31 research outputs found
Clinical Impact of Couch to p and Rails On Imrt and Arc Therapy
No full textPurpose: To evaluate the clinical impact of the Varian Exact Couch on dose and volume coverage to targets and critical structures and tumor control probability (TCP) for 6-MV IMRT and Arc Therapy.
Methods: Five clinical prostate patients were planned with both, 6-MV 8-field IMRT and 6-MV 2-field RapidArc using the Eclipse treatment planning system (TPS). These plans neglected treatment couch attenuation, as is standard clinical practice. Dose distributions were then recalculated in Eclipse with the inclusion of the Varian Exact Couch (imaging couch top) and the rails in varying configurations. The changes in dose and coverage were evaluated using the DVHs from each plan iteration. We used a tumor control probability (TCP) model to calculate losses in tumor control resulting from not accounting for the couch top and rails. We also verified dose measurements in a phantom.
Results: Failure to account for the treatment couch and rails resulted in clinically unacceptable dose and volume coverage losses to the target for both IMRT and RapidArc. The couch caused average dose losses (relative to plans that ignored the couch) to the prostate of 4.2% and 2.0% for IMRT with the rails out and in, respectively, and 3.2% and 2.9% for RapidArc with the rails out and in, respectively. On average, the percentage of the target covered by the prescribed dose dropped to 35% and 84% for IMRT (rails out and in, respectively) and to 18% and 17% for RapidArc (rails out and in, respectively). The TCP was also reduced by as much as 10.5% (6.3% on average). Dose and volume coverage losses for IMRT plans were primarily due to the rails, while the imaging couch top contributed most to losses for RapidArc. Both the couch top and rails contribute to dose and coverage losses that can render plans clinically unacceptable. A follow-up study we performed found that the less attenuating unipanel mesh couch top available with the Varian Exact couch does not cause a clinically impactful loss of dose or coverage for IMRT but still causes an unacceptable loss for RapidArc.
Conclusions: Both the imaging couch top and rails contribute to dose and coverage loss to a degree that, if included, would prevent the plan from meeting clinical planning criteria. Therefore, the imaging and mesh couch tops and rails should be accounted for in Arc Therapy and the imaging couch and rails only in IMRT treatment planning
2D vs 3D gamma analysis: Establishment of comparable clinical action limits
Get PDFPurpose: As clinics begin to use 3D metrics for intensity-modulated radiation therapy (IMRT) quality assurance; these metrics will often produce results different from those produced by their 2D counterparts. 3D and 2D gamma analyses would be expected to produce different values, because of the different search space available. We compared the results of 2D and 3D gamma analysis (where both datasets were generated the same way) for clinical treatment plans. Methods: 50 IMRT plans were selected from our database and recalculated using Monte Carlo. Treatment planning system-calculated (“evaluated”) and Monte Carlo-recalculated (“reference”) dose distributions were compared using 2D and 3D gamma analysis. This analysis was performed using a variety of dose-difference (5%, 3%, 2%, and 1%) and distance-to-agreement (5, 3, 2, and 1 mm) acceptance criteria, low-dose thresholds (5%, 10%, and 15% of the prescription dose), and data grid sizes (1.0, 1.5, and 3.0 mm). Each comparison was evaluated to determine the average 2D and 3D gamma and percentage of pixels passing gamma.Results: Average gamma and percentage of passing pixels for each acceptance criterion demonstrated better agreement for 3D than for 2D analysis for every plan comparison. Average difference in the percentage of passing pixels between the 2D and 3D analyses with no low-dose threshold ranged from 0.9% to 2.1%. Similarly, using a low-dose threshold resulted in a differences ranging from 0.8% to 1.5%. No appreciable differences in gamma with changes in the data density (constant difference: 0.8% for 2D vs. 3D) were observed.Conclusion: We found that 3D gamma analysis resulted in up to 2.9% more pixels passing than 2D analysis. Factors such as inherent dosimeter differences may be an important additional consideration to the extra dimension of available data that was evaluated in this study.------------------------------------Cite this article as: Pulliam KB, Huang JY, Bosca R, Followill D, Kry SF. 2D vs. 3D gamma analysis: Establishment of comparable clinical action limits. Int J Cancer Ther Oncol 2014; 2(2):020231. DOI: 10.14319/ijcto.0202.3
Copyright & Risk: Scoping the Wellcome Digital Library Project
Get PDFCopyright & Risk: Scoping the Wellcome Digital Library is a comprehensive case study which aims to assess the merits of the risk-managed approach to copyright clearance adopted by the Wellcome Library (WL) in the course of their pilot digitisation project Codebreakers: Makers of Modern Genetics.
