Novel hybrid treatment planning approach for irradiation a pediatric craniospinal axis

This study presents a new treatment planning approach merging 3D-CRT and VMAT fields into a hybrid treatment plan (HybTP), in order to achieve an optimum dose coverage of the planning target volume (PTV) and protection of OAR. Craniospinal axis irradiation (CSI) treated with 3D conformal radiotherapy (3D-CRT) is associated with high doses to the heart and eye lenses but provides better sparing of lungs and kidneys compared to volumetric modulated arc therapy (VMAT). VMAT treatment spares eye lenses and the heart, but lungs and kidneys are not as effective as 3D-CRT. Thus, a combination of both techniques (HybTP) may be optimal in sparing all these organs at risk (OAR). The results of HybTP are compared with helical tomotherapy (HT), intensity modulated radio therapy (IMRT), VMAT, and 3D-CRT plans. Hybrid, HT, VMAT, IMRT, and 3D-CRT treatment plans for a male child (age 6 years) with medulloblastoma were created and compared. A total dose of 35.2 Gy (PTV) with a dose per fraction of 1.6 Gy was prescribed. The following dose acceptance criteria were defined: The plans were compared regarding dose homogeneity index (HI) and conformity index (CI), PTV coverage, (particularly at cribriform plate) and doses at OARs. Best conformity was achieved with HT (CI = 0.98) followed by VMAT (CI = 0.96), IMRT (CI = 0.91), HybTP (CI = 0.86), and 3D-CRT (CI = 0.83). The homogeneity index varied marginally. For both HT and IMRT the HI was 0.07, and for 3D-CRT, VMAT and HybTP the HI was between 0.13 and 0.15. The cribriform plate was sufficiently covered by HybTP, VMAT, and 3D-CRT. The dose acceptance criteria for OARs were met by HT and HybTP. VMAT did not meet the criteria for lung (Dmean = right 10.4 Gy/left 10.2 Gy), 3D-CRT did not meet the criteria for eye lenses (Dmax = right 32.3 Gy/left 33.1), and heart (V25≈44%) and IMRT did not meet the criteria for lung (Dmean = right 11.1 Gy/left 11.2 Gy) and eye lenses (Dmax = right 12.2 Gy/left 13.1). HybTP meets all defined acceptance criteria and has proved to be a reasonable alternative for CSI. With HybTP that combines VMAT at the brain and heart with 3D-CRT posterior spinal fields (to spare lungs and kidneys), both appropriate coverage of the PTV and sparing of OAR can be achieved.

Monitoring Respiratory Motion during VMAT Treatment Delivery Using Ultra-Wideband Radar

The goal of this paper is to evaluate the potential of a low-cost, ultra-wideband radar system for detecting and monitoring respiratory motion during radiation therapy treatment delivery. Radar signals from breathing motion patterns simulated using a respiratory motion phantom were captured during volumetric modulated arc therapy (VMAT) delivery. Gantry motion causes strong interference affecting the quality of the extracted respiration motion signal. We developed an artificial neural network (ANN) model for recovering the breathing motion patterns. Next, automated classification into four classes of breathing amplitudes is performed, including no breathing, breath hold, free breathing and deep inspiration. Breathing motion patterns extracted from the radar signal are in excellent agreement with the reference data recorded by the respiratory motion phantom. The classification accuracy of simulated deep inspiration breath hold breathing was 94% under the worst case interference from gantry motion and linac operation. Ultra-wideband radar systems can achieve accurate breathing rate estimation in real-time during dynamic radiation delivery. This technology serves as a viable alternative to motion detection and respiratory gating systems based on surface detection, and is well-suited to dynamic radiation treatment techniques. Novelties of this work include detection of the breathing signal using radar during strong interference from simultaneous gantry motion, and using ANN to perform adaptive signal processing to recover breathing signal from large interference signals in real time.

