Environmental science and pollution research international, Jan 15, 2016
In this study, a novel chemical-free approach for cleaning oil-contaminated sand with self-collap... more In this study, a novel chemical-free approach for cleaning oil-contaminated sand with self-collapsing air microbubbles (MBs) with diameter less than 50 μm was developed without the use of chemicals, such as surfactants and alkalis. Diesel and rotary-vane pump oil-contaminated fine and medium sands were treated with MBs to study the effect of oil viscosity and sand grain size on oil removal with MBs. About 95 % of diesel removal was achieved for 24 h old 10 % (w/w) diesel-contaminated medium sand in contrast to only 70 % removal from fine sand after 40-min treatment with MBs. While rotary-vane pump oil removal exceeds that of diesel after 40-min treatment with MBs, combination of mechanical stirring with MBs significantly enhanced the oil removal rate, whereby 95 % diesel removal was achieved from fine sand in 30 min in contrast to only 52 % diesel removal with MBs alone. A possible MBs cleaning mechanism for oil-contaminated sand was also proposed. This study provides experimental e...
Characterization of the acoustic field of a shock wave lithotripter is important for determining ... more Characterization of the acoustic field of a shock wave lithotripter is important for determining the performance of the device. In this study, we compare the performance of a newly developed Light Spot Hydrophone (LSHD) with the current standard, i.e., the Fiber Optic Probe Hydrophone (FOPH). An electromagnetic (EM) shock wave lithotripter was selected and each hydrophone was used to map
International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group, 2016
HIFU becomes an effective and non-invasive modality of solid tumour/cancer ablation. Simulation o... more HIFU becomes an effective and non-invasive modality of solid tumour/cancer ablation. Simulation of the non-linear acoustic wave propagation using a phased-array transducer in multiple layered media using different focusing strategies and the consequent lesion formation are essential in HIFU planning in order to enhance the efficacy and efficiency of treatment. An angular spectrum approach with marching fractional steps was applied in the wave propagation from phased-array HIFU transducer, and diffraction, attenuation, and non-linearity effects were accounted for by a second-order operator splitting scheme. The simulated distributions of the first three harmonics along and transverse to the transducer axis were compared to the hydrophone measurements. The bioheat equation was used to simulate the subsequent temperature elevation using the deposited acoustic energy, and lesion formation was determined by the thermal dose. Better agreement was found between the measured harmonics distr...
Proceedings of the Second Joint 24th Annual Conference and the Annual Fall Meeting of the Biomedical Engineering Society] [Engineering in Medicine and Biology, 2000
Chemotherapeutic drug delivery is often ineffective within solid tumors, but increasing the drug ... more Chemotherapeutic drug delivery is often ineffective within solid tumors, but increasing the drug dose would result in systemic toxicity. The use of high-intensity focused ultrasound (HIFU) has the potential to enhance penetration of small molecules. However, operation parameters need to be optimized before the use of chemotherapeutic drugs in vivo and translation to clinical trials. In this study, the effects of pulsed HIFU (pHIFU) parameters (spatial-average pulse-average intensity, duty factor and pulse repetition frequency) on the penetration as well as content of small molecules were evaluated in ex vivo porcine kidneys. Specific HIFU parameters resulted in more than 40 times greater Evans blue content and 3.5 times the penetration depth compared with untreated samples. When selected parameters were applied to porcine kidneys in vivo, a 2.3-fold increase in concentration was obtained after a 2-min exposure to pHIFU. Pulsed HIFU has been found to be an effective modality to enhance both the concentration and penetration depth of small molecules in tissue using the optimized HIFU parameters. Although, performed in normal tissue, this study has the promise of translation into tumor tissue.
