Super-collimation is the propagation of a light beam without spreading that occurs when the light beam is guided by the dispersion properties of a photonic crystal, rather than by defects in the photonic crystal. Super-collimation has many potential applications, the most straight-forward of which is in the area of integrated optical circuits, where super-collimation can be utilized for optical...

The accuracy of the dose planning system (Leksell GammaPlan) used in Gamma Knife (model-B) radiosurgery was verified using both the GafChromic films MD-55 (improved) and the EGS4 Monte Carlo technique. The Monte Carlo technique was employed to calculate the dose distribution along the x-, y- and z-axes when a single shot with opening of all 201 sources was delivered at the centre of a simulated...

Fan-beam collimators are used in single-photon-emission computed tomography (SPECT) to improve the sensitivity for imaging of small organs. The disadvantage of fan-beam collimation is the truncation of projection data surrounding the organ of interest or, in those cases of imaging large patients, of the organ itself, producing reconstruction artifacts. A spatially varying focal length fan-beam ...

OBJECTIVE This study compared the 123I thyroid uptake measurements obtained from a gamma camera fitted with a low-energy all-purpose (LEAP) collimator to those obtained from a thyroid uptake probe and gamma camera fitted with a pinhole (PH) collimator. METHODS Thirty-one patients (27 female and 4 male patients) were studied for comparison between a probe and a gamma camera fitted with LEAP co...

A metal-less RXI collimator has been designed using the Simultaneous multiple surface method (SMS). Unlike conventional RXI collimators, whose back surface and parts of the front surface have to be metalized, this collimator is completely metal-free, made only of plastic (PMMA). The collimator’s back surface is designed as a grooved surface providing two TIR reflections for all rays impinging o...

A laboratory-based reflectometer designed for characterizing the reflectivity of optical coatings in 30- to 200-nm wavelength range was recently developed at IPOE. An RF-produced gas-discharge light source is applied generate characteristic lines. The mounted on a grazing incident monochromator with 146-deg deviation angle between and diffracted arms. By precisely adjusting toroidal grating ins...

PURPOSE To report on the physical aspects of a system in which radiotherapy functionality was added to a micro-computed tomography (microCT) scanner, to evaluate the accuracy of this instrument, and to and demonstrate the application of this technology for irradiating tumors growing within the lungs of mice. METHODS AND MATERIALS A GE eXplore RS120 microCT scanner was modified by the addition...

UNLABELLED The aim of this study was to determine the reproducibility of measurements of the size and severity of myocardial defects from 99mTc sestamibi cardiac phantom studies performed on multiple different gamma camera systems. METHODS A total of 250 gamma camera systems were evaluated over a 5-y period as part of the validation process of multiple multicenter trials. Each laboratory perf...

For a short bunch in an elliptical collimator we demonstrate that, as in a purely round collimator, the wake can be estimated from the primary fields of the beam alone. We obtain the wakes in the LCLS rectangular-to-round, undulator transitions using a hybrid method that includes indirect numerical (field) integration and an analytical potential energy term. For the LCLS 1 nC bunch charge confi...