Gamma dose measurement in a d(80) + Be neutron beam.

abstract：PURPOSE:X-ray phase-contrast tomography (PCT) is a rapidly emerging imaging modality for reconstructing estimates of an object's three-dimensional x-ray refractive index distribution. Unlike conventional x-ray computed tomography methods, the statistical properties of the reconstructed images in PCT remain unexplored. ...

journal_title：Medical physics

authors： Chou CY,Anastasio MA

更新日期：2010-01-01 00:00:00

abstract：PURPOSE:The aim of this paper was to investigate the relationship between the physical and subjective (observer) image quality metrics in digital chest radiography. METHODS:Five digital radiography systems, four with indirect flat panel detector and one with storage phosphor-based computed radiography system, were use...

journal_title：Medical physics

authors： Yalcin A,Olgar T,Sancak T,Atac GK,Akyar S

更新日期：2020-09-01 00:00:00

abstract：:Breast-conserving surgery combined with subsequent radiation therapy is a standard procedure in breast cancer treatment. The disadvantage of whole-breast beam irradiation is that it requires 20-25 treatment days, which is inconvenient for patients with limited mobility or who reside far from the treatment center. Howe...

journal_title：Medical physics

authors： De Jean P,Beaulieu L,Fenster A

更新日期：2009-11-01 00:00:00

abstract：:An analytic representation proposed for the relative intensity distribution of the extra-focal source in a two-component x-ray source model serves as the basis for calculation. From this representation, a closed-form expression for head scatter factors defined on the central beam axis is derived by integrating over th...

journal_title：Medical physics

authors： Yu MK,Sloboda R

更新日期：1995-12-01 00:00:00

abstract：PURPOSE:Optoacoustic imaging enables mapping the optical absorption of biological tissue using optical excitation and acoustic detection. Although most image-reconstruction algorithms are based on the assumption of a detector with an isotropic sensitivity, the geometry of the detector often leads to a response with spa...

journal_title：Medical physics

authors： Rosenthal A,Ntziachristos V,Razansky D

更新日期：2011-07-01 00:00:00

abstract：PURPOSE:To use EGSnrc Monte Carlo simulations for magnetic field dosimetry to determine optimal measurement orientations, calculate beam quality conversion factors for 32 cylindrical and three parallel-plate (PP) ion chambers, evaluate the beam quality and angular dependence of these factors, and examine the magnetic f...

journal_title：Medical physics

authors： Malkov VN,Rogers DWO

更新日期：2018-02-01 00:00:00

abstract：PURPOSE:To present EBT2 film verification of treatment planning with the eXtend System, a relocatable frame system for multiple-fraction or serial multiple-session radiosurgery. METHODS:A human head shaped phantom simulated the verification process for fractionated Gamma Knife (GK) treatment. Phantom preparation for e...

journal_title：Medical physics

authors： Gopishankar N,Bisht RK

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Photoacoustic imaging has proven to be able to detect vascularization-driven optical absorption contrast associated with tumors. In order to detect breast tumors located a few centimeter deep in tissue, a sensitive ultrasound detector is of crucial importance for photoacoustic mammography. Further, because the ...

journal_title：Medical physics

authors： Xia W,Piras D,van Hespen JC,van Veldhoven S,Prins C,van Leeuwen TG,Steenbergen W,Manohar S

更新日期：2013-03-01 00:00:00

abstract：:The dose received in the buildup region outside the primary beam has been measured for 60Co gamma rays and 6- and 18-MV X rays. The variation of this dose with field size and depth was evaluated. The effect of blocking trays and the importance of their design was determined. ...

journal_title：Medical physics

authors： Horton JL

更新日期：1984-05-01 00:00:00

abstract：PURPOSE:Brachytherapy with 106 Ru/106 Rh plaques offers good outcomes for small-to-medium choroidal melanomas and retinoblastomas. The dose measurement of the plaques is challenging, due to the small range of the emitted beta particles and steep dose gradients involved. The scarce publications on film dosimetry of 106 ...

