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The 9982 radioactive material shipping package, or the 9982, differs from the others by allowing a multitude of radionuclides instead of a single defined set. While allowing flexibility, this requires more justification on why these contents would be worthwhile and why they would not cause various safety hazards when shipped together. The latter was covered through mass limit calculations, and the potential uses for the package are shown through comparison with historical shipments. Here, the mass limits were already calculated[1] and used to show three example shipments are suitable for the 9982 as well. Plutonium stored in 3013 containers[2], training sources shipped in 9977 packages[3], and americium standards shipped in 9978 packages[4] were all analyzed. The mass of each radionuclide and the corresponding mass limit were used to first determine if the listed content could be shipped. If so, the maximum allowed mass of such contents is also calculated in order to see if the 200-gram fissile limit for the 9982 would be violated if additional material was packed. The sum-of-the-fractions method produces contents that do not violate the mass limits or exceed the 200-gram fissile limit. These sets also serve as realistic examples of what may be shipped in the 9982. Well-founded example contents will help the approval of the package by showing its compatibility with previously shipped material. Unfounded hypothetical contents would not show the usefulness of having a wide variety of allowed radionuclides. More contents may be developed in order to incorporate other radionuclides that were not present in these three examples. The light elements will also need to be evaluated due to their exclusion currently preventing some materials from being allowed in the 9982.
DOE-STD-1189-2016 Process Standard – Stage Gates Establishment of Regulatory Requirements Clarity of Path Forward Integration of Safety and Design Reduce Project Risk by Establishing Regulatory Certainty through formal regulatory approvals. Flexibility in risk analysis and presentation methods. ANSI/ANS 15.21, DOE-STD-3009, LMP/TICAP
In this presentation, the Editors will outline our vision for the future of Medical Physics and review recent work-in-progress initiatives to implement this vision. Finally, we will close with guidance to authors on how to write a good Medical Physics paper. A major focus will be the transition to a new publisher in 2017 following a more than 40-year association with American Institute of Physics Publishing (AIPP). Vision for Medical Physics and status of current initiatives: Jeff Williamson, Editor-in-Chief The broad vision of Medical Physics is “to continue the Journal’s tradition of publishing the very best science that propels our discipline forward and improves our contribution to patient care.” More concretely, the Journal should be the preeminent forum for exchange of cutting edge medical physics science. We seek to identify the best contributions in (a) high impact clinical physics innovations; (b) clinical translation and validation of basic science innovations; and (c) cutting edge basic science developments with potential for patient care improvements. Among the challenges and opportunities, we face are: electronic-only and open access publishing; competition from new radiological science journals; trends towards more interactive, social-media based scientific communities; and diversification of the medical physics research, authorship, and readership domains, including clinical applications quite foreign to core ABR clinical competencies. Recently implemented and ongoing initiatives include: Revised Table of Contents (TOC) and more contemporary topical submission categories Structured review template in HTML format Comprehensive hierarchical taxonomy for identifying reviewer expertise Formal process for soliciting high quality and impact Review and Vision 20/20 Articles We have recruited four Review Article Co-editors: John Rowlands and Ingrid Reiser (imaging physics) and Joao Seco and Tim Zhu (therapy physics). The Co-Editors will identify timely topics and solicit high profile authors to submit review manuscripts. To submit an article, authors will need to work with an assigned Co-Editor to develop a mutually acceptable outline and abstract. 5) A new and exciting class of articles: Medical Physics Dataset Articles (MPDAs) MPDAs describe scientifically or clinically valuable open-access datasets with high potential for contributing to the research of medical physicists working on related problems. In contrast to Research Articles, MPDAs should not include hypothesis testing; or data analyses supporting generalizable conclusions. The publically accessible dataset must be permanently archived before the MPDA can be published. This initiative is being led by Joe Deasy. Update on new publisher transition: The transition of AAPM scientific publishing operations to a major publishing house is a major opportunity to expand Medical Physics readership and its scholarly impact. The advantages include: (a) common manuscript management and web hosting platforms for Medical Physics and its sister journal, JACMP; (b) greater than 4-fold expansion of subscribing institutions; and (c) resources to mount data-driven, highly targeted marketing campaigns to enhance citation and download rates. A transition update of this epochal development, which has only begun as of this writing (3/31/16), will be given. Improving manuscript quality via structured reviews, enhanced scientific category taxonomy, and outreach: Shiva Das, Therapy Physics Editor Medical Physics is committed to continuous improvement with the ultimate goal of improving the potential impact of accepted manuscripts. In order to do so, Medical Physics must be able to tap into important/emerging areas and be able to select high quality contributions consistently via discerning reviews. Improving the quality of reviews is crucial to selecting high quality manuscripts and also to improving manuscript impact via feedback in the review process. With this in mind, Medical Physics is in the process of: (a) fostering outreach to important areas that are currently underrepresented in Medical Physics; (b) implementing a structured template review form; and (c) implementing a comprehensive scientific category taxonomy to identify reviewers who are best suited to an article. Outreach efforts have begun to various scientific areas. Strategies to increase submissions from these areas will be discussed. As a consequence of this effort, a special issue on particle therapy is under development. A review template was implemented in late 2014 on a limited test basis. Based on reviewer feedback, the template was restructured and shortened to capture essential review elements. The restructured template is due to be released shortly. The new scientific category taxonomy is in the process of being deployed to reviewers and associate editors. Salient aspects of the structured review template and scientific category taxonomy will be discussed in this talk. Writing good scientific papers and responding to critiques: Mitch Goodsitt, Imaging Physics Editor The essential components of the abstract, introduction, methods, discussion and conclusion sections of manuscripts, as well as the desired writing style and style of the figures and tables will be reviewed. Publishable Medical Physics manuscripts must include clear and concise statements of the novelty and clinical and/or scientific importance of the authors’ work. Examples of novelty include: new technical solution to an important clinical problem; new generalizable knowledge; and first demonstration that an existing engineering solution solves a clinical problem. Please note that we encourage authors of recently published conference proceedings (e.g., SPIE, IEEE) papers on novel medical physics related work to submit more substantial versions of that work to our journal. All submissions must include: sufficient background information and rationale; enough detail for others to reproduce the authors’ work; sufficient statistical analysis to refute or validate the authors’ hypotheses; a description of how the present work compares to, is distinct from, and improves upon others’ work; and sections devoted to the limitations of the study and future directions. Writing should be polished. Poor wording, grammar and composition frustrate the review process. Our journal does not have copyeditors for revising manuscripts. When authors receive critiques from the referees and associate editor, the authors should provide a detailed point-by-point response to each comment. The authors’ rebuttal should include the text of the original criticism, the authors’ response, and a pasted copy of the modified text along with the line numbers in the revised article. The new text should be highlighted in a different font color in the revised submission. Following these recommendations will improve submissions and facilitate the review process.
