Results 111 to 120 of about 4,762,893 (253)

Parallel bundles in planar map geometries [PDF]

arXiv, 2005
Parallel lines are very important objects in Euclid plane geometry and its behaviors can be gotten by one's intuition. But in a planar map geometry, a kind of the Smarandache geometries, the sutation is complex since it may contains elliptic or hyperbolic points.
arxiv  

Monte Carlo modeling of radiation dose from radiation therapy with superficial x‐rays

Journal of Applied Clinical Medical Physics, EarlyView.
Abstract Introduction Superficial x‐rays (50–100 kVp) are used for treating non‐melanoma skin cancer and intraoperative radiation therapy (IORT). At these energies, the photoelectric effect significantly increases absorbed dose to bone compared to soft tissue.
Reham Barghash, Tiffany W. Martin, Amber R. Prebble, Del Leary   +3 more
wiley   +1 more source

Explicit Enumerative Geometry for the Real Grassmannian of Lines in Projective Space [PDF]

Duke Math. J., 87 (1997) 59-85, 1995
We extend the classical Schubert calculus of enumerative geometry for the Grassmann variety of lines in projective space from the complex realm to the real. Specifically, given any collection of Schubert conditions on lines in projective space which generically determine a finite number of lines, we show there exist real generic conditions determining ...
arxiv  

Quantification and dosimetric impact of intra‐fractional bladder changes during CBCT‐guided online adaptive radiotherapy for pelvic cancer treatments

Journal of Applied Clinical Medical Physics, EarlyView.
Abstract Purpose This study quantitatively evaluates bladder changes and their dosimetric impact during the on‐couch adaptive process on a commercial CBCT‐based online adaptive radiotherapy (CT‐gART) platform. Methods Data from 183 fractions of ten patients receiving online ART for pelvic cancers were analyzed retrospectively.
Ingrid Valencia Lozano, Elizabeth Buss, Catherine S. Spina, David P. Horowitz, Lisa A. Kachnic, Michael Price, Yi‐Fang Wang, Reshma Munbodh   +7 more
wiley   +1 more source

Velocity-resolved Ionization Mapping of Broad Line Region. I. Insights into Diverse Geometry and Kinematics

The Astrophysical Journal
Broad emission lines of active galactic nuclei (AGNs) originate from the broad-line region (BLR), consisting of dense gas clouds in orbit around an accreting supermassive black hole. Understanding the geometry and kinematics of this region is crucial for
Sha-Sha Li, Hai-Cheng Feng, H. T. Liu, J. M. Bai, Xiang Ji, Yu-Xuan Pang, Cheng Cheng, Kai-Xing Lu, Jian-Guo Wang, Rui Li   +9 more
doaj   +1 more source

Fundamentals of Broken Line Convex Geometry [PDF]

arXiv
We develop the fundamentals of a new theory of convex geometry -- which we call "broken line convex geometry". This is a theory of convexity where the ambient space is the rational tropicalization of a cluster variety, as opposed to an ambient vector space.
arxiv  

Line problems in nonlinear computational geometry [PDF]

arXiv, 2006
We first review some topics in the classical computational geometry of lines, in particular the O(n^{3+\epsilon}) bounds for the combinatorial complexity of the set of lines in R^3 interacting with $n$ objects of fixed description complexity. The main part of this survey is recent work on a core algebraic problem--studying the lines tangent to k ...
arxiv  

Development of a generic focal spot measurement method suitable for bore‐type linacs

Journal of Applied Clinical Medical Physics, EarlyView.
Abstract Purpose In linear accelerators, deviations in the x‐ray focal spot position significantly affect the accuracy of radiation therapy. However, as the focal spot position in bore‐type linac systems such as the Radixact system, cannot be assessed using conventional methods, a new evaluation method is required.
Hidetoshi Shimizu, Kazuharu Nishitani, Tomoki Kitagawa, Koji Sasaki, Takahiro Aoyama, Takeshi Kodaira   +5 more
wiley   +1 more source

Feature Lines for Illustrating Medical Surface Models: Mathematical Background and Survey [PDF]

arXiv, 2015
This paper provides a tutorial and survey for a specific kind of illustrative visualization technique: feature lines. We examine different feature line methods. For this, we provide the differential geometry behind these concepts and adapt this mathematical field to the discrete differential geometry.
arxiv  

A method for measuring spatial resolution based on clinical chest CT sequence images

Journal of Applied Clinical Medical Physics, EarlyView.
Abstract Purpose This study aimed to develop and validate a method for characterizing the spatial resolution of clinical chest computed tomography (CT) sequence images. Methods An algorithm for characterizing spatial resolution based on clinical chest CT sequence images was developed in Matlab (2021b).
Ying Liu, Jingying Shen, Haowei Zhang, Haikuan Liu   +3 more
wiley   +1 more source