Measurement of patient entrance surface dose rates for fluoroscopic x-ray units.

abstract：:In this study, the safety compliance for nonuniform field exposures is discussed using coupling factor concepts. The coupling factor, which is defined in the International Electrotechnical Commission 62311 standard, is extended to consider the effects of harmonics and also to apply to the specific absorption rate (for...

journal_title：Physics in medicine and biology

authors： Sunohara T,Hirata A,Laakso I,De Santis V,Onishi T

更新日期：2015-10-21 00:00:00

abstract：:Scattered doses, e.g. neutron doses in proton therapy, are of concern in radiation therapy. Although measured data are the gold standard, Monte Carlo simulations allow a more realistic consideration of patient anatomy via whole-body phantoms. When calculating neutron doses with Monte Carlo techniques, the dose can be ...

journal_title：Physics in medicine and biology

authors： Jarlskog CZ,Paganetti H

更新日期：2008-09-07 00:00:00

abstract：:Cylindrical homogenous phantoms for magnetic resonance (MR) elastography in biomedical research provide one way to validate an imaging systems performance, but the simplified geometry and boundary conditions can cloak complexity arising at tissue interfaces. In an effort to develop a more realistic gel tissue phantom ...

journal_title：Physics in medicine and biology

authors： Schwartz BL,Yin Z,Magin RL

更新日期：2016-09-21 00:00:00

abstract：:The total system error (TSE) of a CyberKnife® system was measured using two phantom-based methods and one patient-based method. The standard radiochromic film (RCF) end-to-end (E2E) test using an anthropomorphic head and neck phantom and isocentric treatment delivery was used with the 6Dskull, Fiducial and Xsight® spi...

journal_title：Physics in medicine and biology

authors： Pantelis E,Moutsatsos A,Antypas C,Zoros E,Pantelakos P,Lekas L,Romanelli P,Zourari K,Hourdakis CJ

更新日期：2018-08-20 00:00:00

abstract：:Heavy-ion radiotherapy exploits the high biological effectiveness of localized energy deposition delivered by so-called Bragg-peak particles. Recent publications have challenged the established procedures to calculate biological effective dose distributions in treatment planning. They emphasize the importance of very ...

journal_title：Physics in medicine and biology

authors： Elsässer T,Gemmel A,Scholz M,Schardt D,Krämer M

更新日期：2009-04-07 00:00:00

abstract：:This study evaluates the dosimetric performance of the polymer gel dosimeter 'Methacrylic and Ascorbic acid in Gelatin, initiated by Copper' and its suitability for quality assurance and analysis of I-131-targeted radionuclide therapy dosimetry. Four batches of gel were manufactured in-house and sets of calibration vi...

journal_title：Physics in medicine and biology

authors： Gear JI,Charles-Edwards E,Partridge M,Flux GD

更新日期：2011-11-21 00:00:00

abstract：:In recent years, optical techniques based on diffusion approximation have demonstrated their ability to gain rich spectral information about bone. However, these methods normally assume homogeneity, while cancellous bone and marrow form a highly heterogeneous two-phase medium. This paper studies the limitations of thi...

journal_title：Physics in medicine and biology

authors： Margallo-Balbás E,Taroni P,Pifferi A,Koolstra JH,v Ruijven LJ,French PJ

更新日期：2010-09-07 00:00:00

abstract：:We present a new version of STIR (Software for Tomographic Image Reconstruction), an open source object-oriented library implemented in C++ for 3D positron emission tomography reconstruction. This library has been designed such that it can be used for many algorithms and scanner geometries, while being portable to var...

journal_title：Physics in medicine and biology

authors： Thielemans K,Tsoumpas C,Mustafovic S,Beisel T,Aguiar P,Dikaios N,Jacobson MW

更新日期：2012-02-21 00:00:00

abstract：:We compare two different implementations of a 3D SPECT system model for iterative reconstruction, both of which compensate for non-uniform photon attenuation and depth-dependent system response. One implementation performs fast rotation of images represented using a basis of rectangular voxels, whereas the other repre...

journal_title：Physics in medicine and biology

authors： Yendiki A,Fessler JA

更新日期：2004-06-07 00:00:00

abstract：:The transverse magnetic field of an MRI-linac sweeps contaminant electrons away from the radiation beam. Films oriented perpendicular to the magnetic field and 5 cm from the radiation beam edge show a projection of the divergent beam, indicating that contaminant electrons spiral along magnetic field lines and deposit ...

