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Evaluation of the ray-casting analytical algorithm for pencil beam scanning proton therapy

PHYSICS IN MEDICINE AND BIOLOGY 2019年第6期64卷 art. no. 065021-art. no. 065021页

作者： Winterhalter, Carla Zepter, Stefan Shim, Sojin Meier, Gabriel Bolsi, Alessandra Fredh, Anna Hrbacek, Jan Oxley, David Zhang, Ye Weber, Damien C. Lomax, Antony Safai, Sairos Paul Scherrer Inst Ctr Proton Therapy Villigen Switzerland Swiss Fed Inst Technol Dept Phys Zurich Switzerland Swiss Fed Inst Technol Dept Mech & Proc Engn Zurich Switzerland EPF Lausanne Sect Phys Lausanne Switzerland Univ Hosp Bern Radiat Oncol Dept Bern Switzerland Univ Hosp Zurich Radiat Oncol Dept Zurich Switzerland

For pencil beam scanned (PBS) proton therapy, analytical dose calculation engines are still typically used for the optimisation process, and often for the final evaluation of the plan. Recently however, the suitability of analytical calculations for planning PBS treatments has been questioned. Conceptually, the two main approaches for these analytical dose calculations are the ray-casting (RC) and the pencil-beam (PB) method. In this study, we compare dose distributions and dosimetric indices, calculated on both the clinical dose calculation grid and as a function of dose grid resolution, to Monte Carlo (MC) calculations. The analysis is done using a comprehensive set of clinical plans which represent a wide choice of treatment sites. When analysing dose difference histograms for relative treatment plans, pencil beam calculations with double grid resolution perform best, with on average 97.7%/91.9% (RC), 97.9%/92.7% (RC, double grid resolution), 97.6%/91.0% (PB) and 98.6%/94.0% (PB, double grid resolution) of voxels agreeing within +/- 5%/+/- 3% between the analytical and the MC calculations. Even though these point-to-point dose comparison shows differences between analytical and MC calculations, for all algorithms, clinically relevant dosimetric indices agree within +/- 4% for the PTV and within +/- 5% for critical organs. While the clinical agreement depends on the treatment site, there is no substantial difference of indices between the different algorithms. The pencil-beam approach however comes at a higher computational cost than the ray-casting calculation. In conclusion, we would recommend using the ray-casting algorithm for fast dose optimization and subsequently combine it with one MC calculation to scale the absolute dose and assure the quality of the treatment plan.

关键词： proton therapy pencil beam scanning Monte Carlo simulation analytical algorithm ray-casting algorithm pencil-beam algorithm

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A NOVEL PARALLEL ray-casting algorithm 13

A NOVEL PARALLEL RAY-CASTING ALGORITHM

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13th IEEE International Computer Conference on Wavelet Active Media Technology and Information Processing (ICCWAMTIP)

作者： Zhang, Yan Gao, Peng Li, Xiao-Qing Harbin Inst Technol Shenzhen Grad Sch Microelect Ctr Shenzhen 518000 Peoples R China

ISBN: (纸本)9781509061266

The ray-casting algorithm is an important method for fast real-time surface display from 3D medical images. Based on ray-casting algorithm, a novel parallel ray-casting algorithm is proposed in this paper. A novel operation is introduced and defined as a star operation, and star operations can be computed in parallel in the proposed algorithm compared with the serial chain of star operations in the ray-casting algorithm. The computation complexity of the proposed algorithm is reduced from O(n) to O(log(2)(n))

关键词： 3D medical image display ray-casting algorithm parallel algorithm computation complexity

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ray-casting algorithm and Its Considerations for Parallel Processing Optimization techniques for parallel ray-casting algorithm 14

Ray-Casting Algorithm and Its Considerations for Parallel Pr...

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14 International Symposium on Integrated Circuits (ISIC)

作者： Cho, Hanjoo Kim, Young Hwan Pohang Univ Sci & Technol POSTECH Dept Elect Engn Pohang South Korea

ISBN: (纸本)9781479948338

This paper presents the considerations for improving the processing speed of ray-casting algorithm, which is widely used to visualize medical images, by using a parallel processing unit. The most important considerations are to exploit memory bandwidth and to maintain high occupancy. To improve memory bandwidth, cache-hit-rate should be kept high. For that, z-order cache is applied to data-load-operations and data-store-patterns are arranged to be coalesced. The tasks of the ray-casting algorithm are equally distributed into the cores of a parallel processing unit to achieve high occupancy. Furthermore, an interpolation process, which is frequently used in the sampling step of the ray-casting algorithm and has high complexity, is implemented to hardwired logic to improve processing speed. As a result of these optimizations, the processing speed was improved over four hundred times than the ray-casting algorithm without optimization.

