Evaluations of magnetic resonance imaging parameters with simple phantoms.

abstract：PURPOSE:To demonstrate an objective approach to determining if a negative report from the Radiological Physics Center (RPC) of greater than 10% error is valid or has clinical significance. METHODS:The discrepancy involved the clinical activity (mgRaEq) of Cs-137 sources, some manufactured by 3M and some by Amersham. M...

journal_title：Medical physics

authors： Grant W 3rd,Mcgary J,Rosen I,Nitsch P,Davidson S

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Osteoporosis is a common bone disease associated with increased risk of low-trauma fractures leading to substantial morbidity, mortality, and financial costs. Clinically, osteoporosis is defined by low bone mineral density (BMD); however, increasing evidence suggests that trabecular bone (TB) microarchitectural...

journal_title：Medical physics

authors： Saha PK,Liu Y,Chen C,Jin D,Letuchy EM,Xu Z,Amelon RE,Burns TL,Torner JC,Levy SM,Calarge CA

更新日期：2015-09-01 00:00:00

abstract：PURPOSE:To perform radiomic analysis of primary tumors extracted from pretreatment contrast-enhanced computed tomography (CE-CT) images for patients with oropharyngeal cancers to identify discriminant features and construct an optimal classifier for the characterization and prediction of human papilloma virus (HPV) sta...

journal_title：Medical physics

authors： Bagher-Ebadian H,Lu M,Siddiqui F,Ghanem AI,Wen N,Wu Q,Liu C,Movsas B,Chetty IJ

更新日期：2020-02-01 00:00:00

abstract：:A new calibration algorithm (GLAaS) to derive absolute dose maps from images acquired with the Varian PV-aS500 electronic portal imager (based on amorphous silicon detectors) has been developed incorporating the dependence of detector response on primary and transmitted radiation and on field size. Detector calibratio...

journal_title：Medical physics

authors： Nicolini G,Fogliata A,Vanetti E,Clivio A,Cozzi L

更新日期：2006-08-01 00:00:00

abstract：PURPOSE:By means of Monte Carlo (MC) simulations and indirect measurements, we have evaluated the maximum dose rates achievable with conventional x-ray tubes and related them to FLASH therapy dose rates of >40 Gy/s. METHODS:Monte Carlo models of two 160 kV x-ray tubes, the 3-kW MXR-160/22 and the 6-kW MXR-165, were bu...

journal_title：Medical physics

authors： Bazalova-Carter M,Esplen N

更新日期：2019-12-01 00:00:00

abstract：PURPOSE:4d cone-beam computed tomography (CBCT) scans are usually reconstructed by extracting the motion information from the 2d projections or an external surrogate signal, and binning the individual projections into multiple respiratory phases. In this "after-the-fact" binning approach, however, projections are uneve...

journal_title：Medical physics

authors： Fast MF,Wisotzky E,Oelfke U,Nill S

更新日期：2013-09-01 00:00:00

abstract：:The measurement of the radioactivity administered to the patient is one of the major components of 90Y microsphere liver brachytherapy. The activity of 90Y microspheres in a glass delivery vial was measured in a dose calibrator. The calibration value to use for 90Y in the dose calibrator was verified using an activity...

journal_title：Medical physics

authors： Dezarn WA,Kennedy AS

更新日期：2007-06-01 00:00:00

abstract：PURPOSE:Contrast-enhanced imaging of the breast is frequently used in breast MRI and has recently become more common in mammography. The purpose of this study was to make single-scan contrast-enhanced imaging feasible for photon-counting breast CT (pcBCT) and to assess the spectral performance of a pcBCT scanner by eva...

journal_title：Medical physics

authors： Ruth V,Kolditz D,Steiding C,Kalender WA

更新日期：2020-07-01 00:00:00

abstract：:In patients with lymphoma, identification and quantification of the tumor extent on serial CT examinations is critical for assessing tumor response to therapy. In this paper, we present a computer method to automatically match and segment lymphomas in follow-up CT images. The method requires that target lymph nodes in...

