Calculation of photon energy deposition kernels and electron dose point kernels in water.

Abstract:

:Effects of changes in the physics of EGSnrc compared to EGS4/PRESTA on energy deposition kernels for monoenergetic photons and on dose point kernels for beta sources in water are investigated. In the diagnostic energy range, Compton binding corrections were found to increase the primary energy fraction up to 4.5% at 30 keV with a corresponding reduction of the scatter component of the kernels. Rayleigh scattered photons significantly increase the scatter component of the kernels and reduce the primary energy fraction with a maximum 12% reduction also at 30 keV where the Rayleigh cross section in water has its maximum value. Sampling the photo-electron angular distribution produces a redistribution of the energy deposited by primaries around the interaction site causing differences of up to 2.7 times in the backscattered energy fraction at 20 keV. Above the pair production threshold, the dose distribution versus angle of the primary dose component is significantly different from the EGS4 results. This is related to the more accurate angular sampling of the electron-positron pair direction in EGSnrc as opposed to using a fixed angle approximation in default EGS4. Total energy fractions for photon beams obtained with EGSnrc and EGS4 are almost the same within 0.2%. This fact suggests that the estimate of the total dose at a given point inside an infinite homogeneous water phantom irradiated by broad beams of photons will be very similar for kernels calculated with both codes. However, at interfaces or near boundaries results can be very different especially in the diagnostic energy range. EGSnrc calculated kernels for monoenergetic electrons (50 keV, 100 keV, and 1 MeV) and beta spectra (32P and 90Y) are in excellent agreement with reported EGS4 values except at 1 MeV where inclusion of spin effects in EGSnrc produces an increase of the effective range of electrons. Comparison at 1 MeV with an ETRAN calculation of the electron dose point kernel shows excellent agreement.

journal_name

Med Phys

journal_title

Medical physics

authors

Mainegra-Hing E,Rogers DW,Kawrakow I

doi

10.1118/1.1861412

subject

Has Abstract

pub_date

2005-03-01 00:00:00

pages

685-99

issue

3

eissn

0094-2405

issn

2473-4209

journal_volume

32

pub_type

杂志文章
  • Nonlocal atlas-guided multi-channel forest learning for human brain labeling.

    abstract:PURPOSE:It is important for many quantitative brain studies to label meaningful anatomical regions in MR brain images. However, due to high complexity of brain structures and ambiguous boundaries between different anatomical regions, the anatomical labeling of MR brain images is still quite a challenging task. In many ...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.4940399

    authors: Ma G,Gao Y,Wu G,Wu L,Shen D

    更新日期:2016-02-01 00:00:00

  • Feature-based multibody rigid registration of CT and ultrasound images of lumbar spine.

    abstract:PURPOSE:Fusion of intraprocedure ultrasound and preprocedure CT data is proposed for guidance in percutaneous spinal injections, a common procedure for pain management. CT scan of the lumbar spine is usually collected in a supine position, whereas spinal injections are performed in prone or sitting positions. This lead...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.4711753

    authors: Rasoulian A,Abolmaesumi P,Mousavi P

    更新日期:2012-06-01 00:00:00

  • Image segmentation with a novel regularized composite shape prior based on surrogate study.

    abstract:PURPOSE:Incorporating training into image segmentation is a good approach to achieve additional robustness. This work aims to develop an effective strategy to utilize shape prior knowledge, so that the segmentation label evolution can be driven toward the desired global optimum. METHODS:In the variational image segmen...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.4945046

    authors: Zhao T,Ruan D

    更新日期:2016-05-01 00:00:00

  • Evaluation of inherent gray-level dynamic range in a digital image using the runs test and join-count statistics.

    abstract::The dynamic range of the gray level of a digital image is limited by the noise it contains. Two statistical methods called "runs test" and "join-count statistic" are used to measure the noise level in a digital image. A residual image is formed by subtracting an original image from its smoothed version. Theoretically,...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.597058

    authors: Chuang KS,Huang HK

    更新日期:1993-01-01 00:00:00

  • Observation and correction of transient cavitation-induced PRFS thermometry artifacts during radiofrequency ablation, using simultaneous ultrasound/MR imaging.

