Anniversary paper: Role of medical physicists and the AAPM in improving geometric aspects of treatment accuracy and precision.

abstract：PURPOSE:Micro-CT is widely used for small animal imaging in preclinical studies of cardiopulmonary disease, but further development is needed to improve spatial resolution, temporal resolution, and material contrast. We present a technique for visualizing the changing distribution of iodine in the cardiac cycle with du...

journal_title：Medical physics

authors： Johnston SM,Johnson GA,Badea CT

更新日期：2012-08-01 00:00:00

abstract：:Electron energy spectra and angular distributions, including angular spreads, were measured using magnetic spectrometer techniques, at isocenter, for two clinical linear accelerators: one scanning beam machine, which achieves field flatness by scanning a pencil beam over the desired field at the patient plane, and one...

journal_title：Medical physics

authors： Deasy JO,Almond PR,McEllistrem MT

更新日期：1996-05-01 00:00:00

abstract：:Two new liquid ionization chamber (LIC) designs, consisting of cylindrical and plane-parallel configurations, are presented. They are designed to be suitable for high-precision measurements of absorbed dose-to-water at dose rates and photon energies typical for LDR intermediate photon energy brachytherapy sources. The...

journal_title：Medical physics

authors： Wickman G,Johansson B,Bahar-Gogani J,Holmström T,Grindborg JE

更新日期：1998-06-01 00:00:00

abstract：PURPOSE:To investigate the optimal use of XR-RV3 GafChromic(®) films to assess patient skin dose in interventional radiology while addressing the means to reduce uncertainties in dose assessment. METHODS:XR-Type R GafChromic films have been shown to represent the most efficient and suitable solution to determine patie...

journal_title：Medical physics

authors： Farah J,Trianni A,Ciraj-Bjelac O,Clairand I,De Angelis C,Delle Canne S,Hadid L,Huet C,Jarvinen H,Negri A,Novák L,Pinto M,Siiskonen T,Waryn MJ,Knežević Ž

更新日期：2015-07-01 00:00:00

abstract：PURPOSE:The study aims to investigate whether Nakagami parameters--estimated from the statistical distribution of the backscattered ultrasound radio-frequency (RF) signals--could provide a means for quantitative characterization of parotid-gland injury resulting from head-and-neck radiotherapy. METHODS:A preliminary c...

journal_title：Medical physics

authors： Yang X,Tridandapani S,Beitler JJ,Yu DS,Wu N,Wang Y,Bruner DW,Curran WJ,Liu T

更新日期：2014-02-01 00:00:00

abstract：:A method for optimizing MR imaging pulse sequence parameters in a statistical framework is presented. Parameters are defined to be optimal when the resulting scalar images yield optimal image segmentations using Bayesian pixel classification. Thus, Bayes risk is used as the objective function to minimize. Approximatio...

journal_title：Medical physics

authors： Prince JL,Pham D,Tan O

更新日期：1995-10-01 00:00:00

abstract：PURPOSE:Within the European project ALLEGRO (grant agreement no. 231965), the out-of-field dose delivered to a patient when treated with different radiotherapy modalities was investigated. The study compared the dose distribution during photon and particle irradiations both in a water and an anthropomorphic phantom to ...

journal_title：Medical physics

authors： Kaderka R,Durante M,Berger T,Reitz G,Tessa C

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:The feasibility of magnetic resonance image (MRI)-based proton therapy is based, among several other factors, on the implementation of appropriate extensions on current dose calculation methods. This work aims to develop a pencil beam algorithm (PBA) for dose calculation of proton beams within magnetic field re...

journal_title：Medical physics

authors： Padilla-Cabal F,Georg D,Fuchs H

更新日期：2018-05-01 00:00:00

abstract：PURPOSE:Recently, brain tumor segmentation has made important progress. However, the quality of manual labels plays an important role in the performance, while in practice, it could vary greatly and in turn could substantially mislead the learning process and decrease the accuracy. We need to design a mechanism to comb...

journal_title：Medical physics

authors： Cheng G,Ji H,He L

更新日期：2020-09-24 00:00:00

abstract：PURPOSE:Experimental dosimetry of high-dose-rate (HDR) 192 Ir brachytherapy (BT) sources is complicated due to high dose and dose-rate gradients, and softening of photon energy spectrum with depth. A single crystal synthetic diamond detector microDiamond (PTW 60019, Freiburg, Germany) has a small active volume, high se...

