A method has been developed using which the foreground (body) in a fluoroscopy image of the peripherals can be segmented from the background (existing collimation and direct exposure). The extracted information about where the body is in an image is used to suggest settings for the collimator hardware during image acquisition. Segmentation is achieved through global feature extraction and super...

Combining results from Schmidt (1999) for the local cosmic rate and mean peak luminosity of γ-ray bursts (GRBs) with results on the history of the cosmic star formation rate, we provide estimates for the local GRB rate per unit blue luminosity in galaxies. For a moderate increase in SFR with redshift, we find a GRB rate per unit B luminosity of 2.4× 10h70 L −1 ⊙ yr . The corresponding mean γ-ra...

During my dental training, I was taught intraoral radiography using only rectangular collimation. Once out of the dental school in 1993, I realized that not many practices used rectangular collimators. Often-heard reasons for not using a rectangular collimator are cone-cutting errors and the fact that it is easier to aim with a circular collimator. Later, during my training as a dental and maxi...

Although x-ray imaging is widely used in biomedical applications, biological soft tissues have small density changes, leading to low contrast resolution for attenuation-based x-ray imaging. Over the past years, x-ray small-angle scattering was studied as a new contrast mechanism to enhance subtle structural variation within the soft tissue. In this paper, we present a detection method to extrac...

Current standard clinical SPECT techniques provide a resolution of at best 1 cm and sensitivity in the order of 10. Performance is largely determined by the collimator. Basic geometry couples resolution and sensitivity; the problem of high-resolution imaging is a formidable one because, to image at constant Signal-to-Noise, resolution improvements must be supported by simultaneous sensitivity i...

Collimated magnetized plasma structures are commonly observed on galactic, stellar, and laboratory scales. The Caltech plasma gun produces magnetically driven plasma jets bearing a striking resemblance to astrophysical jets and solar coronal loops by imposing boundary conditions analogous to those plasmas. This paper presents experimental observations of gun-produced plasma jets that support a ...