Dose and detectability for a cone-beam C-arm CT system revisited.

abstract：PURPOSE:This study introduces a new hybrid ZTE/Dixon MR-based attenuation correction (MRAC) method including bone density estimation for PET/MRI and quantifies the effects of bone attenuation on metastatic lesion uptake in the pelvis. METHODS:Six patients with pelvic lesions were scanned using fluorodeoxyglucose (18F-...

journal_title：Medical physics

authors： Leynes AP,Yang J,Shanbhag DD,Kaushik SS,Seo Y,Hope TA,Wiesinger F,Larson PE

更新日期：2017-03-01 00:00:00

abstract：:Motion and deformation of the cardiac wall may be measured by following the positions of implanted radiopaque markers in three dimensions, using two x-ray cameras simultaneously. Regularly, calibration of the position measurement system is obtained by registration of the images of a calibration object, containing 10-2...

journal_title：Medical physics

authors： Muijtjens AM,Roos JM,Arts T,Hasman A

更新日期：1999-02-01 00:00:00

abstract：:The modulation transfer function (MTF) and the noise power spectrum (NPS) are widely recognized as the most relevant metrics of resolution and noise performance in radiographic imaging. These quantities have commonly been measured using various techniques, the specifics of which can have a bearing on the accuracy of t...

journal_title：Medical physics

authors： Samei E,Ranger NT,Dobbins JT 3rd,Chen Y

更新日期：2006-05-01 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：:MR acoustic radiation force (ARF) imaging was developed for measuring tiSsue elastic properties using focused ultrasound to deliver a localized tissue motion. In this study, an imaging ultrasound transducer was mounted on the focused ultrasound transducer and ultrasound motion tracking was performed simultaneously to ...

journal_title：Medical physics

authors： Huang Y,Curiel L,Kukic A,Plewes DB,Chopra R,Hynynen K

更新日期：2009-06-01 00:00:00

abstract：:Administration of x-ray contrast agents during heart catheterization examination increases the absorbed radiation dose in tissue. To estimate the dose absorbed by the blood of children undergoing diagnostic heart catheterization and angiocardiography, a number of measurements and calculations were conducted. First, en...

journal_title：Medical physics

authors： Callisen HH,Norman A,Adams FH

更新日期：1979-11-01 00:00:00

abstract：PURPOSE:To develop and evaluate the impact on lesion conspicuity of a software-based x-ray scatter correction algorithm for digital breast tomosynthesis (DBT) imaging into which a precomputed library of x-ray scatter maps is incorporated. METHODS:A previously developed model of compressed breast shapes undergoing mamm...

journal_title：Medical physics

authors： Feng SS,D'Orsi CJ,Newell MS,Seidel RL,Patel B,Sechopoulos I

更新日期：2014-03-01 00:00:00

abstract：PURPOSE:To correct for the deviations of the detector response when typical radiation detectors are used under non-reference conditions, factor kNR was calculated from the known energy dependence of the detector response at photon energies from 10 keV upwards and from clinical photon spectra within a large water phanto...

journal_title：Medical physics

authors： Chofor N,Poppe B,Harder D

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Proton radiotherapy for head-and-neck cancer (HNC) aims to improve organ-at-risk (OAR) sparing over photon radiotherapy. However, it may be less robust for setup and range uncertainties. The authors investigated OAR sparing and plan robustness for spot-scanning proton planning techniques and compared these with...

journal_title：Medical physics

authors： Barten DL,Tol JP,Dahele M,Slotman BJ,Verbakel WF

更新日期：2015-11-01 00:00:00

abstract：PURPOSE:Measured values of ultrasound attenuation in bone represent a combination of different loss mechanisms. As a wave is transmitted from a fluid into bone, reflections occur at the interface. In the bone, mode conversion occurs between longitudinal and shear modes and the mechanical wave is scattered by its comple...