In this presentation, the Editors will outline our vision for the future of Medical Physics and review recent work-in-progress initiatives to implement this vision. Finally, we will close with guidance to authors on how to write a good Medical Physics paper. A major focus will be the transition to a new publisher in 2017 following a more than 40-year association with American Institute of Physics Publishing (AIPP). Vision for Medical Physics and status of current initiatives: Jeff Williamson, Editor-in-Chief The broad vision of Medical Physics is “to continue the Journal’s tradition of publishing the very best science that propels our discipline forward and improves our contribution to patient care.” More concretely, the Journal should be the preeminent forum for exchange of cutting edge medical physics science. We seek to identify the best contributions in (a) high impact clinical physics innovations; (b) clinical translation and validation of basic science innovations; and (c) cutting edge basic science developments with potential for patient care improvements. Among the challenges and opportunities, we face are: electronic-only and open access publishing; competition from new radiological science journals; trends towards more interactive, social-media based scientific communities; and diversification of the medical physics research, authorship, and readership domains, including clinical applications quite foreign to core ABR clinical competencies. Recently implemented and ongoing initiatives include: Revised Table of Contents (TOC) and more contemporary topical submission categories Structured review template in HTML format Comprehensive hierarchical taxonomy for identifying reviewer expertise Formal process for soliciting high quality and impact Review and Vision 20/20 Articles We have recruited four Review Article Co-editors: John Rowlands and Ingrid Reiser (imaging physics) and Joao Seco and Tim Zhu (therapy physics). The Co-Editors will identify timely topics and solicit high profile authors to submit review manuscripts. To submit an article, authors will need to work with an assigned Co-Editor to develop a mutually acceptable outline and abstract. 5) A new and exciting class of articles: Medical Physics Dataset Articles (MPDAs) MPDAs describe scientifically or clinically valuable open-access datasets with high potential for contributing to the research of medical physicists working on related problems. In contrast to Research Articles, MPDAs should not include hypothesis testing; or data analyses supporting generalizable conclusions. The publically accessible dataset must be permanently archived before the MPDA can be published. This initiative is being led by Joe Deasy. Update on new publisher transition: The transition of AAPM scientific publishing operations to a major publishing house is a major opportunity to expand Medical Physics readership and its scholarly impact. The advantages include: (a) common manuscript management and web hosting platforms for Medical Physics and its sister journal, JACMP; (b) greater than 4-fold expansion of subscribing institutions; and (c) resources to mount data-driven, highly targeted marketing campaigns to enhance citation and download rates. A transition update of this epochal development, which has only begun as of this writing (3/31/16), will be given. Improving manuscript quality via structured reviews, enhanced scientific category taxonomy, and outreach: Shiva Das, Therapy Physics Editor Medical Physics is committed to continuous improvement with the ultimate goal of improving the potential impact of accepted manuscripts. In order to do so, Medical Physics must be able to tap into important/emerging areas and be able to select high quality contributions consistently via discerning reviews. Improving the quality of reviews is crucial to selecting high quality manuscripts and also to improving manuscript impact via feedback in the review process. With this in mind, Medical Physics is in the process of: (a) fostering outreach to important areas that are currently underrepresented in Medical Physics; (b) implementing a structured template review form; and (c) implementing a comprehensive scientific category taxonomy to identify reviewers who are best suited to an article. Outreach efforts have begun to various scientific areas. Strategies to increase submissions from these areas will be discussed. As a consequence of this effort, a special issue on particle therapy is under development. A review template was implemented in late 2014 on a limited test basis. Based on reviewer feedback, the template was restructured and shortened to capture essential review elements. The restructured template is due to be released shortly. The new scientific category taxonomy is in the process of being deployed to reviewers and associate editors. Salient aspects of the structured review template and scientific category taxonomy will be discussed in this talk. Writing good scientific papers and responding to critiques: Mitch Goodsitt, Imaging Physics Editor The essential components of the abstract, introduction, methods, discussion and conclusion sections of manuscripts, as well as the desired writing style and style of the figures and tables will be reviewed. Publishable Medical Physics manuscripts must include clear and concise statements of the novelty and clinical and/or scientific importance of the authors’ work. Examples of novelty include: new technical solution to an important clinical problem; new generalizable knowledge; and first demonstration that an existing engineering solution solves a clinical problem. Please note that we encourage authors of recently published conference proceedings (e.g., SPIE, IEEE) papers on novel medical physics related work to submit more substantial versions of that work to our journal. All submissions must include: sufficient background information and rationale; enough detail for others to reproduce the authors’ work; sufficient statistical analysis to refute or validate the authors’ hypotheses; a description of how the present work compares to, is distinct from, and improves upon others’ work; and sections devoted to the limitations of the study and future directions. Writing should be polished. Poor wording, grammar and composition frustrate the review process. Our journal does not have copyeditors for revising manuscripts. When authors receive critiques from the referees and associate editor, the authors should provide a detailed point-by-point response to each comment. The authors’ rebuttal should include the text of the original criticism, the authors’ response, and a pasted copy of the modified text along with the line numbers in the revised article. The new text should be highlighted in a different font color in the revised submission. Following these recommendations will improve submissions and facilitate the review process.
