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Medical L-A-S-E-R

Dr. Ali Saad/ biomedical technology KSU. 2. ? 1961 Ruby laser invented (Maiman)??1965 Argon laser applied to eye surgery? Surgical applications??Opthalmology??General surgery??Ob-gyn??Cardiac??Orthopaedic??Plastic/dermatology. Medical L-A-S-E-R. Dr. Ali Saad/ biomedical technology KSU. 3. T

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Medical L-A-S-E-R

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    1. Dr. Ali Saad/ biomedical technology KSU 1 Medical L-A-S-E-R

    2. Dr. Ali Saad/ biomedical technology KSU 2

    3. Dr. Ali Saad/ biomedical technology KSU 3

    4. Dr. Ali Saad/ biomedical technology KSU 4

    5. Dr. Ali Saad/ biomedical technology KSU 5

    6. Dr. Ali Saad/ biomedical technology KSU 6 Laser Tissue Interaction • Energy is reflected, transmitted, absorbed and scattered • Lambert Beer law I = Io 10-aX a= absorption coefficient X = thickness of material Io = incident intensity I = transmitted intensity • Extinction length = 1/a = L; where 90% of the intensity is absorbed.

    7. Dr. Ali Saad/ biomedical technology KSU 7 Laser Tissue Interaction

    8. Dr. Ali Saad/ biomedical technology KSU 8 Laser Tissue Interaction Power density important for tissue vaporization Spot size minimum proportional to wavelength Shorter wavelength ~ Smaller spot size

    9. Dr. Ali Saad/ biomedical technology KSU 9 Carbon Dioxide Laser 10.6 um - Far infra-red - need visible aiming Gas mix - 5CO2 + 10N2 + 85He Electrical pumping - DC or RF ??100+ watts may be used ??10-20% efficient • Absorbed by all tissue/H2O • Extinction length is .03mm - vaporization • Fiberoptic losses significant - use lens

    10. Dr. Ali Saad/ biomedical technology KSU 10 ND:Yag Laser • 1.06 um - Infra-red • ND doped YAG crystal • Optical pumping • 1% efficiency • Two types Continuous/pulsed for general surgery Excellent for coagulation, deep heating Weakly absorbed by H2O - transmit through H2O Can go thru fiberoptics easily Q-switched for opthalmology

    11. Dr. Ali Saad/ biomedical technology KSU 11 Argon and argon dye laser • 488 nanometers - blue light • Argon gas • Electrical pumping • Low efficiency .1% • Little absorption by H2O - high absorption by red objects (e.g. retina) • Small spot size • Argon dye provides multiple wavelengths ??Photoradiation therapy @ 630 nm Eximer

    12. Dr. Ali Saad/ biomedical technology KSU 12 Diode and Holmium Laser - 193 nm - UV, Exciter fluoride gas, electrical pumping, very precise, ophthalmic use (corneal sculpting) ??Diode - aluminum gallium arsenide (AlGaAs) @ 810 nm or indium gallium arsenide (InGaAs) @ 980 nm, fiber optic transmission, long life Holmium:yttrium-aluminum-garnet (Ho:YAG), similar to ND:YAG; 2100 nm; orthopaedic,general and other procedures

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