journal_title：Medical physics

authors： Kaveckyte V,Malusek A,Benmakhlouf H,Alm Carlsson G,Carlsson Tedgren Å

更新日期：2018-01-01 00:00:00

abstract：PURPOSE:Dynamic 18 F-FDG PET allows quantitative estimation of cerebral glucose metabolism both at the regional and local (voxel) level. Although sensitive to noise and highly computationally expensive, nonlinear least-squares (NLS) optimization stands as the reference approach for the estimation of the kinetic model p...

journal_title：Medical physics

authors： Ben Bouallègue F,Vauchot F,Mariano-Goulart D

更新日期：2019-03-01 00:00:00

abstract：:A filtered backprojection algorithm is developed for single photon emission computed tomography (SPECT) imaging with an astigmatic collimator having a displaced center of rotation. The astigmatic collimator has two perpendicular focal lines, one that is parallel to the axis of rotation of the gamma camera and one that...

journal_title：Medical physics

authors： Wang H,Smith MF,Stone CD,Jaszczak RJ

更新日期：1998-08-01 00:00:00

abstract：PURPOSE:In this study, a dedicated device for ion chamber measurements of absorbed dose-to-water for a Nucletron microSelectron-v2 HDR (192)Ir brachytherapy source is presented. The device uses two ionization chambers in a so-called sandwich assembly. Using this setup and by taking the average reading of the two chambe...

journal_title：Medical physics

authors： Araki F,Kouno T,Ohno T,Kakei K,Yoshiyama F,Kawamura S

更新日期：2013-09-01 00:00:00

abstract：:We investigated protection strategies of organs at risk (OARs) in intensity modulated radiation therapy (IMRT). These strategies apply to delivery of IMRT to moving body anatomies that show relative displacement of OAR in close proximity to a tumor target. We formulated an efficient genetic algorithm which makes it po...

journal_title：Medical physics

authors： Abolfath RM,Papiez L

更新日期：2009-07-01 00:00:00

abstract：:Recent working groups of the AAPM [Almond et al., Med. Phys. 26, 1847 (1999)] and the IAEA (Andreo et al., Draft V.7 of "An International Code of Practice for Dosimetry based on Standards of Absorbed Dose to Water," IAEA, 2000) have described guidelines to base reference dosimetry of high energy photon beams on absorb...

journal_title：Medical physics

authors： Seuntjens JP,Ross CK,Shortt KR,Rogers DW

更新日期：2000-12-01 00:00:00

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

authors： Rogers DWO,Townson RW

更新日期：2019-11-01 00:00:00

abstract：:Approximately 70-85% of breast biopsies are performed on benign lesions. To reduce this high number of biopsies performed on benign lesions, a case-based reasoning (CBR) classifier was developed to predict biopsy results from BI-RADS findings. We used 1433 (931 benign) biopsy-proven mammographic cases. CBR similarity ...

journal_title：Medical physics

authors： Bilska-Wolak AO,Floyd CE Jr

更新日期：2002-09-01 00:00:00

abstract：PURPOSE:To investigate the geometry dependence of the detector response function (DRF) of three commonly used scanning ionization chambers and its impact on a convolution-based method to address the volume averaging effect (VAE). METHODS:A convolution-based approach has been proposed recently to address the ionization...

journal_title：Medical physics

authors： Barraclough B,Li JG,Lebron S,Fan Q,Liu C,Yan G

更新日期：2016-05-01 00:00:00

abstract：PURPOSE:The use of 4D computed tomography (4D-CT) of the lung is important in lung cancer radiotherapy for tumor localization and treatment planning. Sometimes, dense sampling is not acquired along the superior-inferior direction. This disadvantage results in an interslice thickness that is much greater than in-plane v...

journal_title：Medical physics

authors： Zhang Y,Wu X,Yang W,Feng Q,Chen W

更新日期：2014-11-01 00:00:00

abstract：:Purpose To investigate narrow, elongated magnetically focused proton beams and compare their properties with passively collimated beams using Monte Carlo simulation. METHODS:We performed Geant4 Monte Carlo simulations involving a single quadrapole focusing magnet, thereby creating a flattened beam with an elongated e...

journal_title：Medical physics

authors： McAuley G,Barnes S,Wroe A,Slater J

更新日期：2012-06-01 00:00:00

abstract：:The fast imaging method named skipped phase encoding and edge deghosting (SPEED) has been demonstrated to reduce scan time considerably with typical magnetic resonance imaging data. In this work, SPEED is simplified with improved efficiency to accelerate the scan of sparse objects; we refer to this method as S-SPEED. ...

