Simultaneous implementation of unrelated tumour sites on the MR Linac: A review of the commissioning process from a radiographer perspective and lessons learned.

INTRODUCTION: This work reports on a systematic approach to select MRI sequences, quantify inter-observer image registration variation and determine patient positioning for the clinical implementation of MR-guided adaptive radiotherapy (MRgRT) in patients with oropharyngeal (H&N) and lung cancer. METHODS: A total of 30 participants (N=10 H&N and N=10 lung cancer patients and N=10 healthy participants) were scanned on the Elekta Unity Magnetic Resonance Linear Accelerator (MRL). Participant experience questionnaires were used to determine the most appropriate positioning device for lung treatments and tolerability of H&N immobilization devices within the confined MR Linac environment. Visual guided assessments (VGAs) completed by three observers (one oncologist and two radiographers) were used to determine the most suitable tissue weighting (using vendor-provided 3D T1w and T2w sequences) for online image registration. Offline MRI to CT and MRI to MRI rigid registrations were undertaken by nine radiographers using bony and soft tissue matching. Single-factor ANOVA and paired t-tests were utilized to determine the interobserver variation. RESULTS: Based on oncologist and patient feedback, lung cancer patients would be treated in a vac-bag with their arms by their sides, while H&N cancer patients would be immobilized using a 5-point fixation device and 5-point personalized thermoplastic shell. There was no clear preference for T1w or T2w images in the H&N cohort. However, observers preferred T2w sequences for tumour and organ at risk (OAR) visualization in the lung images. When a bony match was conducted, single-factor ANOVA tests showed no statistically significant differences between all H&N image registration types (p=0.09). For the soft-tissue registrations, T1w-CT and T1w-T1w registrations showed a statistically significant (p=0.01) reduction in inter-observer variability over T2w-CT registrations. Paired t-tests showed no statistically significant differences for bony or soft tissue matches using T1w or T2w sequences to the planning CT in the lung cohorts (p=0.63 and p=0.52, respectively). CONCLUSION: We describe the systematic approach to the selection of strategies for imaging, immobilization, and online image registration we used for H&N and lung cancer treatments on the MRL. This has facilitated the selection of the most appropriate adaptive MRgRT strategies for treating these sites at our institution.

A novel use for routine CBCT imaging during radiotherapy to detect COVID-19.

INTRODUCTION: Thoracic CT is a useful tool in the early diagnosis of patients with COVID-19. Typical appearances include patchy ground glass shadowing. Thoracic radiotherapy uses daily cone beam CT imaging (CBCT) to check for changes in patient positioning and anatomy prior to treatment through a qualitative assessment of lung appearance by radiographers. Observation of changes related to COVID-19 infection during this process may facilitate earlier testing improving patient management and staff protection. METHODS: A tool was developed to create overview reports for all CBCTs for each patient throughout their treatment. Reports contain coronal maximum intensity projection (MIP's) of all CBCTs and plots of lung density over time. A single therapeutic radiographer undertook a blinded off-line audit that reviewed 150 patient datasets for tool optimisation in which medical notes were compared to image findings. This cohort included 75 patients treated during the pandemic and 75 patients treated between 2014 and 2017. The process was repeated retrospectively on a subset of the 285 thoracic radiotherapy patients treated between January-June 2020 to assess the efficiency of the tool and process. RESULTS: Three patients in the n = 150 optimisation cohort had confirmed COVID-19 infections during their radiotherapy. Two of these were detected by the reported image assessment process. The third case was not detected on CBCT due to minimal density changes in the visible part of the lungs. Within the retrospective cohort four patients had confirmed COVID-19 based on RT-PCR tests, three of which were retrospectively detected by the reported process. CONCLUSION: The preliminary results indicate that the presence of COVID-19 can be detected on CBCT by therapeutic radiographers. IMPLICATIONS FOR PRACTICE: This process has now been extended to clinical service with daily assessments of all thoracic CBCTs. Changes noted are referred for oncologist review.