    abstract:PURPOSE:MR thermometry based on the proton resonance frequency shift (PRFS) is the most commonly used method for the monitoring of thermal therapies. As the chemical shift of water protons is temperature dependent, the local temperature variation (relative to an initial baseline) may be calculated from time-dependent p...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.3309439

    authors: Viallon M,Terraz S,Roland J,Dumont E,Becker CD,Salomir R

    更新日期:2010-04-01 00:00:00

  • Evaluation of a direct motion estimation/correction method in respiratory-gated PET/MRI with motion-adjusted attenuation.

    abstract:PURPOSE:Respiratory motion compensation in PET/CT and PET/MRI is essential as motion is a source of image degradation (motion blur, attenuation artifacts). In previous work, we developed a direct method for joint image reconstruction/motion estimation (JRM) for attenuation-corrected (AC) respiratory-gated PET, which us...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1002/mp.12253

    authors: Bousse A,Manber R,Holman BF,Atkinson D,Arridge S,Ourselin S,Hutton BF,Thielemans K

    更新日期:2017-06-01 00:00:00

  • Unequal weighting of given doses in opposed fields in treatment of cancer of the tonsillar region using 60Co, 4-, 8-, 15-, 24-MVp photons.

    abstract::Weighting of given doses from parallel opposed fields is a widespread practice in radiation therapy of cancer in the tonsillar region. In order to determine when weighting is useful, dose distributions on the central axis were calculated for various energies (60Co, 4-, 8-, 15-, and MVp photons), weighting factors, and...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.594276

    authors: Wollin M,Gilbert HA,Kagan AR

    更新日期:1976-03-01 00:00:00

  • On the uncertainties in effective dose estimates of adult CT head scans.

    abstract::Estimates of the effective dose to adult patients from computed tomography (CT) head scanning can be calculated using a number of different methods. These estimates can be used for a variety of purposes, such as improving scanning protocols, comparing different CT imaging centers, and weighing the benefits of the scan...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.2952359

    authors: Gregory KJ,Bibbo G,Pattison JE

    更新日期:2008-08-01 00:00:00

  • Resampling: an optimization method for inverse planning in robotic radiosurgery.

    abstract::By design, the range of beam directions in conventional radiosurgery are constrained to an isocentric array. However, the recent introduction of robotic radiosurgery dramatically increases the flexibility of targeting, and as a consequence, beams need be neither coplanar nor isocentric. Such a nonisocentric design per...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.2357020

    authors: Schweikard A,Schlaefer A,Adler JR Jr

    更新日期:2006-11-01 00:00:00

  • Cascaded systems analysis of noise reduction algorithms in dual-energy imaging.

    abstract::An important aspect of dual-energy (DE) x-ray image decomposition is the incorporation of noise reduction techniques to mitigate the amplification of quantum noise. This article extends cascaded systems analysis of imaging performance to DE imaging systems incorporating linear noise reduction algorithms. A general ana...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.2826556

    authors: Richard S,Siewerdsen JH

    更新日期:2008-02-01 00:00:00

  • Quantitative assessment of bone mineral by photon scattering: accuracy and precision considerations.

    abstract::A method to determine the bone mineral density of the calcaneum has been reported earlier by our laboratory. In this method, the calcaneum is irradiated by a 60-keV photon beam from 241Am source and both the coherent and Compton scattered photons are detected by a high-purity Ge detector. The bone mineral density is d...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.595669

    authors: Shukla SS,Karellas A,Leichter I,Craven JD,Greenfield MA

    更新日期:1985-07-01 00:00:00

  • MO-D-BRB-11: Out-Of-Field Dose Measurements in Radiotherapy Using Photons and Particles.

    abstract:PURPOSE:Within the European project ALLEGRO (grant agreement no. 231965), the out-of-field dose delivered to a patient when treated with different radiotherapy modalities was investigated. The study compared the dose distribution during photon and particle irradiations both in a water and an anthropomorphic phantom to ...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.4735792

    authors: Kaderka R,Durante M,Berger T,Reitz G,Tessa C

    更新日期:2012-06-01 00:00:00

  • Physical characteristics of scattered radiation in diagnostic radiology: Monte Carlo simulation studies.

