An optimized leaf-setting algorithm for beam intensity modulation using dynamic multileaf collimators.


:A leaf-setting algorithm is developed for generating arbitrary beam intensity profiles in discrete levels using dynamic multileaf collimators (DMLCs). The algorithm starts with the algebraic expression for the area under the beam profile. It is shown that the coefficients in this expression can be transformed into the specifications for the leaf-setting sequence. It is proven that the algorithm optimizes beam delivery time and total monitor units for the DMLC leaf setting for intensity modulated radiotherapy (IMRT). The algorithm is demonstrated to be applicable to both the 'step-and-shoot' and 'dynamic' type of beam delivery. The graphical interpretation and numerical implementation scheme of the algorithm is illustrated using a simplified example.


Phys Med Biol


Ma L,Boyer AL,Xing L,Ma CM




Has Abstract


1998-06-01 00:00:00












  • Plane wave versus focused transmissions for contrast enhanced ultrasound imaging: the role of parameter settings and the effects of flow rate on contrast measurements.

    abstract::Contrast enhanced ultrasound (CEUS) and dynamic contrast enhanced ultrasound (DCE-US) can be used to provide information about the vasculature aiding diagnosis and monitoring of a number of pathologies including cancer. In the development of a CEUS imaging system, there are many choices to be made, such as whether to ...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Moghimirad E,Bamber J,Harris E

    更新日期:2019-04-23 00:00:00

  • Influence of sulphuric acid contaminants on Fricke dosimetry.

    abstract::The sulphuric acid used for the preparation of the Fricke dosimeter solution may contain trace impurities that can affect the yield of ferric ions. Two methods, pre-irradiation or oxidation with hydrogen peroxide, have been proposed to reduce the influence of these impurities. Fricke users sometimes omit this treatmen...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Palm A,Mattsson O

    更新日期:2000-09-01 00:00:00

  • Collapsed cone convolution and analytical anisotropic algorithm dose calculations compared to VMC++ Monte Carlo simulations in clinical cases.

    abstract::The purpose of this work was to study and quantify the differences in dose distributions computed with some of the newest dose calculation algorithms available in commercial planning systems. The study was done for clinical cases originally calculated with pencil beam convolution (PBC) where large density inhomogeneit...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Hasenbalg F,Neuenschwander H,Mini R,Born EJ

    更新日期:2007-07-07 00:00:00

  • Polaroid-PET: a PET scanner with detectors fitted with Polaroid for filtering unpolarized optical photons-a Monte Carlo simulation study.

    abstract::We propose and evaluate the performance of an improved preclinical positron emission tomography (PET) scanner design, referred to as Polaroid-PET, consisting of a detector equipped with a layer of horizontal Polaroid to filter scintillation photons with vertical polarization. This makes it possible to improve the spat...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Sanaat A,Ashrafi-Belgabad A,Zaidi H

    更新日期:2020-12-02 00:00:00

  • Investigation of practical approaches to evaluating cumulative dose for cone beam computed tomography (CBCT) from standard CT dosimetry measurements: a Monte Carlo study.

    abstract::A function called Gx(L) was introduced by the International Commission on Radiation Units and Measurements (ICRU) Report-87 to facilitate measurement of cumulative dose for CT scans within long phantoms as recommended by the American Association of Physicists in Medicine (AAPM) TG-111. The Gx(L) function is equal to t...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Abuhaimed A,Martin CJ,Sankaralingam M,Gentle DJ

    更新日期:2015-07-21 00:00:00

  • Bulk optical properties of healthy female breast tissue.

    abstract::We have measured the bulk optical properties of healthy female breast tissues in vivo in the parallel plate, transmission geometry. Fifty-two volunteers were measured. Blood volume and blood oxygen saturation were derived from the optical property data using a novel method that employed a priori spectral information t...

    journal_title:Physics in medicine and biology

    pub_type: 临床试验,杂志文章


    authors: Durduran T,Choe R,Culver JP,Zubkov L,Holboke MJ,Giammarco J,Chance B,Yodh AG

