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Ancient Near Eastern (ANE) texts should be interpreted against the background of the magico-mythical cosmology of their time, and the Bible is no exception. Earlier scholars were, however, hesitant to recognise this reality as a result of disagreement over how to define myths and because of the problematic idealistic framework that they followed. This framework viewed biblical religion as superior to other ANE religions and thus devoid of myths and the belief in magic. It is, however, argued that the Bible contains both myths and a belief in magic and shares the overarching ANE cosmology. The incompatibility of the scientific cosmology and the magico-mythical cosmology of the ANE causes special problems for modern readers. To prevent modern readers from habitually falling back on their scientific cosmology, and thereby misinterpreting the Bible, it is suggested that a cosmological approach should form the basic framework for all biblical hermeneutics.

The annual global incidence of cancer is projected to rise in 2035 to 25 million cases (13 million deaths), with 70% occurring in low- and middle-income countries (LMICs), where there is a severe shortfall in the availability of radiotherapy [[1]] – an essential component of overall curative and palliative cancer care. A 2015 report by the Global Task Force on Radiotherapy for Cancer Control estimated that by 2035 at least 5000 additional megavolt treatment machines would be needed to meet LMIC demands, together with about 30 000 radiation oncologists, 22 000 medical physicists and 80 000 radiation therapy technologists [[2]]. Among the main reasons for the shortfall identified in the workshop and thoroughly discussed in the Clinical Oncology special issue on radiotherapy in LMICs [[3]] are: (i) the initial cost of linear accelerators, (ii) the cost of service on the machines and (iii) a shortage of trained personnel needed to deliver safe, effective and high-quality treatment. A number of authors who contributed to the Clinical Oncology special issue are participating in the CERN, International Cancer Expert Corps (ICEC), Science and Technology Facilities Council (STFC) collaborative effort described in this editorial (Aggarwal, Coleman, Court, Grover, Palta, Van Dyk and Zubizarreta).

Throughout the international railway community, there are many different designs of elastic fastening systems that have been developed to meet a variety of design specifications and performance expectations. Historically, in North America, the most common types of fastening systems used for concrete crossties are the Safelok I or e-clip systems. In recent years railroads have begun implementing the Skl-style (W) fastening system with concrete crossties in existing and new heavy haul freight railroad mainlines. The magnitude of lateral force applied to the Skl-style fastening system is important information for both design and application purposes. Despite this importance, the lateral force applied to the Skl-style fastening system in a heavy haul freight railroad environment has never been quantified to date. To better understand how the Skl-style system performs under the magnitude of lateral loads observed on heavy haul freight railroads, research was conducted by the Rail Transportation and Engineering Center (RailTEC) at the University of Illinois at Urbana-Champaign (UIUC). The focus of this paper is on laboratory characterization of the lateral load path through the Skl-style fastening system using novel instrumentation techniques that are subjected to heavy haul freight railroad loading conditions. The investigation of fastening system performance included an evaluation of lateral load distribution through the track superstructure, and a single fastening system. Laboratory experimentation concluded that lateral wheel load is primarily distributed to three crossties, the relationship between lateral wheel load and lateral force resisted by field side angled guide plate is non-linear, and that the design of the Skl-style fastening system allows lateral force to be transferred into the crosstie below the worst case concrete compressive fatigue strength. The observations from this study will assist the rail industry in improving fastening system design and developing mechanistic track structure design method.

Recent years have seen various reviews on the lack of access to radiotherapy often based on geographic regions of the world such as Africa, Asia Pacific, Europe, Latin America and North America. Countries are often defined by their national income per capita levels based on World Bank definitions of high income, upper middle income, lower middle income and low income. Within the world regions, there are significant variations in gross national income (GNI) per capita among the different countries, and even within similar income levels, large variations exist. This report presents the actual status of radiotherapy and analyses the current needs and costs to provide full access in the different regions of the world. Actual coverage of the needs ranges from 34% in Africa to over 92% in Europe to about double the needs in North America. In line with this, proportional additional investments and operational costs are as high as more than 200% in Africa to almost none in North America. Two world regions face substantial challenges: Africa, based on the important demands to build new capacity and subsequently to maintain operational capability; and Asia Pacific, due to its high population density, translating into large absolute needs in radiotherapy treatments and resources, and hence in associated costs. With the data highlighting a large variability of GNI/capita even within similar income levels in the various world regions, it is expected that additional investment in resources and costs may be more dependent on income level of the country than on the GNI group or the geographic region of the world.

A sustained increase in heavy axle loads and cumulative freight tonnages, coupled with increased development of high-speed passenger rail, is placing an increasing demand on railway infrastructures. Some of the most-critical areas of the infrastructure in need of further research are track components used in high-speed passenger, heavy haul and shared infrastructure applications. In North America, many design guidelines for these systems use historical wheel loads and design factors that may not necessarily be representative of the loading currently experienced on rail networks. Without a clear understanding of the nature of these loads and how design processes reflect them, it is impossible to adequately evaluate the superstructure in order to make design improvements. Therefore, researchers at the University of Illinois at Urbana-Champaign are conducting research to lay the groundwork for an improved and thorough understanding of the loading environment imparted into the track structure using wheel loads captured by wheel impact load detectors. This paper identifies several design factors that have been developed internationally, and evaluates their effectiveness based on wheel loads using several existing and new evaluative metrics. New design factors are also developed to represent the wheel-loading environment in a different manner. An evaluative approach to historical and innovative design methodologies will provide improvements to designs, based on actual loading experienced on today’s rail networks.

A railroad sleeper and fastening system is composed of many unique parts that, when assembled, attempt to distribute train wheel loads through the system without damaging the components while providing a safe running surface and track geometry for trains to operate on. In order to evaluate the health of the sleeper and fastening system, there are many areas that need to be examined to ensure that key limit states are not exceeded. One key area of concern is the sleeper rail seat, specifically the load magnitude applied to this surface. There are many different metrics to evaluate the rail seat load, and this report will compare these to determine which should be used given different operating and infrastructure conditions. A sample calculation for each methodology was completed in order to compare how the methods differ, and to more fully understand the strengths and limitations of each methodology. These calculations were completed both with a static load and dynamic load, as the individual approaches account for dynamic loads in a variety of ways. For the purpose of this report, these calculations were completed assuming a concrete sleeper infrastructure. The goal of this paper is to provide an evaluation of the existing rail seat load calculation methodologies to improve current concrete sleeper and fastening system design standards through the application of mechanistic design principles.

The pillars constructivist model is designed to offer a unifying clinical paradigm to support consistent learning opportunities across diverse configurations of community and public health clinical sites. Thirty-six students and six faculty members participated in a mixed methods evaluation to assess the model after its inaugural semester of implementation. The evaluation methods included a rating scale that measures the model’s ability to provide consistent learning opportunities at both population health and direct care sites, a case study to measure student growth within the five conceptual pillars, and a faculty focus group. Results revealed that the model served as an effective means of clinical education to support the use of multiple, small-scale public health sites. Although measurements of student growth within the pillars are inconclusive, the findings suggest efficacy. The authors recommend the continued use of the pillars constructivist model in baccalaureate programs, with further study of the author-designed evaluation tools. [ J Nurs Educ. 2015;54(2):97–101.]

