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 (FOV) is used to accommodate the mouse heart. To accelerate the optimization process, the analytic models are applied to rapidly obtain the projection areas of the FOV, the sensitivities and the spatial resolutions of numerous system designs. The candidates of optimal multi-pinhole configuration are then decided by the preliminary evaluations with the analytic models. Subsequently, the pinhole SPECT systems equipped with the designed multi-pinhole apertures are modeled in GATE to generate the imaging system matrices (H matrices) for the system performance assessments. The area under the ROC curves (AUC) of the designed systems is evaluated by signal-known-exactly/background-known-statistically detection tasks with their corresponding H matrices. In addition, the spatial resolutions are estimated by the Fourier crosstalk approach, and the sensitivities are calculated with the H matrices of designed systems, respectively. Furthermore, a series of OSEM reconstruction images of synthetic phantoms, including the hot-rod phantom, mouse heart phantom and Defrise phantom, are reconstructed with the H matrices of designed systems. To quantify the sensitivity and resolution competition in the optimization process, the AUC from the detection tasks and the resolution estimated by the Fourier crosstalk are used as the figure of merits. A trade-off function of AUC and resolution is introduced to find the optimal multi-pinhole configuration. According to the examining results, a 22.5° rotated detector plus a 4-pinhole aperture with 22.5° rotation, 20% multiplexing and 1.52X magnification is the optimized multi-pinhole configuration for the micro pinhole-SPECT applied to mouse cardiac imaging with a camera of 49 × 49 mm(2) active area.
journal_name
Phys Med Bioljournal_title
Physics in medicine and biologyauthors
Lee MW,Lin WT,Chen YCdoi
10.1088/0031-9155/60/2/473subject
Has Abstractpub_date
2015-01-21 00:00:00pages
473-99issue
2eissn
0031-9155issn
1361-6560journal_volume
60pub_type
杂志文章abstract::Generally, the inverse planning of radiation therapy consists mainly of the fluence optimization. The beam angle optimization (BAO) in intensity-modulated radiation therapy (IMRT) consists of selecting appropriate radiation incidence directions and may influence the quality of the IMRT plans, both to enhance better or...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/58/9/2939
更新日期:2013-05-07 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::Recently, there has been a resurgence of interest in arc-based IMRT, through the use of 'conventional' multileaf collimator (MLC) systems that can treat large tumor volumes in a single, or very few pass(es) of the gantry. Here we present a novel 'burst mode' modulated arc delivery approach, wherein 2000 monitor units ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/56/7/002
更新日期:2011-04-07 00:00:00
abstract::We show that it is possible to translate an intensity modulated radiation therapy (IMRT) treatment plan and deliver it as a single arc. This technique is referred to in this paper as aperture modulation arc therapy (AMAT). During this arc, the MLC leaves do not conform to the projection of the target PTV and the machi...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/48/10/307
更新日期:2003-05-21 00:00:00
abstract::Avoiding toxicities in radiotherapy requires the knowledge of tolerable organ doses. For new, experimental fractionation schemes (e.g. hypofractionation) these are typically derived from traditional schedules using the biologically effective dose (BED) model. In this report we investigate the difficulties of establish...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aa9836
更新日期:2018-02-05 00:00:00
abstract::In vitro dielectric properties of ageing porcine tissues were measured in the frequency range of 50 MHz-20 GHz, and the total combined uncertainties of the measurements were assessed. The results show statistically significant reduction with age in both permittivity and conductivity of 10 out of 15 measured tissues. A...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/54/2/004
更新日期:2009-01-21 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
pub_type: 杂志文章
doi:10.1088/1361-6560/aa9502
更新日期:2017-12-19 00:00:00
abstract::Gold nanoparticles (GNPs) have shown potential in recent years as a means of therapeutic dose enhancement in radiation therapy. However, a major challenge in moving towards clinical implementation is the exact characterisation of the dose enhancement they provide. Monte Carlo studies attempt to explore this property, ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/61/5/2014
更新日期:2016-03-07 00:00:00
abstract::The Akaike information criterion and the associated Akaike weights (AW) rank pharmacokinetic models on the basis of goodness-of-fit and number of parameters. The usefulness of this information for improving the haemodynamic parameter estimates from DCE-MRI was investigated through two examples. In each of these, the e...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/57/11/3609
更新日期:2012-06-07 00:00:00
abstract::Using Cherenkov radiation in positron emission tomography (PET) has the potential to improve the time of flight (TOF) resolution and reduce the cost of detectors. In previous studies promising TOF results were achieved when lead fluoride (PbF2) crystals were used instead of a scintillator. In this work, a whole-body P...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/ab6f97
更新日期:2020-03-06 00:00:00
abstract::The presence of motion artifacts is a typical problem in thoracic imaging. However, synchronizing the respiratory cycle with computed tomography (CT) image acquisition can reduce these artifacts. We currently employ a method of in vivo respiratory-gated micro-CT imaging for small laboratory animals (mice). This proced...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/49/17/023
更新日期:2004-09-07 00:00:00
abstract::We developed and validated a Monte-Carlo-based application (RAYDOSE) to generate patient-specific 3D dose maps on the basis of pre-treatment imaging studies. A CT DICOM image is used to model patient geometry, while repeated PET scans are employed to assess radionuclide kinetics and distribution at the voxel level. In...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/58/8/2491
更新日期:2013-04-21 00:00:00
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 s...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/55/6/013
更新日期:2010-03-21 00:00:00
