Abstract:
:Quantification of nuclear medicine image data is a prerequisite for personalized absorbed dose calculations and quantitative biodistribution studies. The spatial response of a detector is a governing factor affecting the accuracy of image quantification, and the aim of this work was to model this impact. To simulate spatial response, a value for the intrinsic spatial resolution (R(intrinsic)) of the gamma camera is needed. R(intrinsic) for (99m)Tc was measured over the field of view (FOV) and an experimental setup was designed to measure R(intrinsic) for radioisotopes with higher photon energies. Monte Carlo (MC) simulations, using the codes SIMIND and GATE, were used to investigate the extrinsic effect of R(intrinsic) as a function of energy and its variation across the FOV. A method was developed to calculate energy-dependent blurring values for input to MC simulations, by separate consideration of the Compton scatter and photoelectric effect in the crystal and statistical variation in the signal. Inclusion of energy-specific blurring values in simulations showed excellent agreement with experimental measurements. The maximum pixel count rate can change by up to 18% when imaged at two different points in the FOV, and errors in the maximum pixel count rate of up to 11% were shown if a blurring value for (99m)Tc was used for simulations of (131)I. We demonstrate that the accuracy of MC simulations of gamma cameras can be significantly improved by accounting for the effect of energy on intrinsic spatial resolution.
journal_name
Phys Med Bioljournal_title
Physics in medicine and biologyauthors
Holstensson M,Partridge M,Buckley SE,Flux GDdoi
10.1088/0031-9155/55/6/013subject
Has Abstractpub_date
2010-03-21 00:00:00pages
1735-51issue
6eissn
0031-9155issn
1361-6560pii
S0031-9155(10)36054-6journal_volume
55pub_type
杂志文章abstract::The dosimetric impact of intrafraction prostate motion was investigated for helical tomotherapy treatments. Measured motion tracks were used to calculate the dosimetric impact on delivered target dose distributions. A dynamic dose calculation engine was developed to facilitate this evaluation. It was found that the D9...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/53/24/005
更新日期:2008-12-21 00:00:00
abstract::At the UMC Utrecht a prototype MR-linac has been installed. The system consists of an 8 MV Elekta linear accelerator and a 1.5 T Philips MRI system. This paper investigates the performance of the IC PROFILER™, a multi-axis ionization chamber array, in a 1.5 T magnetic field. The influence of the magnetic field on the ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/59/7/1845
更新日期:2014-04-07 00:00:00
abstract::This work studies the effect of age on lung dose commitments arising from the inhalation of an atmosphere containing radionuclides of varying half-lives and physical sizes. This dependence is significant in many cases, approaching a ratio of 2 in several instances when the maximum dose at a given age is compared with ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/27/4/005
更新日期:1982-04-01 00:00:00
abstract::Ultrasound shock wave therapy is increasingly used for non-invasive surgery. It requires the focusing of very high pressure amplitude in precisely controlled focal spots. In transcostal therapy of the heart or the liver, the high impedance mismatch between the bones and surrounding tissues gives rise to strong aberrat...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aad9b5
更新日期:2018-09-06 00:00:00
abstract::A new method for correcting simultaneously the attenuation, scatter and resolution effects in SPECT has been developed for the case of a homogeneous medium. It is based on an effective model of the scatter process. This model depends on only four parameters which are determined experimentally and remain independent of...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/39/4/005
更新日期:1994-04-01 00:00:00
abstract::Many models exist for predicting toxicities based on dose-volume histograms (DVHs) or dose-surface histograms (DSHs). This approach has several drawbacks as firstly the reduction of the dose distribution to a histogram results in the loss of spatial information and secondly the bins of the histograms are highly correl...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/56/7/013
更新日期:2011-04-07 00:00:00
abstract::The purpose of this paper is to evaluate the ability of a prototype Compton camera (CC) to measure prompt gamma rays (PG) emitted during delivery of clinical proton pencil beams for prompt gamma imaging (PGI) as a means of providing in vivo verification of the delivered proton radiotherapy beams. A water phantom was i...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/60/18/7085
