Influence of beam characteristics and detector size in negative-pion dose studies.

abstract：:Intra-fractional motion is a concern during prostate radiation therapy, as it may cause deviations between planned and delivered radiation doses. Because accurate motion information during treatment delivery is critical to address dose deviation, we developed the projection marker matching method (PM3), a novel method...

journal_title：Physics in medicine and biology

authors： Chi Y,Rezaeian NH,Shen C,Zhou Y,Lu W,Yang M,Hannan R,Jia X

更新日期：2017-07-07 00:00:00

abstract：:Dental tomographic cone-beam x-ray imaging devices record truncated projections and reconstruct a region of interest (ROI) inside the head. Image reconstruction from the resulting local tomography data is an ill-posed inverse problem. A new Bayesian multiresolution method is proposed for local tomography reconstructio...

journal_title：Physics in medicine and biology

authors： Niinimäki K,Siltanen S,Kolehmainen V

更新日期：2007-11-21 00:00:00

abstract：:The purpose of this work was to study and quantify the differences in dose distributions computed with some of the newest dose calculation algorithms available in commercial planning systems. The study was done for clinical cases originally calculated with pencil beam convolution (PBC) where large density inhomogeneit...

journal_title：Physics in medicine and biology

authors： Hasenbalg F,Neuenschwander H,Mini R,Born EJ

更新日期：2007-07-07 00:00:00

abstract：:The stochastic nature of cavitation implies visualization of the cavitation cloud in real-time and in a discriminative manner for the safe use of focused ultrasound therapy. This visualization is sometimes possible with standard echography, but it strongly depends on the quality of the scanner, and is hindered by diff...

journal_title：Physics in medicine and biology

authors： Arnal B,Baranger J,Demene C,Tanter M,Pernot M

更新日期：2017-02-07 00:00:00

abstract：:The lipid disordering effect of aspirin on the liposomal membrane of dipalmitoyl phosphatidyl choline has recently been studied using the fluorescence polarization method. From the anisotropy-temperature curve, we have calculated here the associated change in van't Hoff enthalpy. Since the fluorescence technique requi...

journal_title：Physics in medicine and biology

authors： De S,Ghosh AK,Basu R,Nandy P

更新日期：1996-03-01 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：:We combine two near-infrared diffuse optical techniques to study variations of blood flow, haemoglobin concentration, and blood oxygen saturation in the functioning rat brain. Diffuse correlation spectroscopy (or flowmetry) monitors changes in the cerebral blood flow, without the use of the principles of tracer cleara...

journal_title：Physics in medicine and biology

authors： Cheung C,Culver JP,Takahashi K,Greenberg JH,Yodh AG

更新日期：2001-08-01 00:00:00

abstract：:An algorithm for dynamic multileaf-collimator (dMLC) tracking of a target performing a known a priori, rigid-body motion during volumetric modulated arc therapy (VMAT), has been experimentally validated and applied to investigate the potential of the Agility (Elekta AB, Stockholm, Sweden) multileaf-collimator (MLC) fo...

journal_title：Physics in medicine and biology

authors： Davies GA,Clowes P,Bedford JL,Evans PM,Webb S,Poludniowski G

更新日期：2013-07-07 00:00:00

abstract：:A new component module (CM), designated DYNVMLC, was developed to fully model the geometry of the Varian Millennium 120 leaf collimator using the BEAMnrc Monte Carlo code. The model includes details such as the leaf driving screw hole, support railing groove and leaf tips. Further modifications also allow sampling of ...

journal_title：Physics in medicine and biology

authors： Heath E,Seuntjens J

更新日期：2003-12-21 00:00:00

abstract：:The purpose of this study was the characterization of local magnetic susceptibility deviations by spectral analysis of their induced magnetic field inhomogeneities. Magnetic resonance spectra and related signal decay curves of local susceptibility deviations were simulated for different volume fractions and compositio...