Contamination Resulting From a Broken 125I Seed During a Brachytherapy Procedure

ABSTRACT

Brachytherapy programs within radiation therapy departments are subject to stringent radiation safety requirements in order to ensure the safety of the staff and patients. Training programs often include brachytherapy-specific radiation safety training modules that address the specific risks associated with radioactive sources, emergency procedures, and regulatory requirements specific to the use of radioisotopes. Unlike other uses of radioactive materials, brachytherapy uses sealed sources and therefore under routine operations does not encounter radioactive contaminants. This article presents an unusual clinical situation in which an 125I brachytherapy seed was damaged during routine clinical workflow, resulting in radioactive contamination within the clinical environment. Decisions made at the time of the incident resulted in contamination that spread beyond the initial location. The incident highlighted a shortcoming of the radiation safety program in preparing staff for the possibility of having to deal with unsealed radioactivity. Brachytherapy programs would be strengthened by including training specific to radioactive contamination in their emergency training to equip staff to respond to unexpected damage to the sealed sources.

A Pre-implementation Study of Volumetric Modulated Arc Therapy for Same-day Planning and Treatment of Vertebral Bone Metastases Within a Rapid-access Palliative Radiotherapy Programme

AIMS

We aimed to develop a process for same-day contouring, planning, quality assurance and delivery of volumetric modulated arc therapy (VMAT) for vertebral bone metastases within our institution's rapid-access palliative radiotherapy programme.

MATERIALS AND METHODS

Two thoracic (T6-7, T3-7) and two lumbar (L2-3, L1-5) targets were contoured on computed tomography images acquired from an anthropomorphic phantom and five patient scans. Inverse planning aimed to provide coverage of a prescribed dose of 8 Gy with a combined lung V2Gy < 25% and a combined kidney mean dose <2 Gy. Serial plans were created to identify an efficient combination of six main planning variables specific to our treatment planning system: (i) voxel size (3 mm versus 5 mm), (ii) Monte Carlo statistical uncertainty (1% per calculation versus 3% per control point), (iii) fluence smoothing (medium versus high), (iv) number of iterations of segment shape changes during optimisation (1 versus 5), (v) dose calculation algorithm (Monte Carlo versus pencil beam) and (vi) number of arcs (single versus multiple). Contouring, planning, quality assurance and treatment delivery were timed.

RESULTS

The combination of planning variables deemed efficient and appropriate was: a 3 mm voxel size, statistical uncertainty of 1% per calculation, medium fluence smoothing, five iterations of segment shape changes, Monte Carlo dose calculation and single full arc delivery. Patient scan contouring times ranged from 7 to 9 min (T6-7), 11-13 min (T3-7), 5-7 min (L2-3) and 8-10 min (L1-5) and planning times ranged from 9 to 15 min (T6-7), 13-25 min (T3-7), 18-25 min (L2-3) and 21-31 min (L1-5). Physics quality assurance times ranged from 15 to 21 min and beam-on times ranged from 3 to 6 min.

CONCLUSIONS

The combined elements of VMAT for thoracic and lumbar vertebral bone metastases were completed in under 2 h. This new process makes same-day contouring, planning, quality assurance and treatment delivery of VMAT feasible within our rapid-access palliative radiotherapy programme.

Cardiorespiratory fitness and accelerometer-determined physical activity following one year of free-living high-intensity interval training and moderate-intensity continuous training: a randomized trial

Background

Free-living adherence to high-intensity interval training (HIIT) has not been adequately tested. This randomized trial examined changes in cardiorespiratory fitness (CRF) and accelerometer-measured purposeful physical activity over 12 months of free-living HIIT versus moderate-intensity continuous training (MICT).

Methods

Ninety-nine previously low-active participants with overweight/obesity were randomly assigned to HIIT (n = 47) or MICT (n = 52). Both interventions were combined with evidence-based behaviour change counselling consisting of 7 sessions over 2 weeks. Individuals in HIIT were prescribed 10 X 1-min interval-based exercise 3 times per week (totalling 75 min) whereas individuals in MICT were prescribed 150 min of steady-state exercise per week (50 mins 3 times per week). Using a maximal cycling test to exhaustion with expired gas analyses, CRF was assessed at baseline and after 6 and 12 months of free-living exercise. Moderate-to-vigorous physical activity of 10+ minutes (MVPA10+) was assessed by 7-day accelerometry at baseline, 3, 6, 9, and 12 months. Intention to treat analyses were conducted using linear mixed models.

