INTRODUCTION The field inhomogeneity mapped using MRI offers the opportunity to characterize tissue magnetic susceptibility. The field measured in a voxel is a dipole kernel convolution of all tissue susceptibility sources surrounding the voxel [1]. The zero cone surfaces of the dipole kernel in Fourier domain undersamples the measured field, causing illposedness for the inverse problem of deri...

We introduce a fast and well-structured package for constructing voxel-based computational phantoms as MCNP(X) input file based on CT DICOM images. Our program which has been implemented under a graphic user inter-face provides several basic image processing tools for manipulating images. The MCNP materials are interpreted from the CT numbers of DICOM images. Two modes of phantom creation have ...

Purpose: GABA is a very important inhibitory neurotransmitter, which is present at a very low concentration in the brain (~1 mM). Special spectral editing is necessary at clinical field strengths in order to detect GABA by magnetic resonance spectroscopy. Jdifference spectroscopy is a very efficient way of spectral editing GABA signal and is widely used. It is a common practice to report [GABA]...

Our institution delivers TBI using a modified Theratron 780 60Co unit. Due to limitations of our treatment planning system in calculating dose for this treatment, we have developed a fast Monte Carlo code to calculate dose distributions within the patient. The algorithm is written in C and uses voxel density information from CT images to calculate dose in heterogeneous media. To test the algori...

A method for quantitative assessment of tree structures is reported allowing evaluation of airway or vascular tree morphology and its associated function. Our skeletonization and branch-point identification method provides a basis for tree quantification or tree matching, tree-branch diameter measurement in any orientation, and labeling individual branch segments. All main components of our met...

Introduction Constant-time point-resolved spectroscopy (CT-PRESS) [1] is a single voxel technique that simplifies the spectral pattern and permits the detection of Jcoupled resonances with high signal-to-noise ratio by using effective homonuclear decoupling [2]. The technique relies on non-selective refocusing, i.e., effective homonuclear decoupling is only achieved if the RF pulses refocus all...

Electric current-induced phase alternations have been imaged by fast magnetic resonance image (MRI) technology. We measured the magnetic resonance phase images induced by pulsed current stimulation from a phantom and detected its sensitivity. The pulsed current-induced phase image demonstrated the feasibility to detect phase changes of the proton magnetic resonance signal that could mimic neuro...

Model based iterative reconstruction (MBIR) algorithms have recently been applied to computed tomography and demonstrated superior image quality. MBIR algorithms also have the potential to incorporate sophisticated models of data acquisition to address artifacts. In this paper, we introduce kinetic models to the MBIR framework, which allow voxel value to change as a function of time. Convention...

A special acrylic phantom designed for both magnetic resonance imaging (MRI) and computed tomography (CT) was used to assess the geometric accuracy of MRI-based stereotactic localization with the Leksell stereotactic head frame and localizer system. The acrylic phantom was constructed in the shape of a cube, 164 mm in each dimension, with three perpendicular arrays of solid acrylic rods, 5 mm i...

Introduction: GafChromic EBT films are one of the self-developing and modern films commercially available for dosimetric verification of treatment planning systems (TPSs). Their high spatial resolution, low energy dependence and near-tissue equivalence make them suitable for verification of dose distributions in radiation therapy. This study was designed to evaluate the dosimetric parameters of...