A brief peek at the cyclotron in our microscope

The influence of low energy bremsstrahlung emission on the performance of electron spectrometers and monochromators is investigated. Despite the occurrence of multi-photon events, the effect of the main azimuthal (organ pipe) mode is likely to be negligible. Potentially more serious is a new radial mode not considered in the classical theory but revealed in the quantum mechanics picture. The progress of the finely focused wave at the spectrometer entrance slit is described by a coherent wave packet of many oscillator states. It is shielded from disruption by a relatively much longer half-life. Cavity effects causing additional suppression of bremsstrahlung emission are briefly discussed.

Risk and Quality in Brachytherapy From a Technical Perspective

AIMS

To provide an overview of the history of incidents in brachytherapy and to describe the pillars in place to ensure that medical physicists deliver high-quality brachytherapy.

MATERIALS AND METHODS

A review of the literature was carried out to identify reported incidents in brachytherapy, together with an evaluation of the structures and processes in place to ensure that medical physicists deliver high-quality brachytherapy. In particular, the role of education and training, the use of process and technical quality assurance and the role of international guidelines are discussed.

RESULTS

There are many human factors in brachytherapy procedures that introduce additional risks into the process. Most of the reported incidents in the literature are related to human factors. Brachytherapy-related education and training initiatives are in place at the societal and departmental level for medical physicists. Additionally, medical physicists have developed process and technical quality assurance procedures, together with international guidelines and protocols. Education and training initiatives, together with quality assurance procedures and international guidelines may reduce the risk of human factors in brachytherapy.

CONCLUSION

Through application of the three pillars (education and training; process control and technical quality assurance; international guidelines), medical physicists will continue to minimise risk and deliver high-quality brachytherapy treatments.

Ironbark: Developing a healthy community program for older Aboriginal people

ISSUE ADDRESSED

Programs by, with and for Aboriginal older people must be culturally safe and relevant. Successful elements include being Aboriginal specific and group based. Co-design with Aboriginal people and stakeholders is essential. We describe the co-design process of developing the Ironbark: Healthy Community program.

METHODS

Aboriginal ways of knowing, being and doing and yarning conversational methods guided the development process, during 2018. A desktop review provided details of current group characteristics and key community stakeholders. Stakeholder engagement regarding views about group operations, participants and benefits also occurred. Aboriginal Elders views of their groups were gathered through yarning circles in New South Wales (NSW). Grounded theory approach was used to ascertain key themes.

RESULTS

Initial engagement occurred with 13 different community stakeholders and organisations in three Australian states (NSW, South Australia (SA), Western Australia (WA)). Three yarning circles occurred with Elders from urban (N = 10), regional coastal (N = 10) and regional country (N = 4) groups. Six key themes were organised in three groups according to an Aboriginal ontology. 1. Knowing: groups provide opportunities to share knowledge and connect socially. Adequate program resourcing and sustainability are valued. 2. Being: groups strengthen culture, providing important social, emotional and other forms of support to age well. 3. Doing: previous program experiences inform perceptions for new program operations. Group venues and operational aspects should be culturally safe, acknowledging diversity among Elders, their preferences and community control. Themes were used to develop the program and its resource manual that were finalised with stakeholders, including steering committee approval.

CONCLUSIONS

Stakeholder feedback at multiple stages and Aboriginal Elders' perspectives resulted in a new co-designed community program involving weekly yarning circles and social activities. So what?: Co-design, guided by Aboriginal ways of knowing, being and doing, can develop programs relevant for Aboriginal people.

Experiences and perceptions of ageing among older First Nations Australians: A rapid review

OBJECTIVE

To identify and describe articles reporting the experiences and perceptions of ageing among older First Nations Australians.

METHODS

Following rapid review and PRISMA guidelines, we searched five databases for peer-reviewed articles published prior to October 2019 that reported qualitative accounts of ageing among older (≥ 45 years) First Nations Australians. Data were extracted and synthesised thematically.

RESULTS

Twenty-one articles were included in the final synthesis. Priorities in ageing highlighted the role of Elders, family, community, culture and connection to ancestral lands. Experiences and perceptions of ageing reflected cultural marginalisation in aged and health care services, and highlighted the importance of cultural identity, resilience and survival as key to ageing well.

CONCLUSIONS

Our review suggests that mainstream ageing frameworks do not fully reflect the priorities of older First Nations Australians. This has important implications for ageing policy and the design and delivery of culturally safe aged and health care services.