更新日期:2015-09-21 00:00:00
abstract::Radionuclides which decay by electron capture accompanied by Auger electron cascades, or by beta emission are thought to be excessively damaging when incorporated into the molecular structure of mammalian cell nuclei and thereby pose a radiation hazard which is not assessable by conventional dosimetry. Survival data, ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/34/7/003
更新日期:1989-07-01 00:00:00
abstract::In radiation therapy, a plan is robust if the calculated and the delivered dose are in agreement, even in the case of different uncertainties. The current practice is to use safety margins, expanding the clinical target volume sufficiently enough to account for treatment uncertainties. This, however, might not be idea...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/56/14/011
更新日期:2011-07-21 00:00:00
abstract::A new thin-target method (patent pending) is described for portal imaging with low-energy (tens of keV) photons from a medical linear accelerator operating in a special mode. Low-energy photons are usually produced in the accelerator target, but are absorbed by the target and flattening filter, both made of medium- or...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/43/8/016
更新日期:1998-08-01 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
pub_type: 杂志文章
doi:10.1088/0031-9155/51/5/013
更新日期:2006-03-07 00:00:00
abstract::With the development of laser technology, laser-driven proton acceleration provides a new method for proton tumor therapy. However, it has not been applied in practice because of the wide and decreasing energy spectrum of laser-accelerated proton beams. In this paper, we propose an analytical model to reconstruct the ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aa6fce
更新日期:2017-07-07 00:00:00
abstract::In recent years there has been a large amount of research into the potential use of radiation sensitive gels for three-dimensional verification of clinical radiotherapy doses. In this paper we report the use of a MAGIC gel dosimeter (Fong et al 2001 Phys. Med. Biol. 46 3105) for the verification of a specific patient'...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/49/9/003
更新日期:2004-05-07 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
pub_type: 杂志文章
doi:10.1088/0031-9155/60/14/5413
更新日期:2015-07-21 00:00:00
abstract::This paper introduces a novel compartmental model describing the excretion of 18F-fluoro-deoxyglucose (FDG) in the renal system and a numerical method based on the maximum likelihood for its reduction. This approach accounts for variations in FDG concentration due to water re-absorption in renal tubules and the increa...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/59/10/2469
更新日期:2014-05-21 00:00:00
abstract::It has been demonstrated that gas-filled microbubble contrast agents, based on their volume changes, can serve as pressure probes in an MR field. It was recently reported that such an MR-based pressure measurement with microbubbles at 1.5 T must make use of microbubbles that have a volumetric magnetic susceptibility d...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/50/20/001
更新日期:2005-10-21 00:00:00
abstract::Mean glandular dose (MGD) is the figure of merit to assess breast dose after a mammographic acquisition. The use of normalized MGD obtained from Monte Carlo computations with measured incident air kerma determines the MGD delivered to patients. The Geant4 Application for Tomographic Emission (GATE) toolkit is a modern...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/58/7/2247
更新日期:2013-04-07 00:00:00
abstract::Determining a multidimensional velocity field within microscale opaque fluid flows is needed in areas such as microfluidic devices, biofluid mechanics and hemodynamics research in animal studies. The ultrasonic particle image velocimetry (EchoPIV) technique is appropriate for measuring opaque flows by taking advantage...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/55/20/003
更新日期:2010-10-21 00:00:00
abstract::Monte Carlo simulation provides a valuable tool in performance assessment and optimization of system design parameters for PET scanners. SimSET is a popular Monte Carlo simulation toolkit that features fast simulation time, as well as variance reduction tools to further enhance computational efficiency. However, SimSE...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/60/3/N35
更新日期:2015-02-07 00:00:00
