An investigation of factors affecting the accuracy of in vivo measurements of skin pigments by reflectance spectrophotometry.

abstract：:X-ray scatter is a significant problem in cone-beam computed tomography when thicker objects and larger cone angles are used, as scattered radiation can lead to reduced contrast and CT number inaccuracy. Advances have been made in x-ray computed tomography (CT) by incorporating a high quality prior image into the imag...

journal_title：Physics in medicine and biology

authors： Brunner S,Nett BE,Tolakanahalli R,Chen GH

更新日期：2011-02-21 00:00:00

abstract：:This study aims to build a feasible mathematical model to analyze the mass evolution of NSCLC during standard fractionated radiotherapy. Seventy-three cases of NSCLC who were received radiotherapy with prescription dose of 2 Gy  ×  30 fx were selected retrospectively and divided into adenocarcinoma (ADC) group and squ...

journal_title：Physics in medicine and biology

authors： Chen J,Wang K,Jian J,Zhang W

更新日期：2019-11-26 00:00:00

abstract：:In this study, the quantitative accuracy of different attenuation correction strategies presently available for the High Resolution Research Tomograph (HRRT) was investigated. These attenuation correction methods differ in reconstruction and processing (segmentation) algorithms used for generating a micro-image from m...

journal_title：Physics in medicine and biology

authors： van Velden FH,Kloet RW,van Berckel BN,Molthoff CF,de Jong HW,Lammertsma AA,Boellaard R

更新日期：2008-01-07 00:00:00

abstract：:In proton scanning systems that employ active energy variation for depth modulation, a switch of the particle energy might typically require 1-2 s. For plans comprising many energy slices, these seconds could sum up to a non-negligible fraction of the total treatment duration. We have applied the Nyquist-Shannon sampl...

journal_title：Physics in medicine and biology

authors： Kang JH,Wilkens JJ,Oelfke U

更新日期：2008-05-07 00:00:00

abstract：:Intensive computation time is required to simulate images of electronic portal imaging device (EPID) using Monte Carlo (MC) technique, limiting the development of applications associated with EPID, such as mega-voltage cone-beam computed tomography (MV-CBCT). In this study, a fast, accurate simulation strategy for MV-...

journal_title：Physics in medicine and biology

authors： Shi M,Myronakis M,Jacobson M,Lehmann M,Ferguson D,Baturin P,Huber P,Fueglistaller R,Harris T,Lozano IV,Williams C,Morf D,Berbeco RI

更新日期：2020-07-06 00:00:00

abstract：:The radiofrequency dielectric behaviour of packed human erythrocytes has been investigated in normal haemoglobins F and AA and also abnormal haemoglobins homozygous SS and heterozygous AS. Dielectric measurements were made in tightly packed blood cells at an average room temperature of 26.5 +/- 0.5 degrees C in the fr...

journal_title：Physics in medicine and biology

authors： Laogun AA,Ajayi NO,Okafor LO,Osamo NO

更新日期：1983-04-01 00:00:00

abstract：:We examine how the choice of CT x-ray beam filtration and phantom size influences patient dose (D) to computed tomography dose index (CTDI) conversion factors (i.e. D/CTDI). The ratio of head to body phantom CTDI(w) for a defined scan technique is alpha, and the ratio of organ dose when the body filter is changed to t...

journal_title：Physics in medicine and biology

authors： Huda W,Sterzik A,Tipnis S

更新日期：2010-01-21 00:00:00

abstract：:Microcalcification is one of the earliest and main indicators of breast cancer. Because dual-energy digital mammography could suppress the contrast between the adipose and glandular tissues of the breast, it is considered a promising technique that will improve the detection of microcalcification. In dual-energy digit...

journal_title：Physics in medicine and biology

authors： Mou X,Chen X,Sun L,Yu H,Ji Z,Zhang L

更新日期：2008-11-21 00:00:00

abstract：:The 'monoenergetic' electron loss model was derived in a previous work to account for pathlength straggling in the Fermi-Eyges pencil beam problem. In this paper, we extend this model to account for energy-loss straggling and secondary knock-on electron transport in order to adequately predict a depth dose curve. To m...

