Variable angle stereo imaging for rapid patient position correction in an in-house real-time position monitoring system.

Purpose: To develop and validate a variable angle stereo image based position correction methodology in an X-ray based in-house online position monitoring system.

Materials And Methods: A stereo imaging module that enables 3D position determination and couch correction of the patient based on images acquired at any arbitrary angle and arbitrary angular separation was developed and incorporated to the in-house SeedTracker real-time position monitoring system. The accuracy of the developed system was studied by imaging an anthropomorphic phantom implanted with radiopaque markers set to known offset positions from its reference position in an Elekta linear accelerator (LA) and associated XVI imaging system.

An assessment of image distortion and CT number accuracy within a wide-bore CT extended field of view.

Although wide bore computed tomography (CT) scanners provide increased space for patients, the scan field of view (sFOV) remains considerably smaller than the bore size. Consequently, patient anatomy which spans beyond the sFOV is truncated and the information is lost. As a solution, some manufacturers provide the capacity to reconstruct CT images from a partial dataset at an extended field of view (eFOV).

Backward and covariant Lyapunov vectors and exponents for hard-disk systems with a steady heat current.

The covariant Lyapunov analysis is generalized to systems attached to deterministic thermal reservoirs that create a heat current across the system and perturb it away from equilibrium. The change in the Lyapunov exponents as a function of heat current is described and explained. Both the nonequilibrium backward and covariant hydrodynamic Lyapunov modes are analyzed and compared.

Dissipation and entropy production in deterministic heat conduction of quasi-one-dimensional systems.

We explore the consequences of a deterministic microscopic thermostat-reservoir contact mechanism. With different temperature reservoirs at each end of a two-dimensional system, a heat current is produced and the system has an anomalous thermal conductivity. The microscopic form for the local heat flux vector is derived and both the kinetic and potential contributions are calculated.

Lyapunov modes as fields.

The numerically observed approximate functional forms for the transverse and longitudinal-momentum proportional (LP) Gram-Schmidt Lyapunov modes have been studied for some time. We construct a field theory for a system where the number of particles is large enough so the Lyapunov mode contributions from each particle can be considered to change continuously with particle position, whose solution gives the observed functional forms for all modes. The wave equations obtained as solutions of the field theory are derived either phenomenologically or from the exact dynamics of two-dimensional hard particles.