Water breakdown studies by Nd-YAG laser pulses of duration 100 fs, 30 ps and 6 ns at wavelength 1064 nm are pre- formed to investigate the physical mechanisms which couple the laser energy into the medium. Calculation...Water breakdown studies by Nd-YAG laser pulses of duration 100 fs, 30 ps and 6 ns at wavelength 1064 nm are pre- formed to investigate the physical mechanisms which couple the laser energy into the medium. Calculations are carried out applying a modified kinetic model of water breakdown previously developed by Kennedy (1995) to investigate the correlation between threshold intensity of breakdown and laser pulse length. The modifications considered the introduction of diffusion and recombination loss processes which might take place under the experimental conditions applied in these calculations. The validity of the model is tested by comparing the calculated threshold intensities and the experimentally measured ones where good agreement is shown. The study of the time evolution of the electron density clarifies the correlation between the pulse length and dominant ionization mechanism. The analysis of the spatial distribution of the electron density along the radial and axial distances of the focal spot showed that the size of the formed plasma increases with the increase of the pulse length. On the other hand, studies of self-focusing effect illustrated that under the investigated experimental conditions the effect of this process has an effective contribution only at laser pulses of the order of femtosecond scale when the laser beam is focused by a lens of a focal length ≥8.0 cm. This result in turns assures that using femtosecond pulses in ophthalmic microsurgery could be a safe tool from the retinal damage.展开更多
Background: The unaesthetic appearance of the female intimate area (vulva, “mound of venus” and perianal region) is a triggering factor of negative psychological responses, embarrassment, anxiety and insecurity in m...Background: The unaesthetic appearance of the female intimate area (vulva, “mound of venus” and perianal region) is a triggering factor of negative psychological responses, embarrassment, anxiety and insecurity in many women. Using rejuvenating equipment for vaginal structure or for the intimate area as a whole is already widespread in the literature, and High-Intensity Focused Ultrasound (HIFU) has proven to be very effective in the clinical practice of many professionals. This study, therefore, aims to describe the fundamentals and applicability that guide the use of HIFU in vulvar rejuvenation. Materials and Methods: Exploratory research was carried out, presented in a narrative review, to highlight the action of HIFU in female intimate rejuvenation. The review explored scientific articles published and available in the following databases: MEDLINE (Medical Literature Analysis and Retrieval System Online), PubMed (National Library of Medicine), SCIELO (Scientific Electronic Library Online), and LILACS (Latin Literature American and the Caribbean in Health Sciences). In addition, some clinical findings obtained through a retrospective analysis of medical records were added to describe the authors’ clinical experience in the use of Focused Ultrasound (HIFU) for vulvar rejuvenation. Results: We verified that the tissues of female external genitalia respond very well to the stimuli of the focused sound waves of the HIFU, being able to produce immediate and lasting results through isolated applications or in association with intradermotherapy or other therapeutic resources. Conclusion: We conclude that using High Intensity Focused Ultrasound aimed at vulvar rejuvenation is safely indicated and assures excellent aesthetic results at the end of the treatment because similarly to other treatment techniques, the thermal stimuli of HIFU are also able to produce an excellent therapeutic response in the dermal tissue of the female intimate area, promoting intense neocollagenesis and generating great aesthetic improvement.展开更多
文摘Water breakdown studies by Nd-YAG laser pulses of duration 100 fs, 30 ps and 6 ns at wavelength 1064 nm are pre- formed to investigate the physical mechanisms which couple the laser energy into the medium. Calculations are carried out applying a modified kinetic model of water breakdown previously developed by Kennedy (1995) to investigate the correlation between threshold intensity of breakdown and laser pulse length. The modifications considered the introduction of diffusion and recombination loss processes which might take place under the experimental conditions applied in these calculations. The validity of the model is tested by comparing the calculated threshold intensities and the experimentally measured ones where good agreement is shown. The study of the time evolution of the electron density clarifies the correlation between the pulse length and dominant ionization mechanism. The analysis of the spatial distribution of the electron density along the radial and axial distances of the focal spot showed that the size of the formed plasma increases with the increase of the pulse length. On the other hand, studies of self-focusing effect illustrated that under the investigated experimental conditions the effect of this process has an effective contribution only at laser pulses of the order of femtosecond scale when the laser beam is focused by a lens of a focal length ≥8.0 cm. This result in turns assures that using femtosecond pulses in ophthalmic microsurgery could be a safe tool from the retinal damage.
文摘Background: The unaesthetic appearance of the female intimate area (vulva, “mound of venus” and perianal region) is a triggering factor of negative psychological responses, embarrassment, anxiety and insecurity in many women. Using rejuvenating equipment for vaginal structure or for the intimate area as a whole is already widespread in the literature, and High-Intensity Focused Ultrasound (HIFU) has proven to be very effective in the clinical practice of many professionals. This study, therefore, aims to describe the fundamentals and applicability that guide the use of HIFU in vulvar rejuvenation. Materials and Methods: Exploratory research was carried out, presented in a narrative review, to highlight the action of HIFU in female intimate rejuvenation. The review explored scientific articles published and available in the following databases: MEDLINE (Medical Literature Analysis and Retrieval System Online), PubMed (National Library of Medicine), SCIELO (Scientific Electronic Library Online), and LILACS (Latin Literature American and the Caribbean in Health Sciences). In addition, some clinical findings obtained through a retrospective analysis of medical records were added to describe the authors’ clinical experience in the use of Focused Ultrasound (HIFU) for vulvar rejuvenation. Results: We verified that the tissues of female external genitalia respond very well to the stimuli of the focused sound waves of the HIFU, being able to produce immediate and lasting results through isolated applications or in association with intradermotherapy or other therapeutic resources. Conclusion: We conclude that using High Intensity Focused Ultrasound aimed at vulvar rejuvenation is safely indicated and assures excellent aesthetic results at the end of the treatment because similarly to other treatment techniques, the thermal stimuli of HIFU are also able to produce an excellent therapeutic response in the dermal tissue of the female intimate area, promoting intense neocollagenesis and generating great aesthetic improvement.