Purpose: To evaluate gross tumor volume (GTV) changes for non‐small cell lungcancer(NSCLC) patients using daily megavoltage CT (MVCT) studies acquired before each treatment fraction on helical tomotherapy, and to relate the potential benefit of adaptive image‐guidedradiotherapy to changes in GTV. Methods: 17 patients were prescribed 30 fractions of radiotherapy on helical tomotherapy for NSCLC at London Regional Cancer Program from December 2005 to March 2007. The GTV was contoured on the daily MVCT studies of each patient. Adapted plans were created using merged MVCT‐kVCT image sets to investigate the advantages of replanning for patients with differing GTV regression characteristics. Results: The average GTV change observed over 30 fractions was −38%, ranging from −12 to −87%. No significant correlation was observed between GTV change and patient's physical or tumor features. The pattern of GTV changes of the 17 patients could be broadly divided into 3 groups with distinctive potential for benefit from adaptive planning. Conclusions: GTV changes are difficult to predict quantitatively based on patient or tumor characteristics. If changes do occur, there are points in time during the treatment course when it may be appropriate to adapt the plan to improve sparing of normal tissues. If the GTV decreases by greater than 30% at any point in the first twenty fractions of treatment, adaptive planning is appropriate to further improve the therapeutic ratio.

In North America, many design guidelines for track components in shared-use railway infrastructure use historic wheel loads that may not necessarily be representative of those seen on rail networks today. Without a clear understanding of the nature of these loads, it is impossible to evaluate the superstructure adequately to make design improvements. Therefore, researchers at the University of Illinois at Urbana–Champaign are conducting research to lay the groundwork for an improved and thorough understanding of the loading environment entering the track structure. Wheel impact load detectors (WILDs) have been used in North America for decades to identify defective wheels that could damage the rail infrastructure or result in a rolling stock failure. Information regarding loads obtained from a WILD can be used to identify trends that not only provide a clearer picture of the existing loading environment created by widely varied traffic characteristics but also can be used in future design and maintenance planning of infrastructure according to the anticipated traffic. The current trends in wheel loads across the North American rail network are discussed, and the effects of speed and other sources of load variability are investigated. In addition to WILD data, instrumented wheel set data were used to gain insight into loading conditions, and preliminary analyses of these data are included. Ultimately this work will lead to useful distinctions of loads for improved design methodologies that are specific to the intended type of traffic traversing a given route or network.

Closing the gap in cancer care within low- and middle-income countries and in indigenous and geographically isolated populations in high-income countries requires investment and innovation. This is particularly true for radiotherapy, for which the global disparity is one of the largest in healthcare today. New models and paradigms and non-traditional collaborations have been proposed to improve global equity in cancer control. We describe recent initiatives from within the radiation oncology community to increase access to treatment, build the low- and middle-income countries' radiation oncology workforce, mobilise more professionals from within high-income countries and raise awareness of the global need for equitable cancer care.

Objectives A new guideline for the early respiratory management of preterm infants that included early nCPAP and INSURE was recently introduced in our NICU. This case series describes the clinical courses of a group of preterm infants managed according to this guideline, and reports the rates of successful extubation within 30 minutes of surfactant administration with and without the use of naloxone and adverse events encountered. Study design Descriptive case series of all preterm babies admitted to our unit who were candidates for INSURE procedure with premedication from August 2012 to August 2013. Results A total of 31 infants were included with a mean birth weight of 1178 grams and a mean gestational age of 28.4 weeks. Twelve out of thirteen (92%) infants in the naloxone group were extubated within 30 minutes of surfactant administration while only 12/18 (67%) in the non-naloxone group were extubated within the same time frame. No adverse reactions were noted with naloxone usage in this context. Conclusion Naloxone can be effective in reversing the respiratory depressive effect of analgesic premedication and in turn facilitates expeditious extubation in some preterm infants intubated for INSURE procedure.

Background: Globally, cancer is the second leading cause of death. Low- and middle-income countries (LMICs) especially lack the sufficient healthcare and oncology workforces needed to screen, diagnose and treat individuals with cancer. While traditional academic and training programs designed to produce healthcare professionals in these countries fill a critical role, few programs exist that maintain, develop, and increase the knowledge, skills, and professional performance of current healthcare and oncology workforces. Mentoring partnerships and twinning programs can provide ongoing education and training that strengthen and build workforce capacity and capability for the full scope of cancer care. Aim: The goal is to achieve resource-appropriate multimodality cancer-care using guideline- and protocol-based education and training and also to develop the capability to conduct world quality research. The model utilizes in-person, in-country site visits lasting from several weeks to months and ongoing connectivity through weekly telemedicine video conferences. Methods: The International Cancer Expert Corps (ICEC) and partner organizations are establishing a network of global and multisectoral partnerships that builds human capacity and capability needed to establish sustainable cancer programs that function at world-class standards. The three-fold mentor-mentee approach ( www.iceccancer.org ) is built by 1) enlisting hubs of expertise to include academic medical centers/universities, private practices and an ICEC Central Hub, 2) enrolling the breadth of expert-mentors needed from a university, practice, professional society and interested individuals, and 3) identifying centers in LMICs - clinics/hospitals/and other care delivery sites in underserved areas, and associates - physicians/allied healthcare workers- seeking mentoring and education. Results: Recent implementation of the ICEC 5-Step Progression Plan provides guidance and serves as an assessment tool for measuring progress between the hubs-centers programs and expert-associate. Twinning programs (hubs-ICEC centers) have been established in multiple sites worldwide including in Africa, Asia and Eurasia. Conclusion: Implementation of the ICEC 5-Step Progression Plan provides a platform from which to track the current stages and progress of twinning mentor-mentee programs, and to evaluate new programs. This information guides the programs and also provides metric-based investment in global health. Critically as the skills in associates and ICEC centers grows, they achieve expert-mentor status and centers become hubs to serve the surrounding regions, thereby enabling geometric growth in cancer care to meet the needs of the growing global burden of cancer. The content is the personal opinion of the authors and not their organizations.

The goal of this study is to validate a deformable model using contour-driven thin-plate splines for application to radiation therapy dose mapping. Our testing includes a virtual spherical phantom as well as real computed tomography (CT) data from ten prostate cancer patients with radio-opaque markers surgically implanted into the prostate and seminal vesicles. In the spherical mathematical phantom, homologous control points generated automatically given input contour data in CT slice geometry were compared to homologous control point placement using analytical geometry as the ground truth. The dose delivered to specific voxels driven by both sets of homologous control points were compared to determine the accuracy of dose tracking via the deformable model. A 3D analytical spherically symmetric dose distribution with a dose gradient of approximately 10% per mm was used for this phantom. This test showed that the uncertainty in calculating the delivered dose to a tissue element depends on slice thickness and the variation in defining homologous landmarks, where dose agreement of 3-4% in high dose gradient regions was achieved. In the patient data, radio-opaque marker positions driven by the thin-plate spline algorithm were compared to the actual marker positions as identified in the CT scans. It is demonstrated that the deformable model is accurate (approximately 2.5 mm) to within the intra-observer contouring variability. This work shows that the algorithm is appropriate for describing changes in pelvic anatomy and for the dose mapping application with dose gradients characteristic of conformal and intensity modulated radiation therapy.

