The Experts below are selected from a list of 162852 Experts worldwide ranked by ideXlab platform
Timothy D Solberg - One of the best experts on this subject based on the ideXlab platform.
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su e t 695 silicon diode measurements of Output Field size factors for proton pencil beam scanning with a dedicated nozzle
Medical Physics, 2015Co-Authors: J Mcglade, L Lin, Timothy D SolbergAbstract:Purpose: Proton irradiation degrades solid state detectors, producing high recombination and leakage currents and ultimately rendering them unusable for dosimetry. In this work we evaluate the performance of a new p-type silicon diode under proton beam irradiation. Methods: A novel p-type silicon diode with improved radiation hardness has recently been developed (IBA Dosimetry, Schwarzenbruck, Germany). The dosimetric properties of the devices were assessed for application in pencil beam scanning (PBS) proton irradiation. Using PBS Fields with 4 mm spaced, uniform intensity spots, dose and dose rate linearity were evaluated over a clinical range. Output factors were measured at energies of 100, 180, and 225 MeV and for Field sizes ranging from 4×4 – 20×20 cm2. Measurements were performed at the center of the square Fields at varying depths upstream from the Bragg peak and compared with previously published results. Results: At shallow depths, the diode exhibits linear behavior (0.1%) over the clinical range of doses and dose rates; the sensitivity of the diode in this region is ∼6.0 nC/Gy. As the depth of measurement approaches within 2 cm of each Bragg peak, the deviation from linearity becomes greater (±2–6%). The diode shows less response with small Fields and - over responds with large Fields.ConclusionAt depths more than 2 cm upstream from the Bragg Peak, the diode shows very good agreement with ion chamber and calculated results for Output factors. This demonstrates that diodes can be used for relative measurements at shallow depths, but should be used with caution at deeper depths and for higher energy. Measurements at all depths exhibit an energy dependence that is characteristic of silicon diodes and requires correction. Detectors provided by IBA Dosimetry GmbH, Schwarzenbruck, Germany
Huaiqiang Gu - One of the best experts on this subject based on the ideXlab platform.
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the effect of oscillator and dipole dipole interaction on multiple optomechanically induced transparency in cavity optomechanical system
Scientific Reports, 2018Co-Authors: Qing Li, Huaiqiang GuAbstract:We theoretically investigate the optomechanically induced transparency (OMIT) phenomenon in a N-cavity optomechanical system doped with a pair of Rydberg atoms with the presence of a strong control Field and a weak probe Field applied to the Nth cavity. It is found that 2N − 1 (N < 10) numbers of OMIT windows can be observed in the Output Field when N cavities couple with N mechanical oscillators and the mechanical oscillators coupled with different even- or odd-labelled cavities can lead to diverse effects on OMIT. Furthermore, the ATS effect appears with the increase of the effective optomechanical coupling rate. On the other hand, two additional transparent windows (extra resonances) occur, when two Rydberg atoms are coupled with the cavity Field. With DDI strength increasing, the extra resonances move to the far off-resonant regime but the left one moves slowly than the right one due to the positive detuning effect of DDI. During this process, Fano resonance also emerges in the absorption profile of Output Field.
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the effect of oscillator and dipole dipole interaction on multiple optomechanically induced transparency in cavity optomechanical system
arXiv: Quantum Physics, 2018Co-Authors: Qing Li, Huaiqiang GuAbstract:We theoretically investigate the optomechanically induced transparency (OMIT) phenomenon in a N-cavity optomechanical system doped with a pair of Rydberg atoms with the presence of a strong pump Field and a weak probe Field applied to the Nth cavity. 2N-1(N<10) number OMIT windows can be observed in the Output Field when N cavities coupled with N mechanical oscillators, respectively. But, the mechanical oscillators coupled with different even-odd label cavities lead to different effect on OMIT. On the other hand, two additional transparent windows (extra resonances) are presented, if two Rydberg atoms are coupled with the cavity Field. With the DDI increasing, it is interesting that the extra resonances move to right and the left extra resonance moves slowly than the right one. During this process, Fano resonance is also shown on the Output Field.
C W Gardiner - One of the best experts on this subject based on the ideXlab platform.
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driving a quantum system with the Output Field from another driven quantum system
Physical Review Letters, 1993Co-Authors: C W GardinerAbstract:Quantum Langevin equations and a master equation are derived for a two-atom system in which the first atom is driven by coherent Field, and the fluorescent light used to drive a second atom. We show that the light beams from both atoms are antibunched, and that they are mutually anticorrelated.
A Gutierrez - One of the best experts on this subject based on the ideXlab platform.
