Comment on: Polarity effects and apparent ion recombination in microionization chambers Med. Phys. 43(5), 2141-2152 (2016).


:In a recent paper of Miller et al. (Med. Phys. 43(5), 2141-2152 (2016), the voltage dependence polarity effect of microionization chambers was studied. It was identified that polarity effect arises from the difference in electric potential between the collecting electrode and the guard electrode, which in turn deforms the electric field and affects the charge collection. Nevertheless, the cause of such potential difference has not been identified. In this letter, we explain that the electric potential perturbation arises from the work function difference of the disparate materials electrodes (collecting vs guard electrodes in the particular case).


Med Phys


Medical physics


Brivio D,Sajo E,Zygmanski P




Has Abstract


2017-03-01 00:00:00












  • Recent progress in x-ray stereoscopes.

    abstract::An improved reconstructed stereoscopic x-ray image display system, based on the principle of binocular parallax, is described. Pulse-synchronized operation of two triode x-ray tubes and one plumbicon TV camera is employed to separate the left and right images for presentation to the two eyes, respectively. The princip...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Zhang S,King PH,Pang XD

    更新日期:1983-09-01 00:00:00

  • Ultrafast treatment plan optimization for volumetric modulated arc therapy (VMAT).

    abstract:PURPOSE:To develop a novel aperture-based algorithm for volumetric modulated are therapy (VMAT) treatment plan optimization with high quality and high efficiency. METHODS:The VMAT optimization problem is formulated as a large-scale convex programming problem solved by a column generation approach. The authors consider...

    journal_title:Medical physics

    pub_type: 信件


    authors: Men C,Romeijn HE,Jia X,Jiang SB

    更新日期:2010-11-01 00:00:00

  • Systematic calibration of an integrated x-ray and optical tomography system for preclinical radiation research.

    abstract:PURPOSE:The cone beam computed tomography (CBCT) guided small animal radiation research platform (SARRP) has been developed for focal tumor irradiation, allowing laboratory researchers to test basic biological hypotheses that can modify radiotherapy outcomes in ways that were not feasible previously. CBCT provides exce...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Yang Y,Wang KK,Eslami S,Iordachita II,Patterson MS,Wong JW

    更新日期:2015-04-01 00:00:00

  • Normalization (division) versus subtraction of digitized images.

    abstract::The propagation of noise in digitized images arrived at by algebraic manipulation of two images has been investigated. The algebraic manipulations investigated were logarithmic subtraction, linear subtraction, and division of the two images. The two images were identical except for the presence of a contrast-adding co...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Baily NA,Rimkus D,Nalcioglu O

    更新日期:1983-01-01 00:00:00

  • Thermoluminescent dosimetry of the SourceTech Medical model STM1251 125I seed.

    abstract::Many new models of 125I seeds are being introduced, mainly due to the increase in prostate seed implants. We have evaluated the SourceTech Medical (STM), model STM1251, 125I seed using thermoluminescent dosimeters (TLDs) in a solid water phantom. TLD cubes, LiF TLD-100, with dimension 1 mm on each edge, were irradiate...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Chiu-Tsao ST,Duckworth TL,Hsiung CY,Li Z,Williamson J,Patel NS,Harrison LB

    更新日期:2003-07-01 00:00:00

  • SU-E-T-162: Rapid Assessment of Cyberknife IRIS Variable Collimator Performance Using a Commercial Diode Array.

    abstract:PURPOSE:To describe an efficient method for verifying the size and centering of the radiation field from the Cyberknife IRIS variable collimator with sub-millimeter accuracy using a general purpose commercially available diode array. METHODS:We present a technique using a conventional diode array (Sun Nuclear Profiler...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Gibbs G,White G,Bulz G

    更新日期:2012-06-01 00:00:00

  • A convolution method for constructing primary beam profiles in the presence of beam modifiers.

    abstract::Empirical functions that describe primary beam profiles for radiotherapy treatment planning systems generally account for finite source size only on beams unmodified by blocks, wedges, or compensating filters. To incorporate the effects of extended sources on such modified beams and to treat the effect of an extended ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Starkschall G

    更新日期:1988-09-01 00:00:00

  • Experimental study of the relationship between the base impedance and its time derivative in impedance plethysmography.

    abstract::Transthoracic electrical impedance Z consists of a constant baseline component Z0 and the time variable component delta Z such that Z = Z0 + delta Z. The first time derivative of Z has a negative peak, the magnitude of which is (dZ/dt)min. Measurements of 170 volunteers show that (dZ/dt)min is a function of the consta...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Djordjevich L,Sadove MS

    更新日期:1981-01-01 00:00:00

  • Upgrade and benchmarking of a 4D treatment planning system for scanned ion beam therapy.

