The Experts below are selected from a list of 31230 Experts worldwide ranked by ideXlab platform
S Yu - One of the best experts on this subject based on the ideXlab platform.
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su g iep1 08 mr geometric distortion dependency on imaging sequence acquisition orientation and Receiver Bandwidth of a dedicated 1 5t mr simulator
Medical Physics, 2016Co-Authors: J Yuan, O Wong, S YuAbstract:Purpose: To investigate the 3D geometric distortion of four potential MR sequences for radiotheraptic applications, and its dependency on sequence-type, acquisition-orientation and Receiver-Bandwidth from a dedicated 1.5T 700mm-wide bore MR-simulator (Magnetom-Aera, Sienmens Healthcare, Erlangen, Germany), using a large customized geometric accuracy phantom. Methods: This work studied 3D gradient-echo (VIBE) and spin-echo (SPACE) sequences for anatomical imaging; a specific ultra-short-TE sequence (PETRA) potentially for bone imaging and MR-based dosimetry; and a motion-insensitive sequence (BLADE) for dynamic applications like 4D-MRI. Integrated geometric-correction was employed, three orthogonal acquisition-orientations and up to three Receiver-Bandwidths were used, yielding 27 acquisitions for testing (Table 1a).A customized geometric accuracy phantom (polyurethane, MR/CT invisible, W×L×H:55×55×32.5cm3) was constructed and filled with 3892 spherical markers (6mm diameter, MR/CT visible) arranged on a 25mm-interval 3D isotropic-grid (Fig.1). The marker positions in MR images were quantitatively calculated and compared against those in the CT-reference using customized MatLab scripts. Results: The average distortion within various diameter-of-spherical-volumes (DSVs) and the usable DSVs under various distortion limits were measured (Tables 1b-c). It was observed that distortions fluctuated when sequence-type, acquisition-orientation or Receiver-Bandwidth changed (e.g. within 300mm-DSV, the lowest/highest average distortions of VIBE were 0.40mm/0.59mm, a 47.5% difference). According to AAPM-TG66 (<1mm distortion, left-most column of Table 1c), PETRA (Largest-DSV:253.9mm) has the potential on brain treatment, while BLADE (Largest-DSV:207.2mm) may need improvement for thoracic/abdominal applications. The results of VIBE (Largest-DSVs:294.3mm, the best among tested acquisitions) and SPACE (Largest-DSVs:267.7mm) suggests their potentials on head and neck applications. These Largest-DSVs were attained on different acquisition-orientations and Receiver-Bandwidths. Conclusion: Geometric distortion was shown to be dependent on sequence-type, acquisition-orientation and Receiver-Bandwidth. In the experiment, no configuration in any one of these factors could consistently reduce distortion while the others were varying. The distortion analysis result is a valuable guideline for sequence selection and optimization for MR-aided radiotherapy applications.
M A Armand - One of the best experts on this subject based on the ideXlab platform.
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on single carrier communication in additive white symmetric alpha stable noise
IEEE Transactions on Communications, 2014Co-Authors: Ahmed Mahmood, Mandar Chitre, M A ArmandAbstract:In this paper we analyze design aspects of a single-carrier digital communications Receiver in the presence of impulsive noise. We use the additive white symmetric $\alpha$ -stable noise $(\hbox{AWS}\alpha\hbox{SN})$ to model the channel noise. By introducing passband sampling, efficient constellations and suitable baseband detectors, we show that the uncoded error performance of the conventional (linear) Receiver can be enhanced given the real and imaginary components of the transmitted symbol are decoded separately. The performance may be improved further by sacrificing the linearity of the system. Various non-linear estimation and joint-detection schemes are discussed and their error performance analyzed. It is shown that if the Receiver Bandwidth is large enough, impulsive noise may be effectively countered in a single-carrier communications system.
David D Wentzloff - One of the best experts on this subject based on the ideXlab platform.
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optimal Receiver Bandwidth for energy detection ppm uwb systems
Wireless Communications and Networking Conference, 2011Co-Authors: Jose Almodovarfaria, Janise Mcnair, David D WentzloffAbstract:Non-coherent UWB Receivers are often implemented using energy detection architectures which are very sensitive to noise in the channel and interference. Therefore, the Receiver Bandwidth plays an important role since the total noise and interference energy is proportional to this Bandwidth. This work provides analytical expressions to find the optimal Receiver Bandwidth and quantifying the effect on the bit-error-rate (BER) due to channel noise and adjacent-channel interference (ACI). A reduction in Receiver Bandwidth beyond the optimal point is shown to have minimal impact on BER performance when ACI is negligible.
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WCNC - Optimal Receiver Bandwidth for energy-detection PPM UWB systems
2011 IEEE Wireless Communications and Networking Conference, 2011Co-Authors: Jose Almodovar-faria, Janise Mcnair, David D WentzloffAbstract:Non-coherent UWB Receivers are often implemented using energy detection architectures which are very sensitive to noise in the channel and interference. Therefore, the Receiver Bandwidth plays an important role since the total noise and interference energy is proportional to this Bandwidth. This work provides analytical expressions to find the optimal Receiver Bandwidth and quantifying the effect on the bit-error-rate (BER) due to channel noise and adjacent-channel interference (ACI). A reduction in Receiver Bandwidth beyond the optimal point is shown to have minimal impact on BER performance when ACI is negligible.
J C Cartledge - One of the best experts on this subject based on the ideXlab platform.
