an objective algorithm (SRS/SSS/SDS). The SRS and SSS for NC were significantly (P < .01) higher than for AC, but well correlated (r >= 0.87). The correlation in SRS/SSS among AC, AC-DEW, and AC-ESSE was excellent (r >= 0.98). AC-ESSE and AC-DEW had higher SRS (P <= .05) than AC, but the SDS values were not significantly different. Concordance with PET normal/abnormal classification was 76% for NC and >=85% for the AC methods. AC significantly improves the accuracy of low-count myocardial perfusion SPECT half-time imaging for the detection of disease compared to NC. Compared to PET, there was no significant difference among AC, AC-DEW, and AC-ESSE.[PUBLICATION ABSTRACT]

New reconstruction algorithms allow reduction in acquisition times or the amount of injected radioactivity. We examined the impact of different corrections on low-count clinical SPECT myocardial perfusion images (MPI) and compared to 82Rb PET/CT. We compared no corrections (NC) to attenuation correction (AC) with and without scatter correction by either a dual-energy-window (AC-DEW) or model-based (AC-ESSE) approach. All reconstructions included resolution recovery. 56 Patients were imaged using a standard rest/stress Tc-99m-tetrofosmin MPI SPECT/CT protocol with an additional half-time acquisition. A 82Rb-rest/stress PET/CT MPI was acquired within 4 weeks. Reconstruction methods were compared using summed rest/stress/difference scores from an objective algorithm (SRS/SSS/SDS). The SRS and SSS for NC were significantly (P < .01) higher than for AC, but well correlated (r ≥ 0.87). The correlation in SRS/SSS among AC, AC-DEW, and AC-ESSE was excellent (r ≥ 0.98). AC-ESSE and AC-DEW had higher SRS (P ≤ .05) than AC, but the SDS values were not significantly different. Concordance with PET normal/abnormal classification was 76% for NC and ≥85% for the AC methods. AC significantly improves the accuracy of low-count myocardial perfusion SPECT half-time imaging for the detection of disease compared to NC. Compared to PET, there was no significant difference among AC, AC-DEW, and AC-ESSE.

Radon decays to a long-lived isotope ²¹⁰Pb with a half-life of about 22 years. Measuring concentrations of ²¹⁰Pb in household dust could be an alternative method of determining indoor radon levels. This novel method for estimating long-term radon concentration was explored in over a hundred Canadian residential homes. The results demonstrate that ²¹⁰Pb concentrations in household dust relate reasonably well to radon concentrations in homes.

Radon decays to a long-lived isotope super(210)Pb with a half-life of about 22years. Measuring concentrations of super(210)Pb in household dust could be an alternative method of determining indoor radon levels. This novel method for estimating long-term radon concentration was explored in over a hundred Canadian residential homes. The results demonstrate that super(210)Pb concentrations in household dust relate reasonably well to radon concentrations in homes.

Radon decays to a long-lived isotope 210 Pb with a half-life of about 22 years. Measuring concentrations of 210 Pb in household dust could be an alternative method of determining indoor radon levels. This novel method for estimating long-term radon concentration was explored in over a hundred Canadian residential homes. The results demonstrate that 210 Pb concentrations in household dust relate reasonably well to radon concentrations in homes.

Clerkship education has been called a ‘black box’ because so little is known about what, how, and under which conditions students learn. Our aim was to develop a blueprint for education in ambulatory and inpatient settings, and in single encounters, traditional rotations, or longitudinal experiences. We identified 548 causal links between conditions, processes, and outcomes of clerkship education in 168 empirical papers published over 7 years and synthesised a theory of how students learn. They do so when they are given affective, pedagogic, and organisational support. Affective support comes from doctors’ and many other health workers’ interactions with students. Pedagogic support comes from informal interactions and modelling as well as doctors’ teaching, supervision, and precepting. Organisational support comes from every tier of a curriculum. Core learning processes of observing, rehearsing, and contributing to authentic clinical activities take place within triadic relationships between students, patients, and practitioners. The phrase ‘supported participation in practice’ best describes the educational process. Much of the learning that results is too tacit, complex, contextualised, and individual to be defined as a set of competencies. We conclude that clerkship education takes place within relationships between students, patients, and doctors, supported by informal, individual, contextualised, and affective elements of the learned curriculum, alongside formal, standardised elements of the taught and assessed curriculum. This research provides a blueprint for designing and evaluating clerkship curricula as well as helping patients, students, and practitioners collaborate in educating tomorrow’s doctors.

There is high risk of suicidality in bipolar disorder (BD), particularly in early onset cases. The literature regarding correlates and putative predictors of suicide attempts (SA), non-suicidal self-injury (NSSI) and suicidal ideation (SI) among youth with BD remains sparse. Participants included 197 adolescents with BD, divided into 4 groups: SA (with or without NSSI), NSSI (with or without SI), SI only, and comparison group (CG; no SA/NSSI/SI). Diagnoses, treatment, and suicidality measures were determined via semi-structured interviews, conducted between 2009 and 2017. Univariate analyses were followed by multinomial regression. Overall, 73.6% of participants had history of SA, NSSI, and/or SI. In comparison to CG, SA and NSSI were each associated with BD-II/-NOS (odds ratio [OR] = 15.99, p = 0.002; OR = 16.76, p = 0.003), female sex (OR = 6.89, p = 0.006; OR = 3.76, p = 0.02), and emotion dysregulation (OR = 1.10, p < 0.001; OR = 1.07, p = 0.004). NSSI and SI were each associated with most severe lifetime depression (OR = 1.10, p = 0.01; OR = 1.10, p = 0.01). SA and SI were associated with psychiatric hospitalization (OR = 19.45, p = 0.001; OR = 6.09, p = 0.03). SA was associated with poorer global functioning at most severe episode (OR = 0.88, p = 0.008). NSSI was associated with not living with both natural parents (OR = 0.22, p = 0.009). Study limitations include cross-sectional and retrospective design, stringent cut-offs for SA and NSSI, and recruitment from a tertiary clinical setting. Three quarters of adolescents with BD have had suicidality and/or self-injury. SA and NSSI were most similar to one another, and most different from CG, supporting the broader construct of self-harm. Future research should address the gap in knowledge regarding how sex differences and neurobiology are associated with the observed clinical differences.

This study examined feasibility and efficacy of curriculum infusion of mindful yoga to foster self-regulation in support of academic performance and health promotion among emerging adolescents. Mindful yoga practices were integrated into 6th grade English Language Arts curricula ( n  = 72 students) while another cohort of students (n = 70) served as the active control group. To assess the impact of infused mindful yoga practices, self-regulation was measured using the Adolescent Self-Regulatory Inventory. Data were collected at three time-points across the year. Students who engaged in mindful yoga demonstrated significant increases in both global and long-term self-regulation compared to the control cohort; however there were no significant changes in short-term self-regulation. Implications for integrating mindful practices into middle school curriculum are discussed with recommendations for future research.