Results

CRF was improved over the 12 months relative to baseline in both HIIT (+ 0.15 l/min, 95% CI 0.08 to 0.23) and MICT (+ 0.11 l/min, 95% CI 0.05 to 0.18). Both groups improved 12-month MVPA10+ above baseline (HIIT: + 36 min/week, 95% CI 17 to 54; MICT: + 69 min/week, 95% CI 49 to 89) with the increase being greater (by 33 min, 95% CI 6 to 60) in MICT (between group difference, P = 0.018).

Conclusion

Despite being prescribed twice as many minutes of exercise and accumulating significantly more purposeful exercise, CRF improvements were similar across 12 months of free-living HIIT and MICT in previously low-active individuals with overweight/obesity.

Platelet Behaviour in Normal Pregnancy, Pregnancy Complicated by Essential Hypertension and Pregnancy-Induced Hypertension

Platelet behaviour was studied throughout pregnancy in a group of women who remained normotensive and a group with essential hypertension (EHT). Women who developed pregnancy-induced hypertension (PIH) were also studied together with a group of non-pregnant female controls. We determined the sensitivity of platelets to arachidonic acid (AA) and determined the effects of dazoxiben, a thromboxane synthetase inhibitor, on AA-induced platelet behaviour.

A marked increase in platelet reactivity was evident in all three groups throughout pregnancy; platelets became more sensitive to AA and less sensitive to the inhibitory effects of dazoxiben. The change was apparent as early as 16 weeks gestation. In normotensive pregnancy and in EHT platelet behaviour had returned to normal six weeks after delivery. Platelets from women who developed PIH were more sensitive to AA than those from the other pregnant women and platelet reactivity had not returned to normal six weeks after delivery.

The results indicate that alterations in platelet behaviour may contribute to the vascular complications that are known to be associated with pregnancy and with PIH in particular.

Explaining trends in alcohol-related harms in Scotland 1991-2011 (II): policy, social norms, the alcohol market, clinical changes and a synthesis

OBJECTIVE

To provide a basis for evaluating post-2007 alcohol policy in Scotland, this paper tests the extent to which pre-2007 policy, the alcohol market, culture or clinical changes might explain differences in the magnitude and trends in alcohol-related mortality outcomes in Scotland compared to England & Wales (E&W).

STUDY DESIGN

Rapid literature reviews, descriptive analysis of routine data and narrative synthesis.

METHODS

We assessed the impact of pre-2007 Scottish policy and policy in the comparison areas in relation to the literature on effective alcohol policy. Rapid literature reviews were conducted to assess cultural changes and the potential role of substitution effects between alcohol and illicit drugs. The availability of alcohol was assessed by examining the trends in the number of alcohol outlets over time. The impact of clinical changes was assessed in consultation with key informants. The impact of all the identified factors were then summarised and synthesised narratively.

RESULTS

The companion paper showed that part of the rise and fall in alcohol-related mortality in Scotland, and part of the differing trend to E&W, were predicted by a model linking income trends and alcohol-related mortality. Lagged effects from historical deindustrialisation and socio-economic changes exposures also remain plausible from the available data. This paper shows that policy differences or changes prior to 2007 are unlikely to have been important in explaining the trends. There is some evidence that aspects of alcohol culture in Scotland may be different (more concentrated and home drinking) but it seems unlikely that this has been an important driver of the trends or the differences with E&W other than through interaction with changing incomes and lagged socio-economic effects. Substitution effects with illicit drugs and clinical changes are unlikely to have substantially changed alcohol-related harms: however, the increase in alcohol availability across the UK is likely to partly explain the rise in alcohol-related mortality during the 1990s.

CONCLUSIONS

Future policy should ensure that alcohol affordability and availability, as well as socio-economic inequality, are reduced, in order to maintain downward trends in alcohol-related mortality in Scotland.

Explaining trends in alcohol-related harms in Scotland, 1991-2011 (I): the role of incomes, effects of socio-economic and political adversity and demographic change

OBJECTIVE

This paper tests the extent to which differing trends in income, demographic change and the consequences of an earlier period of social, economic and political change might explain differences in the magnitude and trends in alcohol-related mortality between 1991 and 2011 in Scotland compared to England & Wales (E&W).

