Estimation of torque on mechanical heart valves due to magnetic resonance imaging including an estimation of the significance of the Lenz effect using a computational model.

abstract：:A radiofrequency and field-gradient pulse sequence is presented permitting the non-invasive, volume-selective and spectroscopically resolved determination of incoherent transport parameters with the aid of an NMR field-gradient method. With proton NMR, diffusion or (quasi-incoherent) perfusion coefficients as low as 1...

journal_title：Physics in medicine and biology

authors： Klammler F,Kimmich R

更新日期：1990-01-01 00:00:00

abstract：:Mechanical properties of biological tissues are significant biomarkers for diagnosing various diseases. Assessing the viscoelastic properties of multi-layer tissues has remained challenging for a long time. Some shear wave models have been proposed to estimate thin-layer tissues' viscoelasticity recently. However, the...

journal_title：Physics in medicine and biology

authors： Lu G,Li R,Qian X,Chen R,Jiang L,Chen Z,Shung KK,Humayun MS,Zhou Q

更新日期：2020-11-12 00:00:00

abstract：:Kilo-voltage (KV) cone-beam computed tomography (CBCT) unit mounted onto a linear accelerator treatment system, often referred to as on-board imager (OBI), plays an increasingly important role in image-guided radiation therapy. While the FDK algorithm is currently used for reconstructing images from clinical OBI data,...

journal_title：Physics in medicine and biology

authors： Han X,Pearson E,Pelizzari C,Al-Hallaq H,Sidky EY,Bian J,Pan X

更新日期：2015-06-21 00:00:00

abstract：:In this paper, we use a more realistic head model with ovoid geometry for approximation of a human head. By inverting the Geselowitz equation, some analytic results on the inverse MEG problem are presented in homogenous ovoid geometry. On one hand, some information about the components of primary current is shown by t...

journal_title：Physics in medicine and biology

authors： Peng L,Cheng J,Jin L

更新日期：2006-11-07 00:00:00

abstract：:Two experimental investigations of the electromagnetic method to measure body composition are presented. In the first experiment, the impedance of a single-loop transmitting antenna, located at the centre of a 150 m helical receiving coil, was observed to have a sharp minimum at 2.40 MHz. The impedance of the antenna ...

journal_title：Physics in medicine and biology

authors： Sutcliffe JF,Smye SW,Smith MA

更新日期：1995-04-01 00:00:00

abstract：:An iterative algorithm has been developed to reduce blur artefacts in images obtained from the Pho/Con multiplane tomographic scanner. In this technique estimates of the activity distribution are convolved with the detector response function and compared with the original blurred image planes. Successive estimates of ...

journal_title：Physics in medicine and biology

authors： Zenari A,Hooper RH,Osborne N,Scrimger JW

更新日期：1985-07-01 00:00:00

abstract：:This paper presents two 4D mathematical observer models for the detection of motion defects in 4D gated medical images. Their performance was compared with results from human observers in detecting a regional motion abnormality in simulated 4D gated myocardial perfusion (MP) SPECT images. The first 4D mathematical obs...

journal_title：Physics in medicine and biology

authors： Lee TS,Frey EC,Tsui BM

更新日期：2015-04-07 00:00:00

abstract：:Magnetic particle imaging is a new approach to visualizing magnetic nanoparticles. It is capable of 3D real-time in vivo imaging of particles injected into the blood stream and is a candidate for medical imaging applications. To date, only one particle type has been imaged at a time, however, the ability to separate s...

journal_title：Physics in medicine and biology

authors： Rahmer J,Halkola A,Gleich B,Schmale I,Borgert J

更新日期：2015-03-07 00:00:00

abstract：:Recently, there has been an increased interest in flattening-filter-free (FFF) linear accelerators. Removal of the filter results in available dose rates up to 24 Gy min(-1) (for nominal energy 10 MV in depth of maximum dose, a source-surface distance of 100 cm and a field size of 10×10 cm2). To guarantee accurate rel...

journal_title：Physics in medicine and biology

authors： Lang S,Hrbacek J,Leong A,Klöck S

更新日期：2012-05-07 00:00:00

abstract：:A method of computing optimized intensity-modulated beam profiles has been further developed and used to generate highly conformal radiotherapy dose distributions. The features of these distributions are shown to be strongly dependent on the tuning built into the algorithm. The optimization aims to achieve a specified...

