A direct incident fluence measurement method based on amorphous silicon electronic portal imaging device(a-Si EPID) has been developed for pretreatment verification of intensity-modulated radiation therapy(IMRT).The E...A direct incident fluence measurement method based on amorphous silicon electronic portal imaging device(a-Si EPID) has been developed for pretreatment verification of intensity-modulated radiation therapy(IMRT).The EPID-based incident fluence conversion method deconvolves EPID images to the primary response distribution based on measured lateral scatter kernels in the EPID detector using Conjugate Gradient algorithm.The primary response is converted to the incident fluence based on measured fluence conversion matrix which corrects for off-axis position dependence of the a-Si EPID response and the "horn" beam profile caused by flatting filter. To verify feasibility and accuracy of this method, square fields of various sizes and two IMRT plans were delivered. The dose distributions computed based on EPID-derived incident fluence were compared with the measurement data. For all square field sizes except the smallest field(2 cm), the mean dose differences in cross-line dose profiles were within 1% excluding the penumbra region, and gamma passing percentages with a 2%/2 mm criterion were about 99%. For two IMRT plans, the least gamma passing percentage for all eight IMRT fields was 98.14% with 2%/3 mm criteria. It can be concluded that our direct EPID-based incident fluence conversion method is accurate and capable of being applied to pretreatment dose verification in clinical routines.展开更多
A compact multi-wavelength hybrid-integrated directly-modulated distributed-feedback laser(DML)transmitter optical sub-assembly(TOSA)has been achieved in our laboratory.The 8-channel distributed feedback(DFB)lasers ar...A compact multi-wavelength hybrid-integrated directly-modulated distributed-feedback laser(DML)transmitter optical sub-assembly(TOSA)has been achieved in our laboratory.The 8-channel distributed feedback(DFB)lasers are monolithically integrated based on the reconstruction-equivalent-chirp(REC)technology.With the high-density and high-speed packaging technique,the laser array and a multi-mode interference(MMI)multiplexer are assembled in the TOSA.The channel spacing of the TOSA is 200 GHz between adjacent lasers.It meets the 8 9 12.5 Gb/s operation demand and gives rather low channel crosstalk of less than-25 dB.This compact TOSA is of effective cost and shows good stability for mass production,which is expected to improve the performance of devices in access networks,data centers and supercomputing.展开更多
基金Supported by National Natural Science Foundation of China(No.11305203)Natural Science Foundation of Anhui Province(No.1508085QH180)
文摘A direct incident fluence measurement method based on amorphous silicon electronic portal imaging device(a-Si EPID) has been developed for pretreatment verification of intensity-modulated radiation therapy(IMRT).The EPID-based incident fluence conversion method deconvolves EPID images to the primary response distribution based on measured lateral scatter kernels in the EPID detector using Conjugate Gradient algorithm.The primary response is converted to the incident fluence based on measured fluence conversion matrix which corrects for off-axis position dependence of the a-Si EPID response and the "horn" beam profile caused by flatting filter. To verify feasibility and accuracy of this method, square fields of various sizes and two IMRT plans were delivered. The dose distributions computed based on EPID-derived incident fluence were compared with the measurement data. For all square field sizes except the smallest field(2 cm), the mean dose differences in cross-line dose profiles were within 1% excluding the penumbra region, and gamma passing percentages with a 2%/2 mm criterion were about 99%. For two IMRT plans, the least gamma passing percentage for all eight IMRT fields was 98.14% with 2%/3 mm criteria. It can be concluded that our direct EPID-based incident fluence conversion method is accurate and capable of being applied to pretreatment dose verification in clinical routines.
基金supported by the National High-Tech Research&Development Program of China(2011AA010303,2013AA014201,and 2011AA010305)the National Natural Sci-ence Foundation of China(61177080)
文摘A compact multi-wavelength hybrid-integrated directly-modulated distributed-feedback laser(DML)transmitter optical sub-assembly(TOSA)has been achieved in our laboratory.The 8-channel distributed feedback(DFB)lasers are monolithically integrated based on the reconstruction-equivalent-chirp(REC)technology.With the high-density and high-speed packaging technique,the laser array and a multi-mode interference(MMI)multiplexer are assembled in the TOSA.The channel spacing of the TOSA is 200 GHz between adjacent lasers.It meets the 8 9 12.5 Gb/s operation demand and gives rather low channel crosstalk of less than-25 dB.This compact TOSA is of effective cost and shows good stability for mass production,which is expected to improve the performance of devices in access networks,data centers and supercomputing.