Frailty in Indigenous Populations: A Scoping Review

Background: Indigenous populations experience high rates of age-related illness when compared to their non-Indigenous counterparts. Frailty is a challenging expression of aging and an important public health priority. The purpose of this review was to map what the existing literature reports around frailty in Indigenous populations and to highlight the current gaps in frailty research within the Indigenous landscape.

Method: Scoping review of English language original research articles focusing on frailty within Indigenous adult populations in settler colonial countries (Australia, Canada, New Zealand and USA). Ten electronic databases and eight relevant institutional websites were searched from inception to October 2020.

Results: Nine articles met our inclusion criteria, finding this population having a higher prevalence of frailty and frailty occurring at younger ages when compared to their non-Indigenous counterparts, but two did not use a formal frailty tool. Females presented with higher levels of frailty. No culturally specific frailty tool was identified, and the included articles did not assess strategies or interventions to manage or prevent frailty in Indigenous peoples.

Conclusions: There was little definitive evidence of the true frailty prevalence, approaches to frailty screening and of potential points of intervention to manage or prevent the onset of frailty. Improvements in the quality of evidence are urgently needed, along with further research to determine the factors contributing to higher rates of frailty within Indigenous populations. Incorporation of Indigenous views of frailty, and instruments and programs that are led and designed by Indigenous communities, are crucial to address this public health priority.

Optimising the Care and Management of Older Offenders: A Scoping Review

BACKGROUND AND OBJECTIVES

The rapid increase in the number of older offenders in many countries presents unique challenges to both correctional and health care systems. In the absence of strong empirical evidence on effective interventions, identifying best practices can help optimise the care and management of this segment of the prisoner population.

RESEARCH DESIGN AND METHODS

We conducted a scoping review of care models, prison programs and different interventions designed to improve the care and management of older offenders. We searched five bibliographic databases and other data sources including OpenGrey, agency documents and government reports published until December 2020. This review employed commonly used steps for conducting a scoping review and applied additional tools to enhance the methodology.

RESULTS

After title and abstract screening and full-text review, a total of 34 studies were included in the analysis. Four themes emerged from the review: 1) institutional logics, 2) adaptations, 3) multidisciplinary teams, and 4) person-centred care and management.

DISCUSSION AND IMPLICATIONS

Best practices identified in this review can help optimise the care and management of older offenders in mainstream prisons. Further action research is recommended to adapt and scale-up the interventions.

Understanding implementation factors and participant experiences of a cluster randomised controlled trial to prevent falls among older Aboriginal people: a process evaluation protocol

INTRODUCTION

Process evaluations examining programme implementation are often conducted in conjunction with effectiveness studies. Their inclusion in studies with Aboriginal participants can give an understanding of programme delivery in Aboriginal community contexts. The Ironbark: Standing Strong and Tall programme was codesigned with Aboriginal communities and includes exercise and facilitated 'yarning' discussion about fall risk and prevention strategies. The programme pilot showed favourable outcomes and acceptability for Aboriginal people aged 45 years and over. The Ironbark: Standing Strong and Tall programme is now being compared with a 'Healthy Community' programme in a cluster randomised controlled trial within Aboriginal health and community services. An embedded process evaluation aims to explore relationships between participation and programme outcomes and the quality of programme implementation.

METHODS AND ANALYSIS

The process evaluation will use a mixed methods design, guided by Indigenous research methodology. It will evaluate quantitative data (number of completed sessions, site coaching checklist tool, participant and facilitator questionnaire data and a participant habit formation scale), as well as qualitative data (open-ended responses from project and site staff and semistructured interviews using yarning with study participants and site managers). A programme logic model was developed to explain the intended inputs, activities, outputs and outcomes, which guided this process evaluation design.

CONCLUSION

This process evaluation of a fall prevention programme for older Aboriginal people using a mixed methods design and data triangulation will allow for a comprehensive understanding of study findings. Multiple study sites allow for generalisability of findings and exploration of variation across sites.

TRIAL REGISTRATION NUMBER

ACTRN12619000349145.

