Recently, the phase compensation technique has allowed the ultrasound to propagate through the skull and focus into the brain. However, the temperature evolution during treatment is hard to control to achieve effectiv...Recently, the phase compensation technique has allowed the ultrasound to propagate through the skull and focus into the brain. However, the temperature evolution during treatment is hard to control to achieve effective treatment and avoid over-high temperature. Proposed in this paper is a method to modulate the temperature distribution in the focal region. It superimposes two signals which focus on two preset different targets with a certain distance. Then the temperature distribution is modulated by changing triggering time delay and amplitudes of the two signals. The simulation model is established based on an 82-element transducer and computed tomography （CT） data of a volunteer＇s head. A finite- difference time-domain （FDTD） method is used to calculate the temperature distributions. The results show that when the distances between the two targets respectively are 7.5-12.5 mm on the acoustic axis and 2.0-3.0 mm in the direction perpendicular to the acoustic axis, a focal region with a uniform temperature distribution （64-65 ℃） can be created. Moreover, the volume of the focal region formed by one irradiation can be adjusted （26.8-266.7 mm3） along with the uniform temperature distribution. This method may ensure the safety and efficacy of HIFU brain tumor therapy.展开更多
After interface layer was simulated by the magnetic nano-particles in the egg white phantom, high intensity focused ultrasound （HIFU） at the same dosage was introduced to radiate the phantom in different depths to b...After interface layer was simulated by the magnetic nano-particles in the egg white phantom, high intensity focused ultrasound （HIFU） at the same dosage was introduced to radiate the phantom in different depths to blow the acoustic interface layer to mimic ＂point＂ exposure. The results showed that the volumes of biological focal region （BFR） were enlarged when the acoustic focal region （AFR） is close with interface layer. This meant that the magnetic nano-particles enhanced the therapeutic efficiency of HIFU. When the distance of the AFR from the interface layer was 10 mm, the size and shape of the BFR were similar with those of the control group, but a larger lesion at the interface, which was harmful for treatment, was observed. When the distance of the AFR to the interface layer increased to 30 mm, the size and shape of the BFR were also similar to those of the control group. When the thickness of the interface layer diminished, the utility of enhancement decreased. Continuous increase of the safe area for treatment and decrease of the utility of enhancement were observed along with the abatement of the thickness of the interface layer展开更多
Over the past 25 years, the average life expectancy for men has increased by 4 years, and the age of prostate cancer detection has decreased an average of 10 years with diagnosis increasingly made at early-stage disea...Over the past 25 years, the average life expectancy for men has increased by 4 years, and the age of prostate cancer detection has decreased an average of 10 years with diagnosis increasingly made at early-stage disease where curative therapy is possible. These changing trends in the age and extent of malignancy at diagnosis have revealed limitations in conventional curative therapies for prostate cancer, including a significant risk of aggressive cancer recurrence, and the risk of long-term genitourinary morbidity and its detrimental impact on patient quality of life (QOL). Greater awareness of the shortcomings in radical prostatectomy, external radiotherapy and brachytherapy have prompted the search for alternative curative therapies that offer comparable rates of cancer control and less treatment-related morbidity to better preserve QOL. High intensity focused ultrasound (HIFU) possesses characteristics that make it an attractive curative therapy option. HIFU is a non-invasive approach that uses precisely-delivered ultrasound energy to achieve tumor cell necrosis without radiation or surgical excision. In current urological oncology, HIFU is used clinically in the treatment of prostate cancer, and is under experimental investigation for therapeutic use in renal and breast malignancies. Clinical research on HIFU therapy for localized prostate cancer began in the 1990s, and there have now been approximately 30,000 prostate cancer patients treated with HIFU, predominantly with the Ablatherm (EDAP TMS, Lyon, France) device. Transurethral resection of the prostate (TURP) has been combined with HIFU since 2000 to reduce prostate size, facilitate tissue destruction, and to minimize side effects. Advances in imaging technologies are expected to further improve the already superior efficacy and morbidity outcomes, and ongoing investigation of HIFU as a focal therapy and in salvage and palliative indications are serving to expand the role of HIFU as a highly versatile non-invasive therapy for prostate cancer.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.81272495)the Natural Science Foundation of Tianjin,China(Grant No.16JC2DJC32200)