    abstract:PURPOSE:Upgrade and benchmarking of a research 4D treatment planning system (4DTPS) suitable for realistic patient treatment planning and treatment simulations taking into account specific requirements for scanned ion beam therapy, i.e., modeling of dose heterogeneities due to interplay effects and range changes caused...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Richter D,Schwarzkopf A,Trautmann J,Krämer M,Durante M,Jäkel O,Bert C

    更新日期:2013-05-01 00:00:00

  • Technical Note: Comparison of peripheral patient dose from MR-guided 60 Co therapy and 6 MV linear accelerator IGRT.

    abstract:PURPOSE:The use of X-ray imaging in radiation therapy can give a substantial dose to the patient. A Cobalt machine combined with an magnetic resonance imaging (MRI) was recently introduced to clinical work. One positive aspect of using non-ionizing imaging devices is the reduction of the patient exposure. The purpose o...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Hauri P,Hälg RA,Schneider U

    更新日期:2017-07-01 00:00:00

  • Gafchromic EBT2 film dosimetry in reflection mode with a novel plan-based calibration method.

    abstract:PURPOSE:A dosimetric system formed by Gafchromic EBT2 radiochromic film and Epson Expression 10000XL flatbed scanner was commissioned for dosimetry. In this paper, several open questions concerning the commissioning of radiochromic films for dosimetry were addressed: (a) is it possible to employ this dosimetric system ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Mendez I,Hartman V,Hudej R,Strojnik A,Casar B

    更新日期:2013-01-01 00:00:00

  • Suitability of laser stimulated TLD arrays as patient dose monitors in high dose x-ray imaging.

    abstract::Skin entrance doses of patients undergoing interventional x-ray procedures are capable of causing skin damage and should be monitored routinely. Single TLD chips are not suitable because the location of maximum skin exposure cannot be predicted. Most photographic films are too sensitive at diagnostic x-ray energies fo...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Geise RA,Schueler BA,Lien W,Jones SC

    更新日期:1997-10-01 00:00:00

  • A novel off-axis scanning method for an enlarged ellipse cone-beam computed tomography field of view.

    abstract:PURPOSE:Current on-board imaging systems commonly used by modern linear accelerators (LINACs) have a limited field of view (FOV) for a cone-beam CT (CBCT) scan, which is typically less than 50 cm. Consequently, truncation artifacts often occur for large patients. The goal of this work is to investigate a novel method t...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Li T,Li X,Yang Y,Heron DE,Huq MS

    更新日期:2010-12-01 00:00:00

  • Image-based 3D modeling study of the influence of vessel density and blood hemoglobin concentration on tumor oxygenation and response to irradiation.

    abstract:PURPOSE:Hypoxia is one of the most important factors influencing clinical outcome after radiotherapy. Improved knowledge of factors affecting the levels and distribution of oxygen within a tumor is needed. The authors constructed a theoretical 3D model based on histological images to analyze the influence of vessel den...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Lagerlöf JH,Kindblom J,Cortez E,Pietras K,Bernhardt P

    更新日期:2013-02-01 00:00:00

  • Sinusoidal modulation analysis for optical system MTF measurements.

    abstract::The modulation transfer function (MTF) is a commonly used metric for defining the spatial resolution characteristics of imaging systems. While the MTF is defined in terms of how an imaging system demodulates the amplitude of a sinusoidal input, this approach has not been in general use to measure MTFs in the medical i...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Boone JM,Yu T,Seibert JA

    更新日期:1996-12-01 00:00:00

  • Factors influencing the performance of patient specific quality assurance for pencil beam scanning IMPT fields.

    abstract:PURPOSE:A detailed analysis of 2728 intensity modulated proton therapy (IMPT) fields that were clinically delivered to patients between 2007 and 2013 at Paul Scherrer Institute (PSI) was performed. The aim of this study was to analyze the results of patient specific dosimetric verifications and to assess possible corre...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Trnková P,Bolsi A,Albertini F,Weber DC,Lomax AJ

    更新日期:2016-11-01 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


    authors: Batchelar DL,Cunningham IA

    更新日期:2002-08-01 00:00:00

  • Evaluation of a device for indirect assessment of automatic exposure control systems.

    abstract::A test device which can indirectly measure the performance of an automatic exposure control system and which offers the potential to reduce the time and film requirements for such tests has been evaluated. Evaluation results demonstrate that the device can successfully predict image optical density to within +/- 0.10 ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Rossi RP

    更新日期:1994-01-01 00:00:00

  • Technical Note: Cortical thickness and density estimation from clinical CT using a prior thickness-density relationship.

    abstract:PURPOSE:Cortical thickness and density are critical components in determining the strength of bony structures. Computed tomography (CT) is one possible modality for analyzing the cortex in 3D. In this paper, a model-based approach for measuring the cortical bone thickness and density from clinical CT images is proposed...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Humbert L,Hazrati Marangalou J,Del Río Barquero LM,van Lenthe GH,van Rietbergen B