    abstract::We applied Monte Carlo methods for the simulation of x-ray scattering in water phantoms. The phantom thickness was varied from 5 to 20 cm, and the monoenergetic incident x rays were varied from 15 to 100 keV. Eight screen pairs and a total absorption system were used as x-ray receptors. We determined the angular, spec...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.595771

    authors: Chan HP,Doi K

    更新日期:1985-03-01 00:00:00

  • Optimizing cone beam CT scatter estimation in egs_cbct for a clinical and virtual chest phantom.

    abstract:PURPOSE:Cone beam computed tomography (CBCT) image quality suffers from contamination from scattered photons in the projection images. Monte Carlo simulations are a powerful tool to investigate the properties of scattered photons.egs_cbct, a recent EGSnrc user code, provides the ability of performing fast scatter calcu...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.4881142

    authors: Thing RS,Mainegra-Hing E

    更新日期:2014-07-01 00:00:00

  • Lung dosimetry in a linac-MRI radiotherapy unit with a longitudinal magnetic field.

    abstract:PURPOSE:There is interest in developing linac-MR systems for MRI-guided radiation therapy. To date, the designs for such linac-MR devices have been restricted to a transverse geometry where the static magnetic field is oriented perpendicular to the direction of the incident photon beam. This work extends possibilities ...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.3475942

    authors: Kirkby C,Murray B,Rathee S,Fallone BG

    更新日期:2010-09-01 00:00:00

  • Calculation of the radiological depth.

    abstract::The concept of the radiological depth is central to all algorithms which calculate radiation dose in a heterogeneous medium. For a discrete heterogeneous medium, consisting of regions of inhomogeneity, the radiological depth is usually presented as the sum over segments of the product of the segment length and the inh...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.595739

    authors: Siddon RL

    更新日期:1985-01-01 00:00:00

  • Flattening filter removal for improved image quality of megavoltage fluoroscopy.

    abstract:PURPOSE:Removal of the linear accelerator (linac) flattening filter enables a high rate of dose deposition with reduced treatment time. When used for megavoltage imaging, an unflat beam has reduced primary beam scatter resulting in sharper images. In fluoroscopic imaging mode, the unflat beam has higher photon count pe...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.4812678

    authors: Christensen JD,Kirichenko A,Gayou O

    更新日期:2013-08-01 00:00:00

  • Optimized knot placement for B-splines in deformable image registration.

    abstract:PURPOSE:To develop an automatic knot placement algorithm to enable the use of NonUniform Rational B-Splines (NURBS) in deformable image registration. METHODS:The authors developed a two-step approach to fit a known displacement vector field (DVF). An initial fit was made with uniform knot spacing. The error generated ...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.3609416

    authors: Jacobson TJ,Murphy MJ

    更新日期:2011-08-01 00:00:00

  • Material-specific analysis using coherent-scatter imaging.

    abstract::Coherent-scatter computed tomography (CSCT) is a novel imaging method we are developing to produce cross-sectional images based on the low-angle (<10 degrees) scatter properties of tissue. At diagnostic energies, this scatter is primarily coherent with properties dependent upon the molecular structure of the scatterer...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.1493216

    authors: Batchelar DL,Cunningham IA

    更新日期:2002-08-01 00:00:00

  • A separable quadratic surrogate total variation minimization algorithm for accelerating accurate CT reconstruction from few-views and limited-angle data.

    abstract:PURPOSE:Total variation minimization (TVM) is a popular and useful method for accurate CT reconstruction from few-views and limited-angle data. However, the optimization procedure of previous TVM-based algorithms is very time-consuming. The purpose of this paper was to accelerate the high image quality CT reconstructio...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1002/mp.12692

    authors: Hou X,Teng Y,Kang Y,Qi S

    更新日期:2018-02-01 00:00:00

  • Contamination dose from photoneutron processes in bodily tissues during therapeutic radiation delivery.

    abstract::Dose to the total body from induced radiation resulting from primary exposure to radiotherapeutic beams is not detailed in routine treatment planning though this information is potentially important for better estimates of health risks including secondary cancers. This information can also allow better management of p...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.1612947

    authors: Difilippo F,Papiez L,Moskvin V,Peplow D,DesRosiers C,Johnson J,Timmerman R,Randall M,Lillie R

    更新日期:2003-10-01 00:00:00

  • Feature selection using factor analysis for Alzheimer's diagnosis using 18F-FDG PET images.