journal_title：Physics in medicine and biology

authors： Seppenwoolde JH,van Zijtveld M,Bakker CJ

更新日期：2005-01-21 00:00:00

abstract：:Beam tracking with scanned carbon ion radiotherapy achieves highly conformal target dose by steering carbon pencil beams to follow moving tumors using real-time magnetic deflection and range modulation. The purpose of this study was to evaluate the robustness of target dose coverage from beam tracking in light of posi...

journal_title：Physics in medicine and biology

authors： Eley JG,Newhauser WD,Richter D,Lüchtenborg R,Saito N,Bert C

更新日期：2015-02-21 00:00:00

abstract：:Measurements of lung nodule volume with multi-detector computed tomography (MDCT) have been shown to be more accurate and precise compared to conventional lower dimensional measurements. Quantifying the size of lesions is potentially more difficult when the object-to-background contrast is low as with lesions in the l...

journal_title：Physics in medicine and biology

authors： Li Q,Gavrielides MA,Zeng R,Myers KJ,Sahiner B,Petrick N

更新日期：2015-01-21 00:00:00

abstract：:Densitometric quantification of coronary artery stenoses in angiographic images can be problematic for two reasons: (i) the x-rays are inadequately oriented with respect to the vessel segments of interest at image acquisition; (ii) non-linear effects due for instance to beam hardening, scattered radiation and veiling ...

journal_title：Physics in medicine and biology

authors： Doriot PA,Dorsaz PA,Dorsaz L,Bodenmann JJ

更新日期：1997-12-01 00:00:00

abstract：:Magnetic resonance imaging (MRI) may be used to image three-dimensional dose distributions of ionizing radiation in tissue equivalent gels infused with ferrous sulphate solutions, commonly known as Fricke gels. In this technique, ferrous (Fe2+) ions are oxidized to ferric (Fe3+) ions by free radicals produced by ioniz...

journal_title：Physics in medicine and biology

authors： Harris PJ,Piercy A,Baldock C

更新日期：1996-09-01 00:00:00

abstract：:MRI-guided prostate biopsy in conventional closed-bore scanners requires transferring the patient outside the bore during needle insertion due to the constrained in-bore space, causing a safety hazard and limiting image feedback. To address this issue, we present our custom-made in-bore setup and software to support M...

journal_title：Physics in medicine and biology

authors： Tokuda J,Tuncali K,Iordachita I,Song SE,Fedorov A,Oguro S,Lasso A,Fennessy FM,Tempany CM,Hata N

更新日期：2012-09-21 00:00:00

abstract：:Using iterative three-dimensional (3D) reconstruction techniques for reconstruction of positron emission tomography (PET) is not feasible on most single-processor machines due to the excessive computing time needed, especially so for the large sinogram sizes of our high-resolution research tomograph (HRRT). In our fir...

journal_title：Physics in medicine and biology

authors： Vollmar S,Michel C,Treffert JT,Newport DF,Casey M,Knöss C,Wienhard K,Liu X,Defrise M,Heiss WD

更新日期：2002-08-07 00:00:00

abstract：:For PET online data acquisition, a centralized coincidence processor (CCP) with a single-thread data processing has been used to select coincidence events for many PET scanners. CCP has the advantage of highly integrated circuit, compact connection between detector front-end and system electronics, and centralized con...

journal_title：Physics in medicine and biology

authors： Cheng X,Hu K,Yang D,Shao Y

更新日期：2021-01-21 00:00:00

abstract：:Therapy with helium ions is currently receiving significantly increasing interest because helium ions have a sharper penumbra than protons and undergo less fragmentation than carbon ions and thus require less complicated dose calculations. For any ion of interest in hadron therapy, the accuracy of dose delivery is lim...

journal_title：Physics in medicine and biology

authors： Ozoemelam I,van der Graaf E,Brandenburg S,Dendooven P

更新日期：2019-12-05 00:00:00

abstract：:A theoretical analysis and numerical solutions are presented for viscosity-dominated flow through a uniform, highly distensible tube with a slit-shaped cross section undergoing peristalsis. At flow rates below an intrinsic upper limit to the peristaltic carrying capacity of the tube, provided that there is always at l...