The sensitivity of estimates of α/β for prostate tumours to dose heterogeneity in 125I brachytherapy implants, as well as to variation in selected radiobiological parameters, is analysed. The tumour control probabilities of brachytherapy and external beam radiotherapy are equated for ranges of α, Tpot, RBE and external beam dose. For each combination of parameters, the equality is used to derive the value of α/β. Different clinical (non-uniform) brachytherapy dose distributions, and three uniform brachytherapy dose distributions (120, 144 and 160 Gy) are used. For 'nominal' input parameter values of Tpot = 45 days, α = 0.2 Gy−1, RBE = 1.4, and an external beam dose of 70 Gy, the values obtained for α/β ranged between 2.1 and 12.3 Gy for all of the clinical DVHs, between 2.1 and 3.8 Gy for the better quality clinical implants and between 1.0 and 1.8 Gy for the uniform brachytherapy doses. When only 2% of the volume receiving the lowest dose is omitted from the clinical DVHs, the estimated α/β values ranged between 1.4 and 2.1 Gy. When ranges of input parameters were also considered, the overall range of α/β values for the clinical brachytherapy dose distributions lay between 1.1 and 12.3 Gy for the three best clinical implants, and between 0.7 and 6.3 Gy for uniform doses. We conclude that estimation of α/β without taking into account dose heterogeneity and inter-patient variation may underestimate the actual value α/β.

The Union for International Cancer Control (UICC) is a membership-based, non-governmental organization with a mandate to “…to unite the cancer community to reduce the global cancer burden, to promote greater equity, and to integrate cancer control into the world health and development agenda.” COMP is an associate member of the UICC. It is well recognized by the UICC that there are major gaps between high, and low and middle income countries, in terms of access to cancer services including access to radiation therapy. In this context, the UICC has developed a Global Task Force on Radiotherapy for Cancer Control with a charge to answer a single question: “What does it cost to close the gap between what exists today and reasonable access to radiotherapy globally?” The Task Force consists of leaders internationally recognized for their radiation treatment related expertise (radiation oncologists, medical physicists, radiation therapists) as well as those with global health and economics specialization. The Task Force has developed three working groups: (1) to look at the global burden of cancer; (2) to look at the infrastructure requirements (facilities, equipment, personnel); and (3) to consider outcomes in terms of numbers of lives saved and palliated patients. A report is due at the World Cancer Congress in December 2014. This presentation reviews the infrastructure considerations under analysis by the second work group. The infrastructure parameters being addressed include capital costs of buildings and equipment and operating costs, which include human resources, equipment servicing and quality control, and general overhead.

Medical Physicists have a general understanding of uncertainties in the radiation treatment process, both with respect to dosimetry and geometry. However, there is a desire to be more quantitative about uncertainty estimation. A recent International Atomic Energy Agency (IAEA) report (about to be published) recommends that we should be as “accurate as reasonably achievable, technical and biological factors being taken into account”. Thus, a single recommendation as a goal for accuracy in radiation therapy is an oversimplification. That report also suggests that individual clinics should determine their own level of uncertainties for their specific treatment protocols. The question is “how do we implement this in clinical practice”? AAPM Monograph 35 (2011 AAPM Summer School) addressed many specific aspects of uncertainties in each of the steps of a course of radiation treatment. The intent of this symposium is: (1) to review uncertainty considerations in the entire radiation treatment process including uncertainty determination for each step and uncertainty propagation for the total process, (2) to consider aspects of robust optimization which optimizes treatment plans while protecting them against uncertainties, and (3) to describe various methods of displaying uncertainties and communicating uncertainties to the relevant professionals. While the theoretical and research aspects will also be described, the emphasis will be on the practical considerations for the medical physicist in clinical practice.Learning Objectives: 1. To review uncertainty determination in the overall radiation treatment process. 2. To consider uncertainty modeling and uncertainty propagation. 3. To highlight the basic ideas and clinical potential of robust optimization procedures to generate optimal treatment plans that are not severely affected by uncertainties. 4. To describe methods of uncertainty communication and display.

Welcome and Introduction - Lawrence N. Rothenberg This symposium is one a continuing series of presentations at AAPM Annual Meetings on the historical aspects of medical physics, radiology, and radiation oncology that have been organized by the AAPM History Committee. Information on previous presentations including “Early Developments in Teletherapy” (Indianapolis 2013), “Historical Aspects of Cross-Sectional Imaging” (Charlotte 2012), “Historical Aspects of Brachytherapy” (Vancouver 2011), “50 Years of Women in Medical Physics” (Houston 2008), and “Roentgen's Early Investigations” (Minneapolis 2007) can be found in the Education Section of the AAPM Website. The Austin 2014 History Symposium will be on “Evolution of Radiation Treatment Planning.” Overview - Radhe Mohan Treatment planning is one of the most critical components in the chain of radiation therapy of cancers. Treatment plans of today contain a wide variety of sophisticated information conveying the potential clinical effectiveness of the designed treatment to practitioners. Examples of such information include dose distributions superimposed on three- or even four-dimensional anatomic images; dose volume histograms, dose, dose-volume and dose-response indices for anatomic structures of interest; etc. These data are used for evaluating treatment plans and for making treatment decisions. The current state-of-the-art has evolved from the 1940s era when the dose more » to the tumor and normal tissues was estimated approximately by manual means. However, the symposium will cover the history of the field from the late-1950's, when computers were first introduced for treatment planning, to the present state involving the use of high performance computing and advanced multi-dimensional anatomic, functional and biological imaging, focusing only on external beam treatment planning. The symposium will start with a general overview of the treatment planning process including imaging, structure delineation, assignment of dose requirements, consideration of uncertainties, selection of beam configurations and shaping of beams, and calculations, optimization and evaluation of dose distributions. This will be followed by three presentations covering the evolution of treatment planning, which parallels the evolution of computers, availability of advanced volumetric imaging and the development of novel technologies such as dynamic multi-leaf collimators and online image guidance. This evolution will be divided over three distinct periods - prior to 1970's, the 2D era; from 1980 to the mid-1990's, the 3D era; and from the mid 1990's to today, the IMRT era. When the World was Flat: The Two-Dimensional Radiation Therapy Era” - Jacob Van Dyk In the 2D era, anatomy was defined with the aid of solder wires, special contouring devices and projection x-rays. Dose distributions were calculated manually from single field, flat surface isodoses on transparencies. Precalculated atlases of generic dose distributions were produced by the International Atomic Energy Agency. Massive time-shared main frames and mini-computers were used to compute doses at individual points or dose distributions in a single plane. Beam shapes were generally rectangular, with wedges, missing tissue compensators and occasional blocks to shield critical structures. Dose calculations were measurement-based or they used primary and scatter calculations based on scatter-air ratio methodologies. Dose distributions were displayed on line printers as alpha-numeric character maps or isodose patterns made with pen plotters. More than Pretty Pictures: 3D Treatment Planning and Conformal Therapy - Benedick A. Fraass The introduction of computed tomography allowed the delineation of anatomy three-dimensionally and, supported partly by contracts from the National Cancer Institute, made possible the introduction and clinical use of 3D treatment planning, leading to development and use of 3D conformal therapy in the 1980's. 3D computer graphics and 3D anatomical structure definitions made possible Beam's Eye View (BEV) displays, making conformal beam shaping and much more sophisticated beam arrangements possible. These conformal plans significantly improved target dose coverage as well as normal tissue sparing. The use of dose volume histograms, gross/clinical/planning target volumes, MRI and PET imaging, multileaf collimators, and computer-controlled treatment delivery made sophisticated planning approaches practical. The significant improvements in dose distributions and analysis achievable with 3D conformal therapy made possible formal dose escalation and normal tissue tolerance clinical studies that set new and improved expectations for improved local control and decreasing complications in many clinical sites. From the Art to the State of the Art: Inverse Planning and IMRT - Thomas R. Bortfeld While the potential of intensity modulation was recognized in the mid- 1980's, intensity-modulated radiotherapy (IMRT) did not become a reality until the mid-1990's. Broad beams of photons could be sub-divided into narrow beamlets whose intensities could be determined using sophisticated optimization algorithms to appropriately balance tumor dose with normal tissue sparing. The development of dynamic multi-leaf collimators (on conventional linear accelerators as well as in helical delivery devices) enabled the efficient delivery of IMRT. The evolution of IMRT planning is continuing in the form of Volumetric Modulated Arc Therapy (VMAT) and through advanced optimization tools, such as multi-criteria optimization, automated IMRT planning, and robust optimization to protect dose distributions against uncertainties. IMRT also facilitates “dose painting” in which different sub-volumes of the target are prescribed different doses. Clearly, these advancements are being made possible by the increasing power and lower cost of computers and developments in other fields such as imaging and operations research. Summary - Radhe Mohan The history does not end here. The advancement of treatment planning is expected to continue, leading to further automation and improvements in conformality and robustness of dose distributions, particularly in the area of particle therapy. Radiobiological modeling will gain emphasis as part of the planning process. Learning Objectives: The scope of changes in technology and the capabilities of radiation treatment planning The impact of these changes in the quality of treatment plans and optimality of dose distributions The impact of development in other fields (imaging, computers, operations research, etc.) on the evolution of radiation treatment planning. « less