Characterization of the acoustic field of high-intensity focused ultrasound (HIFU) transducers by... more Characterization of the acoustic field of high-intensity focused ultrasound (HIFU) transducers by conventional PVDF membrane and needle hydrophones is problematic due to limited bandwidth, spatial averaging, and damage to the hydrophone. Here, we report the use of a self-calibrated fiber-optical probe hydrophone (FOPH-500) for HIFU dosimetry measure- ment. The hydrophone (0.1-mm sensing element) was scanned in the focal volume of a 1.1-MHz HIFU transducer (F=63 mm, f number=0.9) at 0.2-mm steps using a computer-controlled 3D positioning system. When the input voltage Vp-p applied to the transducer was increased from 28 to 225 volts, the peak compressive and tensile pressure values at the transducer focus were found to be P+=1.7-18.9 MPa and P-=-1.33--8.14 MPa, respectively. The corresponding spatial peak intensities were calculated to be ISP=69-3968 W/cm2. Nonlinear propagation with harmonics generation was dominant at high intensity levels, leading to a reduced -6-dB beamwidth of the compressive wave from 1.8 to 1.3 mm and an increased -6-dB beamwidth of the tensile wave from 1.6 to 1.8 mm. Overall, FOPH-500 was found to be a reliable tool for characterizing the acoustic field of HIFU transducers.
Journal of stroke and cerebrovascular diseases : the official journal of National Stroke Association
Stroke is a severe emergent cardiologic disease for death and permanent disability. Ultrasound ex... more Stroke is a severe emergent cardiologic disease for death and permanent disability. Ultrasound exposure could noninvasively enhance the clot lysis of tissue plasminogen activator (tPA) with the presence of microbubbles (MBs). A variety of sonography systems are available in the market, and whether sonothrombolysis is only successful using specific devices is unknown. Three commercial ultrasound systems (Siemens, Philips, and SonoSite) were characterized first for their acoustic field, and then the thrombolysis efficiencies were evaluated using the same in vitro setup and protocol. Despite different acoustic fields and pressure waveforms at the focus, similar sonothrombolysis abilities with tPA and MBs were found, and the presence of temporal bone will worsen the performance slightly (by about 10% in the clot lysis). Therefore, it suggests that satisfactory sonothrombolysis in vivo or in clinics could be achieved using a variety of commercial ultrasound devices if the acoustic output...
The acoustic power of high-intensity focused ultrasound (HIFU) is an important parameter that sho... more The acoustic power of high-intensity focused ultrasound (HIFU) is an important parameter that should be measured prior to each treatment to guarantee effective and safe outcomes. A new calibration technique was developed that involves estimating the pressure distribution, calculating the acoustic power using an underwater pressure blast sensor, and compensating the contribution of harmonics to the acoustic power. The output of a clinical extracorporeal HIFU system (center frequency of ~1 MHz, p+ = 2.5-57.2 MPa, p(-) = -1.8 to -13.9 MPa, ISPPA = 513-22,940 W/cm(2), -6 dB size of 1.6 × 10 mm: lateral × axial) was measured using this approach and then compared with that obtained using a radiation force balance. Similarities were found between each method at acoustic power ranging from 18.2 W to 912 W with an electrical-to-acoustic conversion efficiency of ~42%. The proposed method has advantages of low weight, smaller size, high sensitivity, quick response, high signal-to-noise ratio (...
Extracorporeal shock wave lithotripsy (ESWL) has been used as an effective modality to fragment k... more Extracorporeal shock wave lithotripsy (ESWL) has been used as an effective modality to fragment kidney calculi. Because of the bubble shielding effect in the pre-focal region, the acoustic energy delivered to the focus is reduced. Low pulse repetition frequency (PRF) will be applied to dissolve these bubbles for better stone comminution efficiency. In this study, low intensity pulsed ultrasound (LIPUS) beam was aligned perpendicular to the axis of a shock wave (SW) lithotripter at its focus. The light transmission was used to evaluate the compressive wave and cavitation induced by SWs without or with a combination of LIPUS for continuous sonication. It is found that bubble shielding effect becomes dominated with the SW exposure and has a greater significant effect on cavitation than compressive wave. Using the combined wave scheme, the improvement began at the 5th pulse and gradually increased. Suppression effect on bubble shielding is independent on the trigger delay, but increases...
Recent advances in high intensity focused ultrasound (HIFU), which was developed in the 1940s as ... more Recent advances in high intensity focused ultrasound (HIFU), which was developed in the 1940s as a viable thermal tissue ablation approach, have increased its popularity. In clinics, HIFU has been applied to treat a variety of solid malignant tumors in a well-defined volume, including the pancreas, liver, prostate, breast, uterine fibroids, and soft-tissue sarcomas. In comparison to conventional tumor/cancer treatment modalities, such as open surgery, radio- and chemo-therapy, HIFU has the advantages of non-invasion, non-ionization, and fewer complications after treatment. Over 100 000 cases have been treated throughout the world with great success. The fundamental principles of HIFU ablation are coagulative thermal necrosis due to the absorption of ultrasound energy during transmission in tissue and the induced cavitation damage. This paper reviews the clinical outcomes of HIFU ablation for applicable cancers, and then summarizes the recommendations for a satisfactory HIFU treatmen...
