Geometric studies on variable radius spiral cone-beam scanning.


:The goal is to perform geometric studies on cone-beam CT scanning along a three-dimensional (3D) spiral of variable radius. First, the background for variable radius spiral cone-beam scanning is given in the context of electron-beam CT/micro-CT. Then, necessary and sufficient conditions are proved for existence and uniqueness of PI lines inside the variable radius 3D spiral. These results are necessary steps toward exact cone-beam reconstruction from a 3D spiral scan of variable radius, adapting Katsevich's formula for the standard helical cone-beam scanning. It is shown in the paper that when the longitudinally projected planar spiral is not always convex toward the origin, the PI line may not be unique in the envelope defined by the tangents of the spiral. This situation can be avoided by using planar spirals whose curvatures are always positive. Using such a spiral, a longitudinally homogeneous region inside the corresponding 3D spiral is constructed in which any point is passed by one and only one PI line, provided the angle omega between planar spiral's tangent and radius is bounded by [omega - 90 degrees] < or = < epsilon for some positive epsilon < or = 32.48 degrees. If the radius varies monotonically, this region is larger and one may allow epsilon < or = 51.85 degrees. Examples for 3D spirals based on logarithmic and Archimedean spirals are given. The corresponding generalized Tam-Danielsson detection windows are also formulated.


Med Phys


Medical physics


Yea Y,Zhu J,Wang G




Has Abstract


2004-06-01 00:00:00












  • Comparative dosimetry of diode and diamond detectors in electron beams for intraoperative radiation therapy.

    abstract::The aim of the present study is to examine the validity of using silicon semiconductor detectors in degraded electron beams with a broad energy spectrum and a wide angular distribution. A comparison is made with diamond detector measurements, which is the dosimeter considered to give the best results provided that dos...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Björk P,Knöös T,Nilsson P

    更新日期:2000-11-01 00:00:00

  • Improved modeling of multiple scattering in the Voxel Monte Carlo model.

    abstract::The implementation of an improved model for multiple scattering into the-Voxel Monte Carlo (VMC) algorithm for fast electron dose calculation in radiation therapy is presented. The model takes into account path-length corrections (PLC) and lateral displacement in the individual electron steps. The extraction of the sc...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Kawrakow I

    更新日期:1997-04-01 00:00:00

  • A statistical approach to infer the minimum setup distance of a well chamber to the wall or to the floor for 192Ir HDR calibration.

    abstract::We propose a new method based on statistical analysis technique to determine the minimum setup distance of a well chamber used in the calibration of 192Ir high dose rate (HDR). The chamber should be placed at least this distance away from any wall or from the floor in order to mitigate the effect of scatter. Three dif...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Chang L,Ho SY,Chui CS,Lee JH,Du YC,Chen T

    更新日期:2008-06-01 00:00:00

  • Position detection accuracy of a novel linac-mounted intrafractional x-ray imaging system.

    abstract:PURPOSE:The authors have developed a system that monitors intrafractional target motion perpendicular to the treatment beam with the aid of radioopaque markers by means of separating kV image and megavoltage (MV) treatment field on a single flat-panel detector. METHODS:They equipped a research Siemens Artiste linear a...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Fast MF,Krauss A,Oelfke U,Nill S

    更新日期:2012-01-01 00:00:00

  • SU-E-T-619: A Network-Flow Solution Approach to VMAT Treatment Plan Optimization.

    abstract:PURPOSE:To add mathematical rigor to the merging phase of the recently published two-stage VMAT optimization method called VMERGE. Using an exact merging method, we are able to better characterize the tradeoff between delivery efficiency and dose quality. METHODS:VMERGE begins with an IMRT plan that uses 180 equi-spac...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Salari E,Craft D

    更新日期:2012-06-01 00:00:00

  • Micro-angiography for neuro-vascular imaging. II. Cascade model analysis.

    abstract::A micro-angiographic detector was designed and its performance was previously tested to evaluate its feasibility as an improvement over current x-ray detectors for neuro-interventional imaging. The detector was shown to have a modulation transfer function value of about 2% at the Nyquist frequency of 10 cycles/mm and ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Ganguly A,Rudin S,Bednarek DR,Hoffmann KR

