o Commonly used methods (thermal, chemical,
mechanical and ultrasound) cannot offer much
accuracy.
o Usage of ultrasound h...
Tissue engineering is a field of bioengineering that
recently has seen an immense amount of growth.
It is a multidisciplin...
TISSUE
CONTOURING
AND
RESTRUCTURING.
TISSUE
WELDING.
TISSUE
REGENERATION.
o Lasers are commonly used in general and other
surgeries.
o Basic principles behind these applications of lasers are
the ...
o Dermatological applications.
o Ophthalmic applications.
o Laser angioplasty.
o Otolaryngology.
o Based on the theory of selective photothermolysis.
o Allows highly localized destruction of light
absorbing “targets” in...
Proced
ure
Skin
Resurfacing.
Hair Removal. Tattoo Removal.
Commo
nly used
lasers
CO2
laser
Er:YAG
laser
Alexan
drite
laser...
o Here tattoo pigment is the target chromophore.
o Laser light causes extremely rapid heating of tattoo
pigment granules.
...
o Based on laser-tissue interactions.
o The ophthalmic applications that correct medical
conditions fall into two categori...
Proce
dure.
Laser
Photocoagulation
LTK LASIK
Commonly
used lasers
Argon
Ion
laser
Krypton
ion
laser
Laser
diode
Ho:YAG
las...
o Mainly used for the correction of myopia (near-sightedness).
o Here a pulsed laser beam flattens the cornea by removing ...
o Introduced by Jain and Gorisch(1979), who used Nd:YAG
laser light to seal rat arteries.
Tissue Bonding
Direct
Welding of...
o Microsurgery.
o Reduced inflammation.
o Faster healing.
o Watertight seal.
o Ease and speed of application.
o Moreover i...
Based on the principle of
photothermolysis.
o Laser light is utilized to fuse a proteineous solder to
the tissue surface.
o It provides greater bond strength with les...
o An appropriate dye that will enhance absorption of the
used laser is added to the solder.
o Takes advantage of strong ab...
oUsing laser light to repair tissue damage after
an injury.
Computer-Aided Tissue Engineering.
New Laser Solders and Dyes to Assist
Soldering.
Mechanism of Tissue Ablation and
Wel...
Introduction To Biophotonics
Paras N. Prasad
Laser Surgery and Medicine: Principles and Practice,
Wiley-Liss
Cutaneous ...
Dfygtruyiopiup[
Tyterwret
yu
Tissue engineering with light
Tissue engineering with light
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Tissue engineering with light

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application of light and lasers in living tissues.

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Tissue engineering with light