journal_title：Medical physics

authors： Chang Z,Xiang QS

更新日期：2007-08-01 00:00:00

abstract：PURPOSE:A joint working group was created by the American Association of Physicists in Medicine (AAPM), the European Society for Radiotherapy and Oncology (ESTRO), and the Australasian Brachytherapy Group (ABG) with the charge, among others, to develop a set of well-defined test case plans and perform calculations and ...

journal_title：Medical physics

authors： Ma Y,Vijande J,Ballester F,Tedgren ÅC,Granero D,Haworth A,Mourtada F,Fonseca GP,Zourari K,Papagiannis P,Rivard MJ,Siebert FA,Sloboda RS,Smith R,Chamberland MJP,Thomson RM,Verhaegen F,Beaulieu L

更新日期：2017-11-01 00:00:00

abstract：PURPOSE:Measuring and incorporating a scanner-specific point spread function (PSF) within image reconstruction has been shown to improve spatial resolution in PET. However, due to the short half-life of clinically used isotopes, other long-lived isotopes not used in clinical practice are used to perform the PSF measure...

journal_title：Medical physics

authors： Kotasidis FA,Angelis GI,Anton-Rodriguez J,Matthews JC,Reader AJ,Zaidi H

更新日期：2014-05-01 00:00:00

abstract：PURPOSE:Material-specific imaging and virtual monochromatic imaging/analysis are the two forms of spectral imaging in CT implemented via either energy-integration or photon-counting data acquisition. Aimed at further understanding the fundamentals and providing guidelines on its design and implementation, we quantitati...

journal_title：Medical physics

authors： Tang X,Ren Y

更新日期：2021-01-07 00:00:00

abstract：PURPOSE:This paper provides a comparison between a fast, commercial, in-patient Monte Carlo dose calculation algorithm (GPUMCD) and geant4. It also evaluates the dosimetric impact of the application of an external 1.5 T magnetic field. METHODS:A stand-alone version of the Elekta™ GPUMCD algorithm, to be used within th...

journal_title：Medical physics

authors： Ahmad SB,Sarfehnia A,Paudel MR,Kim A,Hissoiny S,Sahgal A,Keller B

更新日期：2016-02-01 00:00:00

abstract：:It is shown that predictions can be made of scatter-to-primary ratios for a variety of mammographic configurations. The different configurations can be produced by changes in source-detector distance; source-phantom distance; air gap; photon energy; phantom composition, thickness, and cross-sectional area. A detailed ...

journal_title：Medical physics

authors： Bernstein H,Muntz EP

更新日期：1986-11-01 00:00:00

abstract：:In Monte Carlo simulations of light transport in tissues, a grid system is set up to score physical quantities. This study of cylindrically symmetrical problems found that the optimized radial and angular positions for the averaged physical quantities in each grid element are off-center. The error of the extrapolated ...

journal_title：Medical physics

authors： Wang L,Jacques SL

更新日期：1994-07-01 00:00:00

abstract：PURPOSE:The focus of this work was the demonstration and validation of VirtuaLinac with clinical photon beams and to investigate the implementation of low-Z targets in a TrueBeam linear accelerator (Linac) using Monte Carlo modeling. METHODS:VirtuaLinac, a cloud based web application utilizing Geant4 Monte Carlo code,...

journal_title：Medical physics

authors： Parsons D,Robar JL,Sawkey D

更新日期：2014-02-01 00:00:00

abstract：:A computer program was implemented to predict mammography x-ray beam parameters in the range 20-40 kV for Mo/Mo, Mo/Rh, Rh/Rh, and W/Al target/filter combinations. The computation method used to simulate mammography x-ray spectra is based on the Boone et al. model. The beam quality parameters such as the half-value la...

journal_title：Medical physics

authors： Kharrati H,Zarrad B

更新日期：2003-10-01 00:00:00

abstract：PURPOSE:The aiming is getting accurate liver contour structures automatically for following adaptive radiation therapy in daily CBCT images which is very low-contrast comparing the planning CT. METHODS:Probabilistic atlas is constructed by 50 intravenous contrast planning CT images by iterative affine registration pro...

journal_title：Medical physics

authors： Li D,Li H,Yin Y,Chen J

更新日期：2012-06-01 00:00:00