Improved accuracy of markerless motion tracking on bone suppression images: preliminary study for image-guided radiation therapy (IGRT).

abstract：:Reference dosimetry of photon fields is a well-established subject and currently available protocols (such as the IAEA TRS-398 and AAPM TG-51) provide methods for converting the ionization chamber (IC) reading into dose to water, provided reference conditions of charged particle equilibrium (CPE) are fulfilled. But th...

journal_title：Physics in medicine and biology

authors： Pena J,Sánchez-Doblado F,Capote R,Terrón JA,Gómez F

更新日期：2006-03-21 00:00:00

abstract：:Deformable image registration is widely used in various radiation therapy applications including daily treatment planning adaptation to map planned tissue or dose to changing anatomy. In this work, a simple and efficient inverse consistency deformable registration method is proposed with aims of higher registration ac...

journal_title：Physics in medicine and biology

authors： Yang D,Li H,Low DA,Deasy JO,El Naqa I

更新日期：2008-11-07 00:00:00

abstract：:In treatment planning we depend upon accurate knowledge of geometric and range uncertainties. If the uncertainty model is inaccurate then the plan will produce under-dosing of the target and/or overdosing of OAR. We aim to provide a method for which centre and site-specific population range uncertainty due to inter-fr...

journal_title：Physics in medicine and biology

authors： Holloway SM,Holloway MD,Thomas SJ

更新日期：2017-12-19 00:00:00

abstract：:New values of the factors required to convert the reading of a radiation dosemeter calibrated in terms of air kerma (or exposure) into absorbed dose to water for medium-energy x-radiation were given in a code of practice published by the IAEA in 1987. These are not considered to possess sufficient support from other s...

journal_title：Physics in medicine and biology

authors：

更新日期：1991-08-01 00:00:00

abstract：:We present the results of utilizing aligned anatomical information from CT images to locally adjust image smoothness during the reconstruction of three-dimensional (3D) whole-body positron emission tomography (PET) data. The ability of whole-body PET imaging to detect malignant neoplasms is becoming widely recognized....

journal_title：Physics in medicine and biology

authors： Comtat C,Kinahan PE,Fessler JA,Beyer T,Townsend DW,Defrise M,Michel C

更新日期：2002-01-07 00:00:00

abstract：:The aim of the present work was to investigate how the native signal observed in the electron paramagnetic resonance (EPR) spectrum of tooth enamel and dentin is associated with the organic content of the two tissues. This was achieved by comparing the EPR native signal and the optical bands (Raman and infrared, IR) a...

journal_title：Physics in medicine and biology

authors： Fattibene P,Carosi A,De Coste V,Sacchetti A,Nucara A,Postorino P,Dore P

更新日期：2005-03-21 00:00:00

abstract：:Usually, Monte Carlo models are validated against experimental data. However, models of multiple Coulomb scattering (MCS) in the Gaussian approximation are exceptional in that we have theories which are probably more accurate than the experiments which have, so far, been done to test them. In problems directly sensiti...

journal_title：Physics in medicine and biology

authors： Makarova A,Gottschalk B,Sauerwein W

更新日期：2017-07-06 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：:The exponential edge-gradient effect must arise in any x-ray transmission CT scanner whenever long sharp edges of high contrast are encountered. The effect is non-linear and is due to the interaction of the exponential law of x-ray attenuation and the finite width of the scanning beam in the x-y plane. The error induc...

journal_title：Physics in medicine and biology

authors： Joseph PM,Spital RD

更新日期：1981-05-01 00:00:00

abstract：:A new function to treat tetrahedral-mesh geometry was implemented in the particle and heavy ion transport code systems. To accelerate the computational speed in the transport process, an original algorithm was introduced to initially prepare decomposition maps for the container box of the tetrahedral-mesh geometry. Th...

