Improving SAR estimations in MRI using subject-specific models.

abstract：:Biomechanical model based deformable image registration has been widely used to account for prostate deformation in various medical imaging procedures. Biomechanical material properties are important components of a biomechanical model. In this study, the effect of incorporating tumor-specific material properties in t...

journal_title：Physics in medicine and biology

authors： Samavati N,McGrath DM,Jewett MA,van der Kwast T,Ménard C,Brock KK

更新日期：2015-01-07 00:00:00

abstract：:The analysis of (x-ray) mammograms remains qualitative, relying on the judgement of clinicians. We present a novel method to compute a quantitative, normalized measure of tissue radiodensity traversed by the primary beam incident on each pixel of a mammogram, a measure we term the standard attenuation rate (SAR). SAR ...

journal_title：Physics in medicine and biology

authors： Tromans CE,Cocker MR,Brady SM

更新日期：2012-10-21 00:00:00

abstract：:A method is presented to predict beam profiles and outputs for wedged asymmetric fields defined by independent collimator jaws allowing fast generation of beam profiles whilst requiring very little additional data to that already used by most treatment planning systems in generating symmetric field isodoses. Symmetric...

journal_title：Physics in medicine and biology

authors： Millin AE,Smith CW

更新日期：1994-01-01 00:00:00

abstract：:We report on a radiographic measurement of an ex vivo human knee using a grating-based phase-contrast imaging setup and a medical x-ray tube at a tube voltage of 70 kV. The measurement has been carried out using a Talbot-Lau setup that is suitable to achieve a high visibility in the energy regime of medical imaging. I...

journal_title：Physics in medicine and biology

authors： Horn F,Gelse K,Jabari S,Hauke C,Kaeppler S,Ludwig V,Meyer P,Michel T,Mohr J,Pelzer G,Rieger J,Riess C,Seifert M,Anton G

更新日期：2017-08-01 00:00:00

abstract：:Ultrasoft x-rays of 0.3-5 keV have provided a unique tool for the investigation of intracellular mechanisms of radiation action in biological organisms, including mammalian cells. However, their use presents unique practical problems in dosimetry and experimental design. Detailed interpretation of the biological resul...

journal_title：Physics in medicine and biology

authors： Hoshi M,Goodhead DT,Brenner DJ,Bance DA,Chmielewski JJ,Paciotti MA,Bradbury JN

更新日期：1985-10-01 00:00:00

abstract：:Currently, energy spectra of laser accelerated proton beams are far from being monoenergetic. For their application in radiation therapy, energy selection systems using magnetic fields have been proposed to single out particles with the desired energy. These systems allow the choice of protons between a lowest and a h...

journal_title：Physics in medicine and biology

authors： Schell S,Wilkens JJ

更新日期：2009-10-07 00:00:00

abstract：:The weak absorption of shortwave infrared light by skin tissues between 700 and 1500 nm offers an important window for diagnosis by optical means. The strong scattering of shortwave infrared light by the skin, however, presents a challenge to the modelling of light propagation through the skin and the understanding of...

journal_title：Physics in medicine and biology

authors： Du Y,Hu XH,Cariveau M,Ma X,Kalmus GW,Lu JQ

更新日期：2001-01-01 00:00:00

abstract：:The distribution and transport of Hippuran is discussed. The activity leaving both kidneys has been calculated and compared with the bladder activity. It is shown that the Impulse Response Function of the ureter and bladder may be obtained by deconvolution, and data are presented relating to studies on one patient. ...

journal_title：Physics in medicine and biology

authors： Knesaurek K,Spaventi S

更新日期：1981-03-01 00:00:00

abstract：:We describe an improved algorithm for localising equivalent sources of biomagnetic fields in the human brain. The algorithm is an improvement over the sphere model in that it considers two distinct surfaces: an ellipsoid, to model the region of the skull on which the sensors are placed, and a sphere as the medium in w...

journal_title：Physics in medicine and biology

authors： Pistella F,Barone P,Narici L,Ocello N,Pizzella V,Romani GL

更新日期：1987-01-01 00:00:00

abstract：:The Compton camera is an imaging device which has been proposed to detect prompt gammas (PGs) produced by proton-nuclear interactions within tissue during proton beam irradiation. Compton-based PG imaging has been developed to verify proton ranges because PG rays, particularly characteristic ones, have strong correlat...