abstract::Numerous studies have reported the measurements of the dielectric properties of the skin. Clarifying the manner in which the human body interacts with electromagnetic waves is essential for medical research and development, as well as for the safety assessment of electromagnetic wave exposure. The skin comprises sever...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/59/16/4739
更新日期:2014-08-21 00:00:00
abstract::In order to measure in vivo resistivity of tissues in the thorax, the possibility of combining anatomical data extracted from high-resolution images with multiple-electrode impedance measurements, a priori knowledge of the range of tissue resistivities, and a priori data on the instrumentation noise is assessed in thi...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/39/1/001
更新日期:1994-01-01 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::Dynamic radiation therapy techniques require that the treatment head setup varies in time and space during dose delivery. Examples are leaf motion in intensity modulated x-ray therapy, modulator wheel rotation in conventional proton therapy and variable magnet settings in proton beam scanning. Consequently, for Monte ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/49/6/n03
更新日期:2004-03-21 00:00:00
abstract::Managing uncertainty is a major challenge in radiation therapy treatment planning, including uncertainty induced by intrafraction motion, which is particularly important for tumours in the thorax and abdomen. Common methods to account for motion are to introduce a margin or to convolve the static dose distribution wit...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/51/10/014
更新日期:2006-05-21 00:00:00
abstract::Calculations indicate that an assembly consisting of an antimony-beryllium source at the centre of a 4 cm radius water sphere surrounded by a 1 mm thick shell of boron-10 will emit neutrons with a broad spectrum at intermediate energies. A device based on this design was constructed using a water-filled, boron-carbide...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/21/1/007
更新日期:1976-01-01 00:00:00
abstract::The aim of this study is to investigate the feasibility of using conventional jaws to deliver inverse planned intensity-modulated radiotherapy (IMRT) plans for patients with prostate cancer. For ten patients, each had one three-dimensional conformal plan (3D plan) and seven inverse IMRT plans using direct aperture opt...
journal_title:Physics in medicine and biology
pub_type: 杂志文章,随机对照试验
doi:10.1088/0031-9155/52/8/007
更新日期:2007-04-21 00:00:00
abstract::We implemented a hybrid scatter-correction method for 3D PET that combines two scatter-correction methods in a complementary way. The implemented scheme uses a method based on the discrimination of the energy of events (the estimation of trues method (ETM)) and an auxiliary method (the single scatter simulation method...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/47/9/310
更新日期:2002-05-07 00:00:00
abstract::Respiratory-correlated cone-beam CT (CBCT) not only inhibits rapid scanning due to the slow speed of the LINAC head gantry rotation, but its implementation for routine patient imaging is impractical because of the high radiation dose delivered during the process. Digital tomosynthesis (DTS) is a potentially faster tec...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/ab0d50
更新日期:2019-05-02 00:00:00
abstract::Electrical properties (EP), namely conductivity and permittivity, can provide endogenous contrast for tissue characterization. Using electrical property tomography (EPT), maps of EP can be generated from conventional MRI data. This report investigates the feasibility and accuracy of EPT at 21.1 T for multiple RF coils...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/ab3259
更新日期:2020-02-28 00:00:00
abstract::In order to optimize external-beam conformal radiotherapy, patient movement during treatment must be minimized. For treatment on the upper torso, the target organs are known to move substantially due to patient respiration. This paper deals with the technical aspects of gating the radiotherapy beam synchronously with ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/41/1/007
更新日期:1996-01-01 00:00:00
abstract::An X-ray technique has been developed to enable reproducible and quantitative data to be obtained from radiographs taken by a diagnostic X-ray machine. Careful attention has been paid to the alignment of the specimen and the diagnostic tube and to operating conditions. The choice of X-ray spectrum is described togethe...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/22/4/003
更新日期:1977-07-01 00:00:00
abstract::It is well known that the experimental dosimetry of brachytherapy sources presents a challenge. Depending on the particular-dosimeter used, measurements can suffer from poor spatial resolution (ion chambers), lack of 3D information (film) or errors due to the presence of the dosimeter itself distorting the radiation f...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/44/10/305
更新日期:1999-10-01 00:00:00
abstract::Positron emission tomography (PET) iterative 3D reconstruction is a very computational demanding task. One of the main issues of the iterative reconstruction concerns the management of the system response matrix (SRM). The SRM models the relationship between the projection and the voxel space and its memory footprint ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aae12b
更新日期:2018-09-28 00:00:00
abstract::Non-invasive evaluation of the Achilles tendon elastic properties may enhance diagnosis of tendon injury and the assessment of recovery treatments. Shear wave elastography has shown to be a powerful tool to estimate tissue mechanical properties. However, its applicability to quantitatively evaluate tendon stiffness is...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/59/3/505
更新日期:2014-02-07 00:00:00
abstract::As automation in radiation oncology becomes more common, it is important to determine which algorithms are equivalent for a given workflow. Often, algorithm comparisons are performed in isolation; however, clinical context can provide valuable insight into the importance of algorithm features and error magnification i...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/ab9fc8
更新日期:2020-09-28 00:00:00
abstract::In this work, a methodology for using a smartphone camera, in conjunction with a light-tight box operating in reflective transmission mode, is investigated as a proof of concept for use as a film dosimetry system. An imaging system was designed to allow the camera of a smartphone to be used as a pseudo densitometer. T...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aa8b36
更新日期:2017-10-03 00:00:00