Abstract:
:Kinetic parameters are commonly estimated from dynamically acquired nuclear medicine data by first reconstructing a dynamic sequence of images and subsequently fitting the parameters to time-activity curves generated from regions of interest overlaid upon the image sequence. Biased estimates can result from images reconstructed using inconsistent projections of a time-varying distribution of radiopharmaceutical acquired by a rotating SPECT system. If the SPECT data are acquired using cone-beam collimators wherein the gantry rotates so that the focal point of the collimators always remains in a plane, additional biases can arise from images reconstructed using insufficient, as well as truncated, projection samples. To overcome these problems we have investigated the estimation of kinetic parameters directly from SPECT cone-beam projection data by modelling the data acquisition process. To accomplish this it was necessary to parametrize the spatial and temporal distribution of the radiopharmaceutical within the SPECT field of view. In a simulated chest image volume, kinetic parameters were estimated for simple one-compartment models for four myocardial regions of interest. Myocardial uptake and washout parameters estimated by conventional analysis of noiseless simulated cone-beam data had biases ranging between 3-26% and 0-28%, respectively. Parameters estimated directly from the noiseless projection data were unbiased as expected, since the model used for fitting was faithful to the simulation. Statistical uncertainties of parameter estimates for 10,000,000 events ranged between 0.2-9% for the uptake parameters and between 0.3-6% for the washout parameters.
journal_name
Phys Med Bioljournal_title
Physics in medicine and biologyauthors
Huesman RH,Reutter BW,Zeng GL,Gullberg GTdoi
10.1088/0031-9155/43/4/024subject
Has Abstractpub_date
1998-04-01 00:00:00pages
973-82issue
4eissn
0031-9155issn
1361-6560journal_volume
43pub_type
杂志文章abstract::An alternative to gamma (gamma) histograms for ROI-based quantitative comparisons of dose distributions using the gamma concept is proposed. The method provides minimum values of dose difference and distance-to-agreement such that a pre-set fraction of the region of interest passes the gamma test. Compared to standard...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/54/12/N03
更新日期:2009-06-21 00:00:00
abstract::Online proton range/dose verification based on measurements of proton-induced positron emitters is a promising strategy for quality assurance in proton therapy. Because of the nonlinear correlation between the dose distribution and the activity distribution of positron emitters, we aim to establish their relationship ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/ab3564
更新日期:2019-09-04 00:00:00
abstract::Models of the electrical properties of biological tissue have been the subject of many studies. These models have sought to explain aspects of the dielectric dispersion of tissue. This paper develops a mathematical model of the complex permittivity of tissue as a function of frequency f, in the range 10(4) < f < 10(7)...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/52/23/016
更新日期:2007-12-07 00:00:00
abstract::Noise equivalent count rate (NECR) and image noise are two different but related metrics that have been used to predict and assess image quality, respectively. The aim of this study is to investigate, using patient studies, the relationships between injected dose (ID), body mass index (BMI) and scanner type on NECR an...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/56/16/013
更新日期:2011-08-21 00:00:00
abstract::The delivery of volumetric modulated arc therapy (VMAT) requires the simultaneous movement of the linear accelerator gantry, multi-leaf collimators and jaws while the dose rate is varied. In this study, a VMAT delivery emulator was developed to accurately predict the characteristics of a given treatment plan, incorpor...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/56/13/024
更新日期:2011-07-07 00:00:00
abstract::In dynamic renal scintigraphy, the main interest is the radiopharmaceutical redistribution as a function of time. Quality control (QC) of renal procedures often relies on phantom experiments to compare image-based results with the measurement setup. A phantom with a realistic anatomy and time-varying activity distribu...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/58/10/3145
更新日期:2013-05-21 00:00:00
abstract::Intravascular coronary thermography is a method that may detect vulnerable, atherosclerotic plaques and is currently evaluated in a clinical setting. Active macrophages or enzymatic heat releasing processes in vulnerable plaques may act as heat sources. To better understand the parameters of influence on thermographic...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/49/19/001
更新日期:2004-10-07 00:00:00
abstract::In the current work, EPR (electron paramagnetic resonance) dosimetry using alanine films (134 microm thick) was utilized for dose measurements in inhomogeneous phantoms irradiated with radiotherapy photon beams. The main phantom material was PMMA, while either Styrofoam or aluminium was introduced as an inhomogeneity....
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/51/24/003
更新日期:2006-12-21 00:00:00
abstract::Dynamic positron emission tomography (PET) imaging can provide information about metabolic changes over time, used for kinetic analysis and auxiliary diagnosis. Existing deep learning-based reconstruction methods have too many trainable parameters and poor generalization, and require mass data to train the neural netw...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/abc09d
更新日期:2020-10-13 00:00:00
abstract::For quality assurance of hyperthermia treatment planning systems, quantitative validation of the electromagnetic model of an applicator is essential. The objective of this study was to validate a finite-difference time-domain (FDTD) model implementation of the Lucite cone applicator (LCA) for superficial hyperthermia....