journal_title：Physics in medicine and biology

authors： Huang HM,Liu CC,Jan ML,Lee MW

更新日期：2018-04-19 00:00:00

abstract：:In stereotactic radiosurgery, a seven-irradiation film was used to define any discrepancy between the beam and target centres. A mathematical model based on the linac alignment and target set-up was developed to diagnose the discrepancies of the seven-irradiation film between the beam and simulation target centres. Fr...

journal_title：Physics in medicine and biology

authors： Tsai JS

更新日期：1996-09-01 00:00:00

abstract：:The origin of the differences in the refractive index observed between normal and tumor tissues using terahertz spectroscopy has been described quantitatively. To estimate water content differences in tissues, we prepared fresh and paraffin-embedded samples from rats. An approximately 5% increase of water content in t...

journal_title：Physics in medicine and biology

authors： Yamaguchi S,Fukushi Y,Kubota O,Itsuji T,Ouchi T,Yamamoto S

更新日期：2016-09-21 00:00:00

abstract：:As a new method, x-ray diffraction enhanced imaging (DEI) has extremely high sensitivity for weakly absorbing low-Z samples in medical and biological fields. Conventional performance parameters, such as spatial resolution and low-contrast resolution, are not enough to describe the characteristics of a DEI system. This...

journal_title：Physics in medicine and biology

authors： Huang ZF,Kang KJ,Li Z

更新日期：2006-06-21 00:00:00

abstract：:A post-processing noise suppression technique for biomedical MRI images is presented. The described procedure recovers both sharp edges and smooth surfaces from a given noisy MRI image; it does not blur the edges and does not introduce spikes or other artefacts. The fine details of the image are also preserved. The pr...

journal_title：Physics in medicine and biology

authors： Placidi G,Alecci M,Sotgiu A

更新日期：2003-07-07 00:00:00

abstract：:Conventional molecular assessment of tissue through histology, if adapted to fresh thicker samples, has the potential to enhance cancer detection in surgical margins and monitoring of 3D cell culture molecular environments. However, in thicker samples, substantial background staining is common despite repeated rinsing...

journal_title：Physics in medicine and biology

authors： Xu X,Wang Y,Xiang J,Liu JTC,Tichauer KM

更新日期：2017-06-21 00:00:00

abstract：:We have shown that irradiation changes the dielectric properties of human skin at radiofrequencies. Both the dielectric constant and the conductivity of the irradiated skin decrease, especially at low frequencies. The experimental data were analysed using two bioelectric models. Relevant dielectric parameters were det...

journal_title：Physics in medicine and biology

authors： Tamura T,Tenhunen M,Lahtinen T,Repo T,Schwan HP

更新日期：1994-06-01 00:00:00

abstract：:A function called Gx(L) was introduced by the International Commission on Radiation Units and Measurements (ICRU) Report-87 to facilitate measurement of cumulative dose for CT scans within long phantoms as recommended by the American Association of Physicists in Medicine (AAPM) TG-111. The Gx(L) function is equal to t...

journal_title：Physics in medicine and biology

authors： Abuhaimed A,Martin CJ,Sankaralingam M,Gentle DJ

更新日期：2015-07-21 00:00:00

abstract：:Several types of intravascular ultrasound (IVUS) catheters are connected to a motor at their proximal end, in order to let the catheter rotate around its length axis. However, the rotation of the distal axis tip does not follow exactly the rotation of the motor, since the catheter axis is not completely torsion-free a...

journal_title：Physics in medicine and biology

authors： Konings MK,van Leeuwen TG,Mali WP,Viergever MA

更新日期：1998-05-01 00:00:00

abstract：:Microbeam radiation therapy (MRT) is a pre-clinical, spatially-fractionated treatment modality noted for its ability to achieve a large differential response between normal and tumoral tissues. In the present study, TOPAS Monte Carlo (MC) simulations were used to optimize the design of a compact, affordable multi-slit...

journal_title：Physics in medicine and biology

authors： Esplen NM,Chergui L,Johnstone CD,Bazalova-Carter M

更新日期：2018-08-29 00:00:00

abstract：:Spectral x-ray imaging using novel photon counting x-ray detectors (PCDs) with energy resolving abilities is capable of providing energy-selective images. PCDs have energy thresholds, enabling the classification of photons into multiple energy bins. The extra energy information provided may allow materials such as iod...