    更新日期:2003-11-01 00:00:00

  • Super-resolution reconstruction for 4D computed tomography of the lung via the projections onto convex sets approach.

    abstract:PURPOSE:The use of 4D computed tomography (4D-CT) of the lung is important in lung cancer radiotherapy for tumor localization and treatment planning. Sometimes, dense sampling is not acquired along the superior-inferior direction. This disadvantage results in an interslice thickness that is much greater than in-plane v...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Zhang Y,Wu X,Yang W,Feng Q,Chen W

    更新日期:2014-11-01 00:00:00

  • Technical Note: Experimental verification of magnetic field-induced beam deflection and Bragg peak displacement for MR-integrated proton therapy.

    abstract:PURPOSE:Given its sensitivity to anatomical variations, proton therapy is expected to benefit greatly from integration with magnetic resonance imaging for online anatomy monitoring during irradiation. Such an integration raises several challenges, as both systems mutually interact. The proton beam will experience quasi...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Schellhammer SM,Gantz S,Lühr A,Oborn BM,Bussmann M,Hoffmann AL

    更新日期:2018-07-01 00:00:00

  • Unwanted radiation produced by leakage neutrons from medical electron accelerators.

    abstract::Monte Carlo calculations have been made to determine the energy delivered to a phantom by neutrons escaping from the head of a Varian Clinac 35 medical accelerator at an SSD of 1 m. The energy was sorted into two regions: inside and outside a volume defined by a circular beam of area 100 and 600 cm2. For the two beam ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Ing H,Shore RA

    更新日期:1982-01-01 00:00:00

  • Rotational micro-CT using a clinical C-arm angiography gantry.

    abstract::Rotational angiography (RA) gantries are used routinely to acquire sequences of projection images of patients from which 3D renderings of vascular structures are generated using Feldkamp cone-beam reconstruction algorithms. However, these systems have limited resolution (<4 lp/mm). Micro-computed tomography (micro-CT)...

    journal_title:Medical physics

    pub_type: 信件


    authors: Patel V,Hoffmann KR,Ionita CN,Keleshis C,Bednarek DR,Rudin S

    更新日期:2008-10-01 00:00:00

  • SU-E-T-382: An Analysis of VMAT Monthly Quality Assurance.

    abstract:PURPOSE:The purpose of this study is to quantify the change in monthly VMAT quality assurance (QA) and determine the tests to maintain consistent delivery with a baseline. METHODS:VMAT monthly QA has been performed for over 14 months on two Elekta Synergy LINACs. A baseline was established at acceptance and the monthl...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Stenbeck J,Oves S,Gebreamlak W,Alkhatib H

    更新日期:2012-06-01 00:00:00

  • Image reconstruction algorithm for a rotating slat collimator.

    abstract::A slat collimator in single photon emission computed tomography consists of a set of parallel slats. As the collimator spins, the detector measures a one-dimensional projection data set. A complete data set can be obtained by rotating the detector/collimator assembly around the object (patient) while the collimator sp...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Zeng GL,Gagnon D,Matthews CG,Kolthammer JA,Radachy JD,Hawkins WG

    更新日期:2002-07-01 00:00:00

  • Comparison of measured with calculated dose distribution from a 120-MeV electron beam from a laser-plasma accelerator.

    abstract:PURPOSE:To evaluate the dose distribution of a 120-MeV laser-plasma accelerated electron beam which may be of potential interest for high-energy electron radiation therapy. METHODS:In the interaction between an intense laser pulse and a helium gas jet, a well collimated electron beam with very high energy is produced....

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Lundh O,Rechatin C,Faure J,Ben-Ismaïl A,Lim J,De Wagter C,De Neve W,Malka V

    更新日期:2012-06-01 00:00:00

  • Cumulative sum quality control for calibrated breast density measurements.

    abstract:PURPOSE:Breast density is a significant breast cancer risk factor. Although various methods are used to estimate breast density, there is no standard measurement for this important factor. The authors are developing a breast density standardization method for use in full field digital mammography (FFDM). The approach c...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Heine JJ,Cao K,Beam C

    更新日期:2009-12-01 00:00:00

  • Model-based geometric calibration for medical x-ray systems.