Managing confidentiality in illicit drugs research: ethical and legal lessons from studies in remote Aboriginal communities.

Assuring participant confidentiality in illicit drugs research has raised legal questions and challenges both for researchers and ethics committees. There are similar challenges for clinicians. To study cannabis use in Aboriginal people in Arnhem Land (Northern Territory), a risk-management approach was successful. Aboriginal participants were informed in their own language that confidentiality could not be assured if they disclosed information about illegal behaviours. Researchers avoided questions of intrinsic interest to law enforcement. Relationships between researchers and study participants and the integrity of the study were preserved. These considerations have relevance for clinicians as well as researchers dealing with the influence of illicit behaviours on health.

Evaluating the communities care program: best practice for rigorous research to evaluate gender based violence prevention and response programs in humanitarian settings.

BACKGROUND: Gender-based violence (GBV) is a significant issue for women and girls in humanitarian settings. Innovative primary prevention programs are being developed and implemented with existing response programs to change harmful social norms that sustain GBV in humanitarian settings. Social norms are expectations of how women, men, girls and boys should behave, who should have power and control over behavior, and how families and communities value women and girls and support their rights and opportunities. METHODS: The United Nations Children's Fund (UNICEF) led Communities Care program is a primary prevention and response program designed from the understanding that within the context of conflict and displacement, there is an opportunity for positive change in social norms that support gender equity, and decrease GBV. The goal is to support communities in humanitarian settings to create healthy, safe and peaceful environments with quality response services for women and girls by transforming harmful social norms that uphold violence into norms that promote dignity, equity, and non-violence. CONCLUSION: This manuscript will highlight the use of best practices in GBV research to rigorously evaluate the Communities Care program in two diverse in humanitarian settings, Somalia and South Sudan.

Characterisation of hidden defects using the near-field ultrasonic enhancement of Lamb waves.

Defects that propagate from the inside of a structure can be difficult to detect by traditional non-destructive inspection methods. A non-contact inspection method is presented here that uses the near-field interactions of ultrasonic Lamb waves to detect defects propagating into a 1.5 mm thick aluminium sheet from the opposite side to that which is inspected. Near-field interactions of the S0 Lamb waves with the defects are shown to give rise to a characteristic increase in the wave magnitude, which is used to position and characterise these hidden defects. It is shown that such defects are difficult to detect from a study of their influence on ultrasonic transmission alone. Single defects of different depths, and systems of multiple defects with varying separations and relative depths, are successfully detected in both experimental trials and FEM simulations. Reliable single defect detection is achieved for defects with a minimum depth of 30% of the plate thickness, and resolution of multiple defects is achieved for defect separations of 5mm.

The evolving role of saline infusion sonography (SIS) in infertility.

Saline infusion sonography (SIS) has become a valuable diagnostic modality in gynaecology over the last three decades. SIS is now commonly employed for detailed evaluation of the uterine cavity as part of pre-treatment assessment in infertile women. The objective of this paper is review the scientific literature on SIS in infertility. Medline, Ovid and Cochrane databases were searched for relevant articles. The indications, technical aspects and the potential advantages of SIS are discussed. The efficacy and sensitivity of SIS are compared to hysteroscopy in the evaluation of uterine polyps, fibroids, intrauterine adhesions and uterine anomalies. Increasing evidence suggests the use of SIS prior to an in-vitro fertilization (IVF) cycle as it has increased sensitivity in the detection of intrauterine pathology. SIS is cost-effective and results in better patient satisfaction scores than hysteroscopy.

An algorithm for angiographic estimation of blood vessel diameter.

