The Experts below are selected from a list of 185580 Experts worldwide ranked by ideXlab platform
Xiaodong Wang - One of the best experts on this subject based on the ideXlab platform.
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an online ride sharing path Planning Strategy for public vehicle systems
IEEE Transactions on Intelligent Transportation Systems, 2019Co-Authors: Ming Zhu, Xiaoyang Liu, Xiaodong WangAbstract:As efficient traffic-management platforms, public vehicle (PV) systems are envisioned to be a promising approach to solving traffic congestion and pollution for future smart cities. PV systems provide online/dynamic peer-to-peer ride-sharing services with the goal of serving a sufficient number of customers with a minimum number of vehicles and the lowest possible cost. A key component of the PV system is the online ride-sharing scheduling Strategy. In this paper, an efficient path-Planning Strategy based on a greedy algorithm is proposed, which focuses on a limited potential search area for each vehicle by filtering out the requests that violate the passenger service quality level, so that the global search is reduced to a local search. Moreover, the proposed heuristic can be easily used in the future globally optimal algorithm (if it will exist) to speed the computation time. The performance of the proposed solution, such as reduction ratio of computational complexity, is analyzed. Simulations based on the Manhattan taxi data set show that the computing time is reduced by 22% compared with the exhaustive search method under the same service quality performance.
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an online ride sharing path Planning Strategy for public vehicle systems
arXiv: Artificial Intelligence, 2017Co-Authors: Ming Zhu, Xiaoyang Liu, Xiaodong WangAbstract:As efficient traffic-management platforms, public vehicle (PV) systems are envisioned to be a promising approach to solving traffic congestions and pollutions for future smart cities. PV systems provide online/dynamic peer-to-peer ride-sharing services with the goal of serving sufficient number of customers with minimum number of vehicles and lowest possible cost. A key component of the PV system is the online ride-sharing scheduling Strategy. In this paper, we propose an efficient path Planning Strategy that focuses on a limited potential search area for each vehicle by filtering out the requests that violate passenger service quality level, so that the global search is reduced to local search. We analyze the performance of the proposed solution such as reduction ratio of computational complexity. Simulations based on the Manhattan taxi data set show that, the computing time is reduced by 22% compared with the exhaustive search method under the same service quality performance.
Andreas Rimner - One of the best experts on this subject based on the ideXlab platform.
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a novel four dimensional radiotherapy Planning Strategy from a tumor tracking beam s eye view
Physics in Medicine and Biology, 2012Co-Authors: Patrice Cohen, H Xie, D Low, Andreas RimnerAbstract:To investigate the feasibility of four-dimensional radiotherapy (4DRT) Planning from a tumor-tracking beam's eye view (ttBEV) with reliable gross tumor volume (GTV) delineation, realistic normal tissue representation, high Planning accuracy and low clinical workload, we propose and validate a novel 4D conformal Planning Strategy based on a synthesized 3.5D computed tomographic (3.5DCT) image with a motion-compensated tumor. To recreate patient anatomy from a ttBEV in the moving tumor coordinate system for 4DRT Planning (or 4D Planning), the centers of delineated GTVs in all phase CT images of 4DCT were aligned, and then the aligned CTs were averaged to produce a new 3.5DCT image. This GTV-motion-compensated CT contains a motionless target (with motion artifacts minimized) and motion-blurred normal tissues (with a realistic temporal density average). Semi-automatic threshold-based segmentation of the tumor, lung and body was applied, while manual delineation was used for other organs at risk (OARs). To validate this 3.5DCT-based 4D Planning Strategy, five patients with peripheral lung lesions of small size (<5 cm3) and large motion range (1.2–3.5 cm) were retrospectively studied for stereotactic body radiotherapy (SBRT) using 3D conformal radiotherapy Planning tools. The 3.5DCT-based 4D plan (3.5DCT plan) with 9–10 conformal beams was compared with the 4DCT-based 4D plan (4DCT plan). The 4DCT plan was derived from multiple 3D plans based on all phase CT images, each of which used the same conformal beam configuration but with an isocenter shift to aim at the moving tumor and a minor beam aperture and weighting adjustment to maintain plan conformality. The dose–volume histogram (DVH) of the 4DCT plan was created with two methods: one is an integrated DVH (iDVH4D), which is defined as the temporal average of all 3D-phase-plan