Validation of moving target doses using ArcCHECK Planned Dose Perturbation Algorithm

 The aim of the study is to use Planned Dose Perturbation (PDP™) measurement-guided reconstruction method to estimate dynamic 4D dose and evaluate both 3D dose and DVH changes caused by target motion resulting from respiration. Five patients of Ca lung were selected for the study. Target and Organ at risks were (OARs) delineated on 4DCT data set of each patient. Dose of moving target vs. stationary target were simulated and compared for OARs and target by analyzing 3D dose and DVH(Dose Volume Histogram).There was almost 3.5% higher target maximum doses measured with moving target after applying the target motion trajectory data as compared to the stationary target whereas OARs doses were comparable. The results, clinically signifies the importance of motion management in lung tumors.

Simulation of Gas-Particle Channel Flows Using a Two-Fluid Particle-Wall Collision Model Accounting for Wall Roughness

A two-fluid particle-wall collision model accounting for wall roughness is proposed. It accounts for the effects of wall friction, restitution, in particular the wall roughness, and hence the redistribution of particle Reynolds stresses in different directions at the wall, the absorption of turbulent kinetic energy from the kinetic energy of mean motion at the wall and the attenuation of particle motion by the wall. It gives the effect of wall roughness on the particle turbulence. The proposed model is applied to simulate gas-particle horizontal channel flows and is validated using PDPA measurement results. It is shown that presently used zero-gradient boundary conditions and other collision models of particle phase might give false results.

Spray Test of Fuel Nozzle for Lean Pre-Mixed Pre-Vaporized Combustor

An LPP (Lean Pre-mixed Pre-vaporized) combustor is one of the most promising systems to make it possible to reduce NOx emission drastically. To realize low NOx combustors using liquid fuel, uniformity and fine atomization of fuel droplets are essential requirements. Droplet diameters of a fuel nozzle designed for LPP combustor as determined by PDPA measurement system are presented in this paper. An annulus pre-mixing duct was employed for the LPP fuel nozzle test model. Spray tests were conducted at pressures from 0.18MPa to 0.53MPa. Pre-mixing air velocity was also varied. Data show that the test nozzle produces a fine spray. In this paper, fuel droplet size distribution and velocity are presented and effects of air pressure and velocity on atomization are discussed. SMD of fuel droplets increases with the increases of ambient pressure. This is inconsistent with the trend determined by other works. But when the effect of fuel flow rate (or fuel film thickness) is considered, these inconsistencies can be resolved.