journal_title：Physics in medicine and biology

authors： Hackett SL,van Asselen B,Wolthaus JWH,Bluemink JJ,Ishakoglu K,Kok J,Lagendijk JJW,Raaymakers BW

更新日期：2018-05-01 00:00:00

abstract：:Volumetric scintillation dosimetry has the potential to provide fast, high-resolution, three-dimensional radiation dosimetry. However, scintillators exhibit a nonlinear response at the high linear energy transfer (LET) values characteristic of proton Bragg peaks. The purpose of this study was to develop a quenching co...

journal_title：Physics in medicine and biology

authors： Robertson D,Mirkovic D,Sahoo N,Beddar S

更新日期：2013-01-21 00:00:00

abstract：:Accurate real-time prediction of respiratory motion is desirable for effective motion management in radiotherapy for lung tumor targets. Recently, nonparametric methods have been developed and their efficacy in predicting one-dimensional respiratory-type motion has been demonstrated. To exploit the correlation among v...

journal_title：Physics in medicine and biology

authors： Ruan D,Keall P

更新日期：2010-06-07 00:00:00

abstract：:In BANG gel dosimetry, the spin-spin relaxation rate, R2 = I/T2, is related to the radiation dose that has been delivered to the gel phantom. R2 is calculated by fitting the pixel intensities of a set of differently T2-weighted base images. In gel dosimetry for radiotherapy, an accuracy of 5% in dose and 3 mm spatiall...

journal_title：Physics in medicine and biology

authors： De Deene Y,De Wagter C,De Neve W,Achten E

更新日期：2000-07-01 00:00:00

abstract：:Our study aimed to quantitatively evaluate blood flow in the left ventricle (LV) of apical hypertrophic cardiomyopathy (APH) by combining wall thickness obtained from cardiac magnetic resonance imaging (MRI) and myocardial perfusion from single-photon emission computed tomography (SPECT). In this study, we considered ...

journal_title：Physics in medicine and biology

authors： Fukami T,Sato H,Wu J,Lwin TT,Yuasa T,Kawano S,Iida K,Akatsuka T,Hontani H,Takeda T,Tamura M,Yokota H

更新日期：2007-07-21 00:00:00

abstract：:In this work we present the first delivery of intensity modulated arc therapy on the Elekta Unity 1.5 T MR-linac. The machine's current IMRT based control system was modified suitably to enable dynamic delivery of radiation, for the purpose of exploring MRI-guided radiation therapy adaptation modes in a research setti...

journal_title：Physics in medicine and biology

authors： Kontaxis C,Woodhead PL,Bol GH,Lagendijk JJW,Raaymakers BW

更新日期：2020-12-23 00:00:00

abstract：:Lung tumors treated in breath-hold are subject to inter- and intra-breath-hold variations, which makes tumor position monitoring during each breath-hold important. A markerless technique is desirable, but limited tumor visibility on kV images makes this challenging. We evaluated if template matching  +  triangulation ...

journal_title：Physics in medicine and biology

authors： Hazelaar C,Dahele M,Mostafavi H,van der Weide L,Slotman B,Verbakel W

更新日期：2018-05-29 00:00:00

abstract：:3D breast modelling for 2D and 3D breast x-ray imaging would benefit from the availability of digital and physical phantoms that reproduce accurately the complexity of the breast anatomy. While a number of groups have produced digital phantoms with increasing level of complexity, physical phantoms reproducing that sof...

journal_title：Physics in medicine and biology

authors： Esposito G,Mettivier G,Bliznakova K,Bliznakov Z,Bosmans H,Bravin A,Buliev I,Di Lillo F,Ivanov D,Minutillo M,Sarno A,Vignero J,Russo P

更新日期：2019-03-27 00:00:00

abstract：:A method using both patient geometric and dosimetric information was proposed to predict dose-volume histograms (DVHs) of organs at risk (OARs) for a nasopharyngeal cancer (NPC) intensity-modulated radiation therapy (IMRT) plan. A total of 106 nine-field IMRT NPC plans were used in this study. Twenty-six plans were ra...

journal_title：Physics in medicine and biology

authors： Jiao SX,Chen LX,Zhu JH,Wang ML,Liu XW

更新日期：2019-12-05 00:00:00

abstract：:Biomedical fibre-optic sensors are attractive for the measurement of physical, chemical and biochemical parameters and for spectral measurements directly performed on the patient. An overview of fibre-optic sensors for in vivo monitoring is given, with particular attention paid to the advantages that these sensors are...