DVHs, and the other (DVH4D) is based on the dose distribution in a reference phase CT image by dose warping from all phase plans using the displacement vector field (DVF) from a free-form deformable image registration (DIR). The DVH3.5D (for the 3.5DCT plan) was compared with both iDVH4D and DVH4D. To quantify the DVH difference between the 3.5DCT plan and the 4DCT plan, two methods were used: relative difference (%) of the areas underneath the DVH curves and the volumes receiving more than 20% (V20) and 50% (V50) of prescribed dose of these 4D plans. The volume of the delineated GTV from different phase CTs varied dramatically from 24% to 112% among the five patients, whereas the GTV from 3.5DCT deviated from the averaged GTV in 4DCT by only −6%±6%. For Planning tumor volume (PTV) coverage, the difference between the DVH3.5D and iDVH4D was negligible (<1% area), whereas the DVH3.5D and DVH4D were quite different, due to DIR uncertainty (∼2 mm), which propagates to PTV dose coverage with a pronounced uncertainty for small tumors (0.3–4.0 cm3) in stereotactic plans with sharp dose falloff around PTV. For OARs, such as the lung, heart, cord and esophagus, the three DVH curves (DVH3.5D, DVH4D and iDVH4D) were found to be almost identical for the same patients, especially in high-dose regions. For the tumor-containing lung, the relative difference of the areas underneath the DVH curves was found to be small (5.3% area on average), of which 65% resulted from the low-dose region (D < 20%). The averaged V20 difference between the two 4D plans was 1.2% ± 0.8%. For the mean lung dose (MLD), the 3.5DCT plan differed from the 4DCT plan by −1.1%±1.3%. GTV-motion-compensated CT (3.5DCT) produces an accurate and reliable GTV delineation, which is close to the mean GTV from 4DCT. The 3.5DCT plan is equivalent to the 4DCT plan with <1% dose difference to the PTV and negligible dose difference in OARs. The 3.5DCT approach simplifies 4D Planning and provides accurate dose calculation without a substantial increase of clinical workload for motion-tracking delivery to treat small peripheral lung tumors with large motion.
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A novel four-dimensional radiotherapy Planning Strategy from a tumor-tracking beam's eye view
Physics in Medicine and Biology, 2012Co-Authors: Guang Li, Patrice Cohen, Diana Li, Andreas RimnerAbstract:To investigate the feasibility of four-dimensional radiotherapy (4DRT) Planning from a tumor-tracking beam's eye view (ttBEV) with reliable gross tumor volume (GTV) delineation, realistic normal tissue representation, high Planning accuracy and low clinical workload, we propose and validate a novel 4D conformal Planning Strategy based on a synthesized 3.5D computed tomographic (3.5DCT) image with a motion-compensated tumor. To recreate patient anatomy from a ttBEV in the moving tumor coordinate system for 4DRT Planning (or 4D Planning), the centers of delineated GTVs in all phase CT images of 4DCT were aligned, and then the aligned CTs were averaged to produce a new 3.5DCT image. This GTV-motion-compensated CT contains a motionless target (with motion artifacts minimized) and motion-blurred normal tissues (with a realistic temporal density average). Semi-automatic threshold-based segmentation of the tumor, lung and body was applied, while manual delineation was used for other organs at risk (OARs). To validate this 3.5DCT-based 4D Planning Strategy, five patients with peripheral lung lesions of small size (
Ming Zhu - One of the best experts on this subject based on the ideXlab platform.
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an online ride sharing path Planning Strategy for public vehicle systems
IEEE Transactions on Intelligent Transportation Systems, 2019Co-Authors: Ming Zhu, Xiaoyang Liu, Xiaodong WangAbstract:As efficient traffic-management platforms, public vehicle (PV) systems are envisioned to be a promising approach to solving traffic congestion and pollution for future smart cities. PV systems provide online/dynamic peer-to-peer ride-sharing services with the goal of serving a sufficient number of customers with a minimum number of vehicles and the lowest possible cost. A key component of the PV system is the online ride-sharing scheduling Strategy. In this paper, an efficient path-Planning Strategy based on a greedy algorithm is proposed, which focuses on a limited potential search area for each vehicle by filtering out the requests that violate the passenger service quality level, so that the global search is reduced to a local search. Moreover, the proposed heuristic can be easily used in the future globally optimal algorithm (if it will exist) to speed the computation time. The performance of the proposed solution, such as reduction ratio of computational complexity, is analyzed. Simulations based on the Manhattan taxi data set show that the computing time is reduced by 22% compared with the exhaustive search method under the same service quality performance.
