A limit on dose reduction possible with CT reconstruction algorithms without prior knowledge of the scan subject.


PURPOSE:To find an upper bound on the maximum dose reduction possible for any reconstruction algorithm, analytic or iterative, that result from the inclusion of the data statistics. The authors do not analyze noise reduction possible from prior knowledge or assumptions about the object. METHODS:The authors examined the task of estimating the density of a circular lesion in a cross section. Raw data were simulated by forward projection of existing images and numerical phantoms. To assess an upper bound on the achievable dose reduction by any algorithm, the authors assume that both the background and the shape of the lesion are completely known. Under these conditions, the best possible estimate of the density can be determined by solving a weighted least squares problem directly in the raw data domain. Any possible reconstruction algorithm that does not use prior knowledge or make assumptions about the object, including filtered backprojection (FBP) or iterative reconstruction methods with this constraint, must be no better than this least squares solution. The authors simulated 10,000 sets of noisy data and compared the variance in density from the least squares solution with those from FBP. Density was estimated from FBP images using either averaging within a ROI, or streak-adaptive averaging with better noise performance. RESULTS:The bound on the possible dose reduction depends on the degree to which the observer can read through the possibly streaky noise. For the described low contrast detection task with the signal shape and background known exactly, the average dose reduction possible compared to FBP with streak-adaptive averaging was 42% and it was 64% if only the ROI average is used with FBP. The exact amount of dose reduction also depends on the background anatomy, with statistically inhomogeneous backgrounds showing greater benefits. CONCLUSIONS:The dose reductions from new, statistical reconstruction methods can be bounded. Larger dose reductions in the density estimation task studied here are only possible with the introduction of prior knowledge, which can introduce bias.


Med Phys


Medical physics


Hsieh SS,Chesler DA,Fleischmann D,Pelc NJ




Has Abstract


2016-03-01 00:00:00












  • Accurate measurement of characteristic curves of II-TV digital systems by use of aluminum stepwedge technique.

    abstract::In order to determine accurately the relative x-ray intensities transmitted through the different steps of an aluminum stepwedge and incident on an image intensifier (II)-TV digital system, we used a 100-mm camera which was attached to the II output. The characteristic curves of an II-TV digital system, which relate t...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Fujita H,Doi K

    更新日期:1986-11-01 00:00:00

  • Large field of view distortion assessment in a low-field MR-linac.

    abstract:PURPOSE:MR-guided radiation therapy (RT) offers unparalleled soft tissue contrast for localization and target tracking. However, MRI distortions may be detrimental to high precision RT. This work characterizes the gradient nonlinearity (GNL) and total distortions over the first year of clinical operation of a 0.35T MR-...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Nejad-Davarani SP,Kim JP,Du D,Glide-Hurst C

    更新日期:2019-05-01 00:00:00

  • Improvement of registration accuracy in accelerated partial breast irradiation using the point-based rigid-body registration algorithm for patients with implanted fiducial markers.

    abstract:PURPOSE:To investigate image-registration errors when using fiducial markers with a manual method and the point-based rigid-body registration (PRBR) algorithm in accelerated partial breast irradiation (APBI) patients, with accompanying fiducial deviations. METHODS:Twenty-two consecutive patients were enrolled in a pro...

    journal_title:Medical physics

    pub_type: 临床试验,杂志文章


    authors: Inoue M,Yoshimura M,Sato S,Nakamura M,Yamada M,Hirata K,Sasaki M,Fujimoto T,Ogura M,Hiraoka M

    更新日期:2015-04-01 00:00:00

  • Experimental implementation of a joint statistical image reconstruction method for proton stopping power mapping from dual-energy CT data.

    abstract:PURPOSE:To experimentally commission a dual-energy CT (DECT) joint statistical image reconstruction (JSIR) method, which is built on a linear basis vector model (BVM) of material characterization, for proton stopping power ratio (SPR) estimation. METHODS:The JSIR-BVM method builds on the relationship between the energ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Zhang S,Han D,Williamson JF,Zhao T,Politte DG,Whiting BR,O'Sullivan JA

    更新日期:2019-01-01 00:00:00

  • Dose homogeneity specification for reference dosimetry of nonstandard fields.