OBJECTIVES: To determine the relationship between ethical reasoning and gender and occupation among a group of male and female nurses and doctors. DESIGN: Partialist and impartialist forms of ethical reasoning were defined and singled out as being central to the difference between what is known as the "care" moral orientation (Gilligan) and the "justice" orientation (Kohlberg). A structured questionnaire based on four hypothetical moral dilemmas involving combinations of (health care) professional, non-professional, life-threatening and non-life-threatening situations, was piloted and then mailed to a randomly selected sample of doctors and nurses. SETTING: 400 doctors from Victoria, and 200 doctors and 400 nurses from New South Wales. RESULTS: 178 doctors and 122 nurses returned completed questionnaires. 115 doctors were male, 61 female; 50 nurses were male and 72 were female. It was hypothesised that there would be an association between feminine subjects and partialist reasoning and masculine subjects and impartialist reasoning. It was also hypothesised that nurses would adopt a partialist approach to reasoning and doctors an impartialist approach. No relationship between any of these variables was observed.

Modern three-dimensional (3-D) photon dose calculation algorithms need to be fast and accurate if they are to be practical for treatment optimization. Refinements to a previously proposed finite-size pencil beam (FSPB) method are presented in order to fulfill these needs. Specifically, a fast Fourier transform (FFT) convolution technique is used to speed calculation of the FSPB; the fluence spectrum is modeled, and the effects of finite source size, a Gaussian x-ray source intensity profile and partial transmission through a multileaf collimator (MLC) leaf are approximated. The use of FFT techniques in the calculation of small diverging fields involves approximations that are investigated for a 6 MV beam and shown to introduce errors that vary with energy but do not exceed 0.7% on the central axis. Dose distributions calculated by FSPB superposition are in excellent agreement with those calculated by full field FFT convolution. Two key advances over the original implementation of the FSPB model are demonstrated: the fast calculation of the FSPB facilitates development, and the incorporation of realistic beam parameters enables accurate modeling of clinical beams.

A sustained increase in heavy axle loads and cumulative freight tonnages, coupled with increased development of high speed passenger rail, is placing an increasing demand on railway infrastructure. Some of the most critical areas of the infrastructure in need of further research are track components used in high speed passenger, heavy haul, and shared infrastructure applications. In North America, many design guidelines for these systems use historical wheel loads that may not necessarily be representative of those seen on rail networks today. Without a clear understanding of the nature of these loads, it is impossible to adequately evaluate the superstructure to make design improvements. Therefore, researchers at the University of Illinois at Urbana-Champaign (UIUC) are conducting research to lay the groundwork for an improved and thorough understanding of the loading environment entering the track structure. Wheel impact load detectors (WILDs) have been used in North America for decades to identify bad-acting wheels that could damage the rail infrastructure or result in a rolling stock failure. The WILD measures vertical and lateral rail loads imparted by the wheel at the wheel-rail interface, along with other pertinent information related to the specific wheel, car, and train passing the instrumented site. This information can be used to identify and classify trends in the loading features and other characteristics of the rolling stock. These trends not only provide a clearer picture of the existing loading environment created by widely varied traffic characteristics, but can be used in future design and maintenance planning of infrastructure according to the anticipated traffic. This paper will discuss the current trends in wheel loads across the North American rail network while investigating the effects of speed on dynamic and impact loads. Ultimately this work should lead to useful distinctions of loads for improved design methodologies that are specific to the intended type of traffic traversing a given route or network.Copyright © 2013 by ASME

The skin blood flow and venoarteriolar response (VAR) in the feet of young type 1 diabetic patients were studied with laser Doppler flowmetry. The findings were correlated with diabetic microangiopathy in 24 young patients without neuropathy—14 with diabetic microangiopathy, 10 without—and 10 healthy controls. In type 1 diabetic patients the skin blood flow, after lowering of the leg, was significantly higher in the microangiopathic patients than in the healthy controls, 5.3 ± 1.4 vs 3 ± 1.5, (P < 0.01). The VAR index was significantly lower in both groups of diabetics as compared with controls. In conclusion laser Doppler flowmetry is an easy and reliable noninvasive technique to evaluate skin blood flow abnormalities in the feet of young type 1 diabetic patients, including those without neuropathy. The VAR has been found abnormal in the feet of young diabetic patients with and without microangiopathy, regardless of the presence of peripheral neuropathy.

