The rapid development and complexity of new x-ray computed tomography (CT) technologies the need for evidence-based optimization image quality with respect to radiation contrast media dose call an updated approach towards CT performance evaluation.This report offers testing guidelines systems enhanced focus on operational including iterative reconstructions automatic exposure control (AEC) techniques.The was developed based a comprehensive review best methods practices in scientific...

The purpose of this paper is to determine the benefit that can be achieved in image quality for a time-of-flight (TOF) fully three-dimensional (3-D) whole-body positron emission tomography (PET) scanner. We simulate 3-D PET scanner with complete modeling spatial and energy resolutions. based on LaBr/sub 3/ Anger-logic detectors which 300ps timing resolution has been achieved. Multiple simulations were performed 70-cm long uniform cylinders 27-cm 35-cm diameters, containing hot spheres (22,...

In positron emission tomography (PET), the format in which data is stored has a major influence on image reconstruction procedure. The use of list-mode preserves all measured attributes detected photon pairs but events are order that they were measured, allows only sequential access to data. This fact limits number applicable algorithms and often computing speed or memory capacity constraints require do not make full original precise information this paper we show how through change one can...

Philips has recently released the time-of-flight (TOF) PET/CT GEMINI-TF scanner. It uses 4 times 22 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> LYSO crystals, which 600 ps timing resolution, 12% energy resolution and 4.8 spatial resolution. This paper describes system design general approach of TOF reconstruction in Philips' A relaxed list mode ordered subset expectation maximization (LMOSEM) algorithm is used reconstruction, with...

In this paper we propose a comprehensive energy-based scatter correction approach for positron emission tomography (PET). We take advantage of the marked difference between energy spectra unscattered and scattered photons, use detailed information that comes with list-mode data estimation events distribution in space. Also, inside maximum-likelihood expectation maximization (ML-EM) image reconstruction algorithm, introduce energy-dependent factors individualize terms each event, given its...

Purpose: To devise a new methodology for CT image quality evaluation in order to assess the dose reduction potential of iterative reconstruction algorithms (IRA). Methods: Because nonlinear behavior IRA, authors propose task‐based consisting measuring detectability small, low contrast signals at random locations. The test, via simulations, phantom design that facilitates human and numerical observer studies such conditions. setup allows selection regions interest (ROI) around each signal, so...

In this paper is investigated the use of scan statistic for evaluating detectability small nodules in medical images. The scan-statistic method often used applications which random fields must be searched abnormal local features. Several results detection with localization theory are reviewed and a generalization presented using noise nodule distribution obtained by scanning arbitrary areas. One benefit model that it enables determination only few image samples way suitable both simulation...

A proto-type time-of-flight (TOF) 3D PET scanner based on lanthanum bromide detectors has been developed. The LaBr/sub 3/(5%Ce) Anger-logic in this new use 4/spl times/4/spl times/30 mm pixels and continuous light-guide coupled to a hexagonal array of 50-mm PMTs. consists 24 modules with 93-cm detector diameter 25-cm axial field-of-view. Initial characterization performance performed, including energy timing performance. We currently measure an overall system resolution 7.5% is 460 ps,...

In this paper we review several results of the nonparametric receiver operating characteristic (ROC) analysis and present an extension to localization ROC (LROC) analysis. Equations for estimation area under curve variance calculations are derived. Expressions choice optimal ratio between number signal‐absent signal‐present image samples also presented. The can be applied both with continuous or discrete scoring scales. simulation studies carried out validate theoretical derivations show...

Purpose: To develop an efficient nonparametric method for evaluation the detectability of signals at unknown locations in images, as a mean image quality assessment.Methods: We use free-response methodology that allows observer to mark and score all found suspicious image, summarizing these results operating characteristic (FROC) curve. However, unlike relative (or receiver) (ROC), or localization ROC (LROC), FROC curve has undefined, theoretically infinite, right side limit. Therefore area...