Whilst the WL clearly identifies as a library, as a collecting institution it extends from books and periodicals to include archives and manuscripts, art, the moving image and sound associated with the biomedical sciences and the medical humanities.[1] In this case study we consider the digitisation of both library (books) and archive material as part of the Codebreakers project, although our principal interest lies with the archive digitisation strand.
This report assesses the merits of the WL’s approach to copyright compliance by:
Introducing the WL and the Codebreakers mass digitisation project
Outlining the copyright challenges presented by the mass-digitisation effort
Discussing the risk management methods used by the WL in determining which rights should be cleared
Examining the results of the risk-managed copyright clearance process
As a result of this analysis, the research aims to:
Compare the Wellcome experience on Codebreakers to rights clearance exercises attempted by other cultural heritage institutions
Provide policy makers with useful data and insights to inform the debate on copyright exceptions for cultural heritage institutions
Discuss the relevance of this approach for other UK archive institutions
Prior to the preparation of this case study, CREATe published a working paper in March 2013[2], reviewing current and proposed changes to UK copyright law, and specifically exceptions provided for libraries and archives. This was further extended by a review of available literature on the digitisation of archival and library collections for publication online, contextualized with specific examples.
Existing literature reveals that rights clearance procedures impose prohibitive burdens on cultural institutions, through the cost of staff time and training in both diligent search and the process of contacting rightsholders.[3] It also indicates that in most cases, the results of rights clearance processes are unsatisfactory: either copyright holders cannot be identified and traced; or those who are contacted, do not respond to permission requests. Archives, in contrast to libraries, have the added complication of dealing with larger and more varied collections of material, the majority of which has been created for non-commercial purposes; this material is often unpublished at the point of deposit with the archive, and typically includes higher proportions of orphan works (when compared with traditional library collections).[4]
Documented examples of archival rights clearance projects are scarce, and where studies do exist, they have generally been conducted at a large-scale level, and do not contain sufficient detail to enable in-depth analysis of the rights clearance process.[5] Anna Vuopala’s excellent Orphan Works study[6] includes examples of rights clearance projects at 19 institutions, and focuses almost exclusively on the time and cost required to clear rights, which is extremely useful, but leaves out other valuable details about the right clearance process: for example, the number of rightsholders’ contact details found; the refusal rates and reasons given for refusal at each institution; and the number of rightsholders who do not respond to permission requests.
In general, there is a lack of detailed evidence concerning rights clearance in archival digitisation, and especially in relation to projects that employ risk-management strategies in a sector which is known to be highly risk averse. The WL was chosen as an appropriate subject for this case study given the scale of their digitisation aims, and their use of a risk managed approach to copyright compliance.
Codebreakers, as a digitisation project, was never designed to facilitate a study of the process of rights clearance – by the time data collection for the Copyright and Risk Project began, Codebreakers was entering its final stages, with the official launch of the project website taking place in February 2013. As a result, semi-structured interviews were chosen as the most effective method of obtaining data about the project. Interviews were conducted with key project staff at the WL as well as with staff from five partner archives involved in delivering the Codebreakers project.