journal_title：Physics in medicine and biology

authors： Webb S

更新日期：1994-12-01 00:00:00

abstract：:A method of radiation dosimetry is described which is based on the radiation-induced initiation of polymerization of a bulk monomer (e.g. methyl methacrylate) containing a small concentration (about 100 ppm) of a compound which is non-fluorescent but which becomes highly fluorescent when it is incorporated into a grow...

journal_title：Physics in medicine and biology

authors： Warman JM,de Haas MP,Luthjens LH

更新日期：2009-05-21 00:00:00

abstract：:Uncemented prosthetic joint implants used in orthopaedic surgery are usually coated with a porous surface to encourage bone ingrowth. Better contact between the endosteal bone and the porous surface improves ingrowth, and such contact may be increased if the joint further subsides into position in the first weeks foll...

journal_title：Physics in medicine and biology

authors： Berry E,Langkamer VG,Jackson PC,Snow M,Goddard PR,Wells PN

更新日期：1993-02-01 00:00:00

abstract：:Measurement of the dielectric properties of ocular tissues up to 110 GHz was performed by the coaxial probe method. A coaxial sensor was fabricated to allow the measurement of small amounts of biological tissues. Four-standard calibration was applied in the dielectric property measurement to obtain more accurate data ...

journal_title：Physics in medicine and biology

authors： Sasaki K,Isimura Y,Fujii K,Wake K,Watanabe S,Kojima M,Suga R,Hashimoto O

更新日期：2015-08-21 00:00:00

abstract：:This paper presents a method to experimentally validate the beam quality correction factors (kQ) tabulated in IAEA TRS-398 for proton beams and to determine the kQ of non-tabulated ionization chambers (based on the already tabulated values). The method is based exclusively on ionometry and it consists in comparing the...

journal_title：Physics in medicine and biology

authors： Gomà C,Hofstetter-Boillat B,Safai S,Vörös S

更新日期：2015-04-21 00:00:00

abstract：:Projection and backprojection are operations that arise frequently in tomographic imaging. Recently, we proposed a new method for projection and backprojection, which we call distance-driven, and that offers low arithmetic cost and a highly sequential memory access pattern. Furthermore, distance-driven projection and ...

journal_title：Physics in medicine and biology

authors： De Man B,Basu S

更新日期：2004-06-07 00:00:00

abstract：:The accurate determination of mean ionization potential (I m) has the potential to reduce range uncertainty based margins and therefore allow for more focal treatments in proton radiotherapy. Many methods have been proposed to reduce uncertainty in I m and stopping power ratios (SPR), each with varying degrees of accu...

journal_title：Physics in medicine and biology

authors： Sudhyadhom A

更新日期：2017-10-27 00:00:00

abstract：:A bilateral comparison of national dosimetric standards for high dose rate brachytherapy has been conducted between the Laboratoire National Henri Becquerel and the University of Wisconsin Accredited Dosimetry Calibration Laboratory. A complete overview of the methods that are currently in use to establish the two nat...

journal_title：Physics in medicine and biology

authors： Douysset G,Gouriou J,Delaunay F,DeWerd L,Stump K,Micka J,Laboratoire National Henri Becquerel.,University of Wisconsin Accredited Dosimetry Calibration Laboratory.

更新日期：2005-05-07 00:00:00

abstract：:The performance of a light sharing and recirculation mechanism that allows the extraction of depth of interaction (DOI) are investigated in this paper, with a particular focus on timing. In parallel, a method to optimize the coincidence time resolution (CTR) of PET detectors by use of the DOI information is proposed a...

journal_title：Physics in medicine and biology

authors： Pizzichemi M,Polesel A,Stringhini G,Gundacker S,Lecoq P,Tavernier S,Paganoni M,Auffray E

更新日期：2019-08-07 00:00:00

abstract：:Instead of performing a numerical deconvolution, we propose to use a linear piecewise-continuous model of the renal impulse response function for parametric fitting of renal scintigraphy data, to obtain clinically useful renal parameters. The strengths of the present model are its simplicity and speed of computation, ...

journal_title：Physics in medicine and biology

authors： Zhang JL,Zhang L,Koh TS,Shuter B

更新日期：2003-06-21 00:00:00

abstract：:None of the existing protocols or codes of practice for high-energy electron dosimetry take any account of the accelerator-generated bremsstrahlung always present in electron beams. This results in a systematic error in the derivation of the absorbed dose. The purpose of this study is to draw attention to this omissio...

journal_title：Physics in medicine and biology

authors： Klevenhagen SC

更新日期：1994-07-01 00:00:00

abstract：:Over the last 50 years, diagnostic imaging has grown from a state of infancy to a high level of maturity. Many new imaging modalities have been developed. However, modern medical imaging includes not only image production but also image processing, computer-aided diagnosis (CAD), image recording and storage, and image...