    更新日期:2016-04-01 00:00:00

  • A dosimetric comparison of 169Yb and 192Ir for HDR brachytherapy of the breast, accounting for the effect of finite patient dimensions and tissue inhomogeneities.

    abstract::Monte Carlo simulation dosimetry is used to compare 169Yb to 192Ir for breast high dose rate (HDR) brachytherapy applications using multiple catheter implants. Results for bare point sources show that while 169Yb delivers a greater dose rate per unit air kerma strength at the radial distance range of interest to brach...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Lymperopoulou G,Papagiannis P,Angelopoulos A,Karaiskos P,Georgiou E,Baltas D

    更新日期:2006-12-01 00:00:00

  • Monte Carlo and analytical model predictions of leakage neutron exposures from passively scattered proton therapy.

    abstract:PURPOSE:Stray neutron radiation is of concern after radiation therapy, especially in children, because of the high risk it might carry for secondary cancers. Several previous studies predicted the stray neutron exposure from proton therapy, mostly using Monte Carlo simulations. Promising attempts to develop analytical ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Pérez-Andújar A,Zhang R,Newhauser W

    更新日期:2013-12-01 00:00:00

  • Predicting radiotherapy-induced cardiac perfusion defects.

    abstract::The purpose of this work is to compare the efficacy of mathematical models in predicting the occurrence of radiotherapy-induced left ventricular perfusion defects assessed using single-photon emission computed tomography (SPECT). The basis of this study is data from 73 left-sided breast/ chestwall patients treated wit...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Das SK,Baydush AH,Zhou S,Miften M,Yu X,Craciunescu O,Oldham M,Light K,Wong T,Blazing M,Borges-Neto S,Dewhirst MW,Marks LB

    更新日期:2005-01-01 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

  • Characterization and identification of spatial artifacts during 4D-CT imaging.

    abstract:PURPOSE:The purpose of this work is twofold: First, to characterize the artifacts occurring in helical 4D-CT imaging; second, to propose a method that can automatically identify the artifacts in 4D-CT images. The authors have designed a process that can automatically identify the artifacts in 4D-CT images, which may be...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Han D,Bayouth J,Bhatia S,Sonka M,Wu X

    更新日期:2011-04-01 00:00:00

  • Technical Note: Radiotherapy dose characterization of gel dosimetry using shear wave elasticity imaging.

    abstract:PURPOSE:Radiotherapy is an effective treatment for many types of cancer in clinical settings. Gel dosimetry has the potential to record three-dimensional (3D) dose distribution compared to a conventional ion chamber. As the elasticity of the gel is altered after irradiation due to gel polymerization, we aim to measure ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Xie WH,Su CT,Kao YJ,Chang TH,Chang YJ,Yao CH,Hsieh BY

    更新日期:2020-03-01 00:00:00

  • Characteristics of an OSLD in the diagnostic energy range.

    abstract:PURPOSE:Optically stimulated luminescence (OSL) dosimetry has been recently introduced in radiation therapy as a potential alternative to the thermoluminescent dosimeter (TLD) system. The aim of this study was to investigate the feasibility of using OSL point dosimeters in the energy range used in diagnostic imaging. ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Al-Senan RM,Hatab MR

    更新日期:2011-07-01 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

  • "Battered data"--some clinical effects of the abuse of multiple regression methods: the NSD.

    abstract::The NSD equation, D = 1850 x T0.11 x N0.24, is a celebrated transmogrification of Cohen's two well-known collations of data on response to clinical irradiations (3 degrees erythema and 0.90 ablation of skin cancer) in which the relation of D and T is fixed by the data selected by Cohen and the additional constraint th...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Herbert DE Jr

    更新日期:1981-11-01 00:00:00

  • Rigid 2D/3D slice-to-volume registration and its application on fluoroscopic CT images.

    abstract::Registration of single slices from FluoroCT, CineMR, or interventional magnetic resonance imaging to three dimensional (3D) volumes is a special aspect of the two-dimensional (2D)/3D registration problem. Rather than digitally rendered radiographs (DRR), single 2D slice images obtained during interventional procedures...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Birkfellner W,Figl M,Kettenbach J,Hummel J,Homolka P,Schernthaner R,Nau T,Bergmann H

    更新日期:2007-01-01 00:00:00

  • SU-E-T-485: Validation of Acuros XB Dose Calculations in SBRT Lung Planning with Monte Carlo Methods.

    abstract:PURPOSE:The Acuros XB (AXB) Advanced Dose algorithm (Varian Medical Systems) represents a dramatic shift in clinical photon dose calculation methodology from pencil-beam superposition/convolution methods. Early studies evaluating the accuracy of the algorithm in lung have found good agreement with both measurement and ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Bush K,Wang L,Mok E

    更新日期:2012-06-01 00:00:00