journal_title：Physics in medicine and biology

authors： Nik SJ,Meyer J,Watts R

更新日期：2011-09-21 00:00:00

abstract：:For medical applications of ultrasound inside the brain, it is necessary to understand the relationship between the apparent density of skull bone and its corresponding speed of sound and attenuation coefficient. Although there have been previous studies exploring this phenomenon, there is still a need to extend the m...

journal_title：Physics in medicine and biology

authors： Pichardo S,Sin VW,Hynynen K

更新日期：2011-01-07 00:00:00

abstract：:Inverse planning techniques are known to produce intensity-modulated beams (IMBs) that are highly modulated. They are characterized by the fact that they contain high-frequency modulations that are absent in the profiles that are easier to deliver. For the purpose of this study these clinically unwanted fluctuations a...

journal_title：Physics in medicine and biology

authors： Coolens C,Evans PM,Seco J,Webb S

更新日期：2004-09-07 00:00:00

abstract：:The inadequate visibility of microcalcifications-small calcium deposits that cue radiologists to early stages of cancer-is a major limitation in current designs of dedicated breast computed tomography (bCT). This limitation has previously been attributed to the constituent components, spatial resolution, and utilized ...

journal_title：Physics in medicine and biology

authors： Ghazi P

更新日期：2020-12-04 00:00:00

abstract：:The goal of this study is to demonstrate the feasibility of a novel non-coplanar-arc optimization algorithm (CyberArc). This method aims to reduce the delivery time of conventional CyberKnife treatments by allowing for continuous beam delivery. CyberArc uses a 4 step optimization strategy, in which nodes, beams, and c...

journal_title：Physics in medicine and biology

authors： Kearney V,Cheung JP,McGuinness C,Solberg TD

更新日期：2017-06-26 00:00:00

abstract：:Range verification is one of the most relevant tasks in ion beam therapy. In the case of carbon ion therapy, positron emission tomography (PET) is the most widely used method for this purpose, which images the [Formula: see text]-activation following nuclear interactions of the ions with the tissue nuclei. Since the p...

journal_title：Physics in medicine and biology

authors： Hofmann T,Fochi A,Parodi K,Pinto M

更新日期：2019-05-21 00:00:00

abstract：:109Cd K x-ray fluorescence (XRF) measurement systems from two research centres were used to measure tibia lead content in a population (n = 530) of young adults. The group mean bone lead contents (+/-SEM) determined by McMaster University (n = 214) and the University of Maryland (n = 316) were 2.80 +/- 0.51 and 2.33 +...

journal_title：Physics in medicine and biology

authors： McNeill FE,Stokes L,Chettle DR,Kaye WE

更新日期：1999-09-01 00:00:00

abstract：:We have compared two methods of estimating the cellular radiosensitivity of a heterogeneous tumour, namely, via cell-survival and via tumour control probability (TCP) pseudo-experiments. It is assumed that there exists intra-tumour variability in radiosensitivity and that the tumour consists predominantly of radiosens...

journal_title：Physics in medicine and biology

authors： Stavrev P,Stavreva N,Ruggieri R,Nahum A

更新日期：2015-08-07 00:00:00

abstract：:Elevated interstitial fluid pressure is one of the barriers of drug delivery in solid tumors. Recent studies have shown that normalization of tumor vasculature by anti-angiogenic factors may improve the delivery of conventional cytotoxic drugs, possibly by increasing blood flow, decreasing interstitial fluid pressure,...

journal_title：Physics in medicine and biology

authors： Ozturk D,Yonucu S,Yilmaz D,Unlu MB

更新日期：2015-02-21 00:00:00

abstract：:Three-dimensional reconstruction of cardiac vasculature from angiographic C-arm CT (rotational angiography) data is a major challenge. Motion artefacts corrupt image quality, reducing usability for diagnosis and guidance. Many state-of-the-art approaches depend on retrospective ECG-gating of projection data for image ...

journal_title：Physics in medicine and biology

authors： Schwemmer C,Rohkohl C,Lauritsch G,Müller K,Hornegger J

更新日期：2013-06-07 00:00:00

abstract：:In x-ray based imaging of the breast, contrast between fibroglandular (Fg) tissue and adipose (Ad) tissue is a source of anatomic noise. The goal of this work was to validate by simulation and experiment a mathematical framework for modelling the Fg component of anatomic noise in digital mammograpy (DM) and dual-energ...

journal_title：Physics in medicine and biology

authors： Tanguay J,Lalonde R,Bjarnason TA,Yang CJ

更新日期：2019-10-23 00:00:00