STUDY DESIGN

Comparative time trend analyses and arithmetic modelling.

METHODS

Three approaches were utilised to compare Scotland with E&W: 1. We modelled the impact of changes in income on alcohol-related deaths between 1991-2001 and 2001-2011 by applying plausible assumptions of the effect size through an arithmetic model. 2. We used contour plots, graphical exploration of age-period-cohort interactions and calculation of Intrinsic Estimator coefficients to investigate the effect of earlier exposure to social, economic and political adversity on alcohol-related mortality. 3. We recalculated the trends in alcohol-related deaths using the white population only to make a crude approximation of the maximal impact of changes in ethnic diversity.

RESULTS

Real incomes increased during the 1990s but declined from around 2004 in the poorest 30% of the population of Great Britain. The decline in incomes for the poorest decile, the proportion of the population in the most deprived decile, and the inequality in alcohol-related deaths, were all greater in Scotland than in E&W. The model predicted less of the observed rise in Scotland (18% of the rise in men and 29% of the rise in women) than that in E&W (where 60% and 68% of the rise in men and women respectively was explained). One-third of the decline observed in alcohol-related mortality in Scottish men between 2001 and 2011 was predicted by the model, and the model was broadly consistent with the observed trends in E&W and amongst women in Scotland. An age-period interaction in alcohol-related mortality was evident for men and women during the 1990s and 2000s who were aged 40-70 years and who experienced rapidly increasing alcohol-related mortality rates. Ethnicity is unlikely to be important in explaining the trends or differences between Scotland and E&W.

CONCLUSIONS

The decline in alcohol-related mortality in Scotland since the early 2000s and the differing trend to E&W were partly described by a model predicting the impact of declining incomes. Lagged effects from historical social, economic and political change remain plausible from the available data.

Prevalence of metabolic syndrome and its risk factors in Canadian children and adolescents: Canadian Health Measures Survey Cycle 1 (2007–2009) and Cycle 2 (2009–2011)

Introduction

We investigated the prevalence of metabolic syndrome (MetS) and its risk factors, and the influence of socioeconomic status, in Canadian children and adolescents.

Methods

Canadian Health Measures Survey cycle 1 (2007–2009) and cycle 2 (2009–2011) respondents aged 10 to 18 years who provided fasting blood samples were included (n = 1228). The International Diabetes Federation (IDF) consensus definition for children and adolescents (10–15 years) and worldwide adult definition (≥ 16 years) were used to diagnose MetS. Prevalence of MetS and its risk factors were calculated and differences by socioeconomic status were examined using χ2 tests.

Results

The prevalence of MetS was 2.1%. One-third 37.7%) of participants had at least one risk factor, with the most prevalent being abdominal obesity (21.6%), low HDL-C (19.1%) and elevated triglyceride levels (7.9%). This combination of abdominal obesity, low HDL-C and elevated triglyceride levels accounted for 61.5% of MetS cases. Participants from households with the highest income adequacy and educational attainment levels had the lowest prevalence of one or more MetS risk factors, abdominal obesity and low HDL-C.

Conclusion

The prevalence of MetS (2.1%) was lower than previously reported in Canada (3.5%) and the USA (4.2%¬–9.2%), potentially due to the strict application of the IDF criteria for studying MetS. One-third of Canadian children and adolescents have at least one risk factor for MetS. Given that the risk for MetS increases with age, these prevalence estimates, coupled with a national obesity prevalence of almost 10% among youth, point to a growing risk of MetS and other chronic diseases for Canadian youth.

Simulation of a medical linear accelerator for teaching purposes

Simulation software for medical linear accelerators that can be used in a teaching environment was developed. The components of linear accelerators were modeled to first order accuracy using analytical expressions taken from the literature. The expressions used constants that were empirically set such that realistic response could be expected. These expressions were programmed in a MATLAB environment with a graphical user interface in order to produce an environment similar to that of linear accelerator service mode. The program was evaluated in a systematic fashion, where parameters affecting the clinical properties of medical linear accelerator beams were adjusted independently, and the effects on beam energy and dose rate recorded. These results confirmed that beam tuning adjustments could be simulated in a simple environment. Further, adjustment of service parameters over a large range was possible, and this allows the demonstration of linear accelerator physics in an environment accessible to both medical physicists and linear accelerator service engineers. In conclusion, a software tool, named SIMAC, was developed to improve the teaching of linear accelerator physics in a simulated environment. SIMAC performed in a similar manner to medical linear accelerators. The authors hope that this tool will be valuable as a teaching tool for medical physicists and linear accelerator service engineers.