Purpose: The last few years have seen a significant growth of interest in the global radiation therapy crisis. Various organizations are quantifying the need and providing aid in support of addressing the shortfall existing in many low-to-middle income countries (LMICs). The Lancet Oncology Commission report (Lancet Oncol. Sep;16(10):1153-86, 2015) projects a need of 22,000 new medical physicists in LMICs by 2035 if there is to be equal access globally. With the tremendous demand for new facilities, equipment and personnel, it is very important to recognize quality and safety considerations and to address them directly. Methods: A detailed examination of quality and safety publications was undertaken. A paper by Dunscombe (Front. Oncol. 2: 129, 2012) reviewed the recommendations of 7 authoritative reports on safety in radiation therapy and found the 12 most cited recommendations, summarized in order of most to least cited: training, staffing, documentation/standard operating procedures, incident learning, communication/questioning, check lists, QC/PM, dosimetric audit, accreditation, minimizing interruptions, prospective risk assessment, and safety culture. However, these authoritative reports were generally based on input from high income contexts. In this work, the recommendations were analyzed with a special emphasis on issues that are significant in LMICs. Results: The review indicated that there are significant challenges in LMICs with training and staffing ranking at the top in terms quality and safety. Conclusion: With the recognized need for expanding global access to radiation therapy, especially in LMICs, and the backing by multiple support organizations, quality and safety considerations must be overtly addressed. While multidimensional, training and staffing are top priorities. The use of outdated systems with poor interconnectivity, coupled with a lack of systematic QA in high patient load settings are additional concerns. Any support provided to lower resourced settings must address the multiple facets associated with these quality and safety indicators.

Nursing programs are challenged to prepare future nurses to provide care and affect determinants of health for individuals and populations. This article advances a pedagogical model for clinical education that builds concepts related to both population-level care and direct care in the community through a contextual learning approach. Because the conceptual pillars and hybrid constructivist approach allow for conceptual learning consistency across experiences, the model expands programmatic capacity to use diverse community clinical sites that accept only small numbers of students. The concept-based and hybrid constructivist learning approach is expected to contribute to the development of broad intellectual skills and lifelong learning. The pillar concepts include determinants of health and nursing care of population aggregates; direct care, based on evidence and best practices; appreciation of lived experience of health and illness; public health nursing roles and relationship to ethical and professional formation; and multidisciplinary collaboration. [ J Nurs Educ . 2014;53(3, Suppl.):S11–S18.]

Serum angiotensin-converting enzyme (ACE) was measured in 150 insulin-dependent diabetes mellitus (IDDM) patients and 72 healthy subjects by radioassay, using [3H]-hippuryl-glycyl-glycine as a substrate. Mean (SD) serum ACE activity in diabetic patients was 120 +/- 33 nmol ml-1 min-1 (range 46-215) and was significantly increased by 56% compared to control values (77 +/- 23 nmol ml-1 min-1, range 46-125, P0.001). ACE activity125 nmol ml-1 min-1 was observed in 60 of 150 IDDM patients. 96 IDDM patients were normoalbuminuric (22 mg 24 h-1) and 49 patients were micro- or macroalbuminuric (range 22-6010 mg 24 h-1). Micro- and macroalbuminuric IDDM patients were found to have significantly greater ACE activity values than normoalbuminuric patients (128 +/- 36 vs. 115 +/- 30 nmol ml-1 min-1, P = 0.025). Metabolically well-controlled IDDM patients (glycosylated haemoglobinor = 8%) had lower ACE activity values than the patients with glycosylated haemoglobin greater than 8% (109 +/- 20 vs. 127 +/- 32 nmol ml-1 min-1, P0.02). A significant correlation between degree of metabolic control and ACE activity was found (r = 0.435, P0.001) so that an increase in one glycosylated quartile unit is accompanied by an increase in ACE activity of 10.5 nmol ml-1 min-1. Thus ACE activity in the serum of IDDM patients was increased by 56% in 40% of the patients. It was increased in IDDM patients without complications and in patients with retinopathy or nephropathy.(ABSTRACT TRUNCATED AT 250 WORDS)

This article investigates the impact of change and organisational culture on the growth and development of the South African Military Academy. It explores the impact of Nationalist Party rule since 1948 and black majority rule since 1994 on the institutional culture of the South African military and how that influenced the development of the Military Academy. This is intertwined with an investigation of the nature and impact of the diverging military and academic subcultures at the Academy. The article contends that, together with the historical exclusion of blacks and women from the military, the marginalisation of white English-speaking citizens by Nationalist Party rule denied the Academy the exploitation of a significant portion of the country’s human resource potential in the interest of institutional development. The same happened with the introduction of racial quotas and the marginalisation of whites since 1994. The Military Academy has, furthermore, historically been too reflective of the organisational culture of the South African National Defence Force and its predecessors instead of informing that culture to meet the challenges of military professionalism. The Academy has a potentially vital educational role to play in the South African and Sub-Saharan African militaries, but requires some changes in its organisational culture to fulfil that mission.Keywords: South African Military Academy, organisational culture, military culture, military education, Stellenbosch UniversityDisciplines: Military History, Industrial Psychology

The process of radiation therapy is complex and involves many steps. At each step, comprehensive quality assurance procedures are required to ensure the safe and accurate delivery of a prescribed radiation dose. This report deals with a comprehensive commissioning and ongoing quality assurance program specifically for treatment planning computers. Detailed guidelines are provided under the following topics: (a) computer program and system documentation and user training, (b) sources of uncertainties and suggested tolerances, (c) initial system checks, (d) repeated system checks, (e) quality assurance through manual procedures, and in vivo dosimetry, and (f) some additional considerations including administration and manpower requirements. In the context of commercial computerized treatment planning systems, uncertainty estimates and achievable criteria of acceptability are presented for: (a) external photon beams, (b) electron beams, (c) brachytherapy, and (d) treatment machine setting calculations. Although these criteria of acceptability appear large, they approach the limit achievable with most of today's treatment planning systems. However, developers of new or improved dose calculation algorithms should strive for the goal recommended by the International Commission of Radiation Units and Measurements of 2% in relative dose accuracy in low dose gradients or 2 mm spatial accuracy in regions with high dose gradients. For brachytherapy, the aim should be 3% accuracy in dose at distances of 0.5 cm or more at any point for any radiation source. Details are provided for initial commissioning tests and follow-up reproducibility tests. The final quality assurance for each patient is to perform an independent manual check of at least one point in the dose distributions, as well as the machine setting calculation. As a check of the overall treatment planning process, in vivo dosimetry should be performed on a select number of patients.

An experiment has been performed in which fractionated irradiation was given to the whole thorax of Sprague-Dawley rats with schedules chosen so that doses per fraction and overall treatment time were changed independently. Damage was monitored by lethality. The data have been analyzed to yield dose per fraction and time parameters using multiple non-linear regression analysis. The results show that a linear-quadratic cell survival formula, extended to include an exponential time component to account for proliferation or slow repair during the treatment, can predict isoeffective doses to within 7% accuracy over a wide range of times (3.5–49 days) and doses per fraction (1.8–10.2 Gy). Other isoeffect formulae based on the linear-quadratic and empirical power law functions were also evaluated. A linear-quadratic formula with a time dependent alpha parameter fitted the data particularly well. This result suggests an alternative underlying mechanism and requires further investigation.

