Use of forward projection to correct patient motion during SPECT imaging.

abstract：:Inverse treatment planning in intensity modulated particle therapy (IMPT) with scanned carbon-ion beams is currently based on the optimization of RBE-weighted dose to satisfy requirements of target coverage and limited toxicity to organs-at-risk (OARs) and healthy tissues. There are many feasible IMPT plans that meet ...

journal_title：Physics in medicine and biology

authors： Burigo LN,Ramos-Méndez J,Bangert M,Schulte RW,Faddegon B

更新日期：2019-01-04 00:00:00

abstract：:A technique is described for examining the mode of operation of radiation detectors and estimating the losses and gains caused by random summing effects in spectra acquired at high counting rates. The technique is applied to estimating the errors caused by random summing when measuring the amounts of carbon and nitrog...

journal_title：Physics in medicine and biology

authors： Yankuba S,Oldroyd B,Metcalfe SC,Godfrey JE,Oxby CB

更新日期：1989-08-01 00:00:00

abstract：:Margins are employed in radiotherapy treatment planning to mitigate the dosimetric effects of geometric uncertainties for the clinical target volume (CTV). Unfortunately, whilst the use of margins can increase the probability that sufficient dose is delivered to the CTV, it can also result in delivering high dose of r...

journal_title：Physics in medicine and biology

authors： Tsang HS,Kamerling CP,Ziegenhein P,Nill S,Oelfke U

更新日期：2018-10-29 00:00:00

abstract：PURPOSE:A system for long-length intraoperative imaging is reported based on longitudinal motion of an O-arm gantry featuring a multi-slot collimator. We assess the utility of long-length tomosynthesis and the geometric accuracy of 3D image registration for surgical guidance and evaluation of long spinal constructs. M...

journal_title：Physics in medicine and biology

authors： Zhang X,Uneri A,Wu P,Ketcha MD,Jones C,Huang Y,Lo SL,Helm PA,Siewerdsen JH

更新日期：2021-01-21 00:00:00

abstract：:Permanent in vivo verification of IMRT photon beam profiles by a radiation detector with spatial resolution, positioned on the radiation entrance side of the patient, has not been clinically available so far. In this work we present the DAVID system, which is able to perform this quality assurance measurement while th...

journal_title：Physics in medicine and biology

authors： Poppe B,Thieke C,Beyer D,Kollhoff R,Djouguela A,Rühmann A,Willborn KC,Harder D

更新日期：2006-03-07 00:00:00

abstract：:This paper presents a computer simulation of photon interaction with collimator septa, which allows the point spread function of scintillation camera collimators to be calculated. The method simulates photon attenuation along their propagation direction in a determinist way. Using this simulation, the spatial resoluti...

journal_title：Physics in medicine and biology

authors： Gantet P,Esquerré JP,Danet B,Guiraud R

更新日期：1990-05-01 00:00:00

abstract：:Ultrasound may provide a quantitative technique for the characterization of cartilage changes typical of early osteoarthrosis. In this study, specific changes in bovine articular cartilage were induced using collagenase and chondroitinase ABC, enzymes that selectively degrade collagen fibril network and digest proteog...

journal_title：Physics in medicine and biology

authors： Töyräs J,Rieppo J,Nieminen MT,Helminen HJ,Jurvelin JS

更新日期：1999-11-01 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：:The aim of the study is to determine PTV margin for inter-observer variability in the volumetric modulated arc therapy (VMAT) prostate radiotherapy with high-dose volumetric CT (HDVCT) and conventional helical CT (CCT) for planning. Secondly to investigate the impact of geometric (PTV expansion) and dosimetric (confor...

journal_title：Physics in medicine and biology

authors： Cho YB,Alasti H,Kong V,Catton C,Berlin A,Chung P,Bayley A,Jaffray D

更新日期：2019-03-14 00:00:00

abstract：:An optimized configuration of multi-pinhole aperture can improve the spatial resolution and the sensitivity of pinhole SPECT simultaneously. In this study, an optimization strategy of the multi-pinhole configuration with a small detector is proposed for mouse cardiac imaging. A 14 mm-diameter spherical field-of-view (...

journal_title：Physics in medicine and biology

authors： Lee MW,Lin WT,Chen YC

更新日期：2015-01-21 00:00:00

abstract：:Diffusion weighted magnetic resonance imaging offers a non-invasive tool to explore the three-dimensional structure of brain white matter in clinical practice. Anisotropic diffusion hardware phantoms are useful for the quantitative validation of this technique. This study provides guidelines on how to manufacture anis...

journal_title：Physics in medicine and biology

authors： Fieremans E,De Deene Y,Delputte S,Ozdemir MS,Achten E,Lemahieu I

更新日期：2008-10-07 00:00:00

abstract：:Large volume tissue-equivalent proportional counters are of interest in radiation protection metrology, as the sensitivity in terms of counts per unit absorbed dose in these devices increases as the square of the counter diameter. Conventional solutions to the problem of maintaining a uniform electric field within a c...