Gan no rinsho. Japan journal of cancer clinics, 1985
In this paper, first, how to take good ultrasonic pictures of the breast and make correct diagnos... more In this paper, first, how to take good ultrasonic pictures of the breast and make correct diagnosis are discussed. The author stressed the earnest attitude to understand and master the apparatus and correlate ultrasonic pictures with cut surfaces or microscopical figures of the specimen. Secondly, diagnostic criteria preliminarily adopted by the Japan Society of Ultrasonics in Medicine are proposed and are explained practically. The elements of this criteria are shape, border, boundary echoes, internal echoes, posterior echoes, bilateral shadows, changes at surrounding tissues and longitudinal-transverse ratio. Lastly, pictures of the benign and malignant lesions of the breast are shown using typical examples.
Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine, 2015
Transdermal drug delivery makes a critical contribution to medical practice and some advantages o... more Transdermal drug delivery makes a critical contribution to medical practice and some advantages over conventional oral administration and hypodermic injection. Enhancement of percutaneous absorption or penetration of therapeutic agents (ie, drugs and macromolecules) by ultrasound, termed sonophoresis, has been applied and studied for decades. In this study, the penetration percentage through porcine ear skin specimens was determined quantitatively by measuring the fluorescence from nanoparticles of 60, 220, and 840 nm in size in a receptor chamber at different sonication parameters (ie, duty cycle, 20%-100%; acoustic intensity, 0.3-1.0 W/cm(2); duration, 7-30 minutes; and frequency, 1 MHz). In general, the sonophoresis efficiency increased with the acoustic intensity, duty cycle, and sonication duration but decreased with the particle size (mean ± SD, 62.6% ± 5.4% for 60-nm versus 11.9% ± 1.1% for 840-nm polystyrene nanospheres after 30 minutes of sonication at 0.5 W/cm(2) and a 100...
Environmental science and pollution research international, Jan 15, 2016
In this study, a novel chemical-free approach for cleaning oil-contaminated sand with self-collap... more In this study, a novel chemical-free approach for cleaning oil-contaminated sand with self-collapsing air microbubbles (MBs) with diameter less than 50 μm was developed without the use of chemicals, such as surfactants and alkalis. Diesel and rotary-vane pump oil-contaminated fine and medium sands were treated with MBs to study the effect of oil viscosity and sand grain size on oil removal with MBs. About 95 % of diesel removal was achieved for 24 h old 10 % (w/w) diesel-contaminated medium sand in contrast to only 70 % removal from fine sand after 40-min treatment with MBs. While rotary-vane pump oil removal exceeds that of diesel after 40-min treatment with MBs, combination of mechanical stirring with MBs significantly enhanced the oil removal rate, whereby 95 % diesel removal was achieved from fine sand in 30 min in contrast to only 52 % diesel removal with MBs alone. A possible MBs cleaning mechanism for oil-contaminated sand was also proposed. This study provides experimental e...
Characterization of the acoustic field of a shock wave lithotripter is important for determining ... more Characterization of the acoustic field of a shock wave lithotripter is important for determining the performance of the device. In this study, we compare the performance of a newly developed Light Spot Hydrophone (LSHD) with the current standard, i.e., the Fiber Optic Probe Hydrophone (FOPH). An electromagnetic (EM) shock wave lithotripter was selected and each hydrophone was used to map
International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group, 2016
HIFU becomes an effective and non-invasive modality of solid tumour/cancer ablation. Simulation o... more HIFU becomes an effective and non-invasive modality of solid tumour/cancer ablation. Simulation of the non-linear acoustic wave propagation using a phased-array transducer in multiple layered media using different focusing strategies and the consequent lesion formation are essential in HIFU planning in order to enhance the efficacy and efficiency of treatment. An angular spectrum approach with marching fractional steps was applied in the wave propagation from phased-array HIFU transducer, and diffraction, attenuation, and non-linearity effects were accounted for by a second-order operator splitting scheme. The simulated distributions of the first three harmonics along and transverse to the transducer axis were compared to the hydrophone measurements. The bioheat equation was used to simulate the subsequent temperature elevation using the deposited acoustic energy, and lesion formation was determined by the thermal dose. Better agreement was found between the measured harmonics distr...