In this presentation, the Editors will outline our vision for the future of Medical Physics and review recent work-in-progress initiatives to implement this vision. Finally, we will close with guidance to authors on how to write a good Medical Physics paper. A major focus will be the transition to a new publisher in 2017 following a more than 40-year association with American Institute of Physics Publishing (AIPP). Vision for Medical Physics and status of current initiatives: Jeff Williamson, Editor-in-Chief The broad vision of Medical Physics is “to continue the Journal’s tradition of publishing the very best science that propels our discipline forward and improves our contribution to patient care.” More concretely, the Journal should be the preeminent forum for exchange of cutting edge medical physics science. We seek to identify the best contributions in (a) high impact clinical physics innovations; (b) clinical translation and validation of basic science innovations; and (c) cutting edge basic science developments with potential for patient care improvements. Among the challenges and opportunities, we face are: electronic-only and open access publishing; competition from new radiological science journals; trends towards more interactive, social-media based scientific communities; and diversification of the medical physics research, authorship, and readership domains, including clinical applications quite foreign to core ABR clinical competencies. Recently implemented and ongoing initiatives include: Revised Table of Contents (TOC) and more contemporary topical submission categories Structured review template in HTML format Comprehensive hierarchical taxonomy for identifying reviewer expertise Formal process for soliciting high quality and impact Review and Vision 20/20 Articles We have recruited four Review Article Co-editors: John Rowlands and Ingrid Reiser (imaging physics) and Joao Seco and Tim Zhu (therapy physics). The Co-Editors will identify timely topics and solicit high profile authors to submit review manuscripts. To submit an article, authors will need to work with an assigned Co-Editor to develop a mutually acceptable outline and abstract. 5) A new and exciting class of articles: Medical Physics Dataset Articles (MPDAs) MPDAs describe scientifically or clinically valuable open-access datasets with high potential for contributing to the research of medical physicists working on related problems. In contrast to Research Articles, MPDAs should not include hypothesis testing; or data analyses supporting generalizable conclusions. The publically accessible dataset must be permanently archived before the MPDA can be published. This initiative is being led by Joe Deasy. Update on new publisher transition: The transition of AAPM scientific publishing operations to a major publishing house is a major opportunity to expand Medical Physics readership and its scholarly impact. The advantages include: (a) common manuscript management and web hosting platforms for Medical Physics and its sister journal, JACMP; (b) greater than 4-fold expansion of subscribing institutions; and (c) resources to mount data-driven, highly targeted marketing campaigns to enhance citation and download rates. A transition update of this epochal development, which has only begun as of this writing (3/31/16), will be given. Improving manuscript quality via structured reviews, enhanced scientific category taxonomy, and outreach: Shiva Das, Therapy Physics Editor Medical Physics is committed to continuous improvement with the ultimate goal of improving the potential impact of accepted manuscripts. In order to do so, Medical Physics must be able to tap into important/emerging areas and be able to select high quality contributions consistently via discerning reviews. Improving the quality of reviews is crucial to selecting high quality manuscripts and also to improving manuscript impact via feedback in the review process. With this in mind, Medical Physics is in the process of: (a) fostering outreach to important areas that are currently underrepresented in Medical Physics; (b) implementing a structured template review form; and (c) implementing a comprehensive scientific category taxonomy to identify reviewers who are best suited to an article. Outreach efforts have begun to various scientific areas. Strategies to increase submissions from these areas will be discussed. As a consequence of this effort, a special issue on particle therapy is under development. A review template was implemented in late 2014 on a limited test basis. Based on reviewer feedback, the template was restructured and shortened to capture essential review elements. The restructured template is due to be released shortly. The new scientific category taxonomy is in the process of being deployed to reviewers and associate editors. Salient aspects of the structured review template and scientific category taxonomy will be discussed in this talk. Writing good scientific papers and responding to critiques: Mitch Goodsitt, Imaging Physics Editor The essential components of the abstract, introduction, methods, discussion and conclusion sections of manuscripts, as well as the desired writing style and style of the figures and tables will be reviewed. Publishable Medical Physics manuscripts must include clear and concise statements of the novelty and clinical and/or scientific importance of the authors’ work. Examples of novelty include: new technical solution to an important clinical problem; new generalizable knowledge; and first demonstration that an existing engineering solution solves a clinical problem. Please note that we encourage authors of recently published conference proceedings (e.g., SPIE, IEEE) papers on novel medical physics related work to submit more substantial versions of that work to our journal. All submissions must include: sufficient background information and rationale; enough detail for others to reproduce the authors’ work; sufficient statistical analysis to refute or validate the authors’ hypotheses; a description of how the present work compares to, is distinct from, and improves upon others’ work; and sections devoted to the limitations of the study and future directions. Writing should be polished. Poor wording, grammar and composition frustrate the review process. Our journal does not have copyeditors for revising manuscripts. When authors receive critiques from the referees and associate editor, the authors should provide a detailed point-by-point response to each comment. The authors’ rebuttal should include the text of the original criticism, the authors’ response, and a pasted copy of the modified text along with the line numbers in the revised article. The new text should be highlighted in a different font color in the revised submission. Following these recommendations will improve submissions and facilitate the review process.
