Regional compensation for statistical maximum likelihood reconstruction error of PET image pixels.

abstract：:Photon quality correction factors (kQy) for ionization chamber photon dosimetry in an epithermal neutron beam were determined according to a modified absorbed dose to water formalism which was extended to mixed radiation fields. We have studied two commercially available ionization chambers in the epithermal neutron b...

journal_title：Physics in medicine and biology

authors： Munck af Rosenschöld PM,Ceberg CP,Giusti V,Andreo P

更新日期：2002-07-21 00:00:00

abstract：:Burst-tone focused ultrasound exposure in the presence of microbubbles has been demonstrated to be effective at inducing temporal and local opening of the blood-brain barrier (BBB), which promises significant clinical potential to deliver therapeutic molecules into the central nervous system (CNS). Traditional contras...

journal_title：Physics in medicine and biology

authors： Tsai CH,Zhang JW,Liao YY,Liu HL

更新日期：2016-04-07 00:00:00

abstract：:A 3D anatomical computational model is developed to assess thermal effects due to exposure to the electromagnetic field required to power a new investigational active implantable microvalve for the treatment of glaucoma. Such a device, located in the temporal superior eye quadrant, produces a filtering bleb, which is ...

journal_title：Physics in medicine and biology

authors： Schaumburg F,Guarnieri FA

更新日期：2017-05-07 00:00:00

abstract：:Respiratory-correlated 4D-MRI can characterize respiratory-induced motion of tumors and organs-at-risk for radiotherapy treatment planning and is a necessity for image guidance of moving tumors treated on an MRI-linac. Essential for 4D-MRI generation is a robust respiratory surrogate signal. We investigated the feasib...

journal_title：Physics in medicine and biology

authors： Navest RJM,Mandija S,Bruijnen T,Stemkens B,Tijssen RHN,Andreychenko A,Lagendijk JJW,van den Berg CAT

更新日期：2020-01-13 00:00:00

abstract：:Managing uncertainty is a major challenge in radiation therapy treatment planning, including uncertainty induced by intrafraction motion, which is particularly important for tumours in the thorax and abdomen. Common methods to account for motion are to introduce a margin or to convolve the static dose distribution wit...

journal_title：Physics in medicine and biology

authors： Chan TC,Bortfeld T,Tsitsiklis JN

更新日期：2006-05-21 00:00:00

abstract：:This work presents an improvement of the VIPARnd ('nd' stands for 'normoxic, double', or VIP) polymer gel dosimeter. The gel composition was altered by increasing the concentration of the monomeric components, N-vinylpyrrolidone (NVP) and N,N'-methylenebisacrylamide (MBA), in co-solvent solutions. The optimal composit...

journal_title：Physics in medicine and biology

authors： Kozicki M,Jaszczak M,Maras P,Dudek M,Cłapa M

更新日期：2017-02-07 00:00:00

abstract：:A stable cryogel dosimeter was prepared using ferrous benzoic xylenol orange (FBX) in a transparent poly-(vinyl alcohol) (PVA) cryogel matrix. Dose response was evaluated for different numbers of freeze-thaw cycles (FTCs), different concentrations of PVA, and ratios of water/dimethyl sulfoxide. Linear relationships be...

journal_title：Physics in medicine and biology

authors： Eyadeh MM,Farrell TJ,Diamond KR

更新日期：2014-04-07 00:00:00

abstract：:The quantification of tumor motion in sites affected by respiratory motion is of primary importance to improve treatment accuracy. To account for motion, different studies analyzed the translational component only, without focusing on the rotational component, which was quantified in a few studies on the prostate with...

journal_title：Physics in medicine and biology

authors： Paganelli C,Lee D,Greer PB,Baroni G,Riboldi M,Keall P

更新日期：2015-09-21 00:00:00

abstract：:This paper introduces a spatial-diversity method for speckle suppression in optical coherence microscopy. The method is based on combining interference signals from an array of detectors placed in the back focal plane of the objective lens, such that elements receive light backscattered from the sample volume at diffe...