The aim of this study was to determine the effect of reducing the number of image guidance sessions and patient-specific target margins on the dose distribution in the treatment of prostate cancer with helical tomotherapy. 20 patients with prostate cancer who were treated with helical tomotherapy using daily megavoltage CT (MVCT) imaging before treatment served as the study population. The average geometric shifts applied for set-up corrections, as a result of co-registration of MVCT and planning kilovoltage CT studies over an increasing number of image guidance sessions, were determined. Simulation of the consequences of various imaging scenarios on the dose distribution was performed for two patients with different patterns of interfraction changes in anatomy. Our analysis of the daily set-up correction shifts for 20 prostate cancer patients suggests that the use of four fractions would result in a population average shift that was within 1 mm of the average obtained from the data accumulated over all daily MVCT sessions. Simulation of a scenario in which imaging sessions are performed at a reduced frequency and the planning target volume margin is adapted provided significantly better sparing of organs at risk, with acceptable reproducibility of dose delivery to the clinical target volume. Our results indicate that four MVCT sessions on helical tomotherapy are sufficient to provide information for the creation of personalised target margins and the establishment of the new reference position that accounts for the systematic error. This simplified approach reduces overall treatment session time and decreases the imaging dose to the patient.

Currently, megavoltage CT studies in most centres with tomotherapy units are performed prior to every treatment for patient set-up verification and position correction. However, daily imaging adds to the total treatment time, which may cause patient discomfort as well as results in increased imaging dose. In this study, four alternative megavoltage CT imaging protocols (images obtained: during the first five fractions, once per week, alternating fractions and daily on alternative weeks) were evaluated retrospectively using the daily position correction data for 42 patients with lung cancer. The additional uncertainty introduced by using a specific protocol with respect to the daily imaging, or residual uncertainty, was analysed on a patient and population bases. The impact of less frequent imaging schedules on treatment margin calculation was also analysed. Systematic deviations were reduced with increased imaging frequency, while random deviations were largely unaffected. Mean population systematic errors were small for all protocols evaluated. In the protocol showing the greatest error, the treatment margins necessary to accommodate residual errors were 1.2, 1.3 and 1.7 mm larger in the left-right, superior-inferior and anterior-posterior directions, respectively, compared with the margins calculated using the daily imaging data. The increased uncertainty because of the use of less frequent imaging protocols may be acceptable when compared with other sources of uncertainty in lung cancer cases, such as target volume delineation and motion because of respiration. Further work needs to be carried out to establish the impact of increased residual errors on dose distribution.

The magnitude and impact of the corrections required for calculated absorbed doses due to the presence of real anatomic inhomogeneities were studied in 100 “standard” clinical thoracic cases. Correction factor distributions were generated with the equivalent tissue-air ratio method. The correction factors at the point of target absorbed dose, the average within the high dose area, and the average and maximum within the irradiated lung tissue were determined. Results indicate that among patients undergoing similar treatment techniques and radiation energy, correction factors can vary greatly. The diversity in anatomy, geometry, and density emphasizes the need for patient-specific dose calculations if the appropriate accuracy is to be achieved. Even for simple parallel-opposed fields encompassing the mediastinal and bilateral lung regions, the correction at the point of target absorbed dose was found to be as much as 5 to 16% for photon energies between 60 Co and 25 MV. The average correction factor within the high dose region was generally comparable in value. For beams that traverse the lungs obliquely, the correction factor at the point of target absorbed dose was as large as 1.21 with 25 MV photons. These values correlated linearly with the lung pathlength preceding the point. Within lung tissues, the corrections were often more dramatic. Using the dose response curve for normal lung tolerance, the clinical consequence of ignoring the increased dose to lung tissue can be predicted. For 100 patients, the use of uncorrected dose would result in an underestimation of the risk for radiological radiation pneumonitis by 7% on average and by as much as 19% maximally. These data suggest that whenever lung tissue and/or tumor response levels are critical, as is often the case for radical therapy, multi-center trials, and dose response determination, inhomogeneity corrections should be implemented.

Risk factors associated with diabetic microvascular complications, with special reference to ethnic origin, were looked for in 231 young Jewish insulin-dependent diabetes mellitus (IDDM) patients with duration of diabetes ≥10 yr. Median age at diagnosis of diabetes was 9.2 yr (range 0.04–26.2 yr), and median duration of the disease was 15.3 yr (range 10.0–37.2 yr). Sixty-three percent of the patients were Ashkenazi Jews, and 37% were non-Ashkenazi Jews. HbA1 was evaluated every 3 mo in the last 10 yr of follow-up, and albumin excretion rate was tested in three 24-h urine collections. Direct and indirect ophthalmoscopy was performed every year since diagnosis of diabetes, and if retinal pathology was suspected, color photographs were taken. Microalbuminuria was detected in 31% and macroalbuminuria in 7% of the patients. Nonproliferative and proliferative retinopathy was found in 44 and 12% of the patients, respectively. On logistic regression analysis, two variables were significantly and independently associated with diabetic nephropathy—non-Ashkenazi origin and mean HbA1 values over the first 5 of 10 yr of follow-up. Variables significantly and independently related to diabetic retinopathy were non-Ashkenazi origin, mean HbA1 values over the last 10 yr of follow-up, and duration of diabetes. Because non-Ashkenazi Jews in Israel are of lower socioeconomic status than Ashkenazi Jews, we stratified our patients according to their socioeconomic parameters, median HbA1 values, and duration of diabetes. Non-Ashkenazi patients were at a higher risk to develop complications in all strata. We further stratified patients into four quartiles according to mean HbA1 values; there was a steep increase in the risk to develop macroalbuminuria in the 4th quartile of HbA1 (odds ratio [OR] 4.3 vs. 1.2 in the 3rd quartile) and proliferative retinopathy (OR 13.0 in the 4th quartile of HbA, vs. 2.8 in the 3rd quartile). We conclude that non-Ashkenazi Jewish IDDM patients are at significant risk to develop microvascular complications, independent of their glycemic control, duration of diabetes, and socioeconomic status. Careful follow-up and special efforts toward improving glycemic control should be focused on high-risk subgroups of patients.

From 1975 to 1982, 32 patients with a diagnosis of anaplastic carcinoma of the thyroid were entered into a protocol of hyperfractionated accelerated radiotherapy. The tumor dose was 30-45 Gy at 1 Gy per fraction given 4 times a day at 3-h intervals. The results were disappointing with a median survival of less than 6 months. Two patients developed radiation myelopathy at 8 and 13 months, total spinal cord dose being 39.9 and 48.3 Gy, respectively. The risk of spinal cord damage was much higher than expected. The possible radiobiological causes and clinical implications are discussed.

Modern radiotherapy is characterised by a better target definition through medical imaging accompanied by significantly improved radiation delivery methods, most notably Intensity-Modulate Radiation Therapy (IMRT). However, the treatment can only be as accurate as the positioning of patients for their daily radiotherapy fraction. It is in this context that a number of imaging modalities - ranging from ultrasound to on-board kilovoltage imaging and computed tomography (CT) - have found their way into the treatment room where they verify accurate patient positioning prior to or even during delivery of radiation. Helical tomotherapy (HT) combines IMRT delivery with in-built image guidance using megavoltage CT scanning. This paper discusses the initial experience of different centres with IGRT using HT illustrated by a number of clinical examples from the installation in London in Ontario, Canada, one of the world's first HT sites. We found that HT allows the delivery of highly conformal radiation dose distributions combined with adequate daily image acquisition. An important feature of this unit is its seamless integration, which also includes a customised inverse treatment planning system and a quality assurance module for individual patients.