The semi-structured format of the interviews was chosen for its flexibility; a list of questions was chosen, but given the length of the interviews, it was possible to divert from these questions and follow up on unexpected lines of enquiry raised by the interview subjects. Also, by working from a set list of questions, it was still possible to collate the answers to specific questions, thereby producing some quantifiable data. The questions were generated through a discussion of the aims of the project, and through consultation of other similar projects: specifically Jean Dryden’s doctoral research on the practices of Canadian repositories when making their archival material available online.[7]
The interviews covered five specific areas: the respondents’ role within their place of work; their role working on the Codebreakers project; the rights clearance challenges posed by the project; the development of policies and practices over the timeframe of the project; and finally, the respondents’ own views and experience of copyright, divorced from an institutional perspective.
Using this method of enquiry, respondents were asked about policies and practices mandated by the institutions they work for, but also for their own opinions as professionals, built up though work experience, education and training. By encouraging the respondents to reflect on their own experience, it was also possible to use the ‘snowball’ technique to tease out pointers to documentation and other resources used by the respondents, not only in relation to this project, but to their experience working on others as well.
Once completed, the interviews were transcribed to provide usable data. The transcriptions were used for a variety of purposes. Responses to specific questions were logged to give quantifiable results. Where respondents gave specific examples of practices, or policy changes, these are used as evidence in the text of this report. As a result of interviewing respondents at the Wellcome, project documentation was also made available for inclusion in this case study. This material takes two forms: policy documents which were circulated and updated as the project took place; and an internal report produced towards the end of the project, which includes a variety of statistics and more general lessons learned. The documentation has been discussed in the text of the report and examples of specific documents are available in the Appendix.
This combination of anecdotal evidence, combined with results and project documentation, has allowed us to trace the processes by which the WL has used risk management to achieve their digitisation objectives.
[1] The Wellcome Library Collection Development Policy is available athttp://wellcomelibrary.org/content/documents/policy-documents/collection-development-policy.pdf [Accessed: 5 Dec 2013]
[2] Deazley, R., and Stobo, V. (2013) Archives and Copyright: Risk and Reform. Working Paper. CREATe / University of Glasgow, Glasgow, UK.
[3] Ibid
[4] For any work, created by an author who died before 1 January 1969, which was unpublished as of 1 August 1989 (when the CDPA 1988 came into force), the duration of copyright will last until 31 December 2039. CDPA, Schedule 1, s.12(4).
[5] Vuopala, A., “Assessment of the Orphan works issue and Costs for Rights Clearance” (May 2010), available at: and Korn, N., (2009) “In from the Cold” JISC & The Collections Trust, available at: [Accessed: 1 Sep 2013]
[6] Vuopala, A., (2010) – See page 39, and the example of the National Archives ‘Moving Here’ project. 45 rightsholders refused permission, but information regarding the reasons for refusal is not available. As to the rightsholders who could not be identified in relation to 385 documents – it is not made clear whether contact details could not be found for these individuals, or if they were but did not respond to permission requests.