Proceedings of the Second Joint 24th Annual Conference and the Annual Fall Meeting of the Biomedical Engineering Society] [Engineering in Medicine and Biology, 2000
Chemotherapeutic drug delivery is often ineffective within solid tumors, but increasing the drug ... more Chemotherapeutic drug delivery is often ineffective within solid tumors, but increasing the drug dose would result in systemic toxicity. The use of high-intensity focused ultrasound (HIFU) has the potential to enhance penetration of small molecules. However, operation parameters need to be optimized before the use of chemotherapeutic drugs in vivo and translation to clinical trials. In this study, the effects of pulsed HIFU (pHIFU) parameters (spatial-average pulse-average intensity, duty factor and pulse repetition frequency) on the penetration as well as content of small molecules were evaluated in ex vivo porcine kidneys. Specific HIFU parameters resulted in more than 40 times greater Evans blue content and 3.5 times the penetration depth compared with untreated samples. When selected parameters were applied to porcine kidneys in vivo, a 2.3-fold increase in concentration was obtained after a 2-min exposure to pHIFU. Pulsed HIFU has been found to be an effective modality to enhance both the concentration and penetration depth of small molecules in tissue using the optimized HIFU parameters. Although, performed in normal tissue, this study has the promise of translation into tumor tissue.
Characterization of the acoustic field of high-intensity focused ultrasound (HIFU) transducers by... more Characterization of the acoustic field of high-intensity focused ultrasound (HIFU) transducers by conventional PVDF membrane and needle hydrophones is problematic due to limited bandwidth, spatial averaging, and damage to the hydrophone. Here, we report the use of a self-calibrated fiber-optical probe hydrophone (FOPH-500) for HIFU dosimetry measure- ment. The hydrophone (0.1-mm sensing element) was scanned in the focal volume of a 1.1-MHz HIFU transducer (F=63 mm, f number=0.9) at 0.2-mm steps using a computer-controlled 3D positioning system. When the input voltage Vp-p applied to the transducer was increased from 28 to 225 volts, the peak compressive and tensile pressure values at the transducer focus were found to be P+=1.7-18.9 MPa and P-=-1.33--8.14 MPa, respectively. The corresponding spatial peak intensities were calculated to be ISP=69-3968 W/cm2. Nonlinear propagation with harmonics generation was dominant at high intensity levels, leading to a reduced -6-dB beamwidth of the compressive wave from 1.8 to 1.3 mm and an increased -6-dB beamwidth of the tensile wave from 1.6 to 1.8 mm. Overall, FOPH-500 was found to be a reliable tool for characterizing the acoustic field of HIFU transducers.
Journal of stroke and cerebrovascular diseases : the official journal of National Stroke Association
Stroke is a severe emergent cardiologic disease for death and permanent disability. Ultrasound ex... more Stroke is a severe emergent cardiologic disease for death and permanent disability. Ultrasound exposure could noninvasively enhance the clot lysis of tissue plasminogen activator (tPA) with the presence of microbubbles (MBs). A variety of sonography systems are available in the market, and whether sonothrombolysis is only successful using specific devices is unknown. Three commercial ultrasound systems (Siemens, Philips, and SonoSite) were characterized first for their acoustic field, and then the thrombolysis efficiencies were evaluated using the same in vitro setup and protocol. Despite different acoustic fields and pressure waveforms at the focus, similar sonothrombolysis abilities with tPA and MBs were found, and the presence of temporal bone will worsen the performance slightly (by about 10% in the clot lysis). Therefore, it suggests that satisfactory sonothrombolysis in vivo or in clinics could be achieved using a variety of commercial ultrasound devices if the acoustic output...