关键词： ray-casting algorithm parallel processing optimization technique

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Research based on double coverage rate and reliability of gas detector layout optimization

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JOURNAL OF LOSS PREVENTION IN THE PROCESS INDUSTRIES 2020年 68卷 104285-104285页

作者： Cheng, Fangming Zhang, Anbang Wang, Tao Chen, Yan Chang, Zhuchuan Ge, Tianjiao Xian Univ Sci & Technol Sch Safety Sci & Engn Shaanxi Engn Res Ctr Ind Proc Safety & Emergency 58 Yanta Mid Rd Xian 710054 Shaanxi Peoples R China Ordnance Ind Hyg Res Inst Xian 710065 Shaanxi Peoples R China

The gas detector layout should be highly attuned to combustible gas leakage and attain a good reliability in avoiding detector malfunction, which is an important guarantee for the normal production of the chemical industry and other related enterprises. Herein, a gas detector layout optimization method based on double coverage and reliability is proposed. The key gas leakage monitoring area is determined through layout scene field investigation. To improve the detection probability and detection system reliability, the dual coverage target and voting mechanism are set, and the gas detector layout is determined with the ray-casting algorithm according to the coverage target. Combined with FLACS software to simulate a variety of typical leakage conditions under different layout scenarios, the relationship between the leaked gas concentration detected by gas detectors in each layout scheme and time is obtained, and the gas leakage detection probability in each layout scheme, number of detectors that can trigger the alarm, shortest time to trigger the alarm and reliability are comprehensively evaluated. The decision-maker selects the final gas detector layout plan according to the evaluation results and actual site needs. The study shows that the detection probability of each layout scheme set according to the double coverage is high, and multiple detectors can trigger the alarm (up to 100%), which ensures that the alarm can be triggered within 10 s under all applicable conditions. According to the evaluation results, the decision-maker can obtain a layout scheme that not only agrees with the actual site conditions but also attains a high detection probability, short detection time and strong reliability.

关键词： Gas detector arrangement Fraction of coverage Reliability Voting mechanism FLACS ray-casting algorithm

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Concrete CT Image Quick Three-Dimensional Reconstruction Research

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INTERNATIONAL JOURNAL OF PATTERN RECOGNITION AND ARTIFICIAL INTELLIGENCE 2017年第10期31卷 1757005-1757005页

作者： Zhao, Liang Li, Chang-Hua Dang, Fa-Ning Li, Chu-Jun Duan, Zhong-Xing Xian Univ Architecture & Technol Dept Info & Automat Xian 710055 Peoples R China Xian Univ Technol Inst Geotech Engn Xian 710048 Peoples R China

The research of the mechanical properties of concrete, a kind of heterogeneous composite material, was previously established on basis of the mathematical model of random aggregate, which is used to study and analyze the mesoscopic damage mechanism of concrete. Although the shape and distribution of aggregate in the model built by this method are closer to the real structure of concrete, there is still a big difference between them and the real concrete specimen. In order to solve the problem of large amount of redundant computation in the CT reconstruction of full size cube space, a fast reconstruction method based on ray-casting algorithm is proposed. First, a method integrating the new bounding box technology with the plane intersection algorithm clusters were adopted to cut the body data and ray-casting effectively, and then, the polygon scanning and conversion was utilized to reduce the number of cast rays, finally, the adaptive sampling method was used to avoid repeatedly sampling same voxel so that the reconstruction efficiency of whole algorithm and the feasibility of numerical calculation can be enhanced. The experimental results demonstrate that the proposed algorithm can greatly improve the 3D rendering speed of concrete CT without affecting the image quality. It provides a more effective and reliable approach for correctly analyzing the mesoscopic damage mechanism and mechanical characteristics of concrete.

关键词： Concrete CT ray-casting algorithm bounding-box plane intersection algorithm clusters adaptive sampling

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Modeling Tower Crane Operator Visibility to Minimize the Risk of Limited Situational Awareness

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JOURNAL OF COMPUTING IN CIVIL ENGINEERING 2014年第3期28卷 1-15页

作者： Cheng, Tao Teizer, Jochen Georgia Inst Technol Sch Civil & Environm Engn Atlanta GA 30332 USA

