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— Just a test. We present an algorithm for path planning for a flexible robot in complex environments. Our algorithm computes a collision free path by taking into account geometric and physical constraints, including obstacle avoidance, non-penetration constraint, volume preservation, surface tension, and energy minimization. We describe a new algorithm for(More)
Computer models that take account of body movements promise to provide evaluation and improvement of medical imaging devices and technology. ABSTRACT | Recent work in the development of computerized phantoms has focused on the creation of ideal Bhybrid[ models that seek to combine the realism of a patient-based voxelized phantom with the flexibility of a(More)
Respiratory motion can cause artifacts in myocardial SPECT. We incorporate respiratory mechanics into the current 4D MCAT and into the next generation spline-based MCAT phantoms. In order to simulate respiratory motion in the current MCAT phantom, the geometric solids for the diaphragm, heart, ribs, and lungs were altered through manipulation of parameters(More)
Using a heart motion observer, we compared the performance of two image reconstruction techniques, a 3D OS-EM algorithm with post Butterworth spatial filtering and a 4D MAP-RBI-EM algorithm. The task was to classify gated myocardial perfusion (GMP) SPECT images of beating hearts with or without regional motion abnormalities. Noise-free simulated GMP SPECT(More)
The goal is to develop a 4D digital perfusion cardiac-torso (PCAT) phantom, a tracer kinetic extension of the XCAT phantom, by modeling the time activity curves (TACs) of individual organ regions in the phantom for dynamic perfusion PET and SPECT simulation studies. The PCAT phantom is based on a generalized compartmental model, which accepts the blood(More)
This paper describes an automated procedure for creating detailed patient-specific pediatric dosimetry phantoms from a small set of segmented organs in a child's CT scan. The algorithm involves full body mappings from adult template to pediatric images using multichannel large deformation diffeomorphic metric mapping (MC-LDDMM). The parallel implementation(More)
X-ray phase-contrast imaging (XPCI) can dramatically improve soft tissue contrast in X-ray medical imaging. Despite worldwide efforts to develop novel XPCI systems, a numerical framework to rigorously predict the performance of a clinical XPCI system at a human scale is not yet available. We have developed such a tool by combining a numerical(More)
PURPOSE To develop a technique to estimate onboard 4D-CBCT using prior information and limited-angle projections for potential 4D target verification of lung radiotherapy. METHODS Each phase of onboard 4D-CBCT is considered as a deformation from one selected phase (prior volume) of the planning 4D-CT. The deformation field maps (DFMs) are solved using a(More)
PURPOSE We investigate the differences without/with respiratory motion correction in apparent imaging agent localization induced in reconstructed emission images when the attenuation maps used for attenuation correction (from CT) are misaligned with the patient anatomy during emission imaging due to differences in respiratory state. METHODS We(More)
BACKGROUND With the rapidly increasing application of adaptive radiotherapy, large datasets of organ geometries based on the patient's anatomy are desired to support clinical application or research work, such as image segmentation, re-planning, and organ deformation analysis. Sometimes only limited datasets are available in clinical practice. In this(More)