The importance of accurate beam data measurement for SRT/SRS treatment planning

Introduction This study investigated the sensitivity of calculated stereotactic radiotherapy and radiosurgery doses to the accuracy of the beam data used by the treatment planning system. Methods Two sets of field output factors were acquired using fields smaller than approximately 1 cm2, for inclusion in beam data used by the iPlan treatment planning system (Brainlab, Feldkirchen, Germany). One set of output factors were measured using an Exradin A16 ion chamber (Standard Imaging, Middleton, USA). Although this chamber has a relatively small collecting volume (0.007 cm3), measurements made in small fields using this chamber are subject to the effects of volume averaging, electronic disequilibrium and chamber perturbations. The second, more accurate, set of measurements were obtained by applying perturbation correction factors, calculated using Monte Carlo simulations according to a method recommended by Cranmer-Sargison et al. [1] to measurements made using a 60017 unshielded electron diode (PTW, Freiburg, Germany). A series of 12 sample patient treatments were used to investigate the effects of beam data accuracy on resulting planned dose. These treatments, which involved 135 fields, were planned for delivery via static conformal arcs and 3DCRT techniques, to targets ranging from prostates (up to 8 cm across) to meningiomas (usually more than 2 cm across) to arterioveinous malformations, acoustic neuromas and brain metastases (often less than 2 cm across). Isocentre doses were calculated for all of these fields using iPlan, and the results of using the two different sets of beam data were evaluated. Results While the isocentre doses for many fields are identical (difference = 0.0 %), there is a general trend for the doses calculated using the data obtained from corrected diode measurements to exceed the doses calculated using the less-accurate Exradin ion chamber measurements (difference\0.0 %). There are several alarming outliers (circled in the Fig. 1) where doses differ by more than 3 %, in beams from sample treatments planned for volumes up to 2 cm across. Discussion and conclusions These results demonstrate that treatment planning dose calculations for SRT/SRS treatments can be substantially affected when beam data for fields smaller than approximately 1 cm2 are measured inaccurately, even when treatment volumes are up to 2 cm across.

CTCombine : rotating and combining CT data with an accurate detector model to simulate radiotherapy portal imaging at non-zero beam angles

Established Monte Carlo user codes BEAMnrc and DOSXYZnrc permit the accurate and straightforward simulation of radiotherapy experiments and treatments delivered from multiple beam angles. However, when an electronic portal imaging detector (EPID) is included in these simulations, treatment delivery from non-zero beam angles becomes problematic. This study introduces CTCombine, a purpose-built code for rotating selected CT data volumes, converting CT numbers to mass densities, combining the results with model EPIDs and writing output in a form which can easily be read and used by the dose calculation code DOSXYZnrc...

Vertical alignment of process models – how can we get there?

There is a wide variety of drivers for business process modelling initiatives, reaching from business evolution and process optimisation over compliance checking and process certification to process enactment. That, in turn, results in models that differ in content due to serving different purposes. In particular, processes are modelled on different abstraction levels and assume different perspectives. Vertical alignment of process models aims at handling these deviations. While the advantages of such an alignment for inter-model analysis and change propagation are out of question, a number of challenges has still to be addressed. In this paper, we discuss three main challenges for vertical alignment in detail. Against this background, the potential application of techniques from the field of process integration is critically assessed. Based thereon, we identify specific research questions that guide the design of a framework for model alignment.

Alignment and differences between the Australian Water Accounting Standard and the Water Accounting Framework for the Minerals Industry

In 2012, the Bureau of Meteorology under the banner of the Water Accounting Standards Board released the Australian Water Accounting Standard 1 (AWAS 1). This standard has been in development since 2007 with key milestones being the release of the Preliminary Australian Water Accounting Standard in 2009, and the exposure draft of the Australian Water Accounting Standard in 2010. Throughout this period, the Minerals Council of Australia’s Water Accounting Framework has developed concurrently with the Australian standards and the standards have informed elements of the framework. However, the framework is not identical to the standard as the objectives between the two are different. The objective of the Water Accounting Framework is to create consistency in water reporting of the minerals industry and to assist companies reporting to corporate sustainability initiatives. The objective of AWAS 1 is to provide information to water management bodies to facilitate decisions about the allocation of water resources. Companies are to report on an annual basis, not only physical flows of water but contractual requirements to supply and obtain water, regardless of whether the transaction has been fulfilled in the reporting period. In contrast, the Water Accounting Framework only reports on flows that have physically happened. The paper will provide summary information on aspects of AWAS 1 that are most relevant to the minerals industry, show the alignment and differences between AWAS 1 and the Water Accounting Framework and explain how to obtain the information for the AWAS 1 reporting statements.