This study was carried out in an attempt to develop an objective and robust method for measuring changes in the diameters of small blood vessels from X-ray angiographic images. Recognizing potential problems with edge detection methods applied to cylindrical vessels in which the contrast diminishes as the boundary is approached, we have attempted to utilize the X-ray absorbance data across the entire cross section of the vessel. Then, assuming a cylindrical geometry, the absorbance data are fit to the cylindrical absorbance function by use of nonlinear regression analysis. The method was tested and calibrated using glass tubes filled with various concentrations of contrast medium. The diameters of small pulmonary arteries were estimated by applying the method of angiograms obtained from an isolated dog lung lobe. The structure of the residuals obtained after the fitting procedure was analyzed to test the appropriateness of the model for use with images of vessels. The results suggest that this approach will have utility for systematically quantifying vessel dimensions.

Distensibility of small veins of the dog lung.

To determine the distensibility of the intrapulmonary veins (250-2,900 microns diam) of the dog lung, we obtained X-ray angiograms from isolated lung lobes over a vascular pressure range of approximately 0-30 Torr. Over this pressure range the diameter vs. pressure curves tended to flatten out at the high pressures. In the pressure range of 0-19 Torr, we characterized the vessel distensibility by alpha (the ratio of the slope, beta, of the graph of diameter vs. intravascular pressure to the intercept, Do). The average value of alpha was approximately 1.2%/Torr. There was a weak negative correlation (r = -0.32) between alpha and Do. Infusion of enough norepinephrine to produce approximately 50% increase in total lobar vascular resistance produced a decrease in Do and alpha of approximately 33 and 32%, respectively.

Edema development and recovery in neurogenic pulmonary edema.

We determined the time course of changes in extravascular lung water (EVLW) that occur after massive sympathetic activation produced by intracisternal veratrine administration in chloralose-anesthetized dogs. Three groups of dogs were studied. In the first group (n = 9), acute increases in EVLW (occurring within minutes) were determined both by measuring extravascular thermal volume and by gravimetric analysis. In the second (n = 6) and third (n = 7) groups, changes in EVLW were followed for 2-3 h after veratrine administration. Extravascular thermal volume was measured in the second group. In the third group, right atrial injections of a vascular indicator (125I-labeled serum albumin) and an extravascular indicator (3HOH) were made while blood was sampled from the pulmonary artery (PA) and left atrium, and EVLW was determined by deconvolution of the left atrial and PA concentration-time curves. Indicator-dilution and gravimetric EVLW increased acutely only in dogs in which PA pressure exceeded 60 Torr, with two- to four-fold increases in EVLW being observed in dogs that developed the highest PA pressures (maximum 94 Torr). Thus, severe edema can develop rapidly after massive sympathetic nervous system activation but requires extreme degrees of pulmonary hypertension. In several dogs after the acute increase in EVLW associated with the pulmonary hypertension, the indicator-dilution EVLW decreased with time. These decreases appear to effect clearance of edema fluid rather than alterations in perfusion.

Transit time dispersion in the pulmonary arterial tree.

Knowledge of the contributions of arterial and venous transit time dispersion to the pulmonary vascular transit time distribution is important for understanding lung function and for interpreting various kinds of data containing information about pulmonary function. Thus, to determine the dispersion of blood transit times occurring within the pulmonary arterial and venous trees, images of a bolus of contrast medium passing through the vasculature of pump-perfused dog lung lobes were acquired by using an X-ray microfocal angiography system. Time-absorbance curves from the lobar artery and vein and from selected locations within the intrapulmonary arterial tree were measured from the images. Overall dispersion within the lung lobe was determined from the difference in the first and second moments (mean transit time and variance, respectively) of the inlet arterial and outlet venous time-absorbance curves. Moments at selected locations within the arterial tree were also calculated and compared with those of the lobar artery curve. Transit times for the arterial pathways upstream from the smallest measured arteries (200-micron diameter) were less than approximately 20% of the total lung lobe mean transit time. Transit time variance among these arterial pathways (interpathway dispersion) was less than approximately 5% of the total variance imparted on the bolus as it passed through the lung lobe. On average, the dispersion that occurred along a given pathway (intrapathway dispersion) was negligible. Similar results were obtained for the venous tree. Taken together, the results suggest that most of the variation in transit time in the intrapulmonary vasculature occurs within the pulmonary capillary bed rather than in conducting arteries or veins.