The safety of paediatric surgery between COVID-19 surges: an observational study

Despite the ongoing coronavirus disease 2019 (COVID‐19) pandemic, elective paediatric surgery must continue safely through the first, second and subsequent waves of disease. This study presents outcome data from a children's hospital in north‐west England, the region with the highest prevalence of COVID‐19 in England. Children and young people undergoing elective surgery isolated within their household for 14 days, then presented for real‐time reverse transcriptase polymerase chain reaction testing for severe acute respiratory syndrome coronavirus disease‐2 (SARS‐CoV‐2) within 72 h of their procedure (or rapid testing within 24 h in high‐risk cases), and completed a screening questionnaire on admission. Planned surgery resumed on 26 May 2020; in the four subsequent weeks, there were 197 patients for emergency and 501 for elective procedures. A total of 488 out of 501 (97.4%) elective admissions proceeded, representing a 2.6% COVID‐19‐related cancellation rate. There was no difference in the incidence of SARS‐CoV‐2 among children and young people who had or had not isolated for 14 days (p > 0.99). One out of 685 (0.1%) children who had surgery re‐presented to the hospital with symptoms potentially consistent with SARS‐CoV‐2 within 14 days of surgery. Outcomes were similar to those in the same time period in 2019 for length of stay (p = 1.0); unplanned critical care admissions (p = 0.59); and 14‐day hospital re‐admission (p = 0.17). However, the current cohort were younger (p = 0.037); of increased complexity (p < 0.001) and underwent more complex surgery (p < 0.001). The combined use of household self‐isolation, testing and screening questionnaires has allowed the re‐initiation of elective paediatric surgery at high volume while maintaining pre‐COVID‐19 outcomes in children and young people undergoing surgery. This may provide a model for addressing the ongoing challenges posed by COVID‐19, as well as future pandemics.

New instrumentation and cutting edge research

Stimulated by Ondrej Krivanek's contributions, the complex interaction between research and innovations in the instrumentation for electron microscopy is discussed. Specific attention is given to aberration correction and to spectroscopy in both the valence region and at the energies of localised phonons or bond vibrations. Current thinking about projection imaging and dielectric excitation theory may be challenged. More significantly in the new fields of investigation opened up to them, electron microscopists will need to build closer relations, particularly with the photonics and scanning tunnelling microscopy communities. Further improvements in instrumentation could usefully be directed towards imaging and spectroscopy at higher scattering angles as well as the incorporation of other facilities such as photon stimulation and secondary electron imaging.

The evaluation of a 2D diode array in “magic phantom” for use in high dose rate brachytherapy pretreatment quality assurance

PURPOSE

High dose rate (HDR) brachytherapy is a treatment method that is used increasingly worldwide. The development of a sound quality assurance program for the verification of treatment deliveries can be challenging due to the high source activity utilized and the need for precise measurements of dwell positions and times. This paper describes the application of a novel phantom, based on a 2D 11 × 11 diode array detection system, named “magic phantom” (MPh), to accurately measure plan dwell positions and times, compare them directly to the treatment plan, determine errors in treatment delivery, and calculate absorbed dose.

METHODS

The magic phantom system was CT scanned and a 20 catheter plan was generated to simulate a nonspecific treatment scenario. This plan was delivered to the MPh and, using a custom developed software suite, the dwell positions and times were measured and compared to the plan. The original plan was also modified, with changes not disclosed to the primary authors, and measured again using the device and software to determine the modifications. A new metric, the “position–time gamma index,” was developed to quantify the quality of a treatment delivery when compared to the treatment plan. The MPh was evaluated to determine the minimum measurable dwell time and step size. The incorporation of the TG-43U1 formalism directly into the software allows for dose calculations to be made based on the measured plan. The estimated dose distributions calculated by the software were compared to the treatment plan and to calibrated EBT3 film, using the 2D gamma analysis method.

RESULTS

For the original plan, the magic phantom system was capable of measuring all dwell points and dwell times and the majority were found to be within 0.93 mm and 0.25 s, respectively, from the plan. By measuring the altered plan and comparing it to the unmodified treatment plan, the use of the position–time gamma index showed that all modifications made could be readily detected. The MPh was able to measure dwell times down to 0.067 ± 0.001 s and planned dwell positions separated by 1 mm. The dose calculation carried out by the MPh software was found to be in agreement with values calculated by the treatment planning system within 0.75%. Using the 2D gamma index, the dose map of the MPh plane and measured EBT3 were found to have a pass rate of over 95% when compared to the original plan.

CONCLUSIONS

The application of this magic phantom quality assurance system to HDR brachytherapy has demonstrated promising ability to perform the verification of treatment plans, based upon the measured dwell positions and times. The introduction of the quantitative position–time gamma index allows for direct comparison of measured parameters against the plan and could be used prior to patient treatment to ensure accurate delivery.

Characteristic X-ray Production in Thin Crystals

The dependence of the characteristic X-ray production on electron beam orientation is studied using very thin epitaxially grown single crystals. In crystals of Ag and Pd of thickness ~100 Å the L shell yield can change by more than a factor of 2 for small changes in orientation near the [111] direction. Theoretical analysis of the results shows that the different Bloch waves do not produce X-rays independently but that interference effects occur. The significance of these observations is discussed.