journal_title：Physics in medicine and biology

authors： Verma PK,Waker AJ

更新日期：1992-10-01 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：: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：:The dielectric constant and conductivity of muscle, liver, spleen and kidney of cats in vivo and in situ immediately following the animal's death were measured at frequencies from 10 kHz to 100 MHz. A novel multi-ring capacitive sensor and a computer-controlled automatic network analyser (ANA) were employed. The resul...

journal_title：Physics in medicine and biology

authors： Surowiec A,Stuchly SS,Keaney M,Swarup A

更新日期：1986-08-01 00:00:00

abstract：:Delivering accurate radiation dose to blood specimens during biological irradiations is essential in quantifying damage of ionizing radiation. To estimate dose to blood samples as accurately as possible, pieces of EBT2 model GAFCHROMIC™ film were placed within an approximately 10 mm finely ground rice layer that was u...

journal_title：Physics in medicine and biology

authors： Aldelaijan S,Nobah A,Alsbeih G,Moftah B,Aldahlawi I,Alzahrany A,Tomic N,Devic S

更新日期：2013-05-21 00:00:00

abstract：:The UK, European and IAEA protocols for breast dosimetry in mammography use tabulations of conversion factors, which relate measurements of incident air kerma to the mean glandular dose to the breast. To supplement the existing tabulations, a Monte Carlo computer program has been used to calculate conversion factors f...

journal_title：Physics in medicine and biology

authors： Dance DR,Young KC

更新日期：2014-05-07 00:00:00

abstract：:We give an overview of the role of Physics in Medicine and Biology in the development of tomographic reconstruction algorithms. We focus on imaging modalities involving ionizing radiation, CT, PET and SPECT, and cover a wide spectrum of reconstruction problems, starting with classical 2D tomography in the 1970s up to ...

journal_title：Physics in medicine and biology

authors： Defrise M,Gullberg GT

更新日期：2006-07-07 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：:Due to high levels of noise in pixel-wise time-activity curves, the indirect method that generates kinetic parametric images from dynamic positron emission tomography (PET) images often results in poor parametric image quality. We have demonstrated that the quality of parametric images can be improved by denoising dyn...

journal_title：Physics in medicine and biology

authors： Huang HM

更新日期：2020-11-17 00:00:00

abstract：:All dosimetry protocols recommend the use of plane-parallel chambers for dose determination in electron beams with energies below 10-15 MeV. The protocols have assumed chamber perturbation effects to be negligible. The new AAPM Protocol (TG39) includes a cavity replacement factor prepl that differs from unity for some...

journal_title：Physics in medicine and biology

authors： Nilsson B,Montelius A,Andreo P

更新日期：1996-04-01 00:00:00

abstract：:This paper presents a method to obtain the pencil-beam kernels that characterize a megavoltage photon beam generated in a flattening filter free (FFF) linear accelerator (linac) by deconvolution from experimental measurements at different depths. The formalism is applied to perform independent dose calculations in mod...

journal_title：Physics in medicine and biology

authors： Azcona JD,Barbés B,Wang L,Burguete J

更新日期：2016-01-07 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：:The effect of temperature on the optical properties of human dermis and subdermis as a function of near-infrared wavelength has been studied between 25 degrees C and 40 degrees C. Measurements were performed ex vivo on a total of nine skin samples taken from the abdomen of three individuals. The results show a reprodu...

journal_title：Physics in medicine and biology

authors： Laufer J,Simpson R,Kohl M,Essenpreis M,Cope M

更新日期：1998-09-01 00:00:00

abstract：:In this paper we describe measurements of the contrast transfer function, modulation transfer function and point-spread function of an optical coherence tomography (OCT) imaging system through scattering layers having a dimension-less scattering depth over the range 0.2-6.9. The results were found to be insensitive to...

journal_title：Physics in medicine and biology

authors： Woolliams PD,Tomlins PH

更新日期：2011-05-07 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：:In conventional gating approaches for positron emission tomography (PET), a single number of gates is predetermined for the whole field of view (FOV) regardless of spatially variant motion blurring effects, which compromises image quality by under-gating regions of large motion and over-gating static regions. To achie...

journal_title：Physics in medicine and biology

authors： Wang J,Dong Y,Li H,Feng T

更新日期：2018-08-10 00:00:00

abstract：:Heterogeneity corrections for radiotherapy dose calculations are based on the electron density of the disturbing heterogeneity. However, when CT planning a radiotherapy treatment, where metallic hip implants are present, considerable artefacts are seen in the images. Often, an additional problem arises whereby no info...

journal_title：Physics in medicine and biology

authors： Coolens C,Childs PJ

更新日期：2003-06-07 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：:The purpose of this study is to investigate whether quality assurance (QA) for cone-beam computed tomography (CBCT) image rotation is necessary in order to ensure the accuracy of CBCT based image-guided radiation therapy (IGRT) and adaptive radiotherapy (ART). Misregistration of angular coordinates during CBCT acquisi...

journal_title：Physics in medicine and biology

authors： Ayan AS,Lin H,Yeager C,Deville C,McDonough J,Zhu TC,Anderson N,Bar Ad V,Lu HM,Both S

更新日期：2013-02-21 00:00:00