    abstract:PURPOSE:This article presents a computer-aided diagnosis technique for improving the accuracy of the early diagnosis of Alzheimer's disease (AD). Two hundred and ten 18F-FDG PET images from the ADNI initiative [52 normal controls (NC), 114 mild cognitive impairment (MCI), and 53 AD subjects] are studied. METHODS:The p...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.3488894

    authors: Salas-Gonzalez D,Górriz JM,Ramírez J,Illán IA,López M,Segovia F,Chaves R,Padilla P,Puntonet CG

    更新日期:2010-11-01 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

    doi:10.1118/1.598277

    authors: Tsujii O,Freedman MT,Mun SK

    更新日期:1998-06-01 00:00:00

  • Completeness map evaluation demonstrated with candidate next-generation cardiac CT architectures.

    abstract:PURPOSE:In this report, the authors introduce the general concept of the completeness map, as a means to evaluate the completeness of data acquired by a given CT system design (architecture and scan mode). They illustrate the utility of completeness map by applying the completeness map concept to a number of candidate ...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.3700172

    authors: Liu B,Bennett J,Wang G,De Man B,Zeng K,Yin Z,Fitzgerald P,Yu H

    更新日期:2012-05-01 00:00:00

  • Signal, noise power spectrum, and detective quantum efficiency of indirect-detection flat-panel imagers for diagnostic radiology.

    abstract::The performance of an indirect-detection, active matrix flat-panel imager (FPI) at diagnostic energies is reported in terms of measured and theoretical signal size, noise power spectrum (NPS), and detective quantum efficiency (DQE). Based upon a 1536 x 1920 pixel, 127 microns pitch array of a-Si:H thin-film transistor...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.598243

    authors: Siewerdsen JH,Antonuk LE,el-Mohri Y,Yorkston J,Huang W,Cunningham IA

    更新日期:1998-05-01 00:00:00

  • Automatic detection of simulated motion blur in mammograms.

    abstract:PURPOSE:To use machine-learning algorithms and blur measure (BM) operators to automatically detect motion blur in mammograms. Motion blur has been reported to reduce lesion detection performance and mask small abnormalities, resulting in failure to detect them until they reach more advanced stages. Automatic detection ...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1002/mp.14069

    authors: Kamona N,Loew M

    更新日期:2020-04-01 00:00:00

  • Subvoxel precise skeletons of volumetric data based on fast marching methods.

    abstract::The accurate calculation of the skeleton of an object is a problem not satisfactorily solved by existing approaches. Most algorithms require a significant amount of user interaction and use a voxel grid to compute discrete and often coarse approximations of this representation of the data. We present a novel, automati...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.2409238

    authors: Van Uitert R,Bitter I

    更新日期:2007-02-01 00:00:00

  • Measured electron energy and angular distributions from clinical accelerators.

    abstract::Electron energy spectra and angular distributions, including angular spreads, were measured using magnetic spectrometer techniques, at isocenter, for two clinical linear accelerators: one scanning beam machine, which achieves field flatness by scanning a pencil beam over the desired field at the patient plane, and one...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.597817

    authors: Deasy JO,Almond PR,McEllistrem MT

    更新日期:1996-05-01 00:00:00

  • Learning-based automated segmentation of the carotid artery vessel wall in dual-sequence MRI using subdivision surface fitting.

    abstract:PURPOSE:The quantification of vessel wall morphology and plaque burden requires vessel segmentation, which is generally performed by manual delineations. The purpose of our work is to develop and evaluate a new 3D model-based approach for carotid artery wall segmentation from dual-sequence MRI. METHODS:The proposed me...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1002/mp.12476

    authors: Gao S,van 't Klooster R,Kitslaar PH,Coolen BF,van den Berg AM,Smits LP,Shahzad R,Shamonin DP,de Koning PJH,Nederveen AJ,van der Geest RJ

    更新日期:2017-10-01 00:00:00

  • A fast GPU-based Monte Carlo simulation of proton transport with detailed modeling of nonelastic interactions.

    abstract:PURPOSE:Very fast Monte Carlo (MC) simulations of proton transport have been implemented recently on graphics processing units (GPUs). However, these MCs usually use simplified models for nonelastic proton-nucleus interactions. Our primary goal is to build a GPU-based proton transport MC with detailed modeling of elast...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.4921046

    authors: Wan Chan Tseung H,Ma J,Beltran C

    更新日期:2015-06-01 00:00:00