An algorithm for retrospective registration of PET emission and attenuation images is introduced based upon the assumption that no activity should be present outside the body. Since the attenuation image defines anatomy, it is segmented to identify a foreground template of the subject. This template is mapped to the emission image by a geometric transformation, and the emission image pixels tha...

The phenomenon of a phantom limb is a common experience after a limb has been amputated or its sensory roots have been destroyed. A complete break of the spinal cord also often leads to a phantom body below the level of the break. Furthermore, a phantom of the breast, the penis, or of other innervated body parts is reported after surgical removal of the structure. A substantial number of childr...

By Andrè theory, it is well known how to algebraically convert a spread in a projective space to an equivalent spread (representing the same translation plane) in a projective space of different dimension and of different order (corresponding to a subfield of the kernel). The goal of this paper is to establish a geometric connection between any two such equivalent spreads by embedding them in a...

INTRODUCTION For future space missions at the International Space Station, health risk to astronauts caused by space radiation needs to be properly quantified and controlled. The radiation field in space is low-dose rate, but the accumulated dose can be high during long-term missions (1). Radiological risk under such a low dose-rate exposure, i.e. stochastic effect, has generally been evaluated...

A breast tissue-equivalent series (BRTES) of phantoms is manufactured to mimic both the attenuation and the density of the range of glandular and adipose tissue compositions encountered in mammography. The BRTES simulates breast tissues across the range of 20% to 70% glandularity and can be assembled in a variety of thicknesses to represent a compressed breast thickness corresponding to glandul...

The quality and realism of simulated images is currently limited by the quality of the digital phantoms used for the simulations. The transition from simple raster based phantoms to more detailed geometric (mesh) based phantoms has the potential to increase the usefulness of the simulated data. A preliminary breast phantom which contains 12 distinct tissue classes along with the tissue properti...

The work presented herein describes our methods and results for predicting, measuring and correcting geometric distortions in a 3 T clinical magnetic resonance (MR) scanner for the purpose of image guidance in radiation treatment planning. Geometric inaccuracies due to both inhomogeneities in the background field and nonlinearities in the applied gradients were easily visualized on the MR image...

The calibration of a LE Ge detector system has been performed at CIEMAT Whole Body Counter for the assessment of Am in skull and knee. The facility counts with a Cohen phantom simulating a human head with 1000 Bq of Americium homogeneously distributed in the bone equivalent material. Measurements of the LE Ge system with the skull phantom were carried out in an optimisation study of counting ef...

A recipe is presented for the manufacture of highly compressible phantoms for diffuse optical tomography. The recipe is based on polyvinyl alcohol (PVA) slime, a viscoelastic fluid which readily deforms under moderate pressure. Scattering particles and absorbing compounds can be added to provide a uniform material with stable and reproducible optical properties. A linear relationship between th...