The global burden of cancer is growing rapidly with an estimated 15 million new cases per year worldwide in 2015, growing to 19 million by 2025 and 24 million by 2035. The largest component of this growth will occur in low-to-middle income countries (LMICs). About half of these cases will require radiation treatment. The gap for available cancer treatment, including radiation therapy, between high-income countries (HICs) and LMICs is enormous. Accurate data and quantitative models to project the needs and the benefits of cancer treatment are a critical first step in closing the large cancer divide between LMICs and HICs. In this context, the Union for International Cancer Control (UICC) has developed a Global Task Force on Radiotherapy for Cancer Control (GTFRCC) with a charge to answer the question as to what it will take to close the gap between what exists today and reasonable access to radiation therapy globally by 2035 and what the potential clinical and economic benefits are for doing this. The Task Force has determined the projections of cancer incidence and the infrastructure required to provide access to radiation therapy globally. Furthermore it has shown that appropriate investment not only yields improved clinical outcomes for millions of patients but that it also provides an overall economic gain throughout all the income settings where this investment is made. This symposium will summarize the facets associated with this global cancer challenge by reviewing the cancer burden, looking at the requirements for radiation therapy, reviewing the benefits of providing such therapy both from a clinical and economic perspective and finally by looking at what approaches can be used to aid in the alleviation of this global cancer challenge. The speakers are world renowned experts in global public health issues (R. Atun), medical physics (D. Jaffray) and radiation oncology (N. Coleman). Learning Objectives: 1. To describe the global cancer challenge and the corresponding potential benefits of addressing this challenge. 2. To describe what radiation therapy infrastructure, in terms of facilities, equipment and personnel, will be required to address this challenge. 3. To describe models of addressing personnel and infrastructure mobilization and capacity building within regions where significant cancer treatment disparities exist.

Helical tomotherapy (HT) is a novel treatment approach that combines Intensity-Modulate Radiation Therapy (IMRT) delivery with in-built image guidance using megavoltage (MV) CT scanning. The technique utilises a 6 MV linear accelerator mounted on a CT type ring gantry. The beam is collimated to a fan beam, which is intensity modulated using a binary multileaf collimator (MLC). As the patient advances slowly through the ring gantry, the linac rotates around the patient with a leaf-opening pattern optimised to deliver a highly conformal dose distribution to the target in the helical beam trajectory. The unit also allows the acquisition of MVCT images using the same radiation source detuned to reduce its effective energy to 3.5 MV, making the dose required for imaging less than 3 cGy. This paper discusses the major features of HT and describes the advantages and disadvantages of this approach in the context of the commercial Hi-ART system.

The goal of this work is to quantify the impact of image-guided conformal radiation therapy (CRT) on the dose distribution by correcting patient setup uncertainty and inter-fraction tumour motion. This was a retrospective analysis that used five randomly selected prostate cancer patients that underwent approximately 15 computed tomography (CT) scans during their radiation treatment course. The beam arrangement from the treatment plan was imported into each repeat CT study and the dose distribution was recalculated for the new beam setups. Various setup scenarios were then compared to assess the impact of image guidance on radiation treatment precision. These included (1) daily alignment to skin markers, thus representing a conventional beam setup without image guidance, (2) alignment to bony anatomy for correction of daily patient setup error, thus representing on-line portal image guidance, and (3) alignment to the 'CTV of the day' for correction of inter-fraction tumour motion, thus representing on-line CT or ultrasound image guidance. Treatment scenarios (1) and (3) were repeated with a reduced CTV to PTV margin, where the former represents a treatment using small margins without daily image guidance. Daily realignment of the treatment beams to the prostate showed an average increase in minimum tumour dose of 1.5 Gy, in all cases where tumour 'geographic miss' without image guidance was apparent. However, normal tissue sparing did not improve unless the PTV margin was reduced. Daily realignment to the tumour combined with reducing the margin size by a factor of 2 resulted in an average escalation in tumour dose of 9.0 Gy for all five static plans. However, the prescription dose could be escalated by 13.8 Gy when accounting for changes in anatomy by accumulating daily doses using nonlinear image registration techniques. These results provide quantitative information on the effectiveness of image-guided radiation treatment of prostate cancer and demonstrate that the dosimetric impact is patient dependent.

The goal of this research is to calculate the daily and cumulative dose distribution received by the radiotherapy patient while accounting for variable anatomy, by tracking the dose distribution delivered to tissue elements (voxels) that move within the patient. Non-linear image registration techniques (i.e., thin-plate splines) are used along with a conventional treatment planning system to combine the dose distributions computed for each 3D computed tomography (CT) study taken during treatment. For a clinical prostate case, we demonstrate that there are significant localized dose differences due to systematic voxel motion in a single fraction as well as in 15 cumulative fractions. The largest positive dose differences in rectum, bladder and seminal vesicles were 29%, 2% and 24%, respectively, after the first fraction of radiation treatment compared to the planned dose. After 15 cumulative fractions, the largest positive dose differences in rectum, bladder and seminal vesicles were 23%, 32% and 18%, respectively, compared to the planned dose. A sensitivity analysis of control point placement is also presented. This method provides an important understanding of actual delivered doses and has the potential to provide quantitative information to use as a guide for adaptive radiation treatments.

Voluntary HIV Counselling and Testing (VCT) is still in its infancy in South Africa, and although the necessary infrastructure in terms of clinics and hospitals exists, a VCT culture is not yet established in the country. The purpose of this study was to determine the needs, attitudes and beliefs of a sample of South Africans towards VCT, and to investigate possible barriers affecting participation in VCT programs in South Africa. A semi-structured questionnaire was used to survey the views of 1422 people. Results indicate that while subjects were not opposed to VCT in principle, 33% would go to clinics where nobody would know them. The following problems with VCT services were mentioned: Logistical problems (not enough counsellors, long lines, lack of privacy); no trust in the health care system or fearing a breach of confidentiality; fear of rejection; and a lack of follow-up support after diagnosis. Suggestions are made on how to improve VCT services in South Africa.

The objective of this study was to compare the efficacy and safety of insulin glargine, a long-acting insulin analog, with NPH insulin in children and adolescents with type 1 diabetes mellitus (T1DM). In a multicenter, open-label, randomized, 6-month study, 349 patients with TIDM, aged 5-16 years, received insulin glargine once daily or NPH insulin either once or twice daily, based on their prior treatment regimen. Although there was no significant difference between the NPH insulin and insulin glargine treatment groups with respect to baseline to endpoint change in HbA1c levels, fasting blood glucose (FBG) levels decreased significantly more in the insulin glargine group (-1.29 mmol/l) than in the NPH insulin group (-0.68 mmol/L, p = 0.02). The percentage of symptomatic hypoglycemic events was similar between groups; however, fewer patients in the insulin glargine group reported severe hypoglycemia (23% vs 29%) and severe nocturnal hypoglycemia (13% vs 18%), although these differences were not statistically significant (p = 0.22 and p = 0.19, respectively). Fewer serious adverse events occurred in the insulin glargine group than in the NPH insulin group (p < 0.02). A once-daily subcutaneous dose of insulin glargine provides effective glycemic control and is well tolerated in children and adolescents with T1DM.

