Automatic segmentation of the liver and hepatic lesions from abdominal 3D comput-ed tomography(CT)images is fundamental tasks in computer-assisted liver surgery planning.However,due to complex backgrounds,ambiguous bo...Automatic segmentation of the liver and hepatic lesions from abdominal 3D comput-ed tomography(CT)images is fundamental tasks in computer-assisted liver surgery planning.However,due to complex backgrounds,ambiguous boundaries,heterogeneous appearances and highly varied shapes of the liver,accurate liver segmentation and tumor detection are stil-1 challenging problems.To address these difficulties,we propose an automatic segmentation framework based on 3D U-net with dense connections and globally optimized refinement.First-ly,a deep U-net architecture with dense connections is trained to learn the probability map of the liver.Then the probability map goes into the following refinement step as the initial surface and prior shape.The segmentation of liver tumor is based on the similar network architecture with the help of segmentation results of liver.In order to reduce the infuence of the surrounding tissues with the similar intensity and texture behavior with the tumor region,during the training procedure,I x liverlabel is the input of the network for the segmentation of liver tumor.By do-ing this,the accuracy of segmentation can be improved.The proposed method is fully automatic without any user interaction.Both qualitative and quantitative results reveal that the pro-posed approach is efficient and accurate for liver volume estimation in clinical application.The high correlation between the automatic and manual references shows that the proposed method can be good enough to replace the time-consuming and non-reproducible manual segmentation method.展开更多
A 527 nm pump laser generating 1.7 mJ energy with peak power of more than 0.12 GW is demonstrated.The theoretical simulation result shows that it has 10^(6) gain in the picosecond-pump optical parametric chirped pulse...A 527 nm pump laser generating 1.7 mJ energy with peak power of more than 0.12 GW is demonstrated.The theoretical simulation result shows that it has 10^(6) gain in the picosecond-pump optical parametric chirped pulse amplification when the pump laser peak power is 0.1 GW and the intensity is more than 5 GW/cm^(2),and that it can limit the parametric fluorescence in the picosecond time scale of pump duration.The pump laser system adopts a master-oscillator power amplifier,which integrates a more than 30 pJ fiber-based oscillator with a 150μJ regenerative amplifier and a relay-imaged four-pass diode-pump Nd glass amplifier to generate a 1 Hz top hat spatial beam and about 14 ps temporal Guassian pulse with<2%pulse-to-pulse energy stability.The output energy of the power amplifier is limited to 4 mJ for B-integral concern,and the frequency doubling efficiency can reach 65%with input intensity 10 GW/cm^(2).展开更多
We report the first application of a single-shot cross-correlator for pulse duration and pulse contrast diagnostics in Nd:glass petawatt laser.The information of pulse duration,measured in the single-shot,guides the f...We report the first application of a single-shot cross-correlator for pulse duration and pulse contrast diagnostics in Nd:glass petawatt laser.The information of pulse duration,measured in the single-shot,guides the fine adjustment of the pulse compressor in real time.By integrating several shots of measurements at different time delays together,the petawatt pulse profile is obtained within an overall temporal window of~100 ps,indicating a contrast of~10^(4).The measurements suggest that the additional contrast improvement is necessary for the Nd:glass petawatt laser system,which should be different from conventional Ti:sapphire lasers and is also discussed.展开更多
基金Supported by the National Natural Science Foundation of China(12090020,12090025)Zhejiang Provin-cial Natural Science Foundation of China(LSD19H180005)。
文摘Automatic segmentation of the liver and hepatic lesions from abdominal 3D comput-ed tomography(CT)images is fundamental tasks in computer-assisted liver surgery planning.However,due to complex backgrounds,ambiguous boundaries,heterogeneous appearances and highly varied shapes of the liver,accurate liver segmentation and tumor detection are stil-1 challenging problems.To address these difficulties,we propose an automatic segmentation framework based on 3D U-net with dense connections and globally optimized refinement.First-ly,a deep U-net architecture with dense connections is trained to learn the probability map of the liver.Then the probability map goes into the following refinement step as the initial surface and prior shape.The segmentation of liver tumor is based on the similar network architecture with the help of segmentation results of liver.In order to reduce the infuence of the surrounding tissues with the similar intensity and texture behavior with the tumor region,during the training procedure,I x liverlabel is the input of the network for the segmentation of liver tumor.By do-ing this,the accuracy of segmentation can be improved.The proposed method is fully automatic without any user interaction.Both qualitative and quantitative results reveal that the pro-posed approach is efficient and accurate for liver volume estimation in clinical application.The high correlation between the automatic and manual references shows that the proposed method can be good enough to replace the time-consuming and non-reproducible manual segmentation method.
文摘A 527 nm pump laser generating 1.7 mJ energy with peak power of more than 0.12 GW is demonstrated.The theoretical simulation result shows that it has 10^(6) gain in the picosecond-pump optical parametric chirped pulse amplification when the pump laser peak power is 0.1 GW and the intensity is more than 5 GW/cm^(2),and that it can limit the parametric fluorescence in the picosecond time scale of pump duration.The pump laser system adopts a master-oscillator power amplifier,which integrates a more than 30 pJ fiber-based oscillator with a 150μJ regenerative amplifier and a relay-imaged four-pass diode-pump Nd glass amplifier to generate a 1 Hz top hat spatial beam and about 14 ps temporal Guassian pulse with<2%pulse-to-pulse energy stability.The output energy of the power amplifier is limited to 4 mJ for B-integral concern,and the frequency doubling efficiency can reach 65%with input intensity 10 GW/cm^(2).
基金Project(SKL-SPM-202003) supported by the State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals,ChinaProject(1920001004360) supported by the Foshan Science and Technology Innovation Program,China。
基金Supported by the National Natural Science Foundation of China under Grant Nos 61008017 and 11121504.
文摘We report the first application of a single-shot cross-correlator for pulse duration and pulse contrast diagnostics in Nd:glass petawatt laser.The information of pulse duration,measured in the single-shot,guides the fine adjustment of the pulse compressor in real time.By integrating several shots of measurements at different time delays together,the petawatt pulse profile is obtained within an overall temporal window of~100 ps,indicating a contrast of~10^(4).The measurements suggest that the additional contrast improvement is necessary for the Nd:glass petawatt laser system,which should be different from conventional Ti:sapphire lasers and is also discussed.