journal_title：Physics in medicine and biology

authors： Chvetsov AV,Sandison GA,Yeboah C

更新日期：2000-10-01 00:00:00

abstract：:The class of non-rigid registration methods proposed in the framework of PDE-constrained large deformation diffeomorphic metric mapping is a particularly interesting family of physically meaningful diffeomorphic registration methods. Inexact Gauss-Newton-Krylov optimization has shown an excellent numerical accuracy an...

journal_title：Physics in medicine and biology

authors： Hernandez M

更新日期：2019-01-07 00:00:00

abstract：:Results from dielectric studies on the freshwater fish Cyprinus carpio exposed to a sublethal concentration of sodium alkyl benzene sulphonate were compared with those from untreated control fish; recovery from the test solution was also checked. The influence of the anionic detergent on the intracellular matter of fi...

journal_title：Physics in medicine and biology

authors： Bielinska I,Terlecki J

更新日期：1984-05-01 00:00:00

abstract：:An inflatable endorectal balloon (ERB) is often used during stereotactic body radiation therapy (SBRT) for treatment of prostate cancer in order to reduce both intrafraction motion of the target and risk of rectal toxicity. However, the ERB can exert significant force on the prostate, and this work assessed the impact...

journal_title：Physics in medicine and biology

authors： Jones BL,Gan G,Kavanagh B,Miften M

更新日期：2013-11-21 00:00:00

abstract：:Ultrasound Doppler (UD) velocity measurements are commonly used to quantify blood flow velocities in vivo. The aim of our work was to investigate the accuracy of in vivo spectral Doppler measurements of velocity waveforms. Waveforms were derived from spectral Doppler signals and corrected for intrinsic spectral broade...

journal_title：Physics in medicine and biology

authors： Jiang J,Strother C,Johnson K,Baker S,Consigny D,Wieben O,Zagzebski J

更新日期：2011-03-21 00:00:00

abstract：:Multileaf collimator (MLC) calibration and quality control is a time-consuming procedure typically involving the processing, scanning and analysis of films to measure leaf and collimator positions. Faster and more reliable calibration procedures are required for these tasks, especially with the introduction of intensi...

journal_title：Physics in medicine and biology

authors： Baker SJ,Budgell GJ,MacKay RI

更新日期：2005-04-07 00:00:00

abstract：:Quantitative Yttrium-90 ((90)Y) bremsstrahlung single photon emission computed tomography (SPECT) imaging has shown great potential to provide reliable estimates of (90)Y activity distribution for targeted radionuclide therapy dosimetry applications. One factor that potentially affects the reliability of the activity ...

journal_title：Physics in medicine and biology

authors： Rong X,Du Y,Frey EC

更新日期：2012-06-21 00:00:00

abstract：:IMRT optimization is an iterative process in which many dose calculations may be necessary. A fast and accurate dose calculation engine is essential for the optimization program to converge to a reliable solution in a reasonable time. Previously we developed a fast dose calculation method for IMRT optimization based o...

journal_title：Physics in medicine and biology

authors： Wu Q

更新日期：2004-10-07 00:00:00

abstract：:Silicon diodes have good spatial resolution, which makes them advantageous over ionization chambers for dosimetry in fields with high dose gradients. However, silicon diodes overrespond to low-energy photons, that are more abundant in scatter which increase with large fields and larger depths. We present a cavity-theo...

journal_title：Physics in medicine and biology

authors： Eklund K,Ahnesjö A

更新日期：2009-10-21 00:00:00

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：:This study presents a combined small animal holding fixture system, termed a 'bridge capsule', which provides for small animal re-fixation with positional reproducibility. This system comprises separate holding fixtures for the head and lower body and a connecting part to a gas anesthesia system. A mouse is fixed in p...

journal_title：Physics in medicine and biology

authors： Kokuryo D,Kimura Y,Obata T,Yamaya T,Kawamura K,Zhang MR,Kanno I,Aoki I

更新日期：2010-07-21 00:00:00

abstract：:We report the first experimental soft-tissue phase-contrast tomography results using a conventional x-ray tube source, with a millimeter-sized focal spot. The setup is based on a Talbot-Lau grating interferometer operated at a mean energy of 28 keV. We present three-dimensional ex vivo images of a chicken heart sample...

journal_title：Physics in medicine and biology

authors： Bech M,Jensen TH,Feidenhans'l R,Bunk O,David C,Pfeiffer F

更新日期：2009-05-07 00:00:00

abstract：:Online adaptive radiation therapy (ART) based on real-time magnetic resonance imaging represents a paradigm-changing treatment scheme. However, conventional quality assurance (QA) methods based on phantom measurements are not feasible with the patient on the treatment couch. The purpose of this work is to develop a fa...