journal_title：Medical physics

authors： Pinton G,Aubry JF,Bossy E,Muller M,Pernot M,Tanter M

更新日期：2012-01-01 00:00:00

abstract：PURPOSE:Most modern radiotherapy machines are built with a 2D kV imaging system. Combining this imaging system with a 2D-3D inference method would allow for a ready-made option for real-time 3D tumor tracking. This work investigates and compares the accuracy of four existing 2D-3D inference methods using both motion tr...

journal_title：Medical physics

authors： Montanaro T,Nguyen DT,Keall PJ,Booth J,Caillet V,Eade T,Haddad C,Shieh CC

更新日期：2018-03-01 00:00:00

abstract：PURPOSE:Couch and MLC tracking are two promising methods for real-time motion compensation during radiation therapy. So far, couch and MLC tracking experiments have mainly been performed by different research groups, and no direct comparison of couch and MLC tracking of volumetric modulated arc therapy (VMAT) plans has...

journal_title：Medical physics

authors： Hansen R,Ravkilde T,Worm ES,Toftegaard J,Grau C,Macek K,Poulsen PR

更新日期：2016-05-01 00:00:00

abstract：PURPOSE:The aim of this study was to assess the suitability of Gafchromic EBT3 films for reference dose measurements in the beam of a prototype high dose-per-pulse linear accelerator (linac), capable of delivering electron beams with a mean dose-rate (Ḋm ) ranging from 0.07 to 3000 Gy/s and a dose-rate in pulse (Ḋp ) o...

journal_title：Medical physics

authors： Jaccard M,Petersson K,Buchillier T,Germond JF,Durán MT,Vozenin MC,Bourhis J,Bochud FO,Bailat C

更新日期：2017-02-01 00:00:00

abstract：:Monte Carlo calculations have been made to determine the energy delivered to a phantom by neutrons escaping from the head of a Varian Clinac 35 medical accelerator at an SSD of 1 m. The energy was sorted into two regions: inside and outside a volume defined by a circular beam of area 100 and 600 cm2. For the two beam ...

journal_title：Medical physics

authors： Ing H,Shore RA

更新日期：1982-01-01 00:00:00

abstract：PURPOSE:MR thermometry based on the proton resonance frequency shift (PRFS) is the most commonly used method for the monitoring of thermal therapies. As the chemical shift of water protons is temperature dependent, the local temperature variation (relative to an initial baseline) may be calculated from time-dependent p...

journal_title：Medical physics

authors： Viallon M,Terraz S,Roland J,Dumont E,Becker CD,Salomir R

更新日期：2010-04-01 00:00:00

abstract：PURPOSE:To reduce the potential of late toxicity (tissue necrosis and cognitive function loss) from brain radiotherapy, we studied a novel planning technique for MLC-equipped linear accelerators (LINACS) that reduces the high doses delivered outside the PTV, enhancing radiation dose conformity. METHODS:The feasibility...

journal_title：Medical physics

authors： Yang W,Sandler H,Fraass B

更新日期：2012-06-01 00:00:00

abstract：:The calibration (in rad/nC) of an air-filled tissue-equivalent ionization chamber for neutrons of 15-MeV average energy was determined by measuring absolute fluences and calculating the kerma per unit fluence. The neutron calibration determined from the gamma-ray calibration and application of the Bragg-Gray relation ...

journal_title：Medical physics

authors： Barschall HH,Goldberg E

更新日期：1977-03-01 00:00:00

abstract：:The intensity modulated arc has been proposed as an alternative to tomotherapy. Treatment planing systems more typically model the conventional step and shoot or sliding window dynamic multileaf collimator (DMLC) deliveries, and may not support intensity modulated arc therapy (IMAT). As well, another potential drawbac...

journal_title：Medical physics

authors： MacKenzie MA,Robinson DM

更新日期：2002-10-01 00:00:00

abstract：PURPOSE:Modern clinical accelerators are capable of producing ion beams from protons up to neon. This work compares the depth dose distribution and corresponding dose averaged linear energy transfer (LET) distribution, which is related to the biological effectiveness, for different ion beams (¹H, ⁴He, ⁶Li, ⁸Be, ¹⁰B, ¹²...