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400 gbit s single carrier and 1 tbit s three carrier superchannel signals using dual polarization 16 qam with look up table correction and optical pulse shaping
Optics Express, 2014Co-Authors: Jian Hong Ke, J C CartledgeAbstract:A 448 Gbit/s single-carrier dual-polarization 16-ary quadrature-amplitude-modulation (DP 16-QAM) signal and a 1.206 Tbit/s three-carrier DP 16-QAM signal are demonstrated using look-up table (LUT) correction and optical pulse shaping. The LUT correction is used to mitigate the effects of transmitter-based pattern-dependent distortion due to the high symbol rates. A programmable optical filter is employed to narrow the modulated signal spectrum and thereby enhance the spectral efficiency and reduce the requirements on the Receiver Bandwidth and analog-to-digital converter sampling rate. By combining these techniques, the back-to-back required optical signal-to-noise ratios are 26.6 dB and 27.2 dB for BER = 10−3, and transmission over 1200 and 1500 km of standard single-mode fiber with EDFA amplification was achieved for the 448 Gbit/s signal (12% forward error correction (FEC) overhead) and 1.206 Tbit/s signal (20% FEC overhead), respectively.
J Yuan - One of the best experts on this subject based on the ideXlab platform.
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su g iep1 08 mr geometric distortion dependency on imaging sequence acquisition orientation and Receiver Bandwidth of a dedicated 1 5t mr simulator
Medical Physics, 2016Co-Authors: J Yuan, O Wong, S YuAbstract:Purpose: To investigate the 3D geometric distortion of four potential MR sequences for radiotheraptic applications, and its dependency on sequence-type, acquisition-orientation and Receiver-Bandwidth from a dedicated 1.5T 700mm-wide bore MR-simulator (Magnetom-Aera, Sienmens Healthcare, Erlangen, Germany), using a large customized geometric accuracy phantom. Methods: This work studied 3D gradient-echo (VIBE) and spin-echo (SPACE) sequences for anatomical imaging; a specific ultra-short-TE sequence (PETRA) potentially for bone imaging and MR-based dosimetry; and a motion-insensitive sequence (BLADE) for dynamic applications like 4D-MRI. Integrated geometric-correction was employed, three orthogonal acquisition-orientations and up to three Receiver-Bandwidths were used, yielding 27 acquisitions for testing (Table 1a).A customized geometric accuracy phantom (polyurethane, MR/CT invisible, W×L×H:55×55×32.5cm3) was constructed and filled with 3892 spherical markers (6mm diameter, MR/CT visible) arranged on a 25mm-interval 3D isotropic-grid (Fig.1). The marker positions in MR images were quantitatively calculated and compared against those in the CT-reference using customized MatLab scripts. Results: The average distortion within various diameter-of-spherical-volumes (DSVs) and the usable DSVs under various distortion limits were measured (Tables 1b-c). It was observed that distortions fluctuated when sequence-type, acquisition-orientation or Receiver-Bandwidth changed (e.g. within 300mm-DSV, the lowest/highest average distortions of VIBE were 0.40mm/0.59mm, a 47.5% difference). According to AAPM-TG66 (<1mm distortion, left-most column of Table 1c), PETRA (Largest-DSV:253.9mm) has the potential on brain treatment, while BLADE (Largest-DSV:207.2mm) may need improvement for thoracic/abdominal applications. The results of VIBE (Largest-DSVs:294.3mm, the best among tested acquisitions) and SPACE (Largest-DSVs:267.7mm) suggests their potentials on head and neck applications. These Largest-DSVs were attained on different acquisition-orientations and Receiver-Bandwidths. Conclusion: Geometric distortion was shown to be dependent on sequence-type, acquisition-orientation and Receiver-Bandwidth. In the experiment, no configuration in any one of these factors could consistently reduce distortion while the others were varying. The distortion analysis result is a valuable guideline for sequence selection and optimization for MR-aided radiotherapy applications.
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SU-G-IeP1-08: MR Geometric Distortion Dependency On Imaging Sequence, Acquisition Orientation and Receiver Bandwidth of a Dedicated 1.5T MR-Simulator
Medical Physics, 2016Co-Authors: M Law, J Yuan, O WongAbstract:Purpose: To investigate the 3D geometric distortion of four potential MR sequences for radiotheraptic applications, and its dependency on sequence-type, acquisition-orientation and Receiver-Bandwidth from a dedicated 1.5T 700mm-wide bore MR-simulator (Magnetom-Aera, Sienmens Healthcare, Erlangen, Germany), using a large customized geometric accuracy phantom. Methods: This work studied 3D gradient-echo (VIBE) and spin-echo (SPACE) sequences for anatomical imaging; a specific ultra-short-TE sequence (PETRA) potentially for bone imaging and MR-based dosimetry; and a motion-insensitive sequence (BLADE) for dynamic applications like 4D-MRI. Integrated geometric-correction was employed, three orthogonal acquisition-orientations and up to three Receiver-Bandwidths were used, yielding 27 acquisitions for testing (Table 1a).A customized geometric accuracy phantom (polyurethane, MR/CT invisible, W×L×H:55×55×32.5cm3) was constructed and filled with 3892 spherical markers (6mm diameter, MR/CT visible) arranged on a 25mm-interval 3D isotropic-grid (Fig.1). The marker positions in MR images were quantitatively calculated and compared against those in the CT-reference using customized MatLab scripts. Results: The average distortion within various diameter-of-spherical-volumes (DSVs) and the usable DSVs under various distortion limits were measured (Tables 1b-c). It was observed that distortions fluctuated when sequence-type, acquisition-orientation or Receiver-Bandwidth changed (e.g. within 300mm-DSV, the lowest/highest average distortions of VIBE were 0.40mm/0.59mm, a 47.5% difference). According to AAPM-TG66 (