    abstract:PURPOSE:To investigate the sensitivity of the plan-class specific correction factor to dose distributions in composite nonstandard field dosimetry. METHODS:A cylindrical water-filled PMMA phantom was constructed at the center of which reference absorbed dose could be measured. Ten different TomoTherapy(®)-based IMRT f...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Chung E,Soisson E,Seuntjens J

    更新日期:2012-01-01 00:00:00

  • Discriminating solitary cysts from soft tissue lesions in mammography using a pretrained deep convolutional neural network.

    abstract:PURPOSE:It is estimated that 7% of women in the western world will develop palpable breast cysts in their lifetime. Even though cysts have been correlated with risk of developing breast cancer, many of them are benign and do not require follow-up. We develop a method to discriminate benign solitary cysts from malignant...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Kooi T,van Ginneken B,Karssemeijer N,den Heeten A

    更新日期:2017-03-01 00:00:00

  • Determination of the reference air kerma rate for 192Ir brachytherapy sources and the related uncertainty.

    abstract::Different methods exist to determine the air kerma calibration factor of an ionization chamber for the spectrum of a 192Ir high-dose-rate (HDR) or pulsed-dose-rate (PDR) source. An analysis of two methods to obtain such a calibration factor was performed: (i) the method recommended by [Goetsch et al., Med. Phys. 18, 4...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: van Dijk E,Kolkman-Deurloo IK,Damen PM

    更新日期:2004-10-01 00:00:00

  • Three-dimensional dose reconstruction of breast cancer treatment using portal imaging.

    abstract::In this study, we present an algorithm for three-dimensional (3-D) dose reconstruction using portal images obtained with an electronic portal imaging device (EPID). For this purpose an algorithm for 2-D dose reconstruction, which was previously developed in our institution, was adapted. The external contour of the pat...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Louwe RJ,Damen EM,van Herk M,Minken AW,Törzsök O,Mijnheer BJ

    更新日期:2003-09-01 00:00:00

  • SU-E-I-108: Simple Approach to Determine Patient's Entrance Skin Exposure for Radiographic.

    abstract:PURPOSE:To evaluate a model which can predict patient's Entrance Skin Exposure (ESE) from height and weight and a single kVp mR/mAs measurement for radiographic. METHODS:Patient height, weight and post exposure mAs are obtained to assess ESE based on IAEA model. Patient's thickness is obtained by assuming a cylindrica...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Maricle S,Jeutang L,Prasad G

    更新日期:2012-06-01 00:00:00

  • The accuracy of SPECT brain activation images: propagation of registration errors.

    abstract::Functional single photon emission computed tomography (SPECT) images of brain activation are based on a comparison of base line and activation images. The correctness of the functional images depends, among other factors, on the accurate spatial registration (alignment) of the base line and activation image data. The ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Sychra JJ,Pavel DG,Chen Y,Jani A

    更新日期:1994-10-01 00:00:00

  • Effect of finite sample size on feature selection and classification: a simulation study.

    abstract:PURPOSE:The small number of samples available for training and testing is often the limiting factor in finding the most effective features and designing an optimal computer-aided diagnosis (CAD) system. Training on a limited set of samples introduces bias and variance in the performance of a CAD system relative to that...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Way TW,Sahiner B,Hadjiiski LM,Chan HP

    更新日期:2010-02-01 00:00:00

  • Radionuclide photon dose kernels for internal emitter dosimetry.

    abstract::Photon point dose kernels and absorbed fractions were generated in water for the full photon emission spectrum of each radionuclide of interest in nuclear medicine, by simulating the transport of particles using Monte Carlo. The kernels were then fitted to a mathematical expression. Absorbed fractions for point source...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Furhang EE,Sgouros G,Chui CS

    更新日期:1996-05-01 00:00:00

  • Cavity contour segmentation in chest radiographs using supervised learning and dynamic programming.

    abstract:PURPOSE:Efficacy of tuberculosis (TB) treatment is often monitored using chest radiography. Monitoring size of cavities in pulmonary tuberculosis is important as the size predicts severity of the disease and its persistence under therapy predicts relapse. The authors present a method for automatic cavity segmentation i...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Maduskar P,Hogeweg L,de Jong PA,Peters-Bax L,Dawson R,Ayles H,Sánchez CI,van Ginneken B