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development and long term stability of a comprehensive daily qa program for a modern pencil beam scanning pbs proton therapy delivery system
Journal of Applied Clinical Medical Physics, 2019Co-Authors: Suresh Rana, Jaafar Bennouna, James Jebaseelan E Samuel, A GutierrezAbstract:Purpose The main purpose of this study is to demonstrate the clinical implementation of a comprehensive pencil beam scanning (PBS) daily quality assurance (QA) program involving a number of novel QA devices including the Sphinx/Lynx/parallel-plate (PPC05) ion chamber and HexaCheck/multiple imaging modality isocentricity (MIMI) imaging phantoms. Additionally, the study highlights the importance of testing the connectivity among oncology information system (OIS), beam delivery/imaging systems, and patient position system at a proton center with multi-vendor equipment and software. Methods For dosimetry, a daily QA plan with spot map of four different energies (106, 145, 172, and 221 MeV) is delivered on the delivery system through the OIS. The delivery assesses the dose Output, Field homogeneity, beam coincidence, beam energy, width, distal-fall-off (DFO), and spot characteristics - for example, position, size, and skewness. As a part of mechanical and imaging QA, a treatment plan with the MIMI phantom serving as the patient is transferred from OIS to imaging system. The HexaCheck/MIMI phantoms are used to assess daily laser accuracy, imaging isocenter accuracy, image registration accuracy, and six-dimensional (6D) positional correction accuracy for the kV imaging system and robotic couch. Results The daily QA results presented herein are based on 202 daily sets of measurements over a period of 10 months. Total time to perform daily QA tasks at our center is under 30 min. The relative difference (Δrel ) of daily measurements with respect to baseline was within ± 1% for Field homogeneity, ±0.5 mm for range, width and DFO, ±1 mm for spots positions, ±10% for in-air spot sigma, ±0.5 spot skewness, and ±1 mm for beam coincidence (except 1 case: Δrel = 1.3 mm). The average Δrel in dose Output was -0.2% (range: -1.1% to 1.5%). For 6D IGRT QA, the average absolute difference (Δabs ) was ≤0.6 ± 0.4 mm for translational and ≤0.5° for rotational shifts. Conclusion The use of novel QA devices such as the Sphinx in conjunction with the Lynx, PPC05 ion chamber, HexaCheck/MIMI phantoms, and myQA software was shown to provide a comprehensive and efficient method for performing daily QA of a number of system parameters for a modern proton PBS-dedicated treatment delivery unit.
Suresh Rana - One of the best experts on this subject based on the ideXlab platform.
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development and long term stability of a comprehensive daily qa program for a modern pencil beam scanning pbs proton therapy delivery system
Journal of Applied Clinical Medical Physics, 2019Co-Authors: Suresh Rana, Jaafar Bennouna, James Jebaseelan E Samuel, A GutierrezAbstract:Purpose The main purpose of this study is to demonstrate the clinical implementation of a comprehensive pencil beam scanning (PBS) daily quality assurance (QA) program involving a number of novel QA devices including the Sphinx/Lynx/parallel-plate (PPC05) ion chamber and HexaCheck/multiple imaging modality isocentricity (MIMI) imaging phantoms. Additionally, the study highlights the importance of testing the connectivity among oncology information system (OIS), beam delivery/imaging systems, and patient position system at a proton center with multi-vendor equipment and software. Methods For dosimetry, a daily QA plan with spot map of four different energies (106, 145, 172, and 221 MeV) is delivered on the delivery system through the OIS. The delivery assesses the dose Output, Field homogeneity, beam coincidence, beam energy, width, distal-fall-off (DFO), and spot characteristics - for example, position, size, and skewness. As a part of mechanical and imaging QA, a treatment plan with the MIMI phantom serving as the patient is transferred from OIS to imaging system. The HexaCheck/MIMI phantoms are used to assess daily laser accuracy, imaging isocenter accuracy, image registration accuracy, and six-dimensional (6D) positional correction accuracy for the kV imaging system and robotic couch. Results The daily QA results presented herein are based on 202 daily sets of measurements over a period of 10 months. Total time to perform daily QA tasks at our center is under 30 min. The relative difference (Δrel ) of daily measurements with respect to baseline was within ± 1% for Field homogeneity, ±0.5 mm for range, width and DFO, ±1 mm for spots positions, ±10% for in-air spot sigma, ±0.5 spot skewness, and ±1 mm for beam coincidence (except 1 case: Δrel = 1.3 mm). The average Δrel in dose Output was -0.2% (range: -1.1% to 1.5%). For 6D IGRT QA, the average absolute difference (Δabs ) was ≤0.6 ± 0.4 mm for translational and ≤0.5° for rotational shifts. Conclusion The use of novel QA devices such as the Sphinx in conjunction with the Lynx, PPC05 ion chamber, HexaCheck/MIMI phantoms, and myQA software was shown to provide a comprehensive and efficient method for performing daily QA of a number of system parameters for a modern proton PBS-dedicated treatment delivery unit.