文摘Recently, the phase compensation technique has allowed the ultrasound to propagate through the skull and focus into the brain. However, the temperature evolution during treatment is hard to control to achieve effective treatment and avoid over-high temperature. Proposed in this paper is a method to modulate the temperature distribution in the focal region. It superimposes two signals which focus on two preset different targets with a certain distance. Then the temperature distribution is modulated by changing triggering time delay and amplitudes of the two signals. The simulation model is established based on an 82-element transducer and computed tomography （CT） data of a volunteer＇s head. A finite- difference time-domain （FDTD） method is used to calculate the temperature distributions. The results show that when the distances between the two targets respectively are 7.5-12.5 mm on the acoustic axis and 2.0-3.0 mm in the direction perpendicular to the acoustic axis, a focal region with a uniform temperature distribution （64-65 ℃） can be created. Moreover, the volume of the focal region formed by one irradiation can be adjusted （26.8-266.7 mm3） along with the uniform temperature distribution. This method may ensure the safety and efficacy of HIFU brain tumor therapy.
基金the Development Plan for Innovation Teams of Ministry of Education (2005-33)the National Natural Science Foundation of China (30471653)the Natural Science Foundation of Chongqing (2006BA5020)
文摘After interface layer was simulated by the magnetic nano-particles in the egg white phantom, high intensity focused ultrasound （HIFU） at the same dosage was introduced to radiate the phantom in different depths to blow the acoustic interface layer to mimic ＂point＂ exposure. The results showed that the volumes of biological focal region （BFR） were enlarged when the acoustic focal region （AFR） is close with interface layer. This meant that the magnetic nano-particles enhanced the therapeutic efficiency of HIFU. When the distance of the AFR from the interface layer was 10 mm, the size and shape of the BFR were similar with those of the control group, but a larger lesion at the interface, which was harmful for treatment, was observed. When the distance of the AFR to the interface layer increased to 30 mm, the size and shape of the BFR were also similar to those of the control group. When the thickness of the interface layer diminished, the utility of enhancement decreased. Continuous increase of the safe area for treatment and decrease of the utility of enhancement were observed along with the abatement of the thickness of the interface layer
文摘Over the past 25 years, the average life expectancy for men has increased by 4 years, and the age of prostate cancer detection has decreased an average of 10 years with diagnosis increasingly made at early-stage disease where curative therapy is possible. These changing trends in the age and extent of malignancy at diagnosis have revealed limitations in conventional curative therapies for prostate cancer, including a significant risk of aggressive cancer recurrence, and the risk of long-term genitourinary morbidity and its detrimental impact on patient quality of life (QOL). Greater awareness of the shortcomings in radical prostatectomy, external radiotherapy and brachytherapy have prompted the search for alternative curative therapies that offer comparable rates of cancer control and less treatment-related morbidity to better preserve QOL. High intensity focused ultrasound (HIFU) possesses characteristics that make it an attractive curative therapy option. HIFU is a non-invasive approach that uses precisely-delivered ultrasound energy to achieve tumor cell necrosis without radiation or surgical excision. In current urological oncology, HIFU is used clinically in the treatment of prostate cancer, and is under experimental investigation for therapeutic use in renal and breast malignancies. Clinical research on HIFU therapy for localized prostate cancer began in the 1990s, and there have now been approximately 30,000 prostate cancer patients treated with HIFU, predominantly with the Ablatherm (EDAP TMS, Lyon, France) device. Transurethral resection of the prostate (TURP) has been combined with HIFU since 2000 to reduce prostate size, facilitate tissue destruction, and to minimize side effects. Advances in imaging technologies are expected to further improve the already superior efficacy and morbidity outcomes, and ongoing investigation of HIFU as a focal therapy and in salvage and palliative indications are serving to expand the role of HIFU as a highly versatile non-invasive therapy for prostate cancer.