    更新日期:2014-07-01 00:00:00

  • On calculating kerma, collision kerma and radiative yields.

    abstract:PURPOSE:To study the relationships between dose (D), kerma (K), and collision kerma ( K col ) in photon beams and to investigate total radiative yields for electrons and positrons as a functio...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Rogers DWO,Townson RW

    更新日期:2019-11-01 00:00:00

  • Evaluation of a deep learning-based computer-aided diagnosis system for distinguishing benign from malignant thyroid nodules in ultrasound images.

    abstract:PURPOSE:Computer-aided diagnosis (CAD) systems assist in solving subjective diagnosis problems that typically rely on personal experience. A CAD system has been developed to differentiate malignant thyroid nodules from benign thyroid nodules in ultrasound images based on deep learning methods. The diagnostic performanc...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Sun C,Zhang Y,Chang Q,Liu T,Zhang S,Wang X,Guo Q,Yao J,Sun W,Niu L

    更新日期:2020-09-01 00:00:00

  • Implementation of a quality assurance program for computerized treatment planning systems.

    abstract::In the present investigation, the necessary tests for implementing a quality assurance program for a commercial treatment planning system (TPS), recently installed at Sao Paulo University School of Medicine Clinicas Hospital-Brazil, was established and performed in accordance with the new IAEA publication TRS 430, and...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Camargo PR,Rodrigues LN,Furnari L,Rubo RA

    更新日期:2007-07-01 00:00:00

  • FRoG: An independent dose and LETd prediction tool for proton therapy at ProBeam® facilities.

    abstract:PURPOSE:Particle therapy is becoming increasingly available world-wide for precise tumor targeting, its favorable depth dose deposition, and increased biological damage to tumor tissue compared to conventional photon therapy. As demand increases for improved robustness and conformality, next-generation secondary dose c...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Kopp B,Fuglsang Jensen M,Mein S,Hoffmann L,Nyström H,Falk M,Haberer T,Abdollahi A,Debus J,Mairani A

    更新日期:2020-10-01 00:00:00

  • High correlation between radiation dose estimates for 256-slice CT obtained by highly parallelized hybrid Monte Carlo computation and solid-state metal-oxide semiconductor field-effect transistor measurements in physical anthropomorphic phantoms.

    abstract:PURPOSE:Accurate, patient-specific radiation dosimetry for CT scanning is critical to optimize radiation doses and balance dose against image quality. While Monte Carlo (MC) simulation is often used to estimate doses from CT, comparison of estimates to experimentally measured values is lacking for advanced CT scanners ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Prinsen P,Trattner S,Wiegert J,Gerland EL,Shefer E,Morton T,Thompson CM,Cheng B,Halliburton SS,Einstein AJ

    更新日期:2019-11-01 00:00:00

  • Noise power spectra of images from digital mammography detectors.

    abstract::Noise characterization through estimation of the noise power spectrum (NPS) is a central component of the evaluation of digital x-ray systems. We begin with a brief review of the fundamentals of NPS theory and measurement, derive explicit expressions for calculation of the one- and two-dimensional (1D and 2D) NPS, and...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Williams MB,Mangiafico PA,Simoni PU

    更新日期:1999-07-01 00:00:00

  • Combined mixed approach algorithm for in-line phase-contrast x-ray imaging.

    abstract:PURPOSE:In the past decade, phase-contrast imaging (PCI) has been applied to study different kinds of tissues and human body parts, with an increased improvement of the image quality with respect to simple absorption radiography. A technique closely related to PCI is phase-retrieval imaging (PRI). Indeed, PCI is an ima...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: De Caro L,Scattarella F,Giannini C,Tangaro S,Rigon L,Longo R,Bellotti R

    更新日期:2010-07-01 00:00:00

  • The effects of the imaging system on the validity limits of the ray-optical approach to phase contrast imaging.

    abstract::A theoretical analysis of the x-ray phase contrast imaging and its validation via synchrotron radiation imaging is here presented. Two different mathematical models have been followed: the simpler ray-optical approach and the more rigorous Fresnel-Kirchoff diffraction theory. Subsequently, the conditions upon which th...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Peterzol A,Olivo A,Rigon L,Pani S,Dreossi D

    更新日期:2005-12-01 00:00:00

  • A general algorithm for calculation of recombination losses in ionization chambers exposed to ion beams.