One-step macroscopic alignment of conjugated polymer systems by epitaxial crystallization during spin-coating

The one-step preparation of highly anisotropic polymer semiconductor thin films directly from solution is demonstrated. The conjugated polymer poly(3-hexylthiophene) (P3HT) as well as P3HT:fullerene bulk-heterojunction blends can be spin-coated from a mixture of the crystallizable solvent 1,3,5-trichlorobenzene (TCB) and a second carrier solvent such as chlorobenzene. Solidification is initiated by growth of macroscopic TCB spherulites followed by epitaxial crystallization of P3HT on TCB crystals. Subsequent sublimation of TCB leaves behind a replica of the original TCB spherulites. Thus, highly ordered thin films are obtained, which feature square-centimeter-sized domains that are composed of one spherulite-like structure each. A combination of optical microscopy and polarized photoluminescence spectroscopy reveals radial alignment of the polymer backbone in case of P3HT, whereas P3HT:fullerene blends display a tangential orientation with respect to the center of spherulite-like structures. Moreover, grazing-incidence wide-angle X-ray scattering reveals an increased relative degree of crystallinity and predominantly flat-on conformation of P3HT crystallites in the blend. The use of other processing methods such as dip-coating is also feasible and offers uniaxial orientation of the macromolecule. Finally, the applicability of this method to a variety of other semi-crystalline conjugated polymer systems is established. Those include other poly(3-alkylthiophene)s, two polyfluorenes, the low band-gap polymer PCPDTBT, a diketopyrrolopyrrole (DPP) small molecule as well as a number of polymer:fullerene and polymer:polymer blends. Macroscopic spherulite-like structures of the conjugated polymer poly(3-hexylthiophene) (P3HT) grow directly during spin-coating. This is achieved by processing P3HT or P3HT:fullerene bulk heterojunction blends from a mixture of the crystallizable solvent 1,3,5-trichlorobenzene and a second carrier solvent such as chlorobenzene. Epitaxial growth of the polymer on solidified solvent crystals gives rise to circular-symmetric, spherulite-like structures that feature a high degree of anisotropy.

Auto-tune, and why we shouldn't be surprised that Britney can't sing

Put Britney Spears into a YouTube search and the third auto-fill on the list is “Britney Spears without Autotune”. Auto-Tune has become the music industry equivalent of doping in the Tour de France circa 2005; we know everyone’s doing it, but we still have a sense of surprise and outrage when it becomes public. In the last week or so a video has surfaced of the pop singer Britney Spears – with examples of her vocal before and after processing. Whether or not the “before” version is actually the raw material for the “after” version is difficult to say. What’s not difficult to say is that the “before” vocal is distinctly lacking in a demonstrable ability to sing in tune.

Exploring the impact of shared domain knowledge on strategic alignment in the Australian public sector

In this age of ever-increasing information technology (IT) driven environments, governments/or public sector organisations (PSOs) are expected to demonstrate the business value of the investment in IT and take advantage of the opportunities offered by technological advancements. Strategic alignment (SA) emerged as a mechanism to bridge the gap between business and IT missions, objectives, and plans in order to ensure value optimisation from investment in IT and enhance organisational performance. However, achieving and sustaining SA remains a challenge requiring even more agility nowadays to keep up with turbulent organisational environments. The shared domain knowledge (SDK) between the IT department and other diverse organisational groups is considered as one of the factors influencing the successful implementation of SA. However, SDK in PSOs has received relatively little empirical attention. This paper presents findings from a study which investigated the influence of SDK on SA within organisations in the Australian public sector. The developed research model examined the relationship of SDK between business and IT domains with SA using a survey of 56 public sector professionals and executives. A key research contribution is the empirical demonstration that increasing levels of SDK between IT and business groups leads to increased SA.

Degree of value alignment : a grounded theory of rural nurse resignations

INTRODUCTION: The shortage of nurses willing to work in rural Australian healthcare settings continues to worsen. Australian rural areas have a lower retention rate of nurses than metropolitan counterparts, with more remote communities experiencing an even higher turnover of nursing staff. When retention rates are lower, patient outcomes are known to be poorer. This article reports a study that sought to explore the reasons why registered nurses resign from rural hospitals in the state of New South Wales, Australia. METHODS: Using grounded theory methods, this study explored the reasons why registered nurses resigned from New South Wales rural hospitals. Data were collected from 12 participants using semi-structured interviews; each participant was a registered nurse who had resigned from a rural hospital. Nurses who had resigned due to retirement, relocation or maternity leave were excluded. Interviews were transcribed verbatim and imported into NVivo software. The constant comparative method of data collection and analysis was followed until a core category emerged. RESULTS: Nurses resigned from rural hospitals when their personal value of how nursing should occur conflicted with the hospital's organisational values driving the practice of nursing. These conflicting values led to a change in the degree of value alignment between the nurse and hospital. The degree of value alignment occurred in three dynamic stages that nurses moved through prior to resigning. The first stage, sharing values, was a time when a nurse and a hospital shared similar values. The second stage was conceding values where, due to perceived changes in a hospital's values, a nurse felt that patient care became compromised and this led to a divergence of values. The final stage was resigning, a stage where a nurse 'gave up' as they felt that their professional integrity was severely compromised. The findings revealed that when a nurse and organisational values were not aligned, conflict was created for a nurse about how they could perform nursing that aligned with their internalised professional values and integrity. Resignation occurred when nurses were unable to realign their personal values to changed organisational values - the organisational values changed due to rural area health service restructures, centralisation of budgets and resources, cumbersome hierarchies and management structures that inhibited communication and decision making, out-dated and ineffective operating systems, insufficient and inexperienced staff, bullying, and a lack of connectedness and shared vision. CONCLUSIONS: To fully comprehend rural nurse resignations, this study identified three stages that nurses move through prior to resignation. Effective retention strategies for the nursing workforce should address contributors to a decrease in value alignment and work towards encouraging the coalescence of nurses' and hospitals' values. It is imperative that strategies enable nurses to provide high quality patient care and promote a sense of connectedness and a shared vision between nurse and hospital. Senior managers need to have clear ways to articulate and imbue organisational values and be explicit in how these values accommodate nurses' values. Ward-level nurse managers have a significant responsibility to ensure that a hospital's values (both explicit and implicit) are incorporated into ward culture.