In this presentation, the Editors will outline our vision for the future of Medical Physics and review recent work-in-progress initiatives to implement this vision. Finally, we will close with guidance to authors on how to write a good Medical Physics paper. A major focus will be the transition to a new publisher in 2017 following a more than 40-year association with American Institute of Physics Publishing (AIPP). Vision for Medical Physics and status of current initiatives: Jeff Williamson, Editor-in-Chief The broad vision of Medical Physics is “to continue the Journal’s tradition of publishing the very best science that propels our discipline forward and improves our contribution to patient care.” More concretely, the Journal should be the preeminent forum for exchange of cutting edge medical physics science. We seek to identify the best contributions in (a) high impact clinical physics innovations; (b) clinical translation and validation of basic science innovations; and (c) cutting edge basic science developments with potential for patient care improvements. Among the challenges and opportunities, we face are: electronic-only and open access publishing; competition from new radiological science journals; trends towards more interactive, social-media based scientific communities; and diversification of the medical physics research, authorship, and readership domains, including clinical applications quite foreign to core ABR clinical competencies. Recently implemented and ongoing initiatives include: Revised Table of Contents (TOC) and more contemporary topical submission categories Structured review template in HTML format Comprehensive hierarchical taxonomy for identifying reviewer expertise Formal process for soliciting high quality and impact Review and Vision 20/20 Articles We have recruited four Review Article Co-editors: John Rowlands and Ingrid Reiser (imaging physics) and Joao Seco and Tim Zhu (therapy physics). The Co-Editors will identify timely topics and solicit high profile authors to submit review manuscripts. To submit an article, authors will need to work with an assigned Co-Editor to develop a mutually acceptable outline and abstract. 5) A new and exciting class of articles: Medical Physics Dataset Articles (MPDAs) MPDAs describe scientifically or clinically valuable open-access datasets with high potential for contributing to the research of medical physicists working on related problems. In contrast to Research Articles, MPDAs should not include hypothesis testing; or data analyses supporting generalizable conclusions. The publically accessible dataset must be permanently archived before the MPDA can be published. This initiative is being led by Joe Deasy. Update on new publisher transition: The transition of AAPM scientific publishing operations to a major publishing house is a major opportunity to expand Medical Physics readership and its scholarly impact. The advantages include: (a) common manuscript management and web hosting platforms for Medical Physics and its sister journal, JACMP; (b) greater than 4-fold expansion of subscribing institutions; and (c) resources to mount data-driven, highly targeted marketing campaigns to enhance citation and download rates. A transition update of this epochal development, which has only begun as of this writing (3/31/16), will be given. Improving manuscript quality via structured reviews, enhanced scientific category taxonomy, and outreach: Shiva Das, Therapy Physics Editor Medical Physics is committed to continuous improvement with the ultimate goal of improving the potential impact of accepted manuscripts. In order to do so, Medical Physics must be able to tap into important/emerging areas and be able to select high quality contributions consistently via discerning reviews. Improving the quality of reviews is crucial to selecting high quality manuscripts and also to improving manuscript impact via feedback in the review process. With this in mind, Medical Physics is in the process of: (a) fostering outreach to important areas that are currently underrepresented in Medical Physics; (b) implementing a structured template review form; and (c) implementing a comprehensive scientific category taxonomy to identify reviewers who are best suited to an article. Outreach efforts have begun to various scientific areas. Strategies to increase submissions from these areas will be discussed. As a consequence of this effort, a special issue on particle therapy is under development. A review template was implemented in late 2014 on a limited test basis. Based on reviewer feedback, the template was restructured and shortened to capture essential review elements. The restructured template is due to be released shortly. The new scientific category taxonomy is in the process of being deployed to reviewers and associate editors. Salient aspects of the structured review template and scientific category taxonomy will be discussed in this talk. Writing good scientific papers and responding to critiques: Mitch Goodsitt, Imaging Physics Editor The essential components of the abstract, introduction, methods, discussion and conclusion sections of manuscripts, as well as the desired writing style and style of the figures and tables will be reviewed. Publishable Medical Physics manuscripts must include clear and concise statements of the novelty and clinical and/or scientific importance of the authors’ work. Examples of novelty include: new technical solution to an important clinical problem; new generalizable knowledge; and first demonstration that an existing engineering solution solves a clinical problem. Please note that we encourage authors of recently published conference proceedings (e.g., SPIE, IEEE) papers on novel medical physics related work to submit more substantial versions of that work to our journal. All submissions must include: sufficient background information and rationale; enough detail for others to reproduce the authors’ work; sufficient statistical analysis to refute or validate the authors’ hypotheses; a description of how the present work compares to, is distinct from, and improves upon others’ work; and sections devoted to the limitations of the study and future directions. Writing should be polished. Poor wording, grammar and composition frustrate the review process. Our journal does not have copyeditors for revising manuscripts. When authors receive critiques from the referees and associate editor, the authors should provide a detailed point-by-point response to each comment. The authors’ rebuttal should include the text of the original criticism, the authors’ response, and a pasted copy of the modified text along with the line numbers in the revised article. The new text should be highlighted in a different font color in the revised submission. Following these recommendations will improve submissions and facilitate the review process.