journal_title：Medical physics

authors： Hermida-López M,Brualla L

更新日期：2018-04-01 00:00:00

abstract：PURPOSE:The aim of this study is to understand the characteristics of secondary electrons generated from the interaction of gold nanoparticles (GNPs) with x-rays as a function of nanoparticle size and beam energy and thereby further the understanding of GNP-enhanced radiotherapy. METHODS:The effective range, deflectio...

journal_title：Medical physics

authors： Leung MK,Chow JC,Chithrani BD,Lee MJ,Oms B,Jaffray DA

更新日期：2011-02-01 00:00:00

abstract：:The validity of conclusions drawn from multi-institutional radiotherapy studies is dependent upon the degree to which participating hospitals adhere to study requirements. A major effort undertaken by the Quality Assurance Review Center (QARC) assesses whether or not patient data which are deemed evaluable actually co...

journal_title：Medical physics

authors： Reinstein LE,McShan D,Glicksman AS

更新日期：1982-03-01 00:00:00

abstract：PURPOSE:To investigate tight-frame based iterative reconstruction (TFIR) technique for spectral breast computed tomography (CT) using fewer projections while achieving greater image quality. METHODS:The experimental data were acquired with a fan-beam breast CT system based on a cadmium zinc telluride photon-counting d...

journal_title：Medical physics

authors： Zhao B,Gao H,Ding H,Molloi S

更新日期：2013-03-01 00:00:00

abstract：PURPOSE:Radiochromic film provides dose measurement at high spatial resolution, but often is not preferred for routine evaluation of patient-specific intensity modulated radiation therapy (IMRT) plans owing to ease-of-use factors. The authors have established an efficient protocol that combines calibration and measurem...

journal_title：Medical physics

authors： Lewis D,Micke A,Yu X,Chan MF

更新日期：2012-10-01 00:00:00

abstract：:The focal spot of a linear accelerator is often considered to have a fully stable position. In practice, however, the beam control loop of a linear accelerator needs to stabilize after the beam is turned on. As a result, some motion of the focal spot might occur during the start-up phase of irradiation. When acquiring...

journal_title：Medical physics

authors： Sonke JJ,Brand B,van Herk M

更新日期：2003-06-01 00:00:00

abstract：PURPOSE:To track variations in the deformation of the arterial wall noninvasively by estimating the accumulated displacement and strain over a cardiac cycle may provide useful indicators of vascular health. METHODS:In this paper, we propose an approach to track a region of interest (ROI) locally and estimate arterial ...

journal_title：Medical physics

authors： Ge W,Krueger CG,Weichmann A,Shanmuganayagam D,Varghese T

更新日期：2012-07-01 00:00:00

abstract：:Imaging parameters associated with a clinical magnetic resonance imaging (MRI) system, evaluated with the use of simple and inexpensive phantoms, are described in evaluation of a clinical MRI system. Images, obtained with a Diasonics 0.35-T MRI system using an elliptical whole-body radio frequency coil, are presented ...

journal_title：Medical physics

authors： Brateman L,Jennings LW,Nunnally RL,Vaughan JT

更新日期：1986-07-01 00:00:00

abstract：PURPOSE:Until recently the treatment verification for patients undergoing fast neutron therapy at our facility was accomplished through a combination of neutron beam portal films aligned with a graticule mounted on an orthronormal x-ray tube. To eliminate uncertainty with respect to the relative positions of the x-ray ...

journal_title：Medical physics

authors： Halford R,Snyder M

更新日期：2012-06-01 00:00:00

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

authors： Djordjevich L,Sadove MS

更新日期：1981-01-01 00:00:00

abstract：PURPOSE:To determine the diagnostic efficacy of optical coherence tomography (OCT) to identify cervical intraepithelial neoplasia (CIN) grade 2 or higher by computer-aided diagnosis (CADx). METHODS:OCT has been investigated as a screening/diagnostic tool in the management of preinvasive and early invasive cancers of t...