    更新日期:2002-08-21 00:00:00

  • Development of 4D mathematical observer models for the task-based evaluation of gated myocardial perfusion SPECT.

    abstract::This paper presents two 4D mathematical observer models for the detection of motion defects in 4D gated medical images. Their performance was compared with results from human observers in detecting a regional motion abnormality in simulated 4D gated myocardial perfusion (MP) SPECT images. The first 4D mathematical obs...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Lee TS,Frey EC,Tsui BM

    更新日期:2015-04-07 00:00:00

  • The production of positron emitters with millisecond half-life during helium beam radiotherapy.

    abstract::Therapy with helium ions is currently receiving significantly increasing interest because helium ions have a sharper penumbra than protons and undergo less fragmentation than carbon ions and thus require less complicated dose calculations. For any ion of interest in hadron therapy, the accuracy of dose delivery is lim...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Ozoemelam I,van der Graaf E,Brandenburg S,Dendooven P

    更新日期:2019-12-05 00:00:00

  • The energy-dependent electron loss model for pencil beam dose kernels.

    abstract::The 'monoenergetic' electron loss model was derived in a previous work to account for pathlength straggling in the Fermi-Eyges pencil beam problem. In this paper, we extend this model to account for energy-loss straggling and secondary knock-on electron transport in order to adequately predict a depth dose curve. To m...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Chvetsov AV,Sandison GA,Yeboah C

    更新日期:2000-10-01 00:00:00

  • An automatic algorithm for detecting stent endothelialization from volumetric optical coherence tomography datasets.

    abstract::Recent research has suggested that endothelialization of vascular stents is crucial to reducing the risk of late stent thrombosis. With a resolution of approximately 10 microm, optical coherence tomography (OCT) may be an appropriate imaging modality for visualizing the vascular response to a stent and measuring the p...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Bonnema GT,Cardinal KO,Williams SK,Barton JK

    更新日期:2008-06-21 00:00:00

  • UWB pulse propagation into human tissues.

    abstract::In this paper the propagation of a UWB pulse into a layered model of the human body is studied to characterize absorption and reflection of the UWB signal due to the different body tissues. Several time behaviours for the incident UWB pulse are considered and compared with reference to the feasibility of breath and he...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Cavagnaro M,Pittella E,Pisa S

    更新日期:2013-12-21 00:00:00

  • Characterization of noise and background signals in a magnetic particle imaging system.

    abstract::Magnetic Particle Imaging (MPI) is a novel technology, which opens new possibilities for promising biomedical applications. MPI uses magnetic fields to generate a specific response from magnetic nanoparticles (MNPs), to determine their spatial location non-invasively and without using ionizing radiation. One open chal...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Paysen H,Kosch O,Wells J,Loewa N,Wiekhorst F

    更新日期:2020-10-21 00:00:00

  • Online prediction of respiratory motion: multidimensional processing with low-dimensional feature learning.

    abstract::Accurate real-time prediction of respiratory motion is desirable for effective motion management in radiotherapy for lung tumor targets. Recently, nonparametric methods have been developed and their efficacy in predicting one-dimensional respiratory-type motion has been demonstrated. To exploit the correlation among v...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Ruan D,Keall P

    更新日期:2010-06-07 00:00:00

  • Influence of beam characteristics and detector size in negative-pion dose studies.

    abstract::Dose calculations were performed for a tissue phantom irradiated by uniform circular beams of negative pions with an assumed gaussian momentum distribution. The mean momentum of the pions was varied from 104.4 to 171.5 MeV/c (mean range 5-20 cm in unit-density tissue) and the momentum spread from 0 to 5% of the mean. ...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Hamm RN,Wright HA,Turner JE

    更新日期:1979-05-01 00:00:00

  • Measurement of the absolute optical properties and cerebral blood volume of the adult human head with hybrid differential and spatially resolved spectroscopy.