Aberration correction: zooming out to overview

In the structural characterization of thin specimens by projection (atomic column) imaging, the revolutionary development of aberration-corrected electron microscopy has already brought significant improvements not only in spatial resolution but also in improved image contrast. Some highlights from the symposium are summarized. Despite the purchasing and operating costs as well as the demands they place on operator skills, a staggering number of these new microscopes has already been installed worldwide. Serious challenges, therefore, arise including the need to attract customers from a wide range of disciplines where complex structure problems may require the development of new imaging modes. The ability to image at large scattering angles may be useful in mitigating some of the many as-yet uncorrected delocalization mechanisms that then arise and are systematically identified here. Larger specimen volumes made possible by chromatic aberration correction will benefit the development of more relevant in situ observations, particularly in materials science and catalysis. With additional incorporation of phase shifting electrodes or other devices, these chromatic aberration correctors could also be important for efficient phase contrast imaging in easily damaged biological structures. For many of these formidable problems, earlier experience of the optical microscopy community may teach some lessons.

The effect of rectal heterogeneity on wall dose in high dose rate brachytherapy

When treating prostate cancer using high dose rate (HDR) brachytherapy, overdosing the rectal wall may lead to post-treatment rectal complications. An area of concern is related to how the rectal wall dose is calculated by treatment planning systems (TPSs). TPSs are used to calculate the dose delivered to the rectal wall, but they assume that the rectum is a water-equivalent homogeneous medium of infinite size and do not consider the effect that an air-filled "empty" rectal cavity would have on the dose absorbed along the rectal wall. The aim of this research is to quantify the effect that an air cavity has on the rectal wall dose, as its presence changes the backscatter conditions in the region. The MO Skin and RADFET dosimeters proved capable of measuring absolute dose with increasing distance from the HDR Ir-192 brachytherapy source. However, the anterior rectal wall doses measured by the MOSkin and RADFET in an empty rectal cavity were 14.7 +/- 0.2% and 13.7 +/- 0.6% lower than the dose measured in a homogeneous rectal phantom. Monte Carlo simulations corroborated the experimentally obtained results, reporting a -13.2 +/- 0.6% difference. The dose measured at the posterior wall of an empty rectal cavity was between 22% and 26% greater than the dose measured in a full rectal cavity. The heterogeneity of the rectal volume appears to have a significant effect on the rectal dose when compared to calculated rectal dose.

Ultralow-energy excitations and prospects for spatially resolved spectroscopy

The key contribution of electron microscopy methods to condensed matter spectroscopy is undoubtedly spatial resolution. So far this has mainly been manifest through electron energy loss spectroscopy in the 1-eV to 10-keV energy range and has not seriously challenged the dominance of optical, X-ray, and neutron spectroscopy methods over most of the vast field at lower energies. At frequencies up to a few megahertz, corresponding to energies of a few nanoelectron volts and below, direct excitation by pulsed electron beams or electric fields has proved effective. Prospects are discussed for extending spatially resolved spectroscopy to the intermediate energy region, mainly by combining the advantages of electrons with those of photons.

Hunting the Stobbs factor

Image contrast in transmission electron microscopy is often three or more times less than theory predicts. Recent off-axis holography suggests that the origin of this Stobbs factor may lie in thermal diffuse scattering. In the light of this result, possibilities for further observations by TEM, STEM, CBED and holography are suggested as well as frozen phonon computations that include flexural modes.

Valence excitations in electron microscopy: resolved and unresolved issues

Recent progress in the interpretation of spatially localized valence loss spectra is outlined. For a well-defined geometry of dielectric interfaces, detailed and quantitative analysis is now possible. In other cases, useful results may still be available although the common assumption that the spectrum at each point should be directly related to that from a uniform reference sample of appropriate composition may not always be valid.

Threshold Energy Effects in Secondary Electron Emission

In large bandgap semiconductors and insulators, the threshold energies for e-h pair production and ionization damage can lie above the vacuum level. For low energy imaging, a window is then opened whose width is potentially sensitive to local changes in work function, doping level, or acidity. Recent progress and future opportunities for damage-free imaging of these properties using low energy electrons are discussed in the light of the underlying physics, as well as of recent instrumental developments in low energy electron microscopy (LEEM), environmental scanning electron microscopy (ESEM), photoelectron emission microscopy (PEEM), scanned probe microscopy (SPM), and projection electron microscopy.