A new estimation method of maximum intensity, such as I spta in CW and I sppa in PW, in high intensity focused ultrasound (HIFU) field for surgery was developed based on the measurements of acousic power and radical d...A new estimation method of maximum intensity, such as I spta in CW and I sppa in PW, in high intensity focused ultrasound (HIFU) field for surgery was developed based on the measurements of acousic power and radical distribution of the relative acoustic pressure in the focal plane of the field. The acoustic power is measured by the radiation force balance or by the calorimetry. Using a miniature hydrophone to scan along several radial directions with the same angle intervals through the acoustic axis in the focal plane, several radial relative pressure distribution curves can be measured and thus the special cross section area related to the maximum intensity and be calculated. The quotient of the measured acousitc power to the special cross section area is the maximum acoustic intensity in the field. finally as an example, the acoustic field distribution of a CW system was measured and the maximum acoustic intensity estimated was given.展开更多
Bursts of GHz repetition rate pulses involve more ablation mechanisms than single femtosecond pulses.Efficient ablation by GHz laser pulses is a multi-step process,consisting of a first thermal incubation phase,follow...Bursts of GHz repetition rate pulses involve more ablation mechanisms than single femtosecond pulses.Efficient ablation by GHz laser pulses is a multi-step process,consisting of a first thermal incubation phase,followed by a highly efficient ablation phase.GHz ablation therefore combines thermal and non-thermal ablation mechanisms.With an optimal choice of the burst duration,the ablation efficiency can be highly enhanced.Long bursts,comprising tens of pulses to hundreds of pulses,are needed to take full advantage of the increase in ablation efficiency.展开更多
基金National Natural Science Foundation ofChina (No.3 9970 2 0 9)
文摘A new estimation method of maximum intensity, such as I spta in CW and I sppa in PW, in high intensity focused ultrasound (HIFU) field for surgery was developed based on the measurements of acousic power and radical distribution of the relative acoustic pressure in the focal plane of the field. The acoustic power is measured by the radiation force balance or by the calorimetry. Using a miniature hydrophone to scan along several radial directions with the same angle intervals through the acoustic axis in the focal plane, several radial relative pressure distribution curves can be measured and thus the special cross section area related to the maximum intensity and be calculated. The quotient of the measured acousitc power to the special cross section area is the maximum acoustic intensity in the field. finally as an example, the acoustic field distribution of a CW system was measured and the maximum acoustic intensity estimated was given.
文摘Bursts of GHz repetition rate pulses involve more ablation mechanisms than single femtosecond pulses.Efficient ablation by GHz laser pulses is a multi-step process,consisting of a first thermal incubation phase,followed by a highly efficient ablation phase.GHz ablation therefore combines thermal and non-thermal ablation mechanisms.With an optimal choice of the burst duration,the ablation efficiency can be highly enhanced.Long bursts,comprising tens of pulses to hundreds of pulses,are needed to take full advantage of the increase in ablation efficiency.