Purpose: IMRT of the prostate consists of multiple stages of treatment planning and dose delivery, each with inherent anatomical uncertainties. Differential filling of the bladder and rectum can displace the prostate during a course of treatment. The purpose of this study was to assess the effectiveness of adapting to these anatomical changes using various CTimage‐guided adaptive (IGART) strategies. Methods: Our computermodel is based on the Philips Pinnacle treatment planning system. A multi‐fraction simulation of 5‐field IMRT (76 Gy/35 fractions) yields the daily dose accumulation in individual tissue elements. Using megavoltage CT studies of 13 prostate cases, cumulated dose distributions are mapped onto the reference treatment plan. Total dose‐volume histograms are then processed to estimate the changes in tumorcontrol probability (TCP) and normal tissue complication probability (NTCP) for various IGART scenarios. Results: Retargeting of the prostate generally maintains the intended TCP (typically 0.9 versus 0.8 with No Image Guidance) but is often associated with an enhanced risk of rectal toxicity (NTCP rises to 0.05 when Image Guidance is applied). This effect is due mainly to a systematic anterior shift caused by sag in the treatment couch (average 10mm). Without image‐guidance, this offset goes uncorrected, resulting in poorer coverage of the target with consistent avoidance of rectal exposure. Conclusions: Geometric repositioning without dose re‐planning is sufficient to maintain the intended TCP. IGART corrects for sag in the treatment couch and this results in greater risk of rectal toxicity, compared with no IGART. Smaller PTV margins could offset this effect, emphasizing the need for integrated image guided and intensity modulated delivery for optimal results. In the extreme, daily IMRT re‐planning based on in‐room imaging could exploit maximum benefits of this technology but this would require significantly more computing resources and streamlining of procedures at the treatment console. Research funding was provided by the Canadian Health Research Institutes and the Ontario Research and Development Challenge Fund (OCITS Project), with Philips Medical Systems as an industry partner.

Purpose: It is well recognized that computer technology has had a major impact on the practice of radiation oncology. This paper addresses the question as to how these computer advances have specifically impacted the accuracy of radiation dose delivery to the patient. Methods: A review was undertaken of all the key steps in the radiation treatment process ranging from machine calibration to patient treatment verification and irradiation. Using a semi-quantitative scale, each stage in the process was analysed from the point of view of gains in treatment accuracy. Results: Our critical review indicated that computerization related to digital medical imaging (ranging from target volume localization, to treatment planning, to image-guided treatment) has had the most significant impact on the accuracy of radiation treatment. Conversely, the premature adoption of intensity-modulated radiation therapy has actually degraded the accuracy of dose delivery compared to 3-D conformal radiation therapy. While computational power has improved dose calibration accuracy through Monte Carlo simulations of dosimeter response parameters, the overall impact in terms of percent improvement is relatively small compared to the improvements accrued from 3-D/4-D imaging. Conclusions: As a result of computer applications, we are better able to see and track the internal anatomy of the patient before, during and after treatment. This has yielded the most significant enhancement to the knowledge of “in vivo” dose distributions in the patient. Furthermore, a much richer set of 3-D/4-D co-registered dose-image data is thus becoming available for retrospective analysis of radiobiological and clinical responses.

We reviewed our experience with seventeen end-stage renal failure (ESRF) patients aged 80 years or older, chronically dialyzed at our institution, during a seven year period. They represented 7% of the total dialysis population. The male:female ratio increased from 1.7:1 before age of 80 to 3.25:1 after 80. The main reason for ESRF was renal hypertensive disease (41% vs 6.6% before 80). Fourteen patients were treated initially with peritoneal dialysis and three with hemodialysis. The one and two year survival were 50 and 7% respectively. The main cause of death was infectious diseases (50% vs 25% before 80). Patients were hospitalized for a mean of 6.2% of treatment time. No patient asked for discontinuation of therapy. Dialysis therapy is feasible even in the very old, even though the overall survival is relatively short.

Two new Fricke dosimeter gel systems with low diffusion rates have been developed for 3D radiation dosimetry purposes. Both systems consist of a solution of 20% (by weight) polyvinyl alcohol (PVA) in a 50 mM H2SO4 solution with 0.4 mM ferrous ammonium sulphate and xylenol orange (FX). The difference in the two gels is the way that the gelation process was initiated: either by bringing the temperature to (a) +5 degrees C or (b) -20 degrees C before returning them to room temperature. These gels are termed 'hydrogel' and 'cryogel', respectively. The hydrogel is optically transparent, and can be used with either optical or MRI detection methods for dosimetric imaging. The cryogel is rubbery in texture but opaque, so its internal Fe3+ concentration can only be measured with MRI. The hydrogel's optical attenuation coefficient is linear (r2 = 0.99) with dose from 0 to 20 Gy with a sensitivity of 0.106 cm(-1) Gy(-1) (at 543 nm). In terms of MR relaxation rate, the dose response for both the hydrogel and cryogel was linear (r2 = 0.99) with a sensitivity of 0.020 s(-1) Gy(-1) (at 1.5 T). The Fe3+ diffusion coefficient (at 20 degrees C) was measured to be 0.14 mm2 h(-1), which is significantly lower than similar preparations reported for porcine gelatin or agarose. The PVA-FX gels can be stored for long periods of time before exposure to radiation, since the auto-oxidation rate was 10 times less than that of gelatin-Fricke recipes. The new gels developed in this work are a significant improvement on previous Fricke gel systems.

Purpose: To evaluate the image guidance capabilities of helical tomotherapy‐based MVCT, this work compares the inter‐ and intra‐observer contouring uncertainty in KVCT used for radiotherapy planning with MVCT acquired with a tomotherapy unit. Methods and Materials: Five prostate cancer patients who underwent tomotherapy treatment (with daily MVCT) at our institution were selected. One planning KVCT and one randomly selected MVCT from each patient were used. Slice spacings for KVCT and MVCT were 3 mm and 6 mm, respectively. Retrograde urethrography was performed on the KVCT studies only. For inter‐observer study, seven observers contoured the prostate on the 10 CT studies. For intra‐observer study, the same seven observers repeat‐contoured one patient's KVCT and MVCT studies. Quantitative analysis of contour variations was performed using volumes and radial distances. F‐test was performed to detect statistically significant differences between KVCT and MVCT. Results: The inter‐ and intra‐observer contouring variability was larger in MVCT than KVCT. The largest variability was mainly found in the prostate apex and base regions. Up to 1 cm (SD) was found in MVCT. In the prostate apex region, interestingly, large but similar variability between KVCT and MVCT was observed. This suggest that the use of urethrography during KVCT simulation was not very helpful. For F‐test, generally, the regions with significant differences were patient‐dependent and uniformly distributed in all directions. In terms of prostate volume, observers consistenly contoured larger prostate in MVCT (by 10 %). This reflects the poorer soft‐tissue contrast in MVCT than KVCT since observers tend to over‐estimate or over‐draw target volumes under less visible conditions. Conclusions: Based on our data, the application of MVCT for estimating daily organ motion and deformation during image‐guidedradiotherapy(IGRT) is somewhat discouraging. Optimization of slice thickness and dose utilization may result in better imaging performance for prostate delineation and adaptive tomotherapy.