journal_title：Physics in medicine and biology

authors： Wang Y,Mazur TR,Park JC,Yang D,Mutic S,Li HH

更新日期：2017-06-21 00:00:00

abstract：:We have developed a model using Monte Carlo methods to simulate x-ray mammography. All possible physical processes of interaction of x-rays with matter have been taken into account. A simplified geometry of the mammographic apparatus has been considered along with a software phantom of compressed breast. The phantom m...

journal_title：Physics in medicine and biology

authors： Spyrou G,Tzanakos G,Bakas A,Panayiotakis G

更新日期：1998-11-01 00:00:00

abstract：:This study investigates the dosimetric impact of using population-based Hounsfield units (HUs) and ICRU-based HUs as a function of the number of tissue segments for bulk density assignment toward MRI-based treatment planning in the abdomen. To avoid potential geometric differences between CT and MR images, CT images r...

journal_title：Physics in medicine and biology

authors： Hsu SH,Zawisza I,O'Grady K,Peng Q,Tomé WA

更新日期：2018-07-24 00:00:00

abstract：:Values of W (the mean energy required to create an ion pair when a charged particle is stopped in a gas) are needed in radiation dosimetry to convert ionisation chamber current readings to absorbed dose. For neutron dosimetry the most important W values are those for protons, and this paper describes absolute measurem...

journal_title：Physics in medicine and biology

authors： Thomas DJ,Burke M

更新日期：1985-11-01 00:00:00

abstract：:Measurements of standardized uptake values (SUV) can vary due to many causes, including respiratory motion. Various methodologies have been introduced to correct for motion in PET, with quiescent-period-gated (QPG) PET being the most popular approach. QPG has been shown to improve PET image quantification compared to ...

journal_title：Physics in medicine and biology

authors： Meier JG,Einstein SA,Diab RH,Erasmus LJ,Xu G,Mawlawi OR

更新日期：2019-05-16 00:00:00

abstract：:Histotripsy is an ultrasound ablation method that depends on the initiation of a cavitation bubble cloud to fractionate soft tissue. Although previous work has provided significant insight into the process of intrinsic threshold histotripsy, the majority of these studies have used highly focused (i.e. f-number  <  0.6...

journal_title：Physics in medicine and biology

authors： Vlaisavljevich E,Gerhardson T,Hall T,Xu Z

更新日期：2017-02-21 00:00:00

abstract：:A classical trajectory model has been used to predict total cross sections of single and double ionizing processes (including capture processes) for several ion-biological molecule collisional systems in the intermediate and high energy range. In this work, the systems studied are water, adenine or cytosine targets io...

journal_title：Physics in medicine and biology

authors： Abbas I,Champion C,Zarour B,Lasri B,Hanssen J

更新日期：2008-02-21 00:00:00

abstract：:Imaging of the microvasculature is often performed using contrast agents in combination with either ultrasound (US) or magnetic resonance (MR) imaging. Contrast agents are used to enhance medical imaging by highlighting microvascular properties and function. Dynamic signal changes arising from the passage of contrast ...

journal_title：Physics in medicine and biology

authors： Chandrana C,Bevan P,Hudson J,Pang I,Burns P,Plewes D,Chopra R

更新日期：2011-02-07 00:00:00

abstract：:Ultra-wideband (UWB) electromagnetic pulses of nanosecond duration, or nanopulses, have recently been approved by the Federal Communications Commission for a number of different applications. They are also being explored for applications in biotechnology and medicine. The simulation of the propagation of a nanopulse t...

journal_title：Physics in medicine and biology

authors： Simicevic N

更新日期：2005-11-07 00:00:00

abstract：:The aim of this work was to evaluate the accuracy of dose predicted in heterogeneous media by a pencil beam (PB), a collapsed cone (CC) and a Monte Carlo (MC) algorithm. For this purpose, a simple multi-layer phantom composed of Styrofoam and white polystyrene was irradiated with 10 x 10 cm2 as well as 20 x 20 cm2 ope...

journal_title：Physics in medicine and biology

authors： Krieger T,Sauer OA

更新日期：2005-03-07 00:00:00