Bulk Acoustic Wave(BAW)filters find applications in radio frequency(RF)communication systems for Wi-Fi,3G,4G,and 5G networks.In the beyond-5G(potential 6G)era,high-frequency bands(>8 GHz)are expected to require res...Bulk Acoustic Wave(BAW)filters find applications in radio frequency(RF)communication systems for Wi-Fi,3G,4G,and 5G networks.In the beyond-5G(potential 6G)era,high-frequency bands(>8 GHz)are expected to require resonators with high-quality factor(Q)and electromechanical coupling(k_(t)^(2))to form filters with low insertion loss and high selectivity.However,both the Q and k_(t)^(2)of resonator devices formed in traditional uniform polarization piezoelectric films of aluminum nitride(AlN)and aluminum scandium nitride(AlScN)decrease when scaled beyond 8 GHz.In this work,we utilized 4-layer AlScN periodically poled piezoelectric films(P3F)to construct high-frequency(~17–18 GHz)resonators and filters.The resonator performance is studied over a range of device geometries,with the best resonator achieving a k_(t)^(2)of 11.8%and a Qp of 236.6 at the parallel resonance frequency(f_(p))of 17.9 GHz.These resulting figures-of-merit are(FoM_(1)=k_(t)^(2)Qp and FoM_(2)=f_(p)FoM_(1)×10^(-9))27.9 and 500,respectively.These and the k_(t)^(2)are significantly higher than previously reported AlN/AlScN-based resonators operating at similar frequencies.Fabricated 3-element and 6-element filters formed from these resonators demonstrated low insertion losses(IL)of 1.86 and 3.25 dB,and−3 dB bandwidths(BW)of 680 MHz(fractional BW of 3.9%)and 590 MHz(fractional BW of 3.3%)at a~17.4 GHz center frequency.The 3-element and 6-element filters achieved excellent linearity with in-band input third-order intercept point(IIP3)values of+36 and+40 dBm,respectively,which are significantly higher than previously reported acoustic filters operating at similar frequencies.展开更多
Objective:A procedure has been proposed for patient-specific QA that,instead of comparing a measurement to the planned dose,compares the dose calculated by an independent system to the dose calculated by the planning ...Objective:A procedure has been proposed for patient-specific QA that,instead of comparing a measurement to the planned dose,compares the dose calculated by an independent system to the dose calculated by the planning system.It is still prudent,however,to check the accuracy of the beam delivery.For this purpose,the DICOM records from the first treatment fraction can be compared to the planned treatment using an in-house developed planning system.Methods:Totally 1,398 patient portals were subjected to the new QA procedure.The dose distribution for each portal was first recalculated on a water phantom by two treatment planning systems and the dose distributions were compared.When agreement was observed,the patient was allowed to start treatment without a measure-ment.The record from the first day was imported into an in-house planning system which was used to evaluate the delivery for errors and calculate the delivered dose distribution and compare it to the planned dose distribution.Results:A total of 266 portals passed a strict comparison between the clinical and QA dose calculations and directly used for treatment without measurements.For those portals,the comparison of the delivery records to the plan showed that 99%of spot positions deviated less than 0.2 mm and 99.7%of spot metersets deviated by less than 0.3%.On the other hand,64 portals showed spot size deviations greater than the tolerance of15%with some as large as25%.For 32 portals in which the record was used to calculate the delivered dose distribution,the Gamma passing rates between the planned and delivered distributions were always above 95%using a 2%dose difference and 2 mm distance-to-agreement criteria.Conclusions:The new QA process has been implemented slowly with strict constraints.The amount of beam time required has been reduced while maintaining safety.展开更多
文摘Bulk Acoustic Wave(BAW)filters find applications in radio frequency(RF)communication systems for Wi-Fi,3G,4G,and 5G networks.In the beyond-5G(potential 6G)era,high-frequency bands(>8 GHz)are expected to require resonators with high-quality factor(Q)and electromechanical coupling(k_(t)^(2))to form filters with low insertion loss and high selectivity.However,both the Q and k_(t)^(2)of resonator devices formed in traditional uniform polarization piezoelectric films of aluminum nitride(AlN)and aluminum scandium nitride(AlScN)decrease when scaled beyond 8 GHz.In this work,we utilized 4-layer AlScN periodically poled piezoelectric films(P3F)to construct high-frequency(~17–18 GHz)resonators and filters.The resonator performance is studied over a range of device geometries,with the best resonator achieving a k_(t)^(2)of 11.8%and a Qp of 236.6 at the parallel resonance frequency(f_(p))of 17.9 GHz.These resulting figures-of-merit are(FoM_(1)=k_(t)^(2)Qp and FoM_(2)=f_(p)FoM_(1)×10^(-9))27.9 and 500,respectively.These and the k_(t)^(2)are significantly higher than previously reported AlN/AlScN-based resonators operating at similar frequencies.Fabricated 3-element and 6-element filters formed from these resonators demonstrated low insertion losses(IL)of 1.86 and 3.25 dB,and−3 dB bandwidths(BW)of 680 MHz(fractional BW of 3.9%)and 590 MHz(fractional BW of 3.3%)at a~17.4 GHz center frequency.The 3-element and 6-element filters achieved excellent linearity with in-band input third-order intercept point(IIP3)values of+36 and+40 dBm,respectively,which are significantly higher than previously reported acoustic filters operating at similar frequencies.
文摘Objective:A procedure has been proposed for patient-specific QA that,instead of comparing a measurement to the planned dose,compares the dose calculated by an independent system to the dose calculated by the planning system.It is still prudent,however,to check the accuracy of the beam delivery.For this purpose,the DICOM records from the first treatment fraction can be compared to the planned treatment using an in-house developed planning system.Methods:Totally 1,398 patient portals were subjected to the new QA procedure.The dose distribution for each portal was first recalculated on a water phantom by two treatment planning systems and the dose distributions were compared.When agreement was observed,the patient was allowed to start treatment without a measure-ment.The record from the first day was imported into an in-house planning system which was used to evaluate the delivery for errors and calculate the delivered dose distribution and compare it to the planned dose distribution.Results:A total of 266 portals passed a strict comparison between the clinical and QA dose calculations and directly used for treatment without measurements.For those portals,the comparison of the delivery records to the plan showed that 99%of spot positions deviated less than 0.2 mm and 99.7%of spot metersets deviated by less than 0.3%.On the other hand,64 portals showed spot size deviations greater than the tolerance of15%with some as large as25%.For 32 portals in which the record was used to calculate the delivered dose distribution,the Gamma passing rates between the planned and delivered distributions were always above 95%using a 2%dose difference and 2 mm distance-to-agreement criteria.Conclusions:The new QA process has been implemented slowly with strict constraints.The amount of beam time required has been reduced while maintaining safety.
