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- Zimmerman, Brian E, et al.
(författare)
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Multi-centre evaluation of accuracy and reproducibility of planar and SPECT image quantification : An IAEA phantom study
- 2017
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Ingår i: Zeitschrift für Medizinische Physik. - : Elsevier BV. - 1876-4436 .- 0939-3889. ; 27:2, s. 98-112
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Tidskriftsartikel (refereegranskat)abstract
- Accurate quantitation of activity provides the basis for internal dosimetry of targeted radionuclide therapies. This study investigated quantitative imaging capabilities at sites with a variety of experience and equipment and assessed levels of errors in activity quantitation in Single-Photon Emission Computed Tomography (SPECT) and planar imaging. Participants from 9 countries took part in a comparison in which planar, SPECT and SPECT with X ray computed tomography (SPECT-CT) imaging were used to quantify activities of four epoxy-filled cylinders containing 133Ba, which was chosen as a surrogate for 131I. The sources, with nominal volumes of 2, 4, 6 and 23mL, were calibrated for 133Ba activity by the National Institute of Standards and Technology, but the activity was initially unknown to the participants. Imaging was performed in a cylindrical phantom filled with water. Two trials were carried out in which the participants first estimated the activities using their local standard protocols, and then repeated the measurements using a standardized acquisition and analysis protocol. Finally, processing of the imaging data from the second trial was repeated by a single centre using a fixed protocol. In the first trial, the activities were underestimated by about 15% with planar imaging. SPECT with Chang's first order attenuation correction (Chang-AC) and SPECT-CT overestimated the activity by about 10%. The second trial showed moderate improvements in accuracy and variability. Planar imaging was subject to methodological errors, e.g., in the use of a transmission scan for attenuation correction. The use of Chang-AC was subject to variability from the definition of phantom contours. The project demonstrated the need for training and standardized protocols to achieve good levels of quantitative accuracy and precision in a multicentre setting. Absolute quantification of simple objects with no background was possible with the strictest protocol to about 6% with planar imaging and SPECT (with Chang-AC) and within 2% for SPECT-CT.
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2. |
- Munjulury, Raghu, et al.
(författare)
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Analytical weight estimation of landing gear designs
- 2017
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Ingår i: Proceedings of the Institution of Mechanical Engineers. Part G, Journal of Aerospace Engineering. - : SAGE PUBLICATIONS LTD. - 0954-4100 .- 2041-3025. ; 231:12, s. 2214-2227
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Tidskriftsartikel (refereegranskat)abstract
- Landing gear weight calculations can be carried out using statistical or analytical methods. Statistical methods were used in the past and offered quick group weights. However, they are not capable of computing accurately the weight of landing gears, which have special geometries and performance. In this work, landing gear weight is computed using analytical methods based on parametric 3D models. The procedure established by Kraus and Wille is applied as a baseline so as to create a procedure capable of dealing with landing gear weight calculations. This method is designed to be as flexible as possible, giving the user the freedom to modify many options and parameters and integrate landing gear design into Robust Aircraft Parametric Interactive Design.
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