Purpose: Peer reviewers' knowledge of author identity may influence review content, quality, and recommendations. Therefore, the International Journal of Radiation Oncology, Biology, Physics (“Red Journal”) implemented double-blinded peer review in 2011. Given the relatively small size of the specialty and the high frequency of preliminary abstract presentations, we sought to evaluate attitudes, the efficacy of blinding, and the potential impact on the disposition of submissions. Methods and Materials: In May through August 2012, all Red Journal reviewers and 1 author per manuscript completed questionnaires regarding demographics, attitudes, and perceptions of success of blinding. We also evaluated correlates of the outcomes of peer review. Results: Questionnaires were received from 408 authors and 519 reviewers (100%). The majority of respondents favored double blinding; 6% of authors and 13% of reviewers disagreed that double blinding should continue in the Red Journal. In all, 50% of the reviewers did not suspect the identity of the author of the paper that they reviewed; 19% of reviewers believed that they could identify the author(s), and 31% suspected that they could. Similarly, 23% believed that they knew the institution(s) from which the paper originated, and 34% suspected that they did. Among those who at least suspected author identity, 42% indicated that prior presentations served as a clue, and 57% indicated that literature referenced did so. Of those who at least suspected origin and provided details (n=133), 13% were entirely incorrect. Rejection was more common in 2012 than 2011, and submissions from last authors with higher H-indices (>21) were more likely to survive initial review, without evidence of interactions between submission year and author gender or H-index. Conclusions: In a relatively small specialty in which preliminary research presentations are common and occur in a limited number of venues, reviewers are often familiar with research findings and suspect author identity even when manuscript review is blinded. Nevertheless, blinding appears to be effective in many cases, and support for continuing blinding was strong.
Purpose: The authors report on measurements of light output and spatial resolution of microcolumnar CsI:Tl scintillator detectors for x-ray imaging. In addition, the authors discuss the results of simulations aimed at analyzing the results of synchrotron and sealed-source exposures with respect to the contributions of light transport to the total light output. Methods: The authors measured light output from a 490-μm CsI:Tl scintillator screen using two setups. First, the authors used a photomultiplier tube (PMT) to measure the response of the scintillator to sealed-source exposures. Second, the authors performed imaging experiments with a 27-keV monoenergetic synchrotron beam and a slit to calculate the total signal generated in terms of optical photons per keV. The results of both methods are compared to simulations obtained with hybridMANTIS, a coupled x-ray, electron, and optical photon Monte Carlo transport package. The authors report line response (LR) and light output for a range of linear absorption coefficients and describe a model that fits at the same time the light output and the blur measurements. Comparing the experimental results with the simulations, the authors obtained an estimate of the absorption coefficient for the model that provides good agreement with the experimentally measured LR. Finally, the authors report light output simulation results and their dependence on scintillator thickness and reflectivity of the backing surface. Results: The slit images from the synchrotron were analyzed to obtain a total light output of 48 keV{sup −1} while measurements using the fast PMT instrument setup and sealed-sources reported a light output of 28 keV{sup −1}. The authors attribute the difference in light output estimates between the two methods to the difference in time constants between the camera and PMT measurements. Simulation structures were designed to match the light output measured with the camera while providing good agreement with the measured LR resulting in a bulk absorption coefficient of 5 × 10{sup −5} μm{sup −1}. Conclusions: The combination of experimental measurements for microcolumnar CsI:Tl scintillators using sealed-sources and synchrotron exposures with results obtained via simulation suggests that the time course of the emission might play a role in experimental estimates. The procedure yielded an experimentally derived linear absorption coefficient for microcolumnar Cs:Tl of 5 × 10{sup −5} μm{sup −1}. To the author’s knowledge, this is the first time this parameter has been validated against experimental observations. The measurements also offer insight into the relative role of optical transport on the effective optical yield of the scintillator with microcolumnar structure.