[7] Dryden, J., “Copyright issues in the selection of archival material for internet access” (2008) Archival Science 123-4
A six-year review of more than 13,000 patient-specific IMRT QA results from 13 different treatment sites
No full text
The literary phenomenon of 'conflation’ in the reworking of Paul’s letter to the Colossians by the author of the letter to the Ephesians
Get PDFThis thesis is concerned with the nature of the relationship of the Letter to the Ephesians (Eph) to Paul's Letter to the Colossians (Col).The first three chapters seek to argue that this relationship should be designated as "literary dependent". In Chapter I the suggestion made by A.T. Lincoln (Dallas [Texas], 1990) that the contemporary redaction of the Letter of Aristeas by Josephus in his Jewish Antiquities, Book XII, §§ 11-118 is similar to the use the author of Eph made of Col, is exposed to critical review. Chapter II focuses on the phenomenon of repeated 'conflation' in Eph. This literary phenomenon entails that several 'Colossian' texts from different parts of Col are conflated by the author of Eph into one passage and is subjected to exhaustive analysis. It is argued that conflation is the main feature of the literary dependence of Eph on Col but does not occur in Josephus' reworking of the Letter of Aristeas. Chapter III continues the comparison between the method of reworking employed in the Jewish Antiquities and in Eph by pointing out that the fluctuation in verbatim agreement of one document with its source can be meaningful. Chapter IV provides the new synopsis of both letters on which the whole examination is based. This synoptic overview is a desideratum since the previous synoptic editions of the Greek text of both letters by E.J. Goodspeed (Chicago, 1933) and C.L. Mitton (Oxford, 1951) are not accurate enough and unsuitable for research that focuses on the conflations of 'Colossian' verses in Eph. The fifth and last chapter deals with the question why Eph is literary dependent on Col and shows that despite the literary dependence, the theology of Eph is distinctive in comparison with its source Col. The distinctiveness of Eph's theology consists in a critical modification of the stress which Col places on Christ's already accomplished victory over the cosmic powers (Co/ 2.15). In order to safeguard an authoritative reception of his modification of Col, the author of Eph presented his letter as the parallel letter of Col alluded to m Col 4.16. The literary dependence on Col is necessary both to modify its content and to present his own writing as its parallel letter
Direct to consumer advertising via the Internet, a study of hip resurfacing
No full textWith increased use of the internet for health information and direct to consumer advertising from medical companies, there is a concern about the quality of the information available for patients. The aim of this study was to examine the quality of health information on the internet for hip resurfacing. An assessment tool was designed to measure quality of information. Websites were measured on credibility of source; usability; currentness of the information; content relevance; content accuracy/completeness and disclosure/bias. Each website assessed was given a total score, based on number of scores achieved from the above categories websites were further analysed on author, geographical origin and possession of an independent credibility check. There was positive correlation between the overall score for the website and the score of each website in each assessment category. Websites by implant companies, doctors and hospitals scored poorly. Websites with an independent credibility check such as Health on the Net (HoN) scored twice the total scores of websites without. Like other internet health websites, the quality of information on hip resurfacing websites is variable. This study highlights methods by which to assess the quality of health information on the internet and advocates that patients should look for a statement of an "independent credibility check" when searching for information on hip resurfacing
Laughter and madness in post-war American fiction
Get PDFTwo philosophical positions seem evident in post-war American fiction: one
realist, one anti-realist. Using the terms 'revelation' and 'apocalypse' to reflect the
former, and 'entropy' the latter, this thesis proposes that distinctions between the two
can be made by analysis of a text's treatment of the nexus between laughter and
madness.
After an Overview that identifies and defines key terms, the Introduction
considers various theoretical treatments of laughter from which its function can be
ascertained as being both to reinforce stability within social groups and to explore
new alternatives to existing modes of thought. Madness being defined as an inability
to balance the opposing forces of system and anti-system, laughter is therefore vital
to maintain sanity. The Fool emerges as a crucial figure in this process.
Chapter One explores, with reference to Heller's Catch-22, Kesey's One Flew
Over the Cuckoo's Nest and Kerouac's On The Road, the Laughter of Revelation: a
laughing relationship between a Protagonist who is trapped within the system of an
Institution and a Fool who communicates to the Protagonist (through laughter) a
means of escape. Chapter Two then discusses, with reference to Blatty's The
Exorcist, King's It, Morrison's Sula, and Nabokov's Lolita, the Laughter of
Apocalypse: a laughing relationship in which the Fool's laughter (as mockery) is
potentially destructive of both the Protagonist's sanity and the stability of the
Institution. Chapter Three explores, with reference to Vonnegut's Slaughterhouse-5,
Ellis's American Psycho, and Heller's Closing Time, the Laughter of Entropy: the
failure of the laughing relationship that obtains when the dialectic between Institution
(as system) and Fool (as anti-system) collapses.
The concluding remarks reflect the metafictional implications of the foregoing
analyses. It is suggested that, with the collapse of this dialectic (expressed by the
Laughter of Entropy), the traditional relationship between Author and Reader
becomes problematic