journal_title：Physics in medicine and biology

authors： Mignani AG,Baldini F

更新日期：1997-05-01 00:00:00

abstract：:Dosimetry of proton beams is generally evaluated in liquid water, or alternatively in solid phantoms via water equivalent ratios (WER). WER is defined as the ratio of proton range in liquid water to that in a phantom of certain material. Presently, WER is not available in the literature neither for a wide range of ene...

journal_title：Physics in medicine and biology

authors： Safigholi H,Song WY

更新日期：2018-07-27 00:00:00

abstract：:The goal of this study was to assess the impact of set-up uncertainty on compliance with the objectives and constraints of an intensity modulated radiation therapy protocol for early stage cancer of the oropharynx. As the convolution approach to the quantitative study of set-up uncertainties cannot accommodate either ...

journal_title：Physics in medicine and biology

authors： Ploquin N,Song W,Lau H,Dunscombe P

更新日期：2005-08-07 00:00:00

abstract：:Amorphous silicon electronic portal imaging devices (EPIDs) are used to perform routine quality control (QC) checks on the multileaf collimators (MLCs) at this centre. Presently, these checks are performed at gantry angle 0 degrees and are considered to be valid for all other angles. Since therapeutic procedures regul...

journal_title：Physics in medicine and biology

authors： Clarke MF,Budgell GJ

更新日期：2008-01-21 00:00:00

abstract：:Iterative tomographic reconstruction has been established as a viable alternative for data analysis in phase-sensitive x-ray imaging based on the edge-illumination principle. However, previously published approaches did not account for drifts of optical elements during a scan, which can lead to artefacts. Up to now, t...

journal_title：Physics in medicine and biology

authors： Modregger P,Meganck J,Hagen CK,Massimi L,Olivo A,Endrizzi M

更新日期：2019-10-10 00:00:00

abstract：:A rotary positron-emission computed tomography system has been proposed in which detectors are mounted unequally spaced on a ring, so as to provide fine and uniform linear sampling during a 360 degree rotation of the ring around its centre. The usefulness of a simple iterative method for searching for a suitable arran...

journal_title：Physics in medicine and biology

authors： Yamamoto M

更新日期：1981-05-01 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 in vivo electric conductivity (σ) values of tissue are essential for accurate electromagnetic simulations and specific absorption rate (SAR) assessment for applications such as thermal dose computations in hyperthermia. Currently used σ-values are mostly based on ex vivo measurements. In this study the conductivit...

journal_title：Physics in medicine and biology

authors： Balidemaj E,de Boer P,van Lier AL,Remis RF,Stalpers LJ,Westerveld GH,Nederveen AJ,van den Berg CA,Crezee J

更新日期：2016-02-21 00:00:00

abstract：:The UMC Utrecht is constructing a 1.5 T MRI scanner integrated with a linear accelerator (Lagendijk et al 2008 Radiother. Oncol. 86 25-9). The goal of this device is to facilitate soft-tissue contrast based image-guided radiotherapy, in order to escalate the dose to the tumour while sparing surrounding normal tissues....

journal_title：Physics in medicine and biology

authors： Meijsing I,Raaymakers BW,Raaijmakers AJ,Kok JG,Hogeweg L,Liu B,Lagendijk JJ

更新日期：2009-05-21 00:00:00

abstract：:We investigate an optimization-based reconstruction, with an emphasis on image-artifact reduction, from data collected in C-arm cone-beam computed tomography (CBCT) employed in image-guided interventional procedures. In the study, an image to be reconstructed is formulated as a solution to a convex optimization progra...

journal_title：Physics in medicine and biology

authors： Xia D,Langan DA,Solomon SB,Zhang Z,Chen B,Lai H,Sidky EY,Pan X

更新日期：2016-10-21 00:00:00

abstract：:Ultrasound shock wave therapy is increasingly used for non-invasive surgery. It requires the focusing of very high pressure amplitude in precisely controlled focal spots. In transcostal therapy of the heart or the liver, the high impedance mismatch between the bones and surrounding tissues gives rise to strong aberrat...

journal_title：Physics in medicine and biology

authors： Robin J,Simon A,Arnal B,Tanter M,Pernot M

更新日期：2018-09-06 00:00:00

abstract：:Nuclear medicine and radiation therapy, although well established, are still rapidly evolving, by exploiting animal models, aiming to define precise dosimetry in molecular imaging protocols. The purpose of the present study was to create a dataset based on the MOBY phantom for the calculation of organ-to-organ S-value...

journal_title：Physics in medicine and biology

authors： Kostou T,Papadimitroulas P,Loudos G,Kagadis GC

更新日期：2016-03-21 00:00:00