Quantum noise in detectors.


:The variance in the number of x-ray photons absorbed by a detector is derived from theoretical considerations. The distributions in the number of x-ray photons produced by the x-ray tube, transmitted through the patient, and absorbed by the detector are described. These distributions are compounded to yield a distribution in the number of x-ray photons absorbed by a detector. The standard deviation (quantum noise) in this distribution is very well approximated by the commonly used and experimentally verified quantity square root N where N is the average number of x-ray number of x-ray photons absorbed by the detector.


Med Phys


Medical physics


Rimkus D,Baily NA




Has Abstract


1983-07-01 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

  • Are we doing any good by doing really well? (Where's the Bacon?).

    abstract::Francis Bacon, who with Rene Decartes laid the intellectual foundations for Western science in the seventeenth century, asserted that the purpose of all knowledge is "action in the production of works for ... the relief of man's estate." We assess briefly several aspects of a few of the current efforts directed to the...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Herbert D

    更新日期:2003-04-01 00:00:00

  • Introducing gel dosimetry in a clinical environment: customization of polymer gel composition and magnetic resonance imaging parameters used for 3D dose verifications in radiosurgery and intensity modulated radiotherapy.

    abstract::Radiation sensitive gels have been used as dosimeters for clinical dose verification of different radiation therapy modalities. However, the use of gels is not widespread, because careful techniques are required to achieve the dose precision and accuracy aimed for in clinical dose verification. Here, the introduction ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Crescenti RA,Scheib SG,Schneider U,Gianolini S

    更新日期:2007-04-01 00:00:00

  • Pharmacokinetic modeling.

    abstract::For radiation dosimetry calculations of radiolabeled monoclonal antibodies, (MAB), pharmacokinetics are critical. Specifically, pharmacokinetic modeling is a useful component of estimation of cumulated activity in various source organs in the body. It is thus important to formulate general methods of pharmacokinetic m...

    journal_title:Medical physics

    pub_type: 杂志文章,评审


    authors: Strand SE,Zanzonico P,Johnson TK

    更新日期:1993-03-01 00:00:00

  • Monte Carlo based IMRT dose verification using MLC log files and R/V outputs.

    abstract::Conventional IMRT dose verification using film and ion chamber measurements is useful but limited with respect to the actual dose distribution received by the patient. The Monte Carlo simulation has been introduced as an independent dose verification tool for IMRT using the patient CT data and MLC leaf sequence files,...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Luo W,Li J,Price RA Jr,Chen L,Yang J,Fan J,Chen Z,McNeeley S,Xu X,Ma CM

    更新日期:2006-07-01 00:00:00

  • Lag measurement in an a-Se active matrix flat-panel imager.

    abstract::Lag and residual contrast have been quantified in an amorphous selenium (a-Se) active-matrix flat-panel imager (AMFPI) as a function of frame time, kilovoltage (kV) and megavoltage (MV) x-ray photon energies and amount of radiation incident on the detector. The AMFPI contains a 200 microm thick a-Se layer deposited on...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Schroeder C,Stanescu T,Rathee S,Fallone BG

    更新日期:2004-05-01 00:00:00

  • Maximum likelihood estimation in calibrating a stereo camera setup.

    abstract::Motion and deformation of the cardiac wall may be measured by following the positions of implanted radiopaque markers in three dimensions, using two x-ray cameras simultaneously. Regularly, calibration of the position measurement system is obtained by registration of the images of a calibration object, containing 10-2...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Muijtjens AM,Roos JM,Arts T,Hasman A

    更新日期:1999-02-01 00:00:00

  • SU-E-T-213: Development of a Web Wrapper to Facilitate Radiotherapy Research.

    abstract:PURPOSE:Researchers write many computer programs with unique implementations, usually requiring a great amount of effort for other researchers to learn how to install, configure, and use. Some programs require specialized hardware platforms such as GPU workstation or CPU cluster, which may not readily available for man...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Folkerts M,Graves Y,Gautier Q,Kim G,Jia X,Jiang S

    更新日期:2012-06-01 00:00:00

  • Dosimetric properties of radiophotoluminescent glass rod detector in high-energy photon beams from a linear accelerator and cyber-knife.

    abstract::A fully automatic radiophotoluminescent glass rod dosimeter (GRD) system has recently become commercially available. This article discusses the dosimetric properties of the GRD including uniformity and reproducibility of signal, dose linearity, and energy and directional dependence in high-energy photon beams. In addi...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Arakia F,Moribe N,Shimonobou T,Yamashita Y

    更新日期:2004-07-01 00:00:00

  • Calculation of x-ray spectra emerging from an x-ray tube. Part II. X-ray production and filtration in x-ray targets.

    abstract::A new approach to the calculation of the x-ray spectrum emerging from an x-ray tube is proposed. Theoretical results for the bremsstrahlung cross section appearing in the literature are summarized. Four different treatments of electron penetration, based on the work presented in Part I, are then used to generate brems...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Poludniowski GG

