File format obsolescence is a major risk factor threatening the sustainability of and access to digital information. While the preservation community has become increasingly interested in tools for migration and trans...File format obsolescence is a major risk factor threatening the sustainability of and access to digital information. While the preservation community has become increasingly interested in tools for migration and transformation of file formats, the National Library of Australia is developing mechanisms specifically focused on monitoring and assessing the risks of file format obsolescence. This paper reports on the AONS II project, undertaken by the National Library of Australia (NLA) in conjunction with the Australian Partnership for Sustainable Repositories (APSR). The project aimed to develop a software tool which allows users to automatically monitor the status of file formats in their repositories, make risk assessments based on a core set of obsolescence risk questions, and receive notifications when file format risks change or other related events occur. This paper calls for the preservation community to develop a co-operating file format obsolescence community which includes registries, software tool creators and end users to effectively curate digital content in order to maintain long-term access.展开更多
Aim: In prone breast treatments, a carbon fiber support device resides under the contralateral breast. Tangent beams are designed to encompass the treated breast and these often pass through the board at a shallow ang...Aim: In prone breast treatments, a carbon fiber support device resides under the contralateral breast. Tangent beams are designed to encompass the treated breast and these often pass through the board at a shallow angle, resulting in significant attenuation. Our planners account for this attenuation by adding field-in-field dose to the deep part of the breast, through the board. Concern was raised about how accurate the treatment delivery is when the inherent uncertainties of patients’ positions are accounted for. Furthermore, transmission measurements are usually carried out perpendicular to the board, a non-clinical situation. The goal of this study is to evaluate the dosimetric effect of the board and the robustness of the plan to positional uncertainty. Materials and Methods: Twenty-two breast patients treated on a commercial prone breast board between 2017 and 2020 were selected for this retrospective study. To evaluate the board’s attenuation, we compared the plans with the board removed from the dose calculation. To quantify the robustness of this technique, we moved the beam isocenter with respect to the patient and board. Results: Our results showed that when the breast board is removed from a plan which was designed to account for the board attenuation, the average point dose increases by 7.48%, with a maximum of 22%. Comparing results with a mixed Analysis of Variance (ANOVA) and a least-square means analysis, our robustness evaluation indicates that anterior shifts at every magnitude (1 mm through 5 mm) make a significant difference in all dose statistics (D95, max, 95% prescription coverage and homogeneity index) investigated. In/out and right/left shifts resulted in an insignificant change in dose statistics. Conclusion: Prone breast boards can add significant dosimetric uncertainty into the treatment delivery process. Accounting for plan robustness in the design of the plan is highly recommended. A prone breast board design with support moved away from the beam path is warranted.展开更多
基金The author wishes to thank APSR and DEST for supporting this project.
文摘File format obsolescence is a major risk factor threatening the sustainability of and access to digital information. While the preservation community has become increasingly interested in tools for migration and transformation of file formats, the National Library of Australia is developing mechanisms specifically focused on monitoring and assessing the risks of file format obsolescence. This paper reports on the AONS II project, undertaken by the National Library of Australia (NLA) in conjunction with the Australian Partnership for Sustainable Repositories (APSR). The project aimed to develop a software tool which allows users to automatically monitor the status of file formats in their repositories, make risk assessments based on a core set of obsolescence risk questions, and receive notifications when file format risks change or other related events occur. This paper calls for the preservation community to develop a co-operating file format obsolescence community which includes registries, software tool creators and end users to effectively curate digital content in order to maintain long-term access.
文摘Aim: In prone breast treatments, a carbon fiber support device resides under the contralateral breast. Tangent beams are designed to encompass the treated breast and these often pass through the board at a shallow angle, resulting in significant attenuation. Our planners account for this attenuation by adding field-in-field dose to the deep part of the breast, through the board. Concern was raised about how accurate the treatment delivery is when the inherent uncertainties of patients’ positions are accounted for. Furthermore, transmission measurements are usually carried out perpendicular to the board, a non-clinical situation. The goal of this study is to evaluate the dosimetric effect of the board and the robustness of the plan to positional uncertainty. Materials and Methods: Twenty-two breast patients treated on a commercial prone breast board between 2017 and 2020 were selected for this retrospective study. To evaluate the board’s attenuation, we compared the plans with the board removed from the dose calculation. To quantify the robustness of this technique, we moved the beam isocenter with respect to the patient and board. Results: Our results showed that when the breast board is removed from a plan which was designed to account for the board attenuation, the average point dose increases by 7.48%, with a maximum of 22%. Comparing results with a mixed Analysis of Variance (ANOVA) and a least-square means analysis, our robustness evaluation indicates that anterior shifts at every magnitude (1 mm through 5 mm) make a significant difference in all dose statistics (D95, max, 95% prescription coverage and homogeneity index) investigated. In/out and right/left shifts resulted in an insignificant change in dose statistics. Conclusion: Prone breast boards can add significant dosimetric uncertainty into the treatment delivery process. Accounting for plan robustness in the design of the plan is highly recommended. A prone breast board design with support moved away from the beam path is warranted.