journal_title：Physics in medicine and biology

authors： Schmitt JM

更新日期：1997-07-01 00:00:00

abstract：:The biological mechanisms of platelet destruction must be correctly identified before platelet survival curves can be interpreted. This report develops a theory of platelet destruction which is compared with experiments performed on platelets labelled with the radioactive isotope 51Cr. Platelet destruction rate is a c...

journal_title：Physics in medicine and biology

authors： Trowbridge EA,Martin JF

更新日期：1983-12-01 00:00:00

abstract：:Proton, as well as other ion, beams applied by electro-magnetic deflection in pencil-beam scanning (PBS) are minimally perturbed and thus can be quantified a priori by their fundamental interactions in a medium. This a priori quantification permits an optimal reduction of characterizing measurements on a particular PB...

journal_title：Physics in medicine and biology

authors： Clasie B,Depauw N,Fransen M,Gomà C,Panahandeh HR,Seco J,Flanz JB,Kooy HM

更新日期：2012-03-07 00:00:00

abstract：:Laser interstitial thermotherapy (LITT) is employed to destroy tumors in organs, and its outcome strongly depends on the temperature distribution inside the treated tissue. The recent introduction of computed tomography (CT) scan thermometry, based on the CT number dependence of the tissue with temperature, overcomes ...

journal_title：Physics in medicine and biology

authors： Schena E,Saccomandi P,Giurazza F,Caponero MA,Mortato L,Di Matteo FM,Panzera F,Del Vescovo R,Beomonte Zobel B,Silvestri S

更新日期：2013-08-21 00:00:00

abstract：:A correction for loss of events due to dead time in dynamic positron emission tomography (PET) is presented. The model employs a paralysing dead time to describe the behaviour of a tomograph over the range of event rates normally encountered in patient studies (up to 200 000 events/s per detector layer). The Donner 28...

journal_title：Physics in medicine and biology

authors： Mazoyer BM,Roos MS,Huesman RH

更新日期：1985-05-01 00:00:00

abstract：:It has been demonstrated that gas-filled microbubble contrast agents, based on their volume changes, can serve as pressure probes in an MR field. It was recently reported that such an MR-based pressure measurement with microbubbles at 1.5 T must make use of microbubbles that have a volumetric magnetic susceptibility d...

journal_title：Physics in medicine and biology

authors： Dharmakumar R,Plewes DB,Wright GA

更新日期：2005-10-21 00:00:00

abstract：:Contemporary imaging modalities can now provide the surgeon with high quality three- and four-dimensional images depicting not only normal anatomy and pathology, but also vascularity and function. A key component of image-guided surgery (IGS) is the ability to register multi-modal pre-operative images to each other an...

journal_title：Physics in medicine and biology

authors： Peters TM

更新日期：2006-07-21 00:00:00

abstract：:A pencil beam model for the calculation of the lateral scattering in water of protons for any therapeutic energy and depth is presented. It is based on the full Molière theory, taking into account the energy loss and the effects of mixtures and compounds. Concerning the electromagnetic part, the model has no free para...

journal_title：Physics in medicine and biology

authors： Bellinzona EV,Ciocca M,Embriaco A,Ferrari A,Fontana A,Mairani A,Parodi K,Rotondi A,Sala P,Tessonnier T

更新日期：2016-02-21 00:00:00

abstract：:A motorized electron multileaf collimator (eMLC) was developed as an add-on device to the Varian linac for delivery of advanced electron beam therapy. It has previously been shown that electron beams collimated by an eMLC have very similar penumbra to those collimated by applicators and cutouts. Thus, manufacturing pa...

journal_title：Physics in medicine and biology

authors： Eldib A,Jin L,Li J,Ma CM

更新日期：2013-08-21 00:00:00

abstract：:The metabolic content of urine from NIH III nude mice (n = 22) was analysed before and after inoculation with human glioblastoma multiforme (GBM) cancer cells. An age- and gender-matched control population (n = 14) was also studied to identify non-tumour-related changes. Urine samples were collected daily for 6 weeks,...

journal_title：Physics in medicine and biology

authors： Moroz J,Turner J,Slupsky C,Fallone G,Syme A

更新日期：2011-02-07 00:00:00

abstract：:All available imaging devices in nuclear medicine have finite energy resolution. This leads to inclusion of scattered radiation, which in turn degrades the image quality. Different scatter correction schemes therefore try to eliminate the effect of scattered radiation. On the other hand, improvement of the camera's in...