journal_title：Physics in medicine and biology

authors： Doi K

更新日期：2006-07-07 00:00:00

abstract：:In previous work we demonstrated the potential of positron emission tomography (PET) detectors with depth-of-interaction (DOI) encoding capability based on phosphor-coated crystals. A DOI resolution of 8 mm full-width at half-maximum was obtained for 20 mm long scintillator crystals using a delayed charge integration ...

journal_title：Physics in medicine and biology

authors： Roncali E,Phipps JE,Marcu L,Cherry SR

更新日期：2012-10-21 00:00:00

abstract：:Effective use of the [Formula: see text] decay chain in targeted internal radioimmunotherapy requires the retention of both [Formula: see text] and progeny isotopes at the target site. Imaging-based pharmacokinetic tests of these pharmaceuticals must therefore separately yet simultaneously image multiple isotopes that...

journal_title：Physics in medicine and biology

authors： Robertson AKH,Ramogida CF,Rodríguez-Rodríguez C,Blinder S,Kunz P,Sossi V,Schaffer P

更新日期：2017-06-07 00:00:00

abstract：:Fast calculation or simulation of the ablation zone induced by radiofrequency ablation (RFA) has a critical role in hepatic RFA planning and therapy. However, it remains challenging to approximate the ablation zone in real time, especially when more than one probe is involved in one ablation session. This paper presen...

journal_title：Physics in medicine and biology

authors： Chen R,Zhang J,Kong D,Lou Q,Lu F

更新日期：2021-01-27 00:00:00

abstract：:The external radiation exposure from an overhead plume containing gamma emitting radionuclides can contribute substantial dose to the ground receptor during normal operations as well as accidental release conditions of nuclear facilities. In order to estimate the effective dose conversion coefficients (DCCs) directly,...

journal_title：Physics in medicine and biology

authors： Dey R,Patni HK,Deo Singh K,Kulkarni MS,Anand S

更新日期：2019-08-01 00:00:00

abstract：:Despite the early recognition of the potential of proton imaging to assist proton therapy (Cormack 1963 J. Appl. Phys. 34 2722), the modality is still removed from clinical practice, with various approaches in development. For proton-counting radiography applications such as computed tomography (CT), the water-equival...

journal_title：Physics in medicine and biology

authors： Poludniowski G,Allinson NM,Anaxagoras T,Esposito M,Green S,Manolopoulos S,Nieto-Camero J,Parker DJ,Price T,Evans PM

更新日期：2014-06-07 00:00:00

abstract：:The 0.35 T 60Co MRIdian system (ViewRay Inc., Mountain View) has been in clinical use in our institution since May 2016. For quality assurance (QA) of dose delivery and end-to-end testing for this machine, a reliable dosimeter is required. However, it is possible that a magnetic field may cause perturbations to dosime...

journal_title：Physics in medicine and biology

authors： Barten DLJ,Hoffmans D,Palacios MA,Heukelom S,van Battum LJ

更新日期：2018-08-20 00:00:00

abstract：:During minimally invasive surgery (MIS) for lung tumor resection, the localization of tumors or nodules relies on visual inspection of the deflated lung on intra-procedural video. For patients with tumors or nodules located deeper in the lung, this localization is not possible without prior invasive marking techniques...

journal_title：Physics in medicine and biology

authors： Lesage AJ,Rajaram R,Tam AL,Rigaud BS,Brock KK,Rice DC,Cazoulat G

更新日期：2020-09-09 00:00:00

abstract：:Scattered radiation from within the treatment head can contribute significant dose to all parts of a radiotherapy treatment field. A multileaf collimator may be used to create an arbitrarily shaped field, and may also be used, under dynamic control, to modulate the beam intensity over the field. This method of intensi...

journal_title：Physics in medicine and biology

authors： Hounsell AR,Wilkinson JM

更新日期：1997-09-01 00:00:00

abstract：:The optical properties (absorption and scattering coefficients and the scattering anisotropy factor) were measured in vitro for cartilage, liver, lung, muscle, myocardium, skin, and tumour (colon adenocarcinoma CC 531) at 630, 632.8, 790, 850 and 1064 nm. Rabbits, rats, piglets, goats, and dogs were used to obtain the...

journal_title：Physics in medicine and biology

authors： Beek JF,Blokland P,Posthumus P,Aalders M,Pickering JW,Sterenborg HJ,van Gemert MJ

更新日期：1997-11-01 00:00:00