    abstract::A hybrid differential and spatially resolved spectroscopy (SRS) technique has been developed to measure absolute absorption coefficient (mu(a)), reduced scattering coefficient (mu'(s)) and cerebral blood volume (CBV) in the adult human head. A spectrometer with both differential and SRS capabilities has been used to c...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Leung TS,Tachtsidis I,Smith M,Delpy DT,Elwell CE

    更新日期:2006-02-07 00:00:00

  • The preprocessing of retinal images for the detection of fluorescein leakage.

    abstract::Images of the human retina are routinely used in clinical practice for the diagnosis and management of eye disease. Increased permeability of retinal blood vessels, which is a clinically significant feature, can be visualized with a process known as fluorescein angiography as leakage of fluorescence dye into the surro...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Cree MJ,Olson JA,McHardy KC,Sharp PF,Forrester JV

    更新日期:1999-01-01 00:00:00

  • Dose effect of guidewire position in intravascular brachytherapy.

    abstract::It has been reported that the dose effects of metallic guidewires are significant in intravascular brachytherapy (IVBT) using a beta source. The purpose of this work is to investigate the dependence of these dose effects on guidewire position. The EGS4 Monte Carlo codes were used to perform the dose calculations for t...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Shih R,Hsu WL,Li XA

    更新日期:2002-05-21 00:00:00

  • Implementation of tetrahedral-mesh geometry in Monte Carlo radiation transport code PHITS.

    abstract::A new function to treat tetrahedral-mesh geometry was implemented in the particle and heavy ion transport code systems. To accelerate the computational speed in the transport process, an original algorithm was introduced to initially prepare decomposition maps for the container box of the tetrahedral-mesh geometry. Th...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Furuta T,Sato T,Han MC,Yeom YS,Kim CH,Brown JL,Bolch WE

    更新日期:2017-06-21 00:00:00

  • Aluminum equivalence of materials used in diagnostic radiology and its dependence on beam quality.

    abstract::A semi-empirical theory has been derived that relates the aluminum equivalence of various materials used in diagnostic radiology to their attenuation coefficients. The dependence of the aluminum hardness (AHE) and attenuation (AAE) equivalent on the beam quality is described in terms of effective energy. This 'aluminu...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Nagel HD

    更新日期:1986-12-01 00:00:00

  • Novel iterative reconstruction method with optimal dose usage for partially redundant CT-acquisition.

    abstract::In CT imaging, a variety of applications exist which are strongly SNR limited. However, in some cases redundant data of the same body region provide additional quanta. Examples in dual energy CT, the spatial resolution has to be compromised to provide good SNR for material decomposition. However, the respective spectr...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Bruder H,Raupach R,Sunnegardh J,Allmendinger T,Klotz E,Stierstorfer K,Flohr T

    更新日期:2015-11-07 00:00:00

  • An absorptiometry method for the determination of arterial blood concentration of injected iodinated contrast agent.

    abstract::A single photon absorptiometry method to measure the arterial concentration of injected iodinated contrast agent was developed. A prototype absorptiometry unit was built which consists of either a square or circular cross section acrylic (polymethylmethacrylate) cuvette connected to an arterial catheter at one end and...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Yeung WT,Lee TY,Del Maestro RF,Kozak R,Bennett JD,Brown T

    更新日期:1992-09-01 00:00:00

  • Effect of inter-crystal scatter on estimation methods for random coincidences and subsequent correction.

    abstract::Random coincidences can contribute substantially to the background in positron emission tomography (PET). Several estimation methods are being used for correcting them. The goal of this study was to investigate the validity of techniques for random coincidence estimation, with various low-energy thresholds (LETs). Sim...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Torres-Espallardo I,Rafecas M,Spanoudaki V,McElroy DP,Ziegler SI

    更新日期:2008-05-07 00:00:00

  • Inverse treatment planning for an electronic brachytherapy system delivering anisotropic radiation therapy.