  1. 1. o Commonly used methods (thermal, chemical, mechanical and ultrasound) cannot offer much accuracy. o Usage of ultrasound has been found to have some negative impact on tissues. o Thermal mechanism may produce collateral damage. o Chemical methods may leave contaminants on the cell surface. o We cannot easily manipulate intercellular mechanisms with common methods.
  2. 2. Tissue engineering is a field of bioengineering that recently has seen an immense amount of growth. It is a multidisciplinary field that has resulted in 1) Development of materials. 2) Fabrication of engineering tools. 3) Determination of biocompatibility and reduced risk of dysfunction. 4) Skills of implementation.
  3. 3. TISSUE CONTOURING AND RESTRUCTURING. TISSUE WELDING. TISSUE REGENERATION.
  4. 4. o Lasers are commonly used in general and other surgeries. o Basic principles behind these applications of lasers are the following laser-tissue interactions- . . Photochemical Processes. Thermal effects. Photo Ablation. Plasma-induced ablation. Photo disruption.
  5. 5. o Dermatological applications. o Ophthalmic applications. o Laser angioplasty. o Otolaryngology.
  6. 6. o Based on the theory of selective photothermolysis. o Allows highly localized destruction of light absorbing “targets” in skin. o Minimal damage to surrounding tissue. o Applications are as follows- Removal of tattoos. Treatment of vascular malformations. Resurfacing. Hair removal.
  7. 7. Proced ure Skin Resurfacing. Hair Removal. Tattoo Removal. Commo nly used lasers CO2 laser Er:YAG laser Alexan drite laser Diode laser Nd:YAG laser Ruby laser Q- switched frequency doubled Nd:YAG Q- switched alexandri te laser Wavelen gth 10.6 µm 2.94 µm 0.755 µm 0.81 µm 1.064 µm 0.694 µm 0.53 µm 0.75 µm Pulse duration 800 µsec 0.3-10 msec 2-20 msec 0.2-1 sec 10-50 msec 3 msec 10-80 nsec 50 nsec Fluence (energy) 3.5-6.5 J/cm² 5-8 J/cm² 25-40 J/cm² 23-115 J/cm² 90-187 J/cm² 10-60 J/cm² 6-10 J/cm² 2.5-6 J/cm²
  8. 8. o Here tattoo pigment is the target chromophore. o Laser light causes extremely rapid heating of tattoo pigment granules. o This fractures these sub micrometer particles and kills the cells that contain them.
  9. 9. o Based on laser-tissue interactions. o The ophthalmic applications that correct medical conditions fall into two categories: 1. Use of Visible or Near-Visible Infrared Laser Wavelengths to Treat Retinal Disease or Glaucoma. Example- for the treatment of retinal tears and glaucoma. 2. Use of Invisible Wavelengths for Refractive Surgery to Reshape the Cornea for Vision Correction. Example- Laser in situ keratomileusis(LASIK) and photorefractive keratectomy(PRK) for the treatment of myopia.
  10. 10. Proce dure. Laser Photocoagulation LTK LASIK Commonly used lasers Argon Ion laser Krypton ion laser Laser diode Ho:YAG laser ArF excimer laser Wavelength 514.5 nm 647 nm 810 nm 2.1 µm 193 nm Pulse duration CW (.1-1)s CW up to 10ѕ CW up to 2s Pulse (0.25-1)s Pulse (15-25)ns Power (energy) 0.05- 0.2W 0.3- 0.5W 2W 20mJ 50- 250mJ
  11. 11. o Mainly used for the correction of myopia (near-sightedness). o Here a pulsed laser beam flattens the cornea by removing more tissue from the center of the cornea than from its midzone. o As a result, the focus of the eye moves further back toward its desired spot on the retina and corrects the vision for distance.
  12. 12. o Introduced by Jain and Gorisch(1979), who used Nd:YAG laser light to seal rat arteries. Tissue Bonding Direct Welding of Tissues Laser Soldering Dye-enhanced Laser Soldering
  13. 13. o Microsurgery. o Reduced inflammation. o Faster healing. o Watertight seal. o Ease and speed of application. o Moreover it can be used endoscopically and laproscopically to extent the range of its applications to cases where sutures or staples cannot be used.
  14. 14. Based on the principle of photothermolysis.
  15. 15. o Laser light is utilized to fuse a proteineous solder to the tissue surface. o It provides greater bond strength with less collateral damage compared to direct welding. o Commonly used lasers => CO2,Nd:YAG and CW. o Solders used => Blood, egg-white albumin, proteins derived from blood fibrinogen and other albumins.
  16. 16. o An appropriate dye that will enhance absorption of the used laser is added to the solder. o Takes advantage of strong absorption of light by the selected dye and the efficient conversion of light into heat by dye dispersed in the solder. o Allowed the ability to use more common and relatively inexpensive 808-nm diode laser with the help of a biocompatible dye, indocyanine green(ICG).
  17. 17. oUsing laser light to repair tissue damage after an injury.
  18. 18. Computer-Aided Tissue Engineering. New Laser Solders and Dyes to Assist Soldering. Mechanism of Tissue Ablation and Welding. Femtolaser Technology.
  19. 19. Introduction To Biophotonics Paras N. Prasad Laser Surgery and Medicine: Principles and Practice, Wiley-Liss Cutaneous Laser Surgery, Mosby, St. Louis Wikipedia
  20. 20. Dfygtruyiopiup[ Tyterwret yu

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