Pengpeng Zhang

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PURPOSE To assess the effect of metformin intake on cancer incidence and mortality. METHODS Original articles in English published until June 15, 2012 were searched for in electronic databases (MEDLINE, ISI Web of Science and EMBASE databases) and relevant reviews were examined. Meta-analysis was applied to calculate the summary relative risk (SRR) and(More)
PURPOSE To develop an optimization method using volumetric modulated arc therapy (VMAT) and evaluate VMAT plans relative to the standard intensity-modulated radiotherapy (IMRT) approach in prostate cancer. METHODS AND MATERIALS A single gantry rotation was modeled using 177 equispaced beams. Multileaf collimator apertures and dose rates were optimized(More)
PURPOSE The Varian RapidArc is a system for intensity-modulated radiotherapy (IMRT) treatment planning and delivery. RapidArc incorporates capabilities such as variable dose-rate, variable gantry speed, and accurate and fast dynamic multileaf collimators (DMLC), to optimize dose conformality, delivery efficiency, accuracy and reliability. We developed(More)
PURPOSE The purpose of this study is to investigate how the spatial relationship between the isocenters of the first and second radiosurgeries affects the overall outcome. METHODS AND MATERIALS We performed a retrospective study on 40 patients who had repeat gamma knife radiosurgery for trigeminal neuralgia. Only one 4-mm isocenter was applied in both(More)
The widely used 'silicon-on-insulator' (SOI) system consists of a layer of single-crystalline silicon supported on a silicon dioxide substrate. When this silicon layer (the template layer) is very thin, the assumption that an effectively infinite number of atoms contributes to its physical properties no longer applies, and new electronic, mechanical and(More)
Studies suggest that clinical outcomes are improved in repeat trigeminal neuralgia (TN) Gamma Knife radiosurgery if a different part of the nerve from the previous radiosurgery is treated. The MR images taken in the first and repeat radiosurgery need to be coregistered to map the first radiosurgery volume onto the second treatment planning image. We propose(More)
PURPOSE To integrate imaging performance characteristics, specifically sensitivity and specificity, of magnetic resonance angiography (MRA) and digital subtraction angiography (DSA) into arteriovenous malformation (AVM) radiosurgery planning and evaluation. METHODS AND MATERIALS Images of 10 patients with AVMs located in critical brain areas were analyzed(More)
The goal of this study was to implement and validate a noninvasive, quantitative ultrasonic technique for accurate and reproducible measurement of normal-tissue toxicity in radiation therapy. The authors adapted an existing ultrasonic tissue characterization (UTC) technique that used a calibrated 1D spectrum based on region-of-interest analysis. They(More)
PURPOSE To develop a collimator trajectory optimization paradigm for volumetric modulated arc therapy (VMAT) and evaluate this technique in paraspinal stereotactic body radiation therapy (SBRT). METHOD AND MATERIALS We propose a novel VMAT paradigm, Coll-VMAT, which integrates collimator rotation with synchronized gantry rotation, multileaf collimator(More)
PURPOSE To design and optimize trajectory-based, noncoplanar subarcs for volumetric modulated arc therapy (VMAT) deliverable on both Varian TrueBEAM system and traditional accelerators; and to investigate their potential advantages for treating central nervous system (CNS) tumors. METHODS AND MATERIALS To guide the computerized selection of beam(More)