Purpose: Volumetric modulated arc therapy (VMAT) optimization is a computationally challenging problem due to its large data size, high degrees of freedom, and many hardware constraints. High-performance graphics processing units (GPUs) have been used to speed up the computations. However, GPU’s relatively small memory size cannot handle cases with a large dose-deposition coefficient (DDC) matrix in cases of, e.g., those with a large target size, multiple targets, multiple arcs, and/or small beamlet size. The main purpose of this paper is to report an implementation of a column-generation-based VMAT algorithm, previously developed in the authors’ group, on a multi-GPU platform to solve the memory limitation problem. While the column-generation-based VMAT algorithm has been previously developed, the GPU implementation details have not been reported. Hence, another purpose is to present detailed techniques employed for GPU implementation. The authors also would like to utilize this particular problem as an example problem to study the feasibility of using a multi-GPU platform to solve large-scale problems in medical physics. Methods: The column-generation approach generates VMAT apertures sequentially by solving a pricing problem (PP) and a master problem (MP) iteratively. In the authors’ method, the sparse DDC matrix is first stored on a CPU in coordinate list format (COO). On the GPU side, this matrix is split into four submatrices according to beam angles, which are stored on four GPUs in compressed sparse row format. Computation of beamlet price, the first step in PP, is accomplished using multi-GPUs. A fast inter-GPU data transfer scheme is accomplished using peer-to-peer access. The remaining steps of PP and MP problems are implemented on CPU or a single GPU due to their modest problem scale and computational loads. Barzilai and Borwein algorithm with a subspace step scheme is adopted here to solve the MP problem. A head and neck (H and N) cancer case is then used to validate the authors’ method. The authors also compare their multi-GPU implementation with three different single GPU implementation strategies, i.e., truncating DDC matrix (S1), repeatedly transferring DDC matrix between CPU and GPU (S2), and porting computations involving DDC matrix to CPU (S3), in terms of both plan quality and computational efficiency. Two more H and N patient cases and three prostate cases are used to demonstrate the advantages of the authors’ method. Results: The authors’ multi-GPU implementation can finish the optimization process within ∼1 min for the H and N patient case. S1 leads to an inferior plan quality although its total time was 10 s shorter than the multi-GPU implementation due to the reduced matrix size. S2 and S3 yield the same plan quality as the multi-GPU implementation but take ∼4 and ∼6 min, respectively. High computational efficiency was consistently achieved for the other five patient cases tested, with VMAT plans of clinically acceptable quality obtained within 23–46 s. Conversely, to obtain clinically comparable or acceptable plans for all six of these VMAT cases that the authors have tested in this paper, the optimization time needed in a commercial TPS system on CPU was found to be in an order of several minutes. Conclusions: The results demonstrate that the multi-GPU implementation of the authors’ column-generation-based VMAT optimization can handle the large-scale VMAT optimization problem efficiently without sacrificing plan quality. The authors’ study may serve as an example to shed some light on other large-scale medical physics problems that require multi-GPU techniques.
Purpose: Brain single photon emission computed tomography (SPECT) imaging is an important clinical tool, with unique tracers for studying neurological diseases. Nowadays, most commercial SPECT systems are combined with x-ray computed tomography (CT) in so-called SPECT/CT systems to obtain an anatomical background for the functional information. However, while CT images have a high spatial resolution, they have a low soft-tissue contrast, which is an important disadvantage for brain imaging. Magnetic resonance imaging (MRI), on the other hand, has a very high soft-tissue contrast and does not involve extra ionizing radiation. Therefore, the authors designed a brain SPECT insert that can operate inside a clinical MRI. Methods: The authors designed and simulated a compact stationary multipinhole SPECT insert based on digital silicon photomultiplier detector modules, which have shown to be MR-compatible and have an excellent intrinsic resolution (0.5 mm) when combined with a monolithic 2 mm thick LYSO crystal. First, the authors optimized the different parameters of the SPECT system to maximize sensitivity for a given target resolution of 7.2 mm in the center of the field-of-view, given the spatial constraints of the MR system. Second, the authors performed noiseless simulations of two multipinhole configurations to evaluate sampling and reconstructed resolution. Finally, the authors performed Monte Carlo simulations and compared the SPECT insert with a clinical system with ultrahigh-resolution (UHR) fan beam collimators, based on contrast-to-noise ratio and a visual comparison of a Hoffman phantom with a 9 mm cold lesion. Results: The optimization resulted in a stationary multipinhole system with a collimator radius of 150.2 mm and a detector radius of 172.67 mm, which corresponds to four rings of 34 diSPM detector modules. This allows the authors to include eight rings of 24 pinholes, which results in a system volume sensitivity of 395 cps/MBq. Noiseless simulations show sufficient axial sampling (in a Defrise phantom) and a reconstructed resolution of 5.0 mm (in a cold-rod phantom). The authors compared the 24-pinhole setup with a 34-pinhole system (with the same detector radius but a collimator radius of 156.63 mm) and found that 34 pinholes result in better uniformity but a worse reconstruction of the cold-rod phantom. The authors also compared the 24-pinhole system with a clinical triple-head UHR fan beam system based on contrast-to-noise ratio and found that the 24-pinhole setup performs better for the 6 mm hot and the 16 mm cold lesions and worse for the 8 and 10 mm hot lesions. Finally, the authors reconstructed noisy projection data of a Hoffman phantom with a 9 mm cold lesion and found that the lesion was slightly better visible on the multipinhole image compared to the fan beam image. Conclusions: The authors have optimized a stationary multipinhole SPECT insert for MRI and showed the feasibility of doing brain SPECT imaging inside a MRI with an image quality similar to the best clinical SPECT systems available.