abstract::The silicon photomultiplier (Si-PM) is a promising photo-detector for PET for use in magnetic resonance imaging (MRI) systems because it has high gain and is insensitive to static magnetic fields. Recently we developed a Si-PM-based depth-of-interaction PET system for small animals and performed simultaneous measureme...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/57/2/N1
更新日期:2012-01-21 00:00:00
abstract::Diffusion tensor - magnetic resonance electrical impedance tomography (DT-MREIT) is an imaging modality to obtain low-frequency anisotropic conductivity distribution employing diffusion tensor imaging (DTI) and magnetic resonance electrical impedance tomography (MREIT) techniques. DT-MREIT is based on the linear relat...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/abddcf
更新日期:2021-01-20 00:00:00
abstract::A method is described which offers an alternative to conventional Fourier phase/amplitude imaging for analysing representative LV cycles obtained from first-pass cardiac studies. The method involves applying factor analysis to the data and producing functional images of the first two factor loadings after polar transf...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/27/10/007
更新日期:1982-10-01 00:00:00
abstract::We comment on a recent article (Gomà et al 2014 Phys. Med. Biol. 59 4961-71) which compares different routes of reference dosimetry for the energy dependent beam monitor calibration in scanned proton beams. In this article, a 3% discrepancy is reported between a Faraday cup and a plane-parallel ionization chamber in t...
journal_title:Physics in medicine and biology
pub_type: 评论,杂志文章
doi:10.1088/0031-9155/61/17/6585
更新日期:2016-09-07 00:00:00
abstract::Optical experiments are described for measuring the attenuation characteristics of breast tissues at visible and near-infrared wavelengths. Total attenuation coefficients post mortem were measured directly in thin tissue sections. They are usually within the range from 10 to 30 mm-1, are rather higher in fat than in f...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/36/5/002
更新日期:1991-05-01 00:00:00
abstract::This paper reports an inverse arc-modulated radiation therapy planning technique based on linear models. It is implemented with a two-step procedure. First, fluence maps for 36 fixed-gantry beams are generated using a linear model-based intensity-modulated radiation therapy (IMRT) optimization algorithm. The 2D fluenc...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/55/13/020
更新日期:2010-07-07 00:00:00
abstract::Dose calculations were performed for a tissue phantom irradiated by uniform circular beams of negative pions with an assumed gaussian momentum distribution. The mean momentum of the pions was varied from 104.4 to 171.5 MeV/c (mean range 5-20 cm in unit-density tissue) and the momentum spread from 0 to 5% of the mean. ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/24/3/012
更新日期:1979-05-01 00:00:00
abstract::The convergence rates of the fast Padé transform (FPT) and the fast Fourier transform (FFT) are compared. These two estimators are used to process a time-signal encoded at 4 T by means of one-dimensional magnetic resonance spectroscopy (MRS) for healthy human brain. It is found systematically that at any level of trun...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/50/18/010
更新日期:2005-09-21 00:00:00
abstract::In proton therapy, the relative biological effectiveness (RBE) depends on various types of parameters such as linear energy transfer (LET). An analytical model for LET calculation exists (Wilkens' model), but secondary particles are not included in this model. In the present study, we propose a correction factor, L se...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/61/2/740
更新日期:2016-01-21 00:00:00
abstract::Diffusion tensor tractography (DTT) allows one to explore axonal connectivity patterns in neuronal tissue by linking local predominant diffusion directions determined by diffusion tensor imaging (DTI). The majority of existing tractography approaches use continuous coordinates for calculating single trajectories throu...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/54/4/013
更新日期:2009-02-21 00:00:00
abstract::Evaluation of the radioisotopic purity of technetium-99m (99mTc) produced in GBq amounts by proton bombardment of enriched molibdenum-100 (100Mo) metallic targets at low proton energies (i.e. within 15-20 MeV) is conducted. This energy range was chosen since it is easily achievable by many conventional medical cyclotr...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aadc88
更新日期:2018-09-19 00:00:00