    abstract:PURPOSE:Currently applied calibration approaches lead to satisfying 3D roadmapping overlay and 3D reconstruction accuracies; however, the required calibration times are extensive. The aim of this paper is the introduction of a novel model-based approach for geometric system calibrations, leading to a significant reduct...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: van der Maas R,de Jager B,Steinbuch M,Dries J

    更新日期:2015-11-01 00:00:00

  • The potential role of positron emission mammography for detection of breast cancer. A phantom study.

    abstract::Positron emission mammography (PEM) is a new, specialized imaging modality utilizing PET radiopharmaceuticals to detect breast cancer. The capabilities and limitations of PEM in detecting breast tumors were investigated with a series of phantom experiments. The PEM imager was mounted on a standard Lorad biopsy table (...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Raylman RR,Majewski S,Wojcik R,Weisenberger AG,Kross B,Popov V,Bishop HA

    更新日期:2000-08-01 00:00:00

  • Automated segmentation of anatomic regions in chest radiographs using an adaptive-sized hybrid neural network.

    abstract::The purposes of this research are to investigate the effectiveness of our novel image features for segmentation of anatomic regions such as the lungs and the mediastinum in chest radiographs and to develop an automatic computerized method for image processing. A total of 85 screening chest radiographs from Johns Hopki...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Tsujii O,Freedman MT,Mun SK

    更新日期:1998-06-01 00:00:00

  • Creating optimal code for GPU-accelerated CT reconstruction using ant colony optimization.

    abstract:PURPOSE:CT reconstruction algorithms implemented on the GPU are highly sensitive to their implementation details and the hardware they run on. Fine-tuning an implementation for optimal performance can be a time consuming task and require many updates when the hardware changes. There are some techniques that do automati...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Papenhausen E,Zheng Z,Mueller K

    更新日期:2013-03-01 00:00:00

  • Dose in the buildup region outside the primary beam.

    abstract::The dose received in the buildup region outside the primary beam has been measured for 60Co gamma rays and 6- and 18-MV X rays. The variation of this dose with field size and depth was evaluated. The effect of blocking trays and the importance of their design was determined. ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Horton JL

    更新日期:1984-05-01 00:00:00

  • A consistent set of neutron kerma coefficients from thermal to 150 MeV for biologically important materials.

    abstract::Neutron cross sections for nonelastic and elastic reactions on a range of elements have been evaluated for incident energies up to 150 MeV. These cross sections agree well with experimental cross section data for charged-particle production as well as neutron and photon production. Therefore they can be used to determ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Chadwick MB,Barschall HH,Caswell RS,DeLuca PM,Hale GM,Jones DT,MacFarlane RE,Meulders JP,Schuhmacher H,Schrewe UJ,Wambersie A,Young PG

    更新日期:1999-06-01 00:00:00

  • Development and validation of a measurement-based source model for kilovoltage cone-beam CT Monte Carlo dosimetry simulations.

    abstract:PURPOSE:The purpose of this study is to adapt an equivalent source model originally developed for conventional CT Monte Carlo dose quantification to the radiation oncology context and validate its application for evaluating concomitant dose incurred by a kilovoltage (kV) cone-beam CT (CBCT) system integrated into a lin...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: McMillan K,McNitt-Gray M,Ruan D

    更新日期:2013-11-01 00:00:00

  • Treatment planning system and beam data validation for the ZAP-X: a novel self-shielded stereotactic radiosurgery system.

    abstract:PURPOSE:To evaluate the treatment planning system (TPS) performance of the ZAP-X stereotactic radiosurgery (SRS) system through nondosimetric, dosimetric, and end-to-end (E2E) tests. METHODS:A comprehensive set of TPS commissioning and validation tests were developed using published guidelines. Nondosimetric validatio...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Srivastava SP,Jani SS,Pinnaduwage DS,Yan X,Rogers L,Barranco FD,Barani IJ,Sorensen S

    更新日期:2021-01-28 00:00:00

  • Evaluation of volumetric modulated arc therapy for cranial radiosurgery using multiple noncoplanar arcs.