    abstract:PURPOSE:Dosimetry with ionization chambers in clinical ion beams for radiation therapy requires correction for recombination effects. However, common radiation protocols discriminate between initial and general recombination and provide no universal correction method for the presence of both recombination types in ion ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Christensen JB,Tölli H,Bassler N

    更新日期:2016-10-01 00:00:00

  • Experimental study of humidity effect on charge measurement of reference ionization chambers in clinical high-energy photon beams.

    abstract:PURPOSE:In the practice code of dosimetry, humidity effect is assumed to be constant as far as the measurements are performed in the relative humidity (RH) range of (20-80)%; thus, the humidity effect can be ignored with a dose uncertainty of 0.15%. This assumption is based on the previous experimental results by Niate...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Sato Y,Shimizu M,Morishita Y,Sato M,Hoshina M

    更新日期:2019-09-01 00:00:00

  • Radiation dose reduction using a CdZnTe-based computed tomography system: comparison to flat-panel detectors.

    abstract:PURPOSE:Although x-ray projection mammography has been very effective in early detection of breast cancer, its utility is reduced in the detection of small lesions that are occult or in dense breasts. One drawback is that the inherent superposition of parenchymal structures makes visualization of small lesions difficul...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Le Huy Q,Ducote JL,Molloi S

    更新日期:2010-03-01 00:00:00

  • Recognition of healthy and cancerous breast cells: Sensing the differences by dielectric spectroscopy.

    abstract:PURPOSE:The response of human cells to applied electrical signals depends on the cellular health status, because it is influenced by the composition and structure of the main cellular components. Therefore, electrical impedance-based techniques can be considered as sensitive tools to investigate healthy or disease stat...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Ambrico M,Lasalvia M,Ligonzo T,Ambrico PF,Perna G,Capozzi V

    更新日期:2020-10-01 00:00:00

  • Vision 20/20: Molecular-guided surgical oncology based upon tumor metabolism or immunologic phenotype: Technological pathways for point of care imaging and intervention.

    abstract::Surgical guidance with fluorescence has been demonstrated in individual clinical trials for decades, but the scientific and commercial conditions exist today for a dramatic increase in clinical value. In the past decade, increased use of indocyanine green based visualization of vascular flow, biliary function, and tis...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Pogue BW,Paulsen KD,Samkoe KS,Elliott JT,Hasan T,Strong TV,Draney DR,Feldwisch J

    更新日期:2016-06-01 00:00:00

  • An automated procedure for the quality assurance of electron beam output and energy.

    abstract::In this article, we report on the development of a simple and accurate method for quality assurance of electron beam output and energy. Aluminum disks of thicknesses d(max) or d50 of the particular electron energy are positioned sequentially over a parallel-plate ion chamber and the ratio of the two signals is compare...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Woo MK,Videla NG

    更新日期:2004-05-01 00:00:00

  • Noise correlations in images acquired simultaneously with a dual-energy sandwich detector.

    abstract::An energy discriminating detector for dual-energy radiography can be configured as a two-layer sandwich, where the mean energy of photons detected by the two layers differs. To characterize the quantum noise of such a detector, the noise covariance between the two layers must be known in addition to the noise variance...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Sones RA,Barnes GT

    更新日期:1989-11-01 00:00:00

  • Speckle contrast diffuse correlation tomography of complex turbid medium flow.

    abstract:PURPOSE:Developed herein is a three-dimensional (3D) flow contrast imaging system leveraging advancements in the extension of laser speckle contrast imaging theories to deep tissues along with our recently developed finite-element diffuse correlation tomography (DCT) reconstruction scheme. This technique, termed speckl...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Huang C,Irwin D,Lin Y,Shang Y,He L,Kong W,Luo J,Yu G

    更新日期:2015-07-01 00:00:00

  • Penumbral measurements in water for high-energy x rays.

    abstract::Ionization chambers of varying inside diameter have been used to investigate the penumbral region of 60Co, 6-MV, and 31-MV x-ray beams. Measurements were made in water at varying depths up to 25 cm for a square field of side length 10 cm. The dependence of the penumbral widths on both the inside diameter of the ioniza...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Dawson DJ,Schroeder NJ,Hoya JD

    更新日期:1986-01-01 00:00:00