Among the various scanning techniques, spot and raster scanning are the most frequently adopted. Raster scanning turns off the beam only when each isoenergy slice irradiation is completed. This feature intrinsically s...Among the various scanning techniques, spot and raster scanning are the most frequently adopted. Raster scanning turns off the beam only when each isoenergy slice irradiation is completed. This feature intrinsically solves the leakage dose and frequent beam-switching problems encountered during spot scanning. However, to shorten the delivery time of raster scanning, a sophisticated dose control strategy is required to guarantee dose distribution.In this study, a real-time compensation method with raster scanning for synchrotron systems was designed. It is characterized by a small spot-spacing planning strategy and real-time subtraction of the transient number of particles delivered between two planning-spot positions from the planned number of particles of the subsequent raster point.The efficacy of the compensation method was demonstrated by performing accurate raster scanning simulations with an in-house simulation code and accurate final dose evaluations with a commercial treatment planning system.Given the similar dose evaluation criteria under a practical high scanning speed, compared with the spot scanning method, the total delivery time of the compensated raster scanning method was significantly shortened by 53.3% in the case of irradiating a cubical target and by 28.8% in a pelvic case. Therefore, it can be concluded that real-time compensated raster scanning with a fast scanning configuration can significantly shorten the delivery time compared to that of spot scanning. It is important to reduce the pressure on patients caused by prolonged immobilization and to improve patient throughput capacity at particle therapy centers.展开更多
In this work,an old scanning electron microscope(SEM)is refurbished to enhance its image processing capability.How to digitally sample and process an analog image is also presented.An NI PCI-6259 multiple input/output...In this work,an old scanning electron microscope(SEM)is refurbished to enhance its image processing capability.How to digitally sample and process an analog image is also presented.An NI PCI-6259 multiple input/output data acquisition(DAQ)board is used to acquire signals originally being sent to an analog display,and then convert the signals into a digital image.Two output channels are used for raster scan of the horizontal and verticle axes of the image buffer,while one input channel is used to read the brightness signals at various coordinate points.Synchronous method is used to maximize the DAQ speed.Finally,the digitally buffered images are read out to display and saved in a hard drive.The hardware and software designs of this work are explained in great detail,which can serve as a very good example for fast synchronous DAQ,advanced virtual instrument design and structural driver programming with LabVIEW.展开更多
This paper presents a macroblock-level (MB-level) decoding and deblocking method for supporting the flexible macroblock ordering (FMO) and arbitrary slice ordering (ASO) bit streams in H.264 decoder and its SOC/ASIC i...This paper presents a macroblock-level (MB-level) decoding and deblocking method for supporting the flexible macroblock ordering (FMO) and arbitrary slice ordering (ASO) bit streams in H.264 decoder and its SOC/ASIC implementation. By searching the slice containing the current macroblock in the bit stream and switching slices correctly, MBs can be decoded in the raster scan order, while the decoding process can immediately begin as long as the slice containing the current MB is available. This architectural modification enables the MB-level decoding and deblocking 3-stage pipeline, and saves about 20% of SDRAM bandwidth. Implementation results showed that the design achieves real-time decoding of 1080HD (1920×1088@30 fps) at a system clock of 166 MHz.展开更多
基金supported by the National Key Research and Development Program of China(No.2016YFC0105408)。
文摘Among the various scanning techniques, spot and raster scanning are the most frequently adopted. Raster scanning turns off the beam only when each isoenergy slice irradiation is completed. This feature intrinsically solves the leakage dose and frequent beam-switching problems encountered during spot scanning. However, to shorten the delivery time of raster scanning, a sophisticated dose control strategy is required to guarantee dose distribution.In this study, a real-time compensation method with raster scanning for synchrotron systems was designed. It is characterized by a small spot-spacing planning strategy and real-time subtraction of the transient number of particles delivered between two planning-spot positions from the planned number of particles of the subsequent raster point.The efficacy of the compensation method was demonstrated by performing accurate raster scanning simulations with an in-house simulation code and accurate final dose evaluations with a commercial treatment planning system.Given the similar dose evaluation criteria under a practical high scanning speed, compared with the spot scanning method, the total delivery time of the compensated raster scanning method was significantly shortened by 53.3% in the case of irradiating a cubical target and by 28.8% in a pelvic case. Therefore, it can be concluded that real-time compensated raster scanning with a fast scanning configuration can significantly shorten the delivery time compared to that of spot scanning. It is important to reduce the pressure on patients caused by prolonged immobilization and to improve patient throughput capacity at particle therapy centers.
文摘In this work,an old scanning electron microscope(SEM)is refurbished to enhance its image processing capability.How to digitally sample and process an analog image is also presented.An NI PCI-6259 multiple input/output data acquisition(DAQ)board is used to acquire signals originally being sent to an analog display,and then convert the signals into a digital image.Two output channels are used for raster scan of the horizontal and verticle axes of the image buffer,while one input channel is used to read the brightness signals at various coordinate points.Synchronous method is used to maximize the DAQ speed.Finally,the digitally buffered images are read out to display and saved in a hard drive.The hardware and software designs of this work are explained in great detail,which can serve as a very good example for fast synchronous DAQ,advanced virtual instrument design and structural driver programming with LabVIEW.
基金Project (No. 2002AA1Z1190) supported by the National Hi-Tech Research and Development Program (863) of China
文摘This paper presents a macroblock-level (MB-level) decoding and deblocking method for supporting the flexible macroblock ordering (FMO) and arbitrary slice ordering (ASO) bit streams in H.264 decoder and its SOC/ASIC implementation. By searching the slice containing the current macroblock in the bit stream and switching slices correctly, MBs can be decoded in the raster scan order, while the decoding process can immediately begin as long as the slice containing the current MB is available. This architectural modification enables the MB-level decoding and deblocking 3-stage pipeline, and saves about 20% of SDRAM bandwidth. Implementation results showed that the design achieves real-time decoding of 1080HD (1920×1088@30 fps) at a system clock of 166 MHz.