journal_title：Physics in medicine and biology

authors： Griffiths DJ

更新日期：1987-07-01 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：:Reliable treatment planning of highly conformal scanned ion beam therapy demands accurate tools for the determination and characterization of the individual pencil-like beams building up the integral dose delivery and related mixed radiation field. At present, clinically practicable inverse treatment planning systems ...

journal_title：Physics in medicine and biology

authors： Parodi K,Mairani A,Brons S,Hasch BG,Sommerer F,Naumann J,Jäkel O,Haberer T,Debus J

更新日期：2012-06-21 00:00:00

abstract：:Prenatal events such as intrauterine growth restriction and increased cardiovascular risk in later life have been shown to be associated with an increased intima-media thickness (aIMT) of the abdominal aorta in the fetus. In order to assess and manage atherosclerosis and cardiovascular disease risk in adults and child...

journal_title：Physics in medicine and biology

authors： Veronese E,Tarroni G,Visentin S,Cosmi E,Linguraru MG,Grisan E

更新日期：2014-11-07 00:00:00

abstract：:First experimental results with energy-resolved computed tomography (CT) are reported. The contrast-to-noise ratio (CNR) in CT has been improved with x-ray energy weighting for the first time. Further, x-ray energy weighting improved the CNR in material decomposition CT when applied to CT projections prior to dual-ene...

journal_title：Physics in medicine and biology

authors： Shikhaliev PM

更新日期：2008-10-21 00:00:00

abstract：:'Patlak analysis' is a common approach used in Fdopa PET studies to calculate the uptake constant (Ki) of the tracer. It is assumed in the Patlak analysis that the reversible compartment of tissue radioactivity used is in effective equilibrium with the tracer in plasma. Therefore, using the data prior to equilibrium i...

journal_title：Physics in medicine and biology

authors： Yu DC,Huang SC,Barrio JR,Phelps ME

更新日期：1995-07-01 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：:Quantitative assessment of mammographic asymmetry has been investigated for breast cancer risk prediction. A new asymmetry feature extraction method was proposed in this study to enhance the risk prediction accuracy of near-term breast cancer. Breast areas in each pair of bilateral mammographic images were divided int...

journal_title：Physics in medicine and biology

authors： Yan S,Zhang L,Song C

更新日期：2018-10-17 00:00:00

abstract：:Ho-166 is a combined beta-gamma emitter of which the betas can be used therapeutically. From the 81 keV gammas of Ho-166, SPECT images can be obtained, which give opportunities to guide Ho-166 therapy. Accurate reconstruction of Ho-166 images is currently hampered by photopeak-scatter in the patient, down-scatter in t...

journal_title：Physics in medicine and biology

authors： de Wit TC,Xiao J,Nijsen JF,van het Schip FD,Staelens SG,van Rijk PP,Beekman FJ

更新日期：2006-10-07 00:00:00

abstract：:The basic principles of x-ray image formation in radiology have remained essentially unchanged since Röntgen first discovered x-rays over a hundred years ago. The conventional approach relies on x-ray attenuation as the sole source of contrast and draws exclusively on ray or geometrical optics to describe and interpre...

journal_title：Physics in medicine and biology

authors： Bech M,Bunk O,Donath T,Feidenhans'l R,David C,Pfeiffer F

更新日期：2010-09-21 00:00:00

abstract：:An X-ray technique has been developed to enable reproducible and quantitative data to be obtained from radiographs taken by a diagnostic X-ray machine. Careful attention has been paid to the alignment of the specimen and the diagnostic tube and to operating conditions. The choice of X-ray spectrum is described togethe...

journal_title：Physics in medicine and biology

authors： King SD

更新日期：1977-07-01 00:00:00

abstract：:Charge-coupled devices (CCDs) coupled to scintillation crystals can be used for high-resolution imaging with x-rays and gamma rays. When the CCD images can be read out fast enough, the energy and interaction position of individual gamma quanta can be estimated by a real-time image analysis of the scintillation light f...

journal_title：Physics in medicine and biology

authors： Heemskerk JW,Westra AH,Linotte PM,Ligtvoet KM,Zbijewski W,Beekman FJ

更新日期：2007-04-21 00:00:00