journal_title：Medical physics

authors： Kang W,Qi X,Tresser NJ,Kareta M,Belinson JL,Rollins AM

更新日期：2011-01-01 00:00:00

abstract：PURPOSE:Radiation scattered from the breast in digital breast tomosynthesis (DBT) causes image degradation, including loss of contrast between cancerous and background tissue. Unlike in 2-dimensional (2D) mammography, an antiscatter grid cannot readily be used in DBT because changing alignment between the tube and dete...

journal_title：Medical physics

authors： Patel T,Peppard H,Williams MB

更新日期：2016-04-01 00:00:00

abstract：PURPOSE:To demonstrate, via Monte Carlo simulation, that an image obtained from the patient-generated scattered radiation forced to impinge on the detector from a known direction by means of parallel-focused grids, can be used to complement the information conveyed by the primary image, such that accurate stereoscopic ...

journal_title：Medical physics

authors： Garnica-Garza HM

更新日期：2018-02-01 00:00:00

abstract：: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...

journal_title：Medical physics

authors： Brivio D,Sajo E,Zygmanski P

更新日期：2017-03-01 00:00:00

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

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

更新日期：2007-04-01 00:00:00

abstract：:Modern linear accelerators contain multiple isocentres, defined by the mechanical motions of gantry, collimator and table. Isocentre localization for these motions has been performed using film and manual evaluations which have difficulty in relating the individual motions. To address these limitations, we have develo...

journal_title：Medical physics

authors： Heaton R,Smale J,Norrlinger B,Wang Y,van Prooijen M,Islam M

更新日期：2008-07-01 00:00:00

abstract：:The Los Alamos code MCNP4A (Monte Carlo N-Particle version 4A) is currently used to simulate a variety of problems ranging from nuclear reactor analysis to boron neutron capture therapy. A graphical user interface has been developed that automatically sets up the MCNP4A geometry and radiation source requirements for a...

journal_title：Medical physics

authors： DeMarco JJ,Solberg TD,Smathers JB

更新日期：1998-01-01 00:00:00

abstract：PURPOSE:The aim of this study was to use MRI gel dosimetry to determine the dose profile of 50kV MAGNUM® X-ray tube, MOXTEK Inc., in order to calibrate small solid dosimeters of alanine, tooth enamel and LiF-TLDs, commonly used in clinical quality assurance and datation dosimetry. METHODS:MAGIC-f polymer gel was kept ...

journal_title：Medical physics

authors： Schwarcke M,Marques T,Nicolucci P,Filho OB

更新日期：2012-06-01 00:00:00

abstract：:Imaging of radiation dose distribution in gel phantoms by magnetic resonance techniques has previously been reported. In this paper a method of producing gels in which the distributions of radiation dose can also be visualized as a color change is reported. The color developed depends qualitatively and quantitatively ...

journal_title：Medical physics

authors： Appleby A,Leghrouz A

更新日期：1991-03-01 00:00:00

abstract：PURPOSE:The purpose of this technical note is to introduce variance component analysis to the estimation of systematic and random components in setup error of radiotherapy. METHODS:Balanced data according to the one-factor random effect model were assumed. RESULTS:Analysis-of-variance (anova)-based computation was ap...

journal_title：Medical physics

authors： Matsuo Y,Nakamura M,Mizowaki T,Hiraoka M

更新日期：2016-09-01 00:00:00

abstract：PURPOSE:Pulmonary magnetic-resonance-imaging (MRI) and x-ray computed-tomography have provided strong evidence of spatially and temporally persistent lung structure-function abnormalities in asthmatics. This has generated a shift in their understanding of lung disease and supports the use of imaging biomarkers as inter...

journal_title：Medical physics

authors： Guo F,Svenningsen S,Eddy RL,Capaldi DPI,Sheikh K,Fenster A,Parraga G

更新日期：2016-06-01 00:00:00