Purpose: In radiation therapy of pancreatic cancer, tumor alignment prior to each treatment fraction is improved when intratumoral gold fiducial markers (from here onwards: markers), which are visible on computed tomography (CT) and cone beam CT, are used. Visibility of these markers on magnetic resonance imaging (MRI) might improve image registration between CT and magnetic resonance (MR) images for tumor delineation purposes. However, concomitant image artifacts induced by markers are undesirable. The extent of visibility and artifact size depend on MRI-sequence parameters. The authors’ goal was to determine for various markers their potential to be visible and to generate artifacts, using measures that are independent of the MRI-sequence parameters. Methods: The authors selected ten different markers suitable for endoscopic placement in the pancreas and placed them into a phantom. The markers varied in diameter (0.28–0.6 mm), shape, and iron content (0%–0.5%). For each marker, the authors calculated T{sub 2}{sup ∗}-maps and ΔB{sub 0}-maps using MRI measurements. A decrease in relaxation time T{sub 2}{sup ∗} can cause signal voids, associated with visibility, while a change in the magnetic field B{sub 0} can cause signal shifts, which are associated with artifacts. These shifts inhibit accurate tumor delineation. As a measure for potential visibility, the authors used the volume of low T{sub 2}{sup ∗}, i.e., the volume for which T{sub 2}{sup ∗} differed from the background by >15 ms. As a measure for potential artifacts, the authors used the volume for which |ΔB{sub 0}| > 9.4 × 10{sup −8} T (4 Hz). To test whether there is a correlation between visibility and artifact size, the authors calculated the Spearman’s correlation coefficient (R{sub s}) between the volume of low T{sub 2}{sup ∗} and the volume of high |ΔB{sub 0}|. The authors compared the maps with images obtained using a clinical MR-sequence. Finally, for the best visible marker as well as the marker that showed the smallest artifact, the authors compared the phantom data with in vivo MR-images in four pancreatic cancer patients. Results: The authors found a strong correlation (R{sub s} = 1.00, p < 0.01) between the volume of low T{sub 2}{sup ∗} and the volume with high |ΔB{sub 0}|. Visibility in clinical MR-images increased with lower T{sub 2}{sup ∗}. Signal shift artifacts became worse for markers with high |ΔB{sub 0}|. The marker that was best visible in the phantom, a folded marker with 0.5% iron content, was also visible in vivo, but showed artifacts on diffusion weighted images. The marker with the smallest artifact in the phantom, a small, stretched, ironless marker, was indiscernible on in vivo MR-images. Conclusions: Changes in T{sub 2}{sup ∗} and ΔB{sub 0} are sequence-independent measures for potential visibility and artifact size, respectively. Improved visibility of markers correlates strongly to signal shift artifacts; therefore, marker choice will depend on the clinical purpose. When visibility of the markers is most important, markers that contain iron are optimal, preferably in a folded configuration. For artifact sensitive imaging, small ironless markers are best, preferably in a stretched configuration.
Purpose: Magnetic nanoparticles (MNPs) are an important asset in many biomedical applications. An effective working of these applications requires an accurate knowledge of the spatial MNP distribution. A promising, noninvasive, and sensitive technique to visualize MNP distributions in vivo is electron paramagnetic resonance (EPR). Currently only 1D MNP distributions can be reconstructed. In this paper, the authors propose extending 1D EPR toward 2D and 3D using computer simulations to allow accurate imaging of MNP distributions. Methods: To find the MNP distribution belonging to EPR measurements, an inverse problem needs to be solved. The solution of this inverse problem highly depends on the stability of the inverse problem. The authors adapt 1D EPR imaging to realize the imaging of multidimensional MNP distributions. Furthermore, the authors introduce partial volume excitation in which only parts of the volume are imaged to increase stability of the inverse solution and to speed up the measurements. The authors simulate EPR measurements of different 2D and 3D MNP distributions and solve the inverse problem. The stability is evaluated by calculating the condition measure and by comparing the actual MNP distribution to the reconstructed MNP distribution. Based on these simulations, the authors define requirements for the EPR system to cope with the added dimensions. Moreover, the authors investigate how EPR measurements should be conducted to improve the stability of the associated inverse problem and to increase reconstruction quality. Results: The approach used in 1D EPR can only be employed for the reconstruction of small volumes in 2D and 3D EPRs due to numerical instability of the inverse solution. The authors performed EPR measurements of increasing cylindrical volumes and evaluated the condition measure. This showed that a reduction of the inherent symmetry in the EPR methodology is necessary. By reducing the symmetry of the EPR setup, quantitative images of larger volumes can be obtained. The authors found that, by selectively exciting parts of the volume, the authors could increase the reconstruction quality even further while reducing the amount of measurements. Additionally, the inverse solution of this activation method degrades slower for increasing volumes. Finally, the methodology was applied to noisy EPR measurements: using the reduced EPR setup’s symmetry and the partial activation method, an increase in reconstruction quality of ≈80% can be seen with a speedup of the measurements with 10%. Conclusions: Applying the aforementioned requirements to the EPR setup and stabilizing the EPR measurements showed a tremendous increase in noise robustness, thereby making EPR a valuable method for quantitative imaging of multidimensional MNP distributions.