    abstract:PURPOSE:To evaluate a commercial volumetric modulated arc therapy (VMAT), using multiple noncoplanar arcs, for linac-based cranial radiosurgery, as well as evaluate the combined accuracy of the VMAT dose calculations and delivery. METHODS:Twelve patients with cranial lesions of variable size (0.1-29 cc) and two multip...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Audet C,Poffenbarger BA,Chang P,Jackson PS,Lundahl RE,Ryu SI,Ray GR

    更新日期:2011-11-01 00:00:00

  • Dynamic field-of-view imaging to increase temporal resolution in the early phase of contrast media uptake in breast DCE-MRI: A feasibility study.

    abstract:PURPOSE:To increase diagnostic accuracy of breast MRI by increasing temporal resolution and more accurately sampling the early kinetics of contrast media uptake. We tested the feasibility of accelerating bilateral breast DCE-MRI by reducing the FOV, allowing aliasing, and unfolding the resulting images. METHODS:Previo...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Pineda FD,Easley TO,Karczmar GS

    更新日期:2018-03-01 00:00:00

  • Measurement of primary bremsstrahlung spectrum from an 8-MeV linear accelerator.

    abstract::The bremsstrahlung spectrum from an 8-MeV linear accelerator has been measured using a NaI(T1) spectrometer system. The spectrum shows a low-energy cutoff at 0.4 MeV and the maximum photon energy to be approximately 6% greater than the nominal energy. The maximum emission of energy fluence was 1.6 and 1.8 MeV for meas...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Levy LB,Waggener RG,Wright AE

    更新日期:1976-05-01 00:00:00

  • SU-E-T-144: Daily and Monthly Quality Assurance with TomoDose.

    abstract:PURPOSE:Examine the use of TomoDose for Tomotherapy quality assurance. METHODS:Baseline TomoDose profiles are acquired annually in accordance with TG-148. During monthly quality assurance, TomoDose is irradiated with a static beam and referenced to baseline. Differences between superimposed profiles are evaluated mont...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Terrell J

    更新日期:2012-06-01 00:00:00

  • Effect of lateral boundaries on contrast functions in time-resolved transillumination measurements.

    abstract::The method of images is employed to insert the effects of the presence of a single lateral boundary on contrast functions previously derived for an infinite slab using a random walk model of photon transport. The predictions of the model for zero and extrapolated boundary conditions are compared with Monte Carlo (MC) ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Chernomordik V,Gandjbakhche AH,Hebden JC,Zaccanti G

    更新日期:1999-09-01 00:00:00

  • Toward the combined optimization of dynamic axes (CODA) for stereotactic radiotherapy and radiosurgery using fixed couch trajectories.

    abstract:PURPOSE:To develop a novel system for patient-specific combined optimization of couch, collimator, and gantry angles for use in volumetric modulated arc therapy (VMAT) treatment planning. The system was designed to produce highly compact dose distributions by extensively sampling the 4π space. Automated fixed couch tra...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: MacDonald RL,Syme A,Little B,Ward L,Thomas CG

    更新日期:2020-02-01 00:00:00

  • A mobile isocentric C-arm for intraoperative cone-beam CT: Technical assessment of dose and 3D imaging performance.

    abstract:PURPOSE:To characterize the radiation dose and three-dimensional (3D) imaging performance of a recently developed mobile, isocentric C-arm equipped with a flat-panel detector (FPD) for intraoperative cone-beam computed tomography (CBCT) (Cios Spin 3D, Siemens Healthineers) and to identify potential improvements in 3D i...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Sheth NM,De Silva T,Uneri A,Ketcha M,Han R,Vijayan R,Osgood GM,Siewerdsen JH

    更新日期:2020-03-01 00:00:00

  • Comparison of radiograph-based texture analysis and bone mineral density with three-dimensional microarchitecture of trabecular bone.

    abstract:PURPOSE:Hip fracture is a serious health problem and textural methods are being developed to assess bone quality. The authors aimed to perform textural analysis at femur on high-resolution digital radiographs compared to three-dimensional (3D) microarchitecture comparatively to bone mineral density. METHODS:Sixteen ca...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Ranjanomennahary P,Ghalila SS,Malouche D,Marchadier A,Rachidi M,Benhamou C,Chappard C

    更新日期:2011-01-01 00:00:00