journal_title：Medical physics

authors： Kantemiris I,Karaiskos P,Papagiannis P,Angelopoulos A

更新日期：2011-12-01 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

abstract：PURPOSE:To compare beam characteristics of superficial X-rays with 6 MeV Electrons for the purpose of replacing superficial treatments with electron fields for skin lesions. METHODS:Electron beam cutouts were made with 12mm thickness cerrobend in diameters 2-5 cm to match superficial X-ray machine cones. Central axis ...

journal_title：Medical physics

authors： Avadhani J,Sasidharan S,Carton C,Lowen M,Klapproth T,Licitra C

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:To develop an automated technique for evaluating lung stereotactic body radiotherapy (SBRT) plan quality and predicting achievable lung dose constraints. METHODS:We examined the workflow scripting capabilities of a radiation oncology software package (MIM Software Inc) for automatically generating mean dose gr...

journal_title：Medical physics

authors： Atwood T,Xing L,Hristov D

更新日期：2012-06-01 00:00:00

abstract：:Magnetic resonance images can be compromised by constant frequency (CF) noise, such as radio frequency (RF) noise. We investigate the effects of CF noise in four imaging methods with non-uniform k-space sampling: single-shot echo-planar imaging (EPI) with sinusoidal readout gradients, phase-encoded echo-planar spectro...

journal_title：Medical physics

authors： Du W,Karczmar GS,Pan X

更新日期：2002-08-01 00:00:00

abstract：PURPOSE:The GammaPod is a novel dedicated prone breast stereotactic radiosurgery (SRS) device recently developed at the University of Maryland Medical Center. This device utilizes multiple rotating Co-60 sources to create highly conformal dose distributions for breast treatments, including boosts, partial breast irradi...

journal_title：Medical physics

authors： Becker SJ,Culberson WS,Poirier Y,Mutaf Y,Niu Y,Nichols EM,Yi B

更新日期：2020-08-01 00:00:00

abstract：:Techniques have been developed for reducing motion blurring artifacts by using respiratory gated computed tomography (CT) in sinogram space and quantitatively evaluating the artifact reduction. A synthetic sinogram was built from multiple scans intercepting a respiratory gating window. A gated CT image was then recons...

journal_title：Medical physics

authors： Lu W,Parikh PJ,Hubenschmidt JP,Politte DG,Whiting BR,Bradley JD,Mutic S,Low DA

更新日期：2005-11-01 00:00:00

abstract：:The accurate calculation of the skeleton of an object is a problem not satisfactorily solved by existing approaches. Most algorithms require a significant amount of user interaction and use a voxel grid to compute discrete and often coarse approximations of this representation of the data. We present a novel, automati...

journal_title：Medical physics

authors： Van Uitert R,Bitter I

更新日期：2007-02-01 00:00:00

abstract：PURPOSE:Transcranial magnetic resonance-guided focused ultrasound surgery is a noninvasive technique for causing selective tissue necrosis. Variations in density, thickness, and shape of the skull cause aberrations in the location and shape of the focal zone. In this paper, the authors propose a hybrid simulation-MR-AR...

journal_title：Medical physics

authors： Vyas U,Kaye E,Pauly KB

更新日期：2014-03-01 00:00:00

abstract：:A very important issue in contemporary inverse treatment radiotherapy planning is the specification of proper dose-volume constraints limiting the treatment planning algorithm from delivering high doses to the normal tissue surrounding the tumor. Recently we have proposed a method called reverse mapping of normal tiss...

journal_title：Medical physics

authors： Markov K,Schinkel C,Stavreva N,Stavrev P,Weldon M,Fallone BG

更新日期：2006-09-01 00:00:00

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

authors： Starkschall G

更新日期：1988-09-01 00:00:00

abstract：:Neutron and photon energy spectra were measured in different depths and lateral positions in tissue-equivalent phantoms exposed to a therapeutical 14.1 MeV neutron beam. Intensity weighted mass energy absorption coefficients were derived for application in ionization chamber dosimetry in mixed neutron-gamma fields. Th...

journal_title：Medical physics

authors： Schmidt R,Magiera E,Scobel W

更新日期：1980-09-01 00:00:00