PACS number: 87.55Gh, 87.56bd

The CD11b-integrin (ITGAM) and systemic lupus erythematosus

Variations at the ITGAM gene, which encodes for the CD11b chain of the Mac-1 (alphaMbeta2; CD11b/CD18; complement receptor-3) integrin, is one of the strongest genetic risk factors for systemic lupus erythematosus (SLE). More specifically, a genetic variant (rs1143679) which results in an arginine to histidine substitution at position 77 in the extracellular portion of the integrin is associated with disease. It has recently been shown that this amino acid substitution results in a dysfunctional integrin, which is deficient in mediating cell adhesion to integrin ligands, phagocytosis and in addition cannot restrict inflammatory cytokine production in macrophages. In this review, we discuss immunological functions of the Mac-1 integrin and how defects in the genetic variant of Mac-1 may relate to SLE development.

Use of electronic medical record queries to support clinical decision quality assurance

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Background: Clinical Treatment Decisions in radiation oncology direct the patient’s treatment plans. There is a need for Clinical Decisions to be peer reviewed preferably in real time before the patient plan is completed. Traditional peer review of clinical decisions which ensure high quality patient treatments can be challenging in a busy radiation oncology clinic. Leveraging Electronic Medical Records (EMR) to query standard patient staging and demographics data per disease type allows for efficient peer review of the clinical decision. Methods: Through the use of EMR system (Aria, Varian Medical Systems, Palo Alto CA), data is entered into the radiation oncology chart by the primary radiation oncologist during a patient’s work up. Tools within the EMR have been configured to automatically query patient charts and summarize the data. A second Oncologist runs the query, reviews the data and peer reviews clinical decision for radiotherapy including treatment intent, dose and target contours. The radiation oncologist can then discuss modifications with the original oncologist, or indicate to the dosimetrist to continue planning. Those clinical decisions that are uncertain are escalated to review in a traditional peer review setting. Results: The EMR queries have allowed a shift to real time peer review of clinical decisions. The summary of disease specific staging and demographics data has added to efficiency in clinic in both the oncologists’ ability to complete a timely peer review and the lowering the amount of planning rework. Traditional peer review setting is then used to discuss the controversial and complex cases that would receive the most benefit. Conclusions: The ability to leverage electronic medical record data has made the peer review of clinical decisions in our institution more efficient and therefore the majority can be completed in real time.

Long-term percutaneous endoscopic gastrostomy feeding in young adults with multiple disabilities

AIM

To study the outcomes from initiation of percutaneous endoscopic gastrostomy (PEG) feeding in young people with profound multiple disabilities.

METHODS

Observations were made on 40 adults with lifelong intellectual disability (mental retardation) and quadriplegia, in whom PEG feeding was initiated during 1990-2008. There were 20 men and 20 women aged 15-40 years at the time of the audit, living in settings with 24 h registered nurse staffing.

RESULTS

Undernutrition and recurrent aspiration with frequent infections were cited as reasons for PEG feeding. The positive outcomes were that some were said to be more alert for a time following the procedure; and these young adults lived with PEG feeding for an average of 8.5 years, some up to 18 years. In that time, however, they all experienced complications of the PEG insertion, and of the PEG feeding process. There were no measurable improvements in cognition. There were no reductions in prescription of medications. They all required frequent daily interventions by nurses to maintain medical stability. Ten people died during this review period, from continued deterioration in neurological status, with pneumonia cited as the terminal event.

CONCLUSIONS

Unlike other people with neurological deterioration, young adults with lifelong multiple disabilities may live for many years with PEG feeding. There is little gain in quality of life.