The acoustic power of high-intensity focused ultrasound (HIFU) is an important parameter that sho... more The acoustic power of high-intensity focused ultrasound (HIFU) is an important parameter that should be measured prior to each treatment to guarantee effective and safe outcomes. A new calibration technique was developed that involves estimating the pressure distribution, calculating the acoustic power using an underwater pressure blast sensor, and compensating the contribution of harmonics to the acoustic power. The output of a clinical extracorporeal HIFU system (center frequency of ~1 MHz, p+ = 2.5-57.2 MPa, p(-) = -1.8 to -13.9 MPa, ISPPA = 513-22,940 W/cm(2), -6 dB size of 1.6 × 10 mm: lateral × axial) was measured using this approach and then compared with that obtained using a radiation force balance. Similarities were found between each method at acoustic power ranging from 18.2 W to 912 W with an electrical-to-acoustic conversion efficiency of ~42%. The proposed method has advantages of low weight, smaller size, high sensitivity, quick response, high signal-to-noise ratio (...
Extracorporeal shock wave lithotripsy (ESWL) has been used as an effective modality to fragment k... more Extracorporeal shock wave lithotripsy (ESWL) has been used as an effective modality to fragment kidney calculi. Because of the bubble shielding effect in the pre-focal region, the acoustic energy delivered to the focus is reduced. Low pulse repetition frequency (PRF) will be applied to dissolve these bubbles for better stone comminution efficiency. In this study, low intensity pulsed ultrasound (LIPUS) beam was aligned perpendicular to the axis of a shock wave (SW) lithotripter at its focus. The light transmission was used to evaluate the compressive wave and cavitation induced by SWs without or with a combination of LIPUS for continuous sonication. It is found that bubble shielding effect becomes dominated with the SW exposure and has a greater significant effect on cavitation than compressive wave. Using the combined wave scheme, the improvement began at the 5th pulse and gradually increased. Suppression effect on bubble shielding is independent on the trigger delay, but increases...
Recent advances in high intensity focused ultrasound (HIFU), which was developed in the 1940s as ... more Recent advances in high intensity focused ultrasound (HIFU), which was developed in the 1940s as a viable thermal tissue ablation approach, have increased its popularity. In clinics, HIFU has been applied to treat a variety of solid malignant tumors in a well-defined volume, including the pancreas, liver, prostate, breast, uterine fibroids, and soft-tissue sarcomas. In comparison to conventional tumor/cancer treatment modalities, such as open surgery, radio- and chemo-therapy, HIFU has the advantages of non-invasion, non-ionization, and fewer complications after treatment. Over 100 000 cases have been treated throughout the world with great success. The fundamental principles of HIFU ablation are coagulative thermal necrosis due to the absorption of ultrasound energy during transmission in tissue and the induced cavitation damage. This paper reviews the clinical outcomes of HIFU ablation for applicable cancers, and then summarizes the recommendations for a satisfactory HIFU treatmen...
Gan no rinsho. Japan journal of cancer clinics, 1985
In this paper, first, how to take good ultrasonic pictures of the breast and make correct diagnos... more In this paper, first, how to take good ultrasonic pictures of the breast and make correct diagnosis are discussed. The author stressed the earnest attitude to understand and master the apparatus and correlate ultrasonic pictures with cut surfaces or microscopical figures of the specimen. Secondly, diagnostic criteria preliminarily adopted by the Japan Society of Ultrasonics in Medicine are proposed and are explained practically. The elements of this criteria are shape, border, boundary echoes, internal echoes, posterior echoes, bilateral shadows, changes at surrounding tissues and longitudinal-transverse ratio. Lastly, pictures of the benign and malignant lesions of the breast are shown using typical examples.
Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine, 2015
Transdermal drug delivery makes a critical contribution to medical practice and some advantages o... more Transdermal drug delivery makes a critical contribution to medical practice and some advantages over conventional oral administration and hypodermic injection. Enhancement of percutaneous absorption or penetration of therapeutic agents (ie, drugs and macromolecules) by ultrasound, termed sonophoresis, has been applied and studied for decades. In this study, the penetration percentage through porcine ear skin specimens was determined quantitatively by measuring the fluorescence from nanoparticles of 60, 220, and 840 nm in size in a receptor chamber at different sonication parameters (ie, duty cycle, 20%-100%; acoustic intensity, 0.3-1.0 W/cm(2); duration, 7-30 minutes; and frequency, 1 MHz). In general, the sonophoresis efficiency increased with the acoustic intensity, duty cycle, and sonication duration but decreased with the particle size (mean ± SD, 62.6% ± 5.4% for 60-nm versus 11.9% ± 1.1% for 840-nm polystyrene nanospheres after 30 minutes of sonication at 0.5 W/cm(2) and a 100...
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