Purpose: This paper presents an overview of multisource inverse-geometry computed tomography (IGCT) as well as the development of a gantry-based research prototype system. The development of the distributed x-ray source is covered in a companion paper [V. B. Neculaes et al., “Multisource inverse-geometry CT. Part II. X-ray source design and prototype,” Med. Phys. 43, 4617–4627 (2016)]. While progress updates of this development have been presented at conferences and in journal papers, this paper is the first comprehensive overview of the multisource inverse-geometry CT concept and prototype. The authors also provide a review of all previous IGCT related publications. Methods: The authors designed and implemented a gantry-based 32-source IGCT scanner with 22 cm field-of-view, 16 cm z-coverage, 1 s rotation time, 1.09 × 1.024 mm detector cell size, as low as 0.4 × 0.8 mm focal spot size and 80–140 kVp x-ray source voltage. The system is built using commercially available CT components and a custom made distributed x-ray source. The authors developed dedicated controls, calibrations, and reconstruction algorithms and evaluated the system performance using phantoms and small animals. Results: The authors performed IGCT system experiments and demonstrated tube current up to 125 mA with up to 32 focal spots. The authors measured a spatial resolution of 13 lp/cm at 5% cutoff. The scatter-to-primary ratio is estimated 62% for a 32 cm water phantom at 140 kVp. The authors scanned several phantoms and small animals. The initial images have relatively high noise due to the low x-ray flux levels but minimal artifacts. Conclusions: IGCT has unique benefits in terms of dose-efficiency and cone-beam artifacts, but comes with challenges in terms of scattered radiation and x-ray flux limits. To the authors’ knowledge, their prototype is the first gantry-based IGCT scanner. The authors summarized the design and implementation of the scanner and the authors presented results with phantoms and small animals.
The environment framing the modem authorization process span domains of administration, relies on many different authentication sources, and manages complex attributes as part of the authorization process. Cardea facilitates dynamic access control within this environment as a central function of an inter-operable authorization framework. The system departs from the traditional authorization model by separating the authentication and authorization processes, distributing the responsibility for authorization data and allowing collaborating domains to retain control over their implementation mechanisms. Critical features of the system architecture and its handling of the authorization process differentiate the system from existing authorization components by addressing common needs not adequately addressed by existing systems. Continuing system research seeks to enhance the implementation of the current authorization model employed in Cardea, increase the robustness of current features, further the framework for establishing trust and promote interoperability with existing security mechanisms.
Patterns of scientific collaboration and their effect on scientific production have been the subject of many studies. In this paper we analyze the nature of ties between co-authors and study collaboration patterns in science from the perspective of semantic similarity of authors who wrote a paper together and the strength of ties between these authors (i.e. how much have they previously collaborated together). These two views of scientific collaboration are used to analyze publications in the TrueImpactDataset [11], a new dataset containing two types of publications - publications regarded as seminal and publications regarded as literature reviews by field experts. We show there are distinct differences between seminal publications and literature reviews in terms of author similarity and the strength of ties between their authors. In particular, we find that seminal publications tend to be written by authors who have previously worked on dissimilar problems (i.e. authors from different fields or even disciplines), and by authors who are not frequent collaborators. On the other hand, literature reviews in our dataset tend to be the result of an established collaboration within a discipline. This demonstrates that our method provides meaningful information about potential future impacts of a publication which does not require citation information.
Purpose: Pulmonary inflammation is associated with a variety of diseases. Assessing pulmonary inflammation on in vivo imaging may facilitate the early detection and treatment of lung diseases. Although routinely used in thoracic imaging, computed tomography has thus far not been compellingly shown to characterize inflammation in vivo. Alternatively, magnetic resonance imaging (MRI) is a nonionizing radiation technique to better visualize and characterize pulmonary tissue. Prior to routine adoption of MRI for early characterization of inflammation in humans, a rigorous and quantitative characterization of the utility of MRI to identify inflammation is required. Such characterization may be achieved by considering ex vivo histology as the ground truth, since it enables the definitive spatial assessment of inflammation. In this study, the authors introduce a novel framework to integrate 2D histology, ex vivo and in vivo imaging to enable the mapping of the extent of disease from ex vivo histology onto in vivo imaging, with the goal of facilitating computerized feature analysis and interrogation of disease appearance on in vivo imaging. The authors’ framework was evaluated in a preclinical preliminary study aimed to identify computer extracted features on in vivo MRI associated with chronic pulmonary inflammation. Methods: The authors’ image analytics framework first involves reconstructing the histologic volume in 3D from individual histology slices. Second, the authors map the disease ground truth onto in vivo MRI via coregistration with 3D histology using the ex vivo lung MRI as a conduit. Finally, computerized feature analysis of the disease extent is performed to identify candidate in vivo imaging signatures of disease presence and extent. Results: The authors evaluated the framework by assessing the quality of the 3D histology reconstruction and the histology—MRI fusion, in the context of an initial use case involving characterization of chronic inflammation in a mouse model. The authors’ evaluation considered three mice, two with an inflammation phenotype and one control. The authors’ iterative 3D histology reconstruction yielded a 70.1% ± 2.7% overlap with the ex vivo MRI volume. Across a total of 17 anatomic landmarks manually delineated at the division of airways, the target registration error between the ex vivo MRI and 3D histology reconstruction was 0.85 ± 0.44 mm, suggesting that a good alignment of the ex vivo 3D histology and ex vivo MRI had been achieved. The 3D histology-in vivo MRI coregistered volumes resulted in an overlap of 73.7% ± 0.9%. Preliminary computerized feature analysis was performed on an additional four control mice, for a total of seven mice considered in this study. Gabor texture filters appeared to best capture differences between the inflamed and noninflamed regions on MRI. Conclusions: The authors’ 3D histology reconstruction and multimodal registration framework were successfully employed to reconstruct the histology volume of the lung and fuse it with in vivo MRI to create a ground truth map for inflammation on in vivo MRI. The analytic platform presented here lays the framework for a rigorous validation of the identified imaging features for chronic lung inflammation on MRI in a large prospective cohort.