Many construction fatalities involving cranes and ground workers are caused by contact with objects and equipment, in particular being struck by crane loads and parts. One of the main risks in operating a tower crane is the limited visibility of the crane operator. An approach is presented that aims at increasing the situational awareness of a tower crane operator by aligning enhanced understanding of construction site layout with increased operator visibility of ground level operations. The developed method uses sensors to collect two data types, as follows: (1) a laser scanner measures the as-built conditions and geometry of a construction site, and (2) real-time location-tracking technology gathers the mostly dynamic location of workers on the ground. Several algorithms are presented to (1) identify blind spaces from the collected point cloud data that limit the visibility of a crane operator, (2) process real-time location-tracking data of workers on the ground, and (3) fuse the resulting data to create information that allows a quantitative assessment of the situational awareness of a tower crane operator. Results to a field trial are presented and show that a tower crane operator using the developed approach can increase understanding of where and when occluded spaces and ground-level operations occur. The developed methods for creating safety information from range point cloud and trajectory data is a promising approach in significantly improving the currently unsafe operation of tower cranes, one of the most utilized pieces of equipment in construction. (C) 2014 American Society of Civil Engineers.

关键词： As-built data collection Laser scanning Blind-spot analysis ray-casting algorithm Construction safety Equipment operator visibility Prevention through design Tower crane

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三维电磁环境的体绘制技术研究

三维电磁环境的体绘制技术研究

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作者：李灿电子科技大学

学位级别：硕士

With deploying more and more electromagnetic devices into the modern battlefield, the electromagnetic environment becomes increasingly complex, which can deeply affect the result of the military decision. However, due to the invisibility and the untouchability of the electromagnetic wave, failure of describing the electromagnetic environment accurately and intuitively always restricts commanders to make the right decision. Therefore, it's a very urgent problem that how to render the3D electromagnetic environment by computer technology such as computer graphics and parallel computing. This paper focuses on the research of visualization of3D electromagnetic environment. First of all, the value of electromagnetic environment is computed efficiently based on CUDA. Then the volume rendering technique is researched to show the3D electromagnetic environment. Finally, an original algorithm is devised and implemented to merge the result of volume rendering into the3D scene. Some critical techniques and core algorithms are researched and explored thoroughly and a number of innovation research results are made. In details, the main contributions of this paper are listed below: (1) This paper analyzes the process of computation of electromagnetic environment value based on ITM, which is parallelized. Then a CPU-GPU-hybrid-computing-based electromagnetic environment computation model is devised and implemented by CUDA to generate the volume data efficiently. (2) This paper uses the ray-casting algorithm to visualize the3D electromagnetic environment. The algorithm is parallelized based on the traditional one. Aiming at each parameter of ray-casting, new coordinator locations are devised respectively. Finally, the parallelized ray-casting algorithm is implemented by CUDA, which render the3D image of electromagnetic environment efficiently. (3) This paper devises a new transforming algorithm for ray-casting coordinator system based on the matrix coordinator transforma

关键词： ray-casting algorithm Electromagnetic Environment CUDA VirtualBattlefield Scientific Visualization

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Research on 3-D Image Reconstruction Concerning Radices Dentis Based on VTK

Research on 3-D Image Reconstruction Concerning Radices Dent...

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1st International Conference on Communications and Information Processing (ICCIP 2012)

作者： Ji, Changpeng Liu, Dian Liaoning Tech Univ Sch Elect & Informat Engn Huludao 125105 Liaoning Provin Peoples R China

ISBN: (纸本)9783642319679

In modern dental operations, dentists need to fix the position of radices dentis accurately in the process in order to relieve suffering of patients. Three-dimensional image reconstruction concerning radices dentis can help dentists achieve this aim and improve the vivacity and interaction of diagnosis greatly. In this research we adopt visualization tool kit with strong function based on VC6.0, acquire several CT images of a healthy person in DICOM format as the research objects, use the VTKfilter and Laplacian sharpening template for preprocessing of the images, and then adopt the ray-casting algorithm which is developed for volume rendering to construct a three-dimensional visualization model, at last we complete three-dimensional image reconstruction successfully.

关键词： Three-dimensional image reconstruction DICOM VTK volume rendering ray-casting algorithm

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3D visualization of tomographic volume data using the generalized voxel model

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The Visual Computer 1990年第1期6卷 28-36页

作者： Höhne, Karl Heinz Bomans, Michael Pommert, Andreas Riemer, Martin Schiers, Carsten Tiede, Ulf Wiebecke, Gunnar Institute of Mathematics and Computer Science in Medicine University Hospital Eppendorf Hamburg D-2000 Germany

Multi-slice images obtained from computer tomography and magnetic resonance imaging represent a 3D image volume. For its visualization we use a raycasting algorithm working on a gray-scale voxel data model. This model is extended by additional attributes such as membership to an organ or a second imaging modality ("generalized voxel model"). It is shown that the combination of different surface-rendering algorithms together with cutting and transparent display allow a realistic visualization of the human anatomy. © 1990 Springer-Verlag.

关键词： Computer tomography Magnetic resonance imaging ray-casting algorithm Voxel

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