    abstract::An inverse radiation treatment planning algorithm for Sensus Healthcare's SculpturaTM electronic brachytherapy system has been designed. The algorithm makes use of simulated annealing to optimize the conformation number of the treatment plan. The highly anisotropic dose distributions produced by the SculpturaTM x-ray ...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Badali DS,Vainer Y,Ellenor CW,Mitchell CR,Fishman K,Soro N,Price R,Funk T

    更新日期:2021-01-11 00:00:00

  • Automatic T1 bladder tumor detection by using wavelet analysis in cystoscopy images.

    abstract::Correct classification of cystoscopy images depends on the interpreter's experience. Bladder cancer is a common lesion that can only be confirmed by biopsying the tissue, therefore, the automatic identification of tumors plays a significant role in early stage diagnosis and its accuracy. To our best knowledge, the use...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Freitas NR,Vieira PM,Lima E,Lima CS

    更新日期:2018-02-02 00:00:00

  • Simulated lesion, human observer performance comparison between thin-section dedicated breast CT images versus computed thick-section simulated projection images of the breast.

    abstract::The objective of this study was to compare the lesion detection performance of human observers between thin-section computed tomography images of the breast, with thick-section (>40 mm) simulated projection images of the breast. Three radiologists and six physicists each executed a two alterative force choice (2AFC) s...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Chen L,Boone JM,Abbey CK,Hargreaves J,Bateni C,Lindfors KK,Yang K,Nosratieh A,Hernandez A,Gazi P

    更新日期:2015-04-21 00:00:00

  • 4D Monte Carlo simulation of proton beam scanning: modelling of variations in time and space to study the interplay between scanning pattern and time-dependent patient geometry.

    abstract::When dosimetric effects in time-dependent geometries are studied, usually either the results of individual three-dimensional (3D) calculations are combined or probability-based approaches are applied. These methods may become cumbersome and time-consuming if high time resolution is required or if the geometry is compl...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Paganetti H,Jiang H,Trofimov A

    更新日期:2005-03-07 00:00:00

  • Laser shaping of corneal transplants in vitro: area ablation with small overlapping laser spots produced by a pulsed scanning laser beam using an optimizing ablation algorithm.

    abstract::Area laser lathing and trephination of donor corneas is used to produce different types of grafts for human transplantation. 193 nm (ArF excimer) laser radiation is used, since this is known to give a non-thermal laser-tissue interaction with a minimal zone of tissue damage. To guarantee the highest degree of flexibil...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Homolka P,Biowski R,Kaminski S,Barisani T,Husinsky W,Bergmann H,Grabner G

    更新日期:1999-05-01 00:00:00

  • Measurements of angular distributions of Rayleigh and Mie scattering events in biological models.

    abstract::Remission spectroscopy in living tissues can only be performed because scattering processes induce a pronounced amount of backscattered light. New types of scattering chambers were constructed in order to investigate the angular distribution of light intensities caused by scattering events typical for living tissues. ...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Frank KH,Kessler M,Appelbaum K,Albrecht HP,Mauch ED

    更新日期:1989-12-01 00:00:00

  • Characteristics of boron-dose enhancer dependent on dose protocol and 10B concentration for BNCT using near-threshold 7Li(p,n)7Be direct neutrons.

    abstract::The dependence of boron-dose enhancer (BDE) characteristics on dose protocol and 10B concentration was evaluated for BNCT using near-threshold 7Li(p,n)7Be direct neutrons. The treatable protocol depth (TPD) was utilized as an evaluation index. MCNP calculations were performed for near-threshold 7Li(p,n)7Be at a proton...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Tanaka K,Kobayashi T,Bengua G,Nakagawa Y,Endo S,Hoshi M

    更新日期:2005-01-07 00:00:00

  • Calculation of positron range and its effect on the fundamental limit of positron emission tomography system spatial resolution.

    abstract::Developments in positron emission tomography (PET) technology have resulted in systems with finer detector elements designed to further improve spatial resolution. However, there is a limit to what extent reducing detector element size will improve spatial resolution in PET. The spatial resolution of PET imaging is li...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Levin CS,Hoffman EJ

    更新日期:1999-03-01 00:00:00