Model-free numerical deconvolution of recirculating indicator concentration curves.

This paper investigates two model-free methods for numerical deconvolution of recirculating indicator concentration curves. The two methods, damped least squares and discrete orthogonal polynomial deconvolution, are applied to simulated data to verify the reliability of the algorithms. Both deconvolution methods provide damping that results in estimated transport functions that are smooth and reasonable estimates of the actual simulated transport function. On convolution with the simulated input curve, the estimated transport functions provide good fits to the simulated output curve. In addition, methods for identifying an optimal solution and for truncating the artifactually long oscillatory tails of the estimated transport functions are proposed, which appear to allow for reasonably accurate estimation of the mean transit times and variances of the transport functions as well. When either method was applied to indicator dilution data obtained from the pulmonary artery and left atrium, it was computationally stable while producing transport functions that when convolved with the input concentration curves provided good fits to the output concentration curves. The combined simulation and experimental results suggest that the proposed methods should be useful for estimating circulation transport functions from indicator dilution data.

3He ion-beam analysis of water uptake and drug delivery.

3He ion-beam analysis utilises a micronuclear reaction analysis (of deuterium and carbon) and microparticle induced X-ray emission (in this case silicon and chlorine), to determine an elemental map of the surface of a sample. This study used D(2)O to model the behaviour of water in poly(tetrahydrofurfuryl methacrylate-polyethyl methacrylate) and chlorhexidine diacetate doped silicone elastomers. The poly(tetrahydrofurfuryl methacrylate-polyethyl methacrylate) systems demonstrated an initial Fickian absorption process (diffusion coefficient 1.1 x 10(-11) m(2)s(-1)) which indicated the 2-stage nature of the polymer's absorption kinetics. The doped silicone samples demonstrated an osmotic mechanism for the controlled release of drugs, with correlation between the D(2)O and the chlorhexidine diacetate inclusions increasing during the experiment. The technique proved valuable in the analysis of delivery polymers and will undoubtedly have further applications in the development of drug delivery systems.

Increased absorption of aluminium from a normal dietary intake in dementia.

Serum aluminium was significantly raised (p < 0.01) up to 2-3-fold, in patients with dementia including Alzheimers Disease (AD) 0.66 +/- 0.2 (mumol/l mean +/- 1 s.d.) and patients on regular aluminium hydroxide therapy 0.54 +/- 0.17, compared with healthy volunteers 0.21 +/- 0.13, although not as high as in patients with end stage renal failure on regular dialysis 0.88 +/- 0.42. The urine outputs (mumol/l mean +/- 1 s.d.) of aluminium and silicon, respectively, were also significantly increased up to 5-fold in dementia 2.89 +/- 1.78 (n = 23) and 1587 +/- 645 (n = 22) and patients on regular aluminium hydroxide therapy 5.03 +/- 2.08 (n = 8) and 998 +/- 364 (n = 21) compared with healthy volunteers 0.95 +/- 0.82 (n = 84) and 471 +/- 332 (n = 114). The increase in urine aluminium was thus associated with a similarly marked increase in the output of silicon. The increased absorption of aluminium in dementia patients is equivalent to the intestinal loading in Aludrox therapy. Also silicon appears to be important in the renal excretion of the absorbed aluminium. Whether this is a phenomenon related to the elderly or the process of dementia warrants further study.

Kava use, dyslipidaemia and biomarkers of dietary quality in Aboriginal people in Arnhem Land in the Northern Territory (NT), Australia.

