Xiangyang Mei

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In November 2007 Varian Medical Systems released a new version of ECLIPSE (version 8.1.17), which includes a correction to its Anisotropic Analytical Algorithm affecting monitor unit calculations for Enhanced Dynamic Wedge. The purpose of this study is to evaluate and compare the accuracy of the MU calculations for version 8.1.17 with that from the previous(More)
Our overall goal is to develop a new generation of electronic portal imaging devices (EPIDs) with a quantum efficiency (QE) more than an order of magnitude higher and a spatial resolution equivalent to that of EPIDs currently used for portal imaging. A novel design of such a high QE flat-panel based EPID was introduced recently and its feasibility was(More)
MLC gap control is critical for dosimetric accuracy in rotational IMRT (RapidArc, VMAT) treatments. Systematic MLC gap change of 1 mm may cause 3-4% change of EUD to PTV for a typical H&N RapidArc plan. Therefore it is important to monitor MLC gap through QC procedures. For this purpose, we have created dynamic arc sliding window (SW) plans with fixed width(More)
The Anisotropic Analytical Algorithm (AAA) of the Varian Eclipse treatment planning system calculates absolute dose for a variety of beam settings including those with an enhanced dynamic wedge (EDW). This algorithm has gone through a number of version updates since it was first released in July 2005. Previous versions of AAA have come with instructions on(More)
Experimental verification of calculated dose from a treatment planning system is often essential for quality assurance (QA) of intensity modulated radiation therapy (IMRT). Film dosimetry and single ion chamber measurements are commonly used for IMRT QA. Film dosimetry has very good spatial resolution, but is labor intensive and absolute dose is not(More)
Fabrication of highly ordered nanodot arrays of dot size down to tens of nanometers has attracted intensive studies in recent years. Of the various fabrication methods, self-assembled growth based on strain (Stranski-Kranstanov (SK)) has been the choice for the InAs/GaAs system. This mode however, typically results in random location of dots and broad size(More)
PURPOSE MLC leaf gap consistency is critical for the accurate delivery of dynamic IMRT plans. It is estimated that a systematic MLC leaf gap change of 0.6 mm will result in a 2% change to the equivalent uniform dose to a clinical target volume for a typical head and neck sliding window (SW) IMRT plan. The aim of this work is to use the measured dosimetric(More)
Most electronic portal imaging devices (EPIDs) developed so far use a Cu plate/phosphor screen to absorb x rays and convert their energies into light, and the light image is then read out. The main problem with this approach is that the Cu plate/phosphor screen must be thin (approximately 2 mm thick) in order to obtain a high spatial resolution, resulting(More)
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