journal_title：Physics in medicine and biology

authors： Furuta T,Sato T,Han MC,Yeom YS,Kim CH,Brown JL,Bolch WE

更新日期：2017-06-21 00:00:00

abstract：:The purpose of this study was the evaluation of the impact of a variable relative biological effectiveness (RBE) compared to a constant RBE value of 1.1 in proton therapy prostate trials due to uncertainties in α/β ratio. Twenty patients receiving passive scattered proton therapy (PSPT) and fifteen patients receiving ...

journal_title：Physics in medicine and biology

authors： Marteinsdottir M,Paganetti H

更新日期：2019-06-05 00:00:00

abstract：:The use of calibrated tissue-equivalent (TE) ionisation chambers is commonly considered to be the most practical method for total absorbed dose determinations in mixed neutron-photon fields for biomedical applications. The total absorbed dose can be derived from the charge produced within the cavity of an ionisation c...

journal_title：Physics in medicine and biology

authors： Zoetelief J,Broerse JJ

更新日期：1983-05-01 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：:For the first time, three-dimensional images of the newborn infant brain have been generated using measurements of transmitted light. A 32-channel time-resolved imaging system was employed, and data were acquired using custom-made helmets which couple source fibres and detector bundles to the infant head. Images have ...

journal_title：Physics in medicine and biology

authors： Hebden JC,Gibson A,Yusof RM,Everdell N,Hillman EM,Delpy DT,Arridge SR,Austin T,Meek JH,Wyatt JS

更新日期：2002-12-07 00:00:00

abstract：:A semi-empirical theory has been derived that relates the aluminum equivalence of various materials used in diagnostic radiology to their attenuation coefficients. The dependence of the aluminum hardness (AHE) and attenuation (AAE) equivalent on the beam quality is described in terms of effective energy. This 'aluminu...

journal_title：Physics in medicine and biology

authors： Nagel HD

更新日期：1986-12-01 00:00:00

abstract：:The purpose of this work was to characterize expert variation in segmentation of intracranial structures pertinent to radiation therapy, and to assess a registration-driven atlas-based segmentation algorithm in that context. Eight experts were recruited to segment the brainstem, optic chiasm, optic nerves, and eyes, o...

journal_title：Physics in medicine and biology

authors： Deeley MA,Chen A,Datteri R,Noble JH,Cmelak AJ,Donnelly EF,Malcolm AW,Moretti L,Jaboin J,Niermann K,Yang ES,Yu DS,Yei F,Koyama T,Ding GX,Dawant BM

更新日期：2011-07-21 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：:In the IAEA TRS-381 protocol, k(cel) and p(cel) account for the central electrode perturbation during the air kerma chamber calibration and the in-phantom measurements. The values of these correction factors are based mainly on Monte Carlo simulations. In the present work experimental data on k(cel) and p(cel) for the...

journal_title：Physics in medicine and biology

authors： Palm A,Mattsson O

更新日期：1999-05-01 00:00:00

abstract：:All particle beam scanning systems are subject to dose delivery errors due to errors in position, energy and intensity of the delivered beam. In addition, finite scan speeds, beam spill non-uniformities, and delays in detector, detector electronics and magnet responses will all contribute errors in delivery. In this p...

journal_title：Physics in medicine and biology

authors： Coutrakon G,Wang N,Miller DW,Yang Y

更新日期：2010-12-07 00:00:00

abstract：:Compartmental models are widely used for the mathematical modelling of dynamic studies acquired with positron emission tomography (PET). The numerical problem involves the estimation of a sum of decaying real exponentials convolved with an input function. In exponential spectral analysis (SA), the nonlinear estimation...

journal_title：Physics in medicine and biology

authors： Turkheimer FE,Hinz R,Gunn RN,Aston JA,Gunn SR,Cunningham VJ

更新日期：2003-12-07 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：:Estimation of a set of parameters that describe the geometry of the cone-beam computed tomography system plays an important role in the geometrical calibration. In the calibration process, the helical phantom consisting of spherical markers arranged on a helical trajectory has been widely applied. To directly determin...