journal_title：Medical physics

authors： Yan J,Zhao B,Curran S,Zelenetz A,Schwartz LH

更新日期：2007-01-01 00:00:00

abstract：PURPOSE:Mammographic density of glandular breast tissue has a masking effect that can reduce lesion detection accuracy and is also a strong risk factor for breast cancer. Therefore, accurate quantitative estimation of breast density is clinically important. In this study, we investigate experimentally the feasibility o...

journal_title：Medical physics

authors： Ghammraoui B,Badal A,Glick SJ

更新日期：2018-06-03 00:00:00

abstract：:The dosimetry protocols DIN 6800-2 and AAPM TG-51, both based on the absorbed dose to water concept, are compared in their theoretical background and in their application to electron dosimetry. The agreement and disagreement in correction factors and energy parameters used in both protocols will be shown and discussed...

journal_title：Medical physics

authors： Dohm OS,Christ G,Nüsslin F,Schüle E,Bruggmoser G

更新日期：2001-11-01 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:Body composition is known to be associated with many diseases including diabetes, cancers, and cardiovascular diseases. In this paper, we developed a fully automatic body tissue decomposition procedure to segment three major compartments that are related to body composition analysis - subcutaneous adipose tissu...

journal_title：Medical physics

authors： Fu Y,Ippolito JE,Ludwig DR,Nizamuddin R,Li HH,Yang D

更新日期：2020-11-01 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：:A system for measuring two-dimensional (2D) dose distributions in orthogonal anatomical planes in the cranium was developed and used to evaluate the accuracy of coplanar conformal therapy using ExacTrac image guidance. Dose distributions were measured in the axial, sagittal, and coronal planes using a CIRS (Computeriz...

journal_title：Medical physics

authors： Vinci JP,Hogstrom KR,Neck DW

更新日期：2008-08-01 00:00:00

abstract：PURPOSE:The most common material for shielding is concrete, which can be made using various materials of different densities as aggregates. New techniques in radiotherapy, as IMRT and VMAT, require more monitor units and it is important to develop specifically designed shielding materials. METHODS:Arraela S.L. has dev...

journal_title：Medical physics

authors： Mera M,Pereira L,Mera M,Pereira L,Meilán E,Moral FD,Teijeiro A,Salgado M,Andrade B,Gomez F,Fuentes-Vázquez V,Caruncho J,Medina A

更新日期：2012-06-01 00:00:00

abstract：:Errors in the determination of xenon concentrations in arterial blood during inhalation of xenon-oxygen mixtures are used to assess errors in the derivation of regional cerebral blood flow by the xenon-enhanced computed tomography (CT) method. The results of this study indicate that approximating the arterial buildup ...

journal_title：Medical physics

authors： Good WF,Gur D,Yonas H,Herron JM

更新日期：1987-05-01 00:00:00

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

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

更新日期：1994-10-01 00:00:00

abstract：PURPOSE:In intensity-modulated proton therapy (IMPT), protons are used to deliver highly conformal dose distributions, targeting tumors, and sparing organs-at-risk. However, due to uncertainties in both patient setup and relative stopping power (RSP) calculation, margins are added to the treatment volume during treatme...

journal_title：Medical physics

authors： Harms J,Lei Y,Wang T,McDonald M,Ghavidel B,Stokes W,Curran WJ,Zhou J,Liu T,Yang X

更新日期：2020-09-01 00:00:00

abstract：PURPOSE:To investigate the effect of the number of projection views on image noise in cone-beam CT (CBCT) with a flat-panel detector. METHODS:This fairly fundamental consideration in CBCT system design and operation was addressed experimentally (using a phantom presenting a uniform medium as well as statistically moti...

journal_title：Medical physics

authors： Zhao Z,Gang GJ,Siewerdsen JH

更新日期：2014-06-01 00:00:00

abstract：PURPOSE:Monitoring of physiological parameters is a major concern in Intensive Care Units (ICU) given their role in the assessment of vital organ function. Within this context, one issue is the lack of efficient noncontact techniques for respiratory monitoring. In this paper, we present a novel noncontact solution for ...