journal_title：Physics in medicine and biology

authors： Wirth V

更新日期：1989-01-01 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：:Target motion is one of the major limitations of each high precision radiation therapy. Using advanced active beam delivery techniques, such as the magnetic raster scanning system for particle irradiation, the interplay between time-dependent beam and target position heavily distorts the applied dose distribution. Thi...

journal_title：Physics in medicine and biology

authors： Li Q,Groezinger SO,Haberer T,Rietzel E,Kraft G

更新日期：2004-07-21 00:00:00

abstract：:Talbot-Lau interferometry (TLI) provides additional contrast modes for x-ray imaging that are complementary to conventional absorption radiography. TLI is particularly interesting because it is one of the few practical methods for realizing phase contrast with x-rays that is compatible with large-spot high power x-ray...

journal_title：Physics in medicine and biology

authors： Zan G,Vine DJ,Yun W,Lewis SJY,Wang Q,Wang G

更新日期：2020-02-04 00:00:00

abstract：:The purpose of this study was to develop a method to simulate breathing motion induced interplay effects for volumetric modulated arc therapy (VMAT), to verify the proposed method with measurements, and to use the method to investigate how interplay effects vary with different patient- and machine specific parameters....

journal_title：Physics in medicine and biology

authors： Edvardsson A,Nordström F,Ceberg C,Ceberg S

更新日期：2018-04-19 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：:Most solid-state detectors, including 3D dosimeters, show lower signal in the Bragg peak than expected, a process termed quenching. The purpose of this study was to investigate how variation in chemical composition of a recently developed radiochromic, silicone-based 3D dosimeter influences the observed quenching in p...

journal_title：Physics in medicine and biology

authors： Høye EM,Skyt PS,Balling P,Muren LP,Taasti VT,Swakoń J,Mierzwińska G,Rydygier M,Bassler N,Petersen JB

更新日期：2017-02-21 00:00:00

abstract：:Tserng and Kalhan have raised the question of the appropriate equation to use for the measurement of turnover rate in a stable-isotope study. In a comparison of glucose turnover measured with 2H-glucose and with 13C-glucose they used five apparently different equations and obtained conflicting answers. There is, howev...

journal_title：Physics in medicine and biology

authors： Wootton R,Ford GC,Cheng KN,Halliday D

更新日期：1985-10-01 00:00:00

abstract：:The treatment of lung cancer with radiation therapy is hindered by respiratory motion. Real-time adjustments to compensate for this motion are hampered by mechanical system latencies and imaging-rate restrictions. To better understand tumour motion behaviour for adaptive image-guided radiation therapy of lung cancer, ...

journal_title：Physics in medicine and biology

authors： Pepin EW,Wu H,Sandison GA,Langer M,Shirato H

更新日期：2010-06-21 00:00:00

abstract：:Electronic article surveillance (EAS) devices are widely used in most stores as anti-theft systems. In this work, the compliance with international guidelines in the human exposure to these devices is analysed by using the finite-difference time-domain (FDTD) method. Two sets of high resolution numerical phantoms of d...

journal_title：Physics in medicine and biology

authors： Martínez-Búrdalo M,Sanchis A,Martín A,Villar R

更新日期：2010-02-21 00:00:00

abstract：:The effect of temperature on the optical properties of human dermis and subdermis as a function of near-infrared wavelength has been studied between 25 degrees C and 40 degrees C. Measurements were performed ex vivo on a total of nine skin samples taken from the abdomen of three individuals. The results show a reprodu...

journal_title：Physics in medicine and biology

authors： Laufer J,Simpson R,Kohl M,Essenpreis M,Cope M

更新日期：1998-09-01 00:00:00

abstract：:In this paper, we present a new algorithm as an enhancement and preprocessing step for acquired optical coherence tomography (OCT) images of the retina. The proposed method is composed of two steps, first of which is a denoising algorithm with wavelet diffusion based on a circular symmetric Laplacian model, and the se...

journal_title：Physics in medicine and biology

authors： Kafieh R,Rabbani H,Abramoff MD,Sonka M

更新日期：2013-05-07 00:00:00