journal_title：Physics in medicine and biology

authors： Xu M,Zhang C,Liu X,Li D

更新日期：2014-10-07 00:00:00

abstract：:This paper analyzes the radio frequencies (RF) exposure in the head tissues of children using a cellular handset or RF sources (a dipole and a generic handset) at 900, 1800, 2100 and 2400 MHz. Based on magnetic resonance imaging, child head models have been developed. The maximum specific absorption rate (SAR) over 10...

journal_title：Physics in medicine and biology

authors： Wiart J,Hadjem A,Wong MF,Bloch I

更新日期：2008-07-07 00:00:00

abstract：:The aim of this study is to determine the impact of longitudinal micro-CT imaging on the growth of B16F1 tumours in C57BL/6 mice. Sixty mice received 2 × 10(5) B16F1 cells subcutaneously in the hind flank and were divided into control (no scan), 'low-dose' (80 kVp, 70 mA, 8 s, 0.07 Gy), 'medium-dose' (80 kVp, 50 mA, 3...

journal_title：Physics in medicine and biology

authors： Foster WK,Ford NL

更新日期：2011-01-21 00:00:00

abstract：:In situ and in vivo treatment plan verification and beam monitoring as well as dose control during heavy-ion tumour therapy can be performed in principle by measurements of range distributions of beta(+)-emitting nuclei by means of PET techniques. For this purpose the performance of different types of positron camera ...

journal_title：Physics in medicine and biology

authors： Pawelke J,Byars L,Enghardt W,Fromm WD,Geissel H,Hasch BG,Lauckner K,Manfrass P,Schardt D,Sobiella M

更新日期：1996-02-01 00:00:00

abstract：:We have investigated the tongue-and-groove effect on the IMRT dose distributions for a Varian MLC. We have compared the dose distributions calculated using the intensity maps with and without the tongue-and-groove effect. Our results showed that, for one intensity-modulated treatment field, the maximum tongue-and-groo...

journal_title：Physics in medicine and biology

authors： Deng J,Pawlicki T,Chen Y,Li J,Jiang SB,Ma CM

更新日期：2001-04-01 00:00:00

abstract：:RapidArc, recently released by Varian Medical Systems, is a novel extension of IMRT in which an optimized 3D dose distribution may be delivered in a single gantry rotation of 360 degrees or less. The purpose of this study was to investigate the accuracy of the analytical anisotropic algorithm (AAA), the sole algorithm...

journal_title：Physics in medicine and biology

authors： Gagne IM,Ansbacher W,Zavgorodni S,Popescu C,Beckham WA

更新日期：2008-12-21 00:00:00

abstract：:A new hybrid imaging-treatment modality, the MRI-Linac, involves the irradiation of the patient in the presence of a strong magnetic field. This field acts on the charged particles, responsible for depositing dose, through the Lorentz force. These conditions require a dose calculation engine capable of taking into con...

journal_title：Physics in medicine and biology

authors： Hissoiny S,Raaijmakers AJ,Ozell B,Després P,Raaymakers BW

更新日期：2011-08-21 00:00:00

abstract：:Monte Carlo simulation techniques are applied to track the annihilation photons from positron decay, and store the photon histories. Reasonably realistic models of the isotope distribution in the brain and heart during typical PET studies, as well as the traditional phantoms used for measuring PET scanner performance ...

journal_title：Physics in medicine and biology

authors： Thompson CJ,Moreno-Cantu J,Picard Y

更新日期：1992-03-01 00:00:00

abstract：:The effects of radiation damage, tumour repopulation and cell sublethal damage repair and the possibility of extracting information about the model parameters describing them are investigated in this work. Previously published data on two different cultured cell lines were analysed with the help of a tumour control pr...

journal_title：Physics in medicine and biology

authors： Stavrev P,Weldon M,Warkentin B,Stavreva N,Fallone BG

更新日期：2005-07-07 00:00:00