In this paper we describe two ray tracing algorithms for images represented using spherically symmetric basis functions (blobs) on regular grids. The method presented here allows more realistic modeling of the forward projection by considering tube shaped kernels, rather than simple lines. Each kernel is a function radial distance r from its center and can vary with position l along line. projections are computed convolutions blob line integrals. Both procedures incrementally compute square...

We investigate the use of energy dispersive x-ray coherent scatter computed tomography (ED-CSCT) as a non-invasive diagnostic method to differentiate between type I and II breast calcifications. This approach is sensitive differences composition internal crystal structure different types microcalcifications. The study carried out by simulating CSCT system with scanning pencil beam, considering polychromatic source an energy-resolving photon counting detector. In first step, multidimensional...

Coherent scatter computed tomography (CSCT) is a reconstructive x-ray imaging technique that yields the spatially resolved coherent-scatter cross section of investigated object revealing structural information tissue under investigation. In original CSCT proposals reconstruction images from coherently scattered x-rays done at each scattering angle separately using analytic reconstruction. this work we develop maximum likelihood estimation components algorithm (ML-ESCA) iteratively...

Purpose: The authors compared the performance of five protocols intended to reduce dose breast during computed tomography (CT) coronary angiography scans using a model observer unknown-location signal-detectability metric. Methods: simulated CT images an anthropomorphic female thorax phantom for 120 kV reference protocol and "dose reduction" breast: partial angle (posteriorly centered), tube-current modulated (TCM), with shielded breasts, 80 kV, centered). Two image quality tasks were...

The purpose of this work is to determine the benefit which can be achieved in image quality for a time-of-flight (TOF) capable 3D whole-body PET scanner. We simulate scanner with complete modeling spatial and energy resolutions. simulated has diameter 84-cm, an axial FOV 25-cm, uses 4times4times30-mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> pixelated LaBr <sub xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Anger-logic...

A signal detection model is presented that combines a and noise providing mathematical descriptions of the frequency appearance signals, signal‐like features naturally occurring in background. We derive expressions for likelihood functions whole ensemble observed suspicious locations, various possible combinations signals false candidates. As result, this formalism able to describe several new types tests using ratio statistics. have global image abnormality test an individual test. The also...

The objective of this work was to evaluate the advantages and shortcomings associated with Coherent Scatter Computed Tomography (CSCT) systems for breast imaging study possible alternative configurations. relationship between dose in a phantom simple surrogate image quality pencil-beam fan-beam CSCT geometries evaluated via Monte Carlo simulation, an improved setup proposed faster data acquisition. projection datasets have been simulated using new version MC-GPU code that includes model...

In this paper we present the design principles and main features of a new Monte Carlo simulation code for tomography that, through modular object oriented approach, maintains efficiency specialized solutions while incorporating common to general particle transport packages such as presence comprehensive geometrical modeling subsystem. The photon history heterogeneous medium is treated distinct case transport, rather than representation problem, leading efficient tracing voxel-based...

Two dimensional time-of-flight (TOF) and non-TOF PET image sets are analyzed using a scan statistic (or maximum noise nodule search) observer, as well fixed position observer. The results reveal significant differences between the two approaches indicate that usual detectability evaluation techniques, often referred signal known exactly background (SKE/BKE) tasks, insufficiently capture true nature of quality improvement TOF information brings. We review here several detection with...

A major obstacle in performing listmode reconstruction PET imaging is the increased computation time compared to a conventional frame or histogrammed reconstruction. To overcome this challenge clinical setting, it desirable distribute task multiple nodes. previous work investigated impact of high performance communication networks and focused mainly on static distribution. In practice, optimal load balancing difficult. Therefore we have developed dynamic approach, which flexible can easily...

Transmission scans using a single-photon point source on positron emission tomography (PET) scanner are inherently acquired in cone-beam geometry. Traditionally, these data binned into radially parallel oblique projections and then rebinned single-slice rebinning (SSRB) set of two-dimensional sinograms. For axially lines response (LORs), the SSRB approximation results axial tangential blurring transmission image, especially at large radial distances. animal PET recently completed University...