Psychological causes of schizophrenia

This article outlines not only the path of my recovery but also the conclusions of my therapeutic journal that developed over a period of several years. This journal evolved into the following structure: description of personal pain body, moving forward with transformations, and active living--implementation of intention and desire that continues. My journal has evolved from the written word to transformation, current lived experience, and the expectation of good things yet to come. Many transformations were integrated into my thinking and emotions over the years. As I developed solutions to my pain body, the structure of the psychological causes of my paranoid schizophrenia became clear. The voices and interference are at bay, hallucinations and delusions are understood, and paranoid disposition transformed to a more normal way of thinking and reacting. I continue on a low maintenance dose of atypical antipsychotic medication. My hope is that my conclusions will inspire researchers and clinicians and help other peers with their recovery. An open mind, moving forward in work, self-direction, and transformative learning have contributed significantly to my recovery.

Sci-Fri PM: Planning-05: Saving trees and improving workflow

Patient treatment preparation is a multi-step process requiring inputs from a range of disciplines and technologies. Our centre generates just over 4500 treatment plans annually and operates from two main campuses. A large, split program presents unique challenges during treatment preparation and has provided the impetus for a completely electronic treatment process. Throughout 2006 and 2007, we migrated our external beam treatment planning to the Computerized Medical Systems (CMS) product line. Utilizing a thin-client architecture, CMS supports distributed (multi-site) planning. Coincident with the treatment planning upgrade, IMPAC Multi-Access was configured to provide a paperless and filmless treatment record and electronic patient workflow. Standardized treatment objectives were also implemented in the form of site-group approved care plans. Details of the pretreatment process and the CMS / IMPAC implementation will be presented as well as a workflow time analysis. To date, treatment preparation times have been reduced by 25% (2.5 days) as a result of workflow improvements, representing a clear benefit to both staff and patients.

A new method for quantifiable and controlled dosage of particulate matter for in vitro studies: the electrostatic particulate dosage and exposure system (EPDExS)

An exposure chamber is described for the quantifiable addition of fine and ultrafine aerosol particulate matter directly to cells and used to demonstrate the in vitro cytotoxicity of fine 1,4-naphthoquinone particles to murine lung epithelial cells. The electrostatic particulate dosage and exposure system (EPDExS) operates on the principle of electrostatic precipitation and is shown to deposit fine and ultrafine aerosol particles directly to cells with 100% efficiency for particle diameters in the range of 40-530nm. This range is not limited by the EPDExS, but rather by the aerosolization method used for this study. Numbers of particles deposited onto the cells are counted with a condensation particle counter, negating any need to calculate or estimate particle exposure. The process of particle introduction, assessed using Trypan blue dye exclusion, had no effect on cell viability. In combination with a differential mobility classifier, the EPDExS can deliver select particle diameters to cells. The ability to control the diameter and number of particles deposited permits in vitro toxicity studies of particulate matter using different particle dosage metrics, i.e., particle number and size, surface area and mass. Finally, because EPDExS introduces particles directly from the aerosol, it can be used to expose cells grown at air/liquid interfaces.

Physiological bases of genetic differences in cannibalism behavior of the confused flour beetle Tribolium confusum

Physiological causes of genetic differences in cannibalism were examined to gain a better understanding of constraints on behavior evolution. Cannibalism has complex population level consequences in Tribolium confusum, including dramatic effects on population size. Laboratory strains with low and high cannibalism rates, obtained through inbreeding, have maintained distinct levels of cannibalism for over two decades even in the absence of artificial selection to maintain the differences. Why strains differ in their cannibalism rates was examined by measuring: (1) the nutritional benefit from cannibalism in both nutritionally good and poor environments, and (2) the possibility that eggs are an important source of water. How strains achieve differences in cannibalism was examined by testing for differences between strains in their ability to find eggs and in their tendency to eat eggs. Beetles from both strains survive equally well in a nutritionally good environment, but they accomplish this in different ways. The low cannibalism strain has high survivorship with and without cannibalism. The high cannibalism strain has low survivorship when not fed eggs and survivorship equivalent to the low cannibalism strain when fed eggs, suggesting it compensates for poor nutritional adaptation by eating eggs. The strains also differ in feeding behavior; beetles from the high cannibalism strain have a higher appetite for eggs. Beetles from the two strains did not differ in locomotor activity, search efficiency, or need for water. The observed behavioral and nutritional differences may contribute to the maintenance of different levels of cannibalism.