Formation of parametric images requires voxel-by-voxel estimation of rate constants, a process sensitive to noise and computationally demanding. A model-based clustering method for a two-parameter model (CAKS) was extended to the FDG three-parameter model. The concept was to average voxels with similar kinetic signatures to reduce noise. Voxel kinetics were categorized by the first two principa...

This work investigates a new partial volume (PV) image segmentation framework with comparison to a previous PV approach. The new framework utilizes an expectation-maximization (EM) algorithm to estimate simultaneously (1) tissue fractions in each image voxel and (2) statistical model parameters of the image data under the principle of maximum a posteriori probability (MAP). The previous EM appr...

This technical report extends our previous paper on sparse voxel octrees. We first discuss the benefits and drawbacks of voxel representations and how the storage space requirements behave for different kinds of content. Then, we explain in detail our compact data structure for storing voxels and an efficient ray cast algorithm that utilizes this structure, including the contributions of the or...

Introduction The relative anisotropy (RA) exhibits a great contrast between brain white and gray matters [1]. However, RA is susceptible to the influence of noise [2, 3]. Although the proposed inter-voxel indices reduce noise influence on measured diffusion anisotropy [3], the partial volume effect originating from the inter-voxel operation adds uncertainty to the estimated anisotropy depending...

INTRODUCTION The aim of this study was to compare the diagnostic accuracy of cone beam computed tomography (CBCT) scans with different voxel resolutions in the detection of simulated vertical root fracture (VRF). METHODS Sixty teeth, 30 with root fractures and 30 without, were examined through i-CAT tomography at 4 different voxel resolutions (0.125, 0.2, 0.3, 0.4 mm). Three observers scored ...

The partial volume effect (PVE) arises in volumetric images when more than one tissue type occurs in a voxel. In such cases, the voxel intensity depends not only on the imaging sequence and tissue properties, but also on the proportions of each tissue type present in the voxel. We have demonstrated in previous work that ignoring this effect by establishing binary voxel-based segmentations intro...

The translation of retinal images into recognizable objects and scenes is not yet well understood. Beyond edgedetection in primary visual cortex, higher stages of cortical representation are still uncertain. We use a multi-layer convolutional neural network (Krizhevsky, 2012) to provide models for visual selectivities in the ventral visual pathway. We examine individual neural units, or ”kernel...

Starting with a set of calibrated photographs taken of a scene, voxel coloring algorithms reconstruct three-dimensional surface models on a finite spatial domain. In this paper, we present a method that warps the voxel space, so that the domain of the reconstruction extends to an infinite or semi-infinite volume. Doing so enables the reconstruction of objects far away from the cameras, as well ...

Several updated Monte Carlo (MC) codes are available to perform calculations of voxel S values for radionuclide targeted therapy. The aim of this work is to analyze the differences in the calculations obtained by different MC codes and their impact on absorbed dose evaluations performed by voxel dosimetry. Voxel S values for monoenergetic sources (electrons and photons) and different radionucli...