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an online ride sharing path Planning Strategy for public vehicle systems
arXiv: Artificial Intelligence, 2017Co-Authors: Ming Zhu, Xiaoyang Liu, Xiaodong WangAbstract:As efficient traffic-management platforms, public vehicle (PV) systems are envisioned to be a promising approach to solving traffic congestions and pollutions for future smart cities. PV systems provide online/dynamic peer-to-peer ride-sharing services with the goal of serving sufficient number of customers with minimum number of vehicles and lowest possible cost. A key component of the PV system is the online ride-sharing scheduling Strategy. In this paper, we propose an efficient path Planning Strategy that focuses on a limited potential search area for each vehicle by filtering out the requests that violate passenger service quality level, so that the global search is reduced to local search. We analyze the performance of the proposed solution such as reduction ratio of computational complexity. Simulations based on the Manhattan taxi data set show that, the computing time is reduced by 22% compared with the exhaustive search method under the same service quality performance.
A Negri - One of the best experts on this subject based on the ideXlab platform.
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Radioembolization of hepatocarcinoma with ^90Y glass microspheres: development of an individualized treatment Planning Strategy based on dosimetry and radiobiology
European Journal of Nuclear Medicine and Molecular Imaging, 2015Co-Authors: Carlo Chiesa, M Mira, Marco Maccauro, Carlo Spreafico, R Romito, Carlo Morosi, Tiziana Camerini, M Carrara, S Pellizzari, A NegriAbstract:Purpose The aim of this study was to optimize the dosimetric approach and to review the absorbed doses delivered, taking into account radiobiology, in order to identify the optimal methodology for an individualized treatment Planning Strategy based on ^99mTc-macroaggregated albumin (MAA) single photon emission computed tomography (SPECT) images. Methods We performed retrospective dosimetry of the standard TheraSphere® treatment on 52 intermediate ( n = 17) and advanced (i.e. portal vein thrombosis, n = 35) hepatocarcinoma patients with tumour burden
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radioembolization of hepatocarcinoma with 90y glass microspheres development of an individualized treatment Planning Strategy based on dosimetry and radiobiology
European Journal of Nuclear Medicine and Molecular Imaging, 2015Co-Authors: Carlo Chiesa, M Mira, Marco Maccauro, Carlo Spreafico, R Romito, Carlo Morosi, Tiziana Camerini, M Carrara, S Pellizzari, A NegriAbstract:Purpose The aim of this study was to optimize the dosimetric approach and to review the absorbed doses delivered, taking into account radiobiology, in order to identify the optimal methodology for an individualized treatment Planning Strategy based on 99mTc-macroaggregated albumin (MAA) single photon emission computed tomography (SPECT) images.
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radioembolization of hepatocarcinoma with 90 y glass microspheres development of an individualized treatment Planning Strategy based on dosimetry and radiobiology
European Journal of Nuclear Medicine and Molecular Imaging, 2015Co-Authors: Carlo Chiesa, M Mira, Marco Maccauro, Carlo Spreafico, R Romito, Carlo Morosi, Tiziana Camerini, M Carrara, S Pellizzari, A NegriAbstract:The aim of this study was to optimize the dosimetric approach and to review the absorbed doses delivered, taking into account radiobiology, in order to identify the optimal methodology for an individualized treatment Planning Strategy based on 99mTc-macroaggregated albumin (MAA) single photon emission computed tomography (SPECT) images. We performed retrospective dosimetry of the standard TheraSphere® treatment on 52 intermediate (n = 17) and advanced (i.e. portal vein thrombosis, n = 35) hepatocarcinoma patients with tumour burden 10 cc). Apparent radiosensitivity values from TCP were around 0.003/Gy, a factor of 3–5 lower than in EBRT, as found by other authors. The dose-rate effect was negligible: a purely linear model can be applied. Toxicity incidence was significantly larger for Child B7 patients (89 vs 14 %, p < 0.0001), who were therefore excluded from dose-toxicity analysis. Child A toxic vs non-toxic treatments were significantly separated in terms of dose averaged on whole non-tumoural parenchyma (including non-irradiated regions) with AUC from 0.73 to 0.94. TD50 was ≈ 100 Gy. No methodology was superior to parenchyma mean dose, which therefore can be used for Planning, with a limit of TD15 ≈ 75 Gy. A dosimetric treatment Planning criterion for Child A patients without complete obstruction of the portal vein was developed.