journal_title：Medical physics

authors： Nazir S,Pateau V,Bert J,Clement JF,Fayad H,l'Her E,Visvikis D

更新日期：2020-10-28 00:00:00

abstract：:The MCNP Monte Carlo radiation transport code was modified for diagnostic medical physics applications. In particular, the modified code was thoroughly benchmarked for the production of polychromatic tungsten x-ray spectra in the 30-150 kV range. Validating the modified code for coupled electron-photon transport with ...

journal_title：Medical physics

authors： Mercier JR,Kopp DT,McDavid WD,Dove SB,Lancaster JL,Tucker DM

更新日期：2000-12-01 00:00:00

abstract：PURPOSE:Magnetic resonance imaging (MRI)-guided percutaneous cryotherapy of abdominal lesions, an established procedure, uses MRI to guide and monitor the cryoablation of lesions. Methods to precisely guide cryotherapy probes with a minimum amount of trial-and-error are yet to be established. To aid physicians in attai...

journal_title：Medical physics

authors： Shono N,Ninni B,King F,Kato T,Tokuda J,Fujimoto T,Tuncali K,Hata N

更新日期：2020-06-01 00:00:00

abstract：PURPOSE:To determine if NSCLC GTV CT textures can be predictive for tumor shrinkage after proton therapy with concurrent chemotherapy. METHODS:Simulation and weekly 4DCTs were obtained from 25 patients with locally advanced NSCLC treated by proton therapy at a 74 Gy dose level with concurrent chemotherapy. In-house de...

journal_title：Medical physics

authors： Hunter L,Chen Y,Zhang L,Liao Z,Dong L,Court L

更新日期：2012-06-01 00:00:00

abstract：:Digital tomosynthesis (DTS) is a fast, low-dose three-dimensional (3D) imaging approach which yields slice images with excellent in-plane resolution, though low plane-to-plane resolution. A stack of DTS slices can be reconstructed from a single limited-angle scan, with typical scan angles ranging from 10 degrees to 40...

journal_title：Medical physics

authors： Godfrey DJ,Ren L,Yan H,Wu Q,Yoo S,Oldham M,Yin FF

更新日期：2007-08-01 00:00:00

abstract：:Proton NMR spectroscopy was applied to quantitate the measurement of total body water/fat distributions in vivo. A special MR protocol was developed to excite a thick slab of tissue and display the magnitude NMR spectrum of the collected response signal. Very short echo time TE (8 ms) and long repetition time TR (4000...

journal_title：Medical physics

authors： Sobol WT,Elster AD,Hinson WH,Chwals WJ

更新日期：1992-01-01 00:00:00

abstract：:This study evaluates the effects of respiratory motion on breast radiotherapy delivered using segmented multileaf collimator (SMLC) intensity modulation. An anthropomorphic breast phantom was constructed of polystyrene plates between which radiographic films were inserted. The phantom was mounted on a moving platform ...

journal_title：Medical physics

authors： Liu Q,McDermott P,Burmeister J

更新日期：2007-01-01 00:00:00

abstract：PURPOSE:Target localization accuracy of cone-beam CT (CBCT) images used in radiation treatment of respiratory disease sites is affected by motion artifacts (blurring and streaking). The authors have previously reported on a method of respiratory motion correction in thoracic CBCT at end expiration (EE). The previous re...

journal_title：Medical physics

authors： Dzyubak O,Kincaid R,Hertanto A,Hu YC,Pham H,Rimner A,Yorke E,Zhang Q,Mageras GS

更新日期：2014-10-01 00:00:00

abstract：:Spectrally resolved bioluminescence optical tomography is an approach to recover images of, for example, Luciferase activity within a volume using multiwavelength emission data from internal bioluminescence sources. The underlying problem of uniqueness associated with nonspectrally resolved intensity-based bioluminesc...

journal_title：Medical physics

authors： Dehghani H,Davis SC,Pogue BW

更新日期：2008-11-01 00:00:00

abstract：:We proposed to use the prostate dose-volume factor (PDVF), derived from the dose-volume dataset of planning target volume (PTV) in prostate radiotherapy to evaluate treatment plans of prostate volumetric modulated arc therapy (VMAT) and intensity modulated radiotherapy (IMRT). To demonstrate plan evaluation using PDVF...

journal_title：Medical physics

authors： Chow J,Jiang R,Markel D

更新日期：2012-07-01 00:00:00