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/52/11/010
更新日期:2007-06-07 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
pub_type: 杂志文章
doi:10.1088/0031-9155/41/3/003
更新日期:1996-03-01 00:00:00
abstract::We have developed an x-ray imaging system for in vivo four-dimensional computed tomography (4DCT) of small animals for pre-clinical lung investigations. Our customized laboratory facility is capable of high resolution in vivo imaging at high frame rates. Characterization using phantoms demonstrate a spatial resolution...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aab8d2
更新日期:2018-04-20 00:00:00
abstract::A method of measuring the image quality of medical imaging equipment is considered within the framework of statistical decision theory. In this approach, images are regarded as random vectors and image quality is defined in the context of the image information available for performing a specified detection or discrimi...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/38/1/006
更新日期:1993-01-01 00:00:00
abstract::This work is a follow-up study for a recently-proposed 3D radiochromic gel dosimeter that contains a tetrazolium salt and a physical gel matrix made of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (Pluronic F-127). Several tetrazolium salts were examined in this work, including tetrazoli...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aabbb6
更新日期:2018-05-04 00:00:00
abstract::For low-energy (up to 150 kV) x-rays, the ratio of mass-energy absorption coefficients for water to air, (mu(en)/rho)w.air, and the backscatter factor B are used in the conversion of air kerma, measured free-in-air, to water kerma on the surface of a water phantom. For clinical radiotherapy, similar conversion factors...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/44/1/011
更新日期:1999-01-01 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
pub_type: 杂志文章
doi:10.1088/0031-9155/56/9/014
更新日期:2011-05-07 00:00:00
abstract::A common dose-saving technique used in modern CT devices is automatic tube current modulation (TCM), which was originally designed to also reduce the dose in paediatric CT patients. In order to be able to deduce detailed organ doses of paediatric models, dose conversion coefficients normalized to CTDI(vol) for an eigh...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/57/20/6309
更新日期:2012-10-21 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::Spinal screw placement is a challenging task due to small bone corridors and high risk of neurological or vascular complications, benefiting from precision guidance/navigation and quality assurance (QA). Implicit to both guidance and QA is the definition of a surgical plan-i.e. the desired trajectories and device sele...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aa5f42
更新日期:2017-04-07 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
pub_type: 杂志文章
doi:10.1088/0031-9155/50/6/004
更新日期:2005-03-21 00:00:00
abstract::In this work, we investigate longitudinal sampling and aliasing effects in multi-slice helical CT. We demonstrate that longitudinal aliasing can be a significant, complicated, and potentially detrimental effect in multi-slice helical CT reconstructions. Multi-slice helical CT scans are generally undersampled longitudi...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/47/15/318
更新日期:2002-08-07 00:00:00
abstract::A photoluminescent thermometer, based on the transient emission response of a europium-activated calcium sulphide phosphor, is described in detail. This optical thermometry system has special advantages for temperature measurements in microwave and RF fields and potential application in electromagnetically induced cli...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/27/1/011
更新日期:1982-01-01 00:00:00
abstract::Two complementary approaches to the noise suppression problem in on-line portal imaging have been analysed. Temporal filtering by image summation can substantially reduce the amount of noise in an image. In many cases, however, movements of the patient or the radiation source limit the time period over which the avera...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/35/3/011
更新日期:1990-03-01 00:00:00
abstract::Ion beam therapy offers the possibility of a highly conformal tumor-dose distribution; however, this technique is extremely sensitive to inaccuracies in the treatment procedures. Ambiguities in the conversion of Hounsfield units of the treatment planning x-ray CT to relative stopping power (RSP) can cause uncertaintie...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aa5602
更新日期:2017-02-07 00:00:00
abstract::The quality of radiation therapy delivered for treating cancer patients is related to set-up errors and organ motion. Due to the margins needed to ensure adequate target coverage, many breast cancer patients have been shown to develop late side effects such as pneumonitis and cardiac damage. Breathing-adapted radiatio...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/50/19/020
更新日期:2005-10-07 00:00:00
abstract::We tested the ability of a single Compton camera (CC) to produce 3-dimensional (3D) images of prompt gammas (PGs) emitted during the irradiation of a tissue-equivalent plastic phantom with proton pencil beams for clinical doses delivered at clinical dose rates. PG measurements were made with a small prototype CC place...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aaa203
更新日期:2018-01-30 00:00:00
abstract::Monte Carlo (MC) algorithms are recognized as the most accurate methodology for patient dose assessment. For intensity-modulated radiation therapy (IMRT) delivered with dynamic multileaf collimators (DMLCs), accurate dose calculation, even with MC, is challenging. Accurate IMRT MC dose calculations require inclusion o...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/47/17/312
更新日期:2002-09-07 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
pub_type: 杂志文章
doi:10.1088/0031-9155/34/8/010
更新日期:1989-08-01 00:00:00
abstract::Most commonly in radiation therapy, treatments are delivered in a co-planar geometry. Numerous advantages have been reported of adding non-coplanar beams to the treatment plan. The aim of this study was to compare current state-of-the-art VMAT and CyberKnife treatment plans to that of a novel linac design developed at...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/ab246f
更新日期:2019-06-20 00:00:00
abstract::Lung tumors treated in breath-hold are subject to inter- and intra-breath-hold variations, which makes tumor position monitoring during each breath-hold important. A markerless technique is desirable, but limited tumor visibility on kV images makes this challenging. We evaluated if template matching + triangulation ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aac1a9
更新日期:2018-05-29 00:00:00