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a dosimetric treatment Planning Strategy in radioembolization of hepatocarcinoma with 90y glass microspheres
Quarterly Journal of Nuclear Medicine and Molecular Imaging, 2012Co-Authors: Carlo Chiesa, M Mira, Marco Maccauro, Carlo Spreafico, R Romito, Carlo Morosi, S Pellizzari, Carlo Sposito, Sherrie Bhoori, A NegriAbstract:Aim Our goal was to limit liver toxicity and to obtain good efficacy by developing a dosimetric treatment Planning Strategy. While several dosimetric evaluations are reported in literature, the main problem of the safety of the treatment is rarely addressed. Our work is the first proposal of a treatment Planning method for glass spheres, including both liver toxicity and efficacy issues. Methods Fifty-two patients (series 1) had been treated for intermediated/advanced hepatocellular carcinoma (HCC) with glass spheres, according to the Therasphere® prescription of 120 Gy averaged on the injected lobe. They were retrospectively evaluated with voxel dosimetry, adopting the local deposition hypothesis. Regions of interest on tumor and non tumor parenchyma were drawn to determine the parenchyma absorbed dose, averaged also on non irradiated voxels, excluding tumor voxels. The relationship between the mean non tumoral parenchyma absorbed dose D and observed liver decompensation was analyzed. Results Basal Child-Pugh strongly affected the toxicity incidence, which was 22% for A5, 57% for A6, 89% for B7 patients. Restricting the analysis to our numerically richest class (basal Child-Pugh A5 patients), D median values were significantly different between toxic (median 90 Gy) and non toxic treatments (median 58 Gy) at a Mann-Withney test, (P=0.033). Using D as a marker for toxicity, the separation of the two populations in terms of area under ROC curve was 0.75, with 95% C.I. of [0.55-0.95]. The experimental Normal Tissue Complication Probability (NTCP) curve as a function of D resulted in the following values: 0%, 14%, 40%, 67% for D interval of [0-35] Gy, [35-70] Gy, [70-105] Gy, [105-140] Gy. Discussion A limit of about 70 Gy for the mean absorbed dose to parenchyma was assumed for A5 patients, corresponding to a 14% risk of liver decompensation. This result is applicable only to our administration conditions: glass spheres after a decay interval of 3.75 days. Different safety limit (40 Gy) are published for resin spheres, characterized by higher number of particle per GBq (more uniform irradiation, bigger biological effect for the same absorbed dose). Conclusion As result of this study we suggest a constraint of about 70 Gy mean absorbed dose to liver non tumoral parenchyma, corresponding to about 15% probability of radioinduced liver decompensation while still aiming at achieving an absorbed of several hundreds of Gy to lesions.
Xiaoyang Liu - One of the best experts on this subject based on the ideXlab platform.
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an online ride sharing path Planning Strategy for public vehicle systems
IEEE Transactions on Intelligent Transportation Systems, 2019Co-Authors: Ming Zhu, Xiaoyang Liu, Xiaodong WangAbstract:As efficient traffic-management platforms, public vehicle (PV) systems are envisioned to be a promising approach to solving traffic congestion and pollution for future smart cities. PV systems provide online/dynamic peer-to-peer ride-sharing services with the goal of serving a sufficient number of customers with a minimum number of vehicles and the lowest possible cost. A key component of the PV system is the online ride-sharing scheduling Strategy. In this paper, an efficient path-Planning Strategy based on a greedy algorithm is proposed, which focuses on a limited potential search area for each vehicle by filtering out the requests that violate the passenger service quality level, so that the global search is reduced to a local search. Moreover, the proposed heuristic can be easily used in the future globally optimal algorithm (if it will exist) to speed the computation time. The performance of the proposed solution, such as reduction ratio of computational complexity, is analyzed. Simulations based on the Manhattan taxi data set show that the computing time is reduced by 22% compared with the exhaustive search method under the same service quality performance.
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an online ride sharing path Planning Strategy for public vehicle systems
arXiv: Artificial Intelligence, 2017Co-Authors: Ming Zhu, Xiaoyang Liu, Xiaodong WangAbstract:As efficient traffic-management platforms, public vehicle (PV) systems are envisioned to be a promising approach to solving traffic congestions and pollutions for future smart cities. PV systems provide online/dynamic peer-to-peer ride-sharing services with the goal of serving sufficient number of customers with minimum number of vehicles and lowest possible cost. A key component of the PV system is the online ride-sharing scheduling Strategy. In this paper, we propose an efficient path Planning Strategy that focuses on a limited potential search area for each vehicle by filtering out the requests that violate passenger service quality level, so that the global search is reduced to local search. We analyze the performance of the proposed solution such as reduction ratio of computational complexity. Simulations based on the Manhattan taxi data set show that, the computing time is reduced by 22% compared with the exhaustive search method under the same service quality performance.