Heavy kava use has been associated with sudden death in Aboriginal Australians in Arnhem Land (Northern Territory, Australia) where poor diets and a high incidence of premature coronary heart disease are known. Heavy kava users may suffer additional risk if further malnourished. Among 98 people (62 males, 36 females) in one community, 36 never used kava, 26 were past users, and 36 were continuing users. Across kava-using groups skinfold thickness, body mass index and body fat decreased. Total- and LDL-cholesterol were elevated in kava users compared to both former users and never users. HDL-cholesterol was higher in current users vs never users. Across kava-using groups, triglycerides, homocysteine and diet-derived antioxidant vitamins alpha-tocopherol and retinol, did not vary. Plasma carotenoid levels (indicative of vegetable and fruit intake) were very low, but when adjusted for plasma cholesterol, did not vary between kava-using groups. An obsession for kava drinking may mediate kava's direct effects on nutritional status.

Case II diffusion in the PVC and acetone system.

This paper describes how nuclear magnetic resonance (NMR) has been used to study case II diffusion of acetone into PVC. NMR is supported by Ion Beam Nuclear Reaction Analysis and Gravimetric Analysis. A series of experiments with different PVC exposure times to acetone vapour have shown the observable physical characteristics of case II diffusion. Experiments in the temperature range 20-50 degrees C have yielded the temperature dependence of the front velocity and the T2 values of the acetone and PVC components.

Resource requirements to develop a large, remote aboriginal health service: whose responsibility?

In 1994 the Commonwealth funded studies to establish and develop Aboriginal health services. One such study was undertaken in 1995 at Maningrida, Northern Territory: to identify the health-service needs of the population and consider community management structures; to identify Northern Territory expenditure for primary health care; and to provide a three- to five-year development budget. Approximately 2100 Aboriginal residents in the region used the service, including 750 living on 24 outstations within 75 km. Nearly 40 per cent were aged under 15 years. Childhood morbidity was high, with children under two averaging 1.4 hospital admissions per year. The age pyramid reflected premature adult mortality from the third decade of life. Service providers identified inadequate staffing and infrastructure as barriers to service development. Community consultations emphasised the need for resident doctors, improved outstation services and aged and respite care, local training for Aboriginal health workers and housing for staff. These developments would require per capita primary health care expenditure ($872) to be doubled. Aboriginal people in remote areas are disadvantaged through Commonwealth Grants Commission funding formulae and lack of Medicare access. As the sole funding source, the Northern Territory spends over $1.83 million per year providing health services at Maningrida. Additionally, the study proposed that the Commonwealth spend $1.96 million a year over five years on staffing and infrastructure. Local Aboriginal organisations also agreed to allocate resources for health service development. Ineffective implementation, lack of clarification of government responsibilities and funding shortfalls remain barriers to developing remote Aboriginal health services.

WESTCOP: a disease management approach to coronary artery disease.

Disease management is a systematic approach to improving care of populations of patients with specific clinical conditions. Critical to success are the formation of collaborative teams of health care stakeholders, development and promulgation of clinical practice guidelines, and performance measurement and feedback to providers as a process of continuous practice improvement. This article describes a disease management program for patients with coronary artery disease in a provincial health district with a population of 180,000. It discusses the rationale and methods behind the operationalisation of the main program elements, benefits achieved to date and challenges confronted.

Endovenous laser ablation for major varicose tributaries.

OBJECTIVE: The purpose was to determine whether endovenous laser ablation (EVLA) could be used to treat major varicose tributaries as well as saphenous veins. METHODS: From 173 major venous systems in 95 patients treated by EVLA over a 12-month period, 108 had major varicose tributaries, of which 78 (70%) were treated by attempted EVLA of the saphenous veins and associated tributaries. RESULTS: Treatment was successful in 71 venous segments (83%). The lengths of saphenous veins treated were 3-46 (median 18) cm. and the lengths of tributaries treated were 3-38 (median 14) cm. The diameters of treated saphenous veins were 4-10 (median 6) mm, and the estimated mean diameters of treated tributaries were 3-8 (median 5) mm, as measured prior to operation with the patient in 45° reverse Trendelenburg on a tilt table. There were no early or delayed complications. CONCLUSIONS: Major varicose tributaries as well as the saphenous veins can be treated by EVLA in approximately two-thirds of cases, with success in the majority selected and with no significant complications.