    更新日期:2007-06-01 00:00:00

  • SU-E-T-567: Improve Dose Conformity with IMRT Using Shorter Source to Tumor Distance.

    abstract:PURPOSE:To reduce the potential of late toxicity (tissue necrosis and cognitive function loss) from brain radiotherapy, we studied a novel planning technique for MLC-equipped linear accelerators (LINACS) that reduces the high doses delivered outside the PTV, enhancing radiation dose conformity. METHODS:The feasibility...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Yang W,Sandler H,Fraass B

    更新日期:2012-06-01 00:00:00

  • Improved MAGIC gel for higher sensitivity and elemental tissue equivalent 3D dosimetry.

    abstract:PURPOSE:Polymer-based gel dosimeter (MAGIC type) is a preferable phantom material for PET range verification of proton beam therapy. However, improvement in elemental tissue equivalency (specifically O/C ratio) is very desirable to ensure realistic time-activity measurements. METHODS:Glucose and urea was added to the ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Zhu X,Reese TG,Crowley EM,El Fakhri G

    更新日期:2010-01-01 00:00:00

  • An independent algorithm to check the monitor units calculation in radiosurgery.

    abstract::Double checking of the monitor units (MU) is an important step in the quality assurance (QA) process in radiosurgery. In this paper we propose the use of an independent algorithm constructed using the ellipsoid which best fits the measurements taken with the bubble head frame. The monitor units calculated by this inde...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Ramos LI,Monge RM,Aristu JJ,Moreno LA

    更新日期:2008-01-01 00:00:00

  • Computed tomography scanning with simultaneous patient translation.

    abstract::This paper deals with methods of reducing the total time required to acquire the projection data for a set of contiguous computed tomography (CT) images. Normally during the acquisition of a set of slices, the patient is held stationary during data collection and translated to the next axial location during an intersc...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Crawford CR,King KF

    更新日期:1990-11-01 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


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

    更新日期:1998-05-01 00:00:00

  • Low-dose dynamic myocardial perfusion CT imaging using a motion adaptive sparsity prior.

    abstract:PURPOSE:Dynamic myocardial perfusion computed tomography (DM-PCT) imaging offers benefits over quantitative assessment of myocardial blood flow (MBF) for diagnosis and risk stratification of coronary artery disease. However, one major drawback of DM-PCT imaging is that a high radiation level is imparted by repeated sca...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Bian Z,Zeng D,Zhang Z,Gong C,Tian X,Yan G,Huang J,Guo H,Chen B,Zhang J,Feng Q,Chen W,Ma J

    更新日期:2017-09-01 00:00:00

  • 3D image-guided robotic needle positioning system for small animal interventions.

    abstract:PURPOSE:This paper presents the design of a micro-CT guided small animal robotic needle positioning system. In order to simplify the robotic design and maintain a small targeting error, a novel implementation of the remote center of motion is used in the system. The system has been developed with the objective of achie...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Bax JS,Waring CS,Sherebrin S,Stapleton S,Hudson TJ,Jaffray DA,Lacefield JC,Fenster A

    更新日期:2013-01-01 00:00:00

  • Simultaneous super-resolution and contrast synthesis of routine clinical magnetic resonance images of the knee for improving automatic segmentation of joint cartilage: data from the Osteoarthritis Initiative.

    abstract:PURPOSE:High resolution three-dimensional (3D) magnetic resonance (MR) images are well suited for automated cartilage segmentation in the human knee joint. However, volumetric scans such as 3D Double-Echo Steady-State (DESS) images are not routinely acquired in clinical practice which limits opportunities for reliable ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Neubert A,Bourgeat P,Wood J,Engstrom C,Chandra SS,Crozier S,Fripp J

    更新日期:2020-10-01 00:00:00

  • Measuring uncertainty in dose delivered to the cochlea due to setup error during external beam treatment of patients with cancer of the head and neck.

    abstract:PURPOSE:To use Cone Beam CT scans obtained just prior to treatments of head and neck cancer patients to measure the setup error and cumulative dose uncertainty of the cochlea. METHODS:Data from 10 head and neck patients with 10 planning CTs and 52 Cone Beam CTs taken at time of treatment were used in this study. Patie...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Yan M,Lovelock D,Hunt M,Mechalakos J,Hu Y,Pham H,Jackson A

    更新日期:2013-12-01 00:00:00

  • Vessel size measurements in angiograms: manual measurements.

    abstract::Vessel size measurement is perhaps the most often performed quantitative analysis in diagnostic and interventional angiography. Although automated vessel sizing techniques are generally considered to have good accuracy and precision, we have observed that clinicians rarely use these techniques in standard clinical pra...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Hoffmann KR,Dmochowski J,Nazareth DP,Miskolczi L,Nemes B,Gopal A,Wang Z,Rudin S,Bednarek DR

    更新日期:2003-04-01 00:00:00

  • Sampling methods for a matrix ionization chamber system.