Photon beam dose distributions for patients with implanted temporary tissue expanders

This study examines the effects of temporary tissue expanders (TTEs) on the dose distributions of photon beams in breast cancer radiotherapy treatments. EBT2 radiochromic film and ion chamber measurements were taken to quantify the attenuation and backscatter effects of the inhomogeneity. Results illustrate that the internal magnetic port present in a tissue expander causes a dose reduction of approximately 25% in photon tangent fields immediately downstream of the implant. It was also shown that the silicone elastomer shell of the tissue expander reduced the dose to the target volume by as much as 8%. This work demonstrates the importance for an accurately modelled high-density implant in the treatment planning system for post-mastectomy breast cancer patients.

Characterisation of the half-field beam penumbra for a variety of blocking set-ups

Measurements of half-field beam penumbra were taken using EBT2 film for a variety of blocking techniques. It was shown that minimizing the SSD reduces the penumbra as the effects of beam divergence are diminished. The addition of a lead block directly on the surface provides optimal results with a 10-90% penumbra of 0.53 ± 0.02 cm. To resolve the uncertainties encountered in film measurements, future Monte Carlo measurements of halffield penumbras are to be conducted.

Micro foundations of strategic capability development : a case study within the auto industry

The importance of firms’ adaptation processes is prominent in today’s business environment which is characterised by ever changing customers, technologies, and competition. Ever since Schumpeter’s (1942) classic work strategic renewal has been found crucial for firms’ adaptation to environmental change. The role of strategic renewal in firms’ adaptation processes includes development of capabilities for the purpose of sustainability of competitive advantage against environmental changes.

Establishing the impact of temporary tissue expanders on electron and photon beam dose distributions

Purpose: This study investigates the effects of temporary tissue expanders (TTEs) on the dose distributions in breast cancer radiotherapy treatments under a variety of conditions. Methods: Using EBT2 radiochromic film, both electron and photon beam dose distribution measurements were made for different phantoms, and beam geometries. This was done to establish a more comprehensive understanding of the implant’s perturbation effects under a wider variety of conditions. Results: The magnetic disk present in a tissue expander causes a dose reduction of approximately 20% in a photon tangent treatment and 56% in electron boost fields immediately downstream of the implant. The effects of the silicon elastomer are also much more apparent in an electron beam than a photon beam. Conclusions: Evidently, each component of the TTE attenuates the radiation beam to different degrees. This study has demonstrated that the accuracy of photon and electron treatments of post-mastectomy patients is influenced by the presence of a tissue expander for various beam orientations. The impact of TTEs on dose distributions establishes the importance of an accurately modelled high-density implant in the treatment planning system for post-mastectomy patients.

Automated sensory data alignment for environmental and epidermal change monitoring

In this paper we present research adapting a state of the art condition-invariant robotic place recognition algorithm to the role of automated inter- and intra-image alignment of sensor observations of environmental and skin change over time. The approach involves inverting the typical criteria placed upon navigation algorithms in robotics; we exploit rather than attempt to fix the limited camera viewpoint invariance of such algorithms, showing that approximate viewpoint repetition is realistic in a wide range of environments and medical applications. We demonstrate the algorithms automatically aligning challenging visual data from a range of real-world applications: ecological monitoring of environmental change, aerial observation of natural disasters including flooding, tsunamis and bushfires and tracking wound recovery and sun damage over time and present a prototype active guidance system for enforcing viewpoint repetition. We hope to provide an interesting case study for how traditional research criteria in robotics can be inverted to provide useful outcomes in applied situations.

Self and other in communication and cognition : the role of auto-communication and intersubjectivity in autopoiesis of psychic systems

By referring to Niklas Luhmann's theory of self-referential systems, Aldo Mascareño (2008, submitted for publication) gives an account of system-environment interrelatedness, explaining how social and individual constitute each other through the process of communication and co-creation of meanings. Two possible extensions to his account are discussed. Firstly, auto-communication within the system that happens without any external reference needs to be taken into account while describing the existence and constant re-creation of psychic systems. Secondly, in order for the system and environment or two systems to communicate, an imagined and temporary intersubjectivity between the two needs to be assumed.