    abstract::To achieve increased image acquisition speed or better image quality, several read-out methods for a matrix ionization chamber system have been investigated. In this device, which is applied for portal imaging in radiation therapy, 256 x 256 small liquid-filled ionization chambers are scanned by switching the polarizi...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: van Herk M,Bijhold J,Hoogervorst B,Meertens H

    更新日期:1992-03-01 00:00:00

  • Reconstruction of diagnostic x-ray spectra by numerical analysis of transmission data.

    abstract::Numerical reconstruction of x-ray spectra from narrow-beam transmission data was tested with published spectra in the range from 45 to 100 kVp. Transmission curves were calculated from the spectra to simulate measured data. Spectra were reconstructed from these transmission curves with use of an iterative numerical an...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Huang PH,Chen TS,Kase KR

    更新日期:1986-09-01 00:00:00

  • Sensitivities in the production of spread-out Bragg peak dose distributions by passive scattering with beam current modulation.

    abstract::A spread-out Bragg peak (SOBP) is used in proton beam therapy to create a longitudinal conformality of the required dose to the target. In order to create this effect in a passive beam scattering system, a variety of components must operate in conjunction to produce the desired beam parameters. We will describe how th...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Lu HM,Brett R,Engelsman M,Slopsema R,Kooy H,Flanz J

    更新日期:2007-10-01 00:00:00

  • An innovative digital imaging set-up allowing a low-dose approach to phase contrast applications in the medical field.

    abstract::Recently, new imaging modalities based on the detection of weak phase perturbations effects, among which are phase contrast and diffraction imaging, have been developed by several researchers. Due to their high sensitivity to weakly absorbing details, these techniques seem to be very promising for applications in the ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Olivo A,Arfelli F,Cantatore G,Longo R,Menk RH,Pani S,Prest M,Poropat P,Rigon L,Tromba G,Vallazza E,Castelli E

    更新日期:2001-08-01 00:00:00

  • Characteristic performance evaluation of a photon counting Si strip detector for low dose spectral breast CT imaging.

    abstract:PURPOSE:The possible clinical applications which can be performed using a newly developed detector depend on the detector's characteristic performance in a number of metrics including the dynamic range, resolution, uniformity, and stability. The authors have evaluated a prototype energy resolved fast photon counting x-...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Cho HM,Barber WC,Ding H,Iwanczyk JS,Molloi S

    更新日期:2014-09-01 00:00:00

  • Nitroxide conjugate of a thermally responsive elastin-like polypeptide for noninvasive thermometry.

    abstract::Hyperthermia, as an adjuvant with radiation and chemotherapy, has shown promise in the treatment of cancer. The relevant biological effects of a hyperthermia treatment are both time and temperature-dependent, creating a need for accurate thermometry. We present a novel noninvasive thermometry modality that combines a ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Dreher MR,Elas M,Ichikawa K,Barth ED,Chilkoti A,Rosen GM,Halpern HJ,Dewhirst M

    更新日期:2004-10-01 00:00:00

  • Invertibility of the dual energy x-ray data transform.

    abstract:PURPOSE:The Alvarez-Macovski method extracts the x-ray energy-dependent information by expanding the attenuation coefficient as a linear combination of functions of energy multiplied by basis set coefficients. Since the basis functions are known a priori, the coefficients represent all the energy-dependent information....

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Alvarez RE

    更新日期:2019-01-01 00:00:00

  • Quantitative cone-beam CT imaging in radiation therapy using planning CT as a prior: first patient studies.

    abstract:PURPOSE:Quantitative cone-beam CT (CBCT) imaging is on increasing demand for high-performance image guided radiation therapy (IGRT). However, the current CBCT has poor image qualities mainly due to scatter contamination. Its current clinical application is therefore limited to patient setup based on only bony structure...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Niu T,Al-Basheer A,Zhu L

    更新日期:2012-04-01 00:00:00

  • Three-dimensional canine heart model for cardiac elastography.

    abstract:PURPOSE:A three-dimensional finite element analysis based canine heart model is introduced that would enable the assessment of cardiac function. METHODS:The three-dimensional canine heart model is based on the cardiac deformation and motion model obtained from the Cardiac Mechanics Research Group at UCSD. The canine h...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Chen H,Varghese T

    更新日期:2010-11-01 00:00:00

  • Technical Note: Evaluation of a 160-mm/256-row CT scanner for whole-heart quantitative myocardial perfusion imaging.

    abstract:PURPOSE:The authors investigated the performance of a recently introduced 160-mm/256-row CT system for low dose quantitative myocardial perfusion (MP) imaging of the whole heart. This platform is equipped with a gantry capable of rotating at 280 ms per full cycle, a second generation of adaptive statistical iterative r...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: So A,Imai Y,Nett B,Jackson J,Nett L,Hsieh J,Wisenberg G,Teefy P,Yadegari A,Islam A,Lee TY

    更新日期:2016-08-01 00:00:00