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MEDICAL APPLICATIONS OF LASERS
J.K. Chhabra Consultant IIIT Allahabad
Ex Scientist and Deputy Director, C.S.I.O. Chandigath
Medical Applications begin
1967
KUMAR PATEL C. Kumar N. Patel born in Baramati, 1938.
Bachelor's in Poona University at the age of 19 (1958)
MS (1959) and PHD (1961) Stanford University.
Hired by AT&T Bell Labs, Upon joining Bell Labs in 1961,
Discovered laser action in carbon dioxide (1963)
invented the nitrogen carbon dioxide (CO2) laser --- the first gas laser to produce high power radiation continuously (1964).
Among military applications, its most striking contribution has been to
the "Star Wars" system once promoted by Ronald Reagan and still being developed today. In fact, scientists find further uses for Patel's CO2 laser
all the time.
LASER in medicine Cosmetic treatments
Ophthalmology: inner eye surgery
Surgical Laser Scalpel
Dentistry
Cancer , Cytometry and fundamental Research,
laser versus ordinary lights:
The directionality of laser beam offers a great advantage over ordinary lights since it can be concentrate its energy onto a very small spot area. This is because the laser rays can be considered as almost parallel and confined to a well-defined circular spot on a distant object.
Sample problem: we compare the intensity of the light of a bulb of 10 W and that of a laser with output power of 1mW (10-3 W). For calculation, we consider an imagery sphere of radius R of 1m for the light spreading of the bulb, laser beams illuminate a spot of circular area with a radius r = 1mm.
2522 /108
)100(410
410 cmW
cmW
RW
API bulb
bulb−×====
ππ
222
3
2
3
/103)1.0(
1010 cmWcmW
rW
API laser
laser−
−−
×====ππ
400/108/103
25
22
≈××
= −
−
cmWcmW
II
bulb
laser
Mechanisms of laser interaction with human tissues
When a laser beam projected to tissue
•reflection, •transmission, •scattering, •re-emission, •absorption.
Five phenomena:
Laser light interacts with tissue and transfers energy of photons to tissue because absorption occurs.
Selective absorption of laser light by human tissues
Optical Properties of Tissue
Selective absorption
Selective absorption occurs when a given color of light is strongly absorbed by one type of tissue, while transmitted by another. Lasers’ pure color is responsible for selective absorption.
The main absorbing components of tissues are: • Oxyhemoglobin (in blood): the blood’s oxygen carrying
protein, absorption of UV and blue and green light, • Melanin (a pigment in skin, hair, moles, etc): absorption in
visible and near IR light (400nm – 1000nm), • Water (in tissues): transparent to visible light but strong
absorption of UV light below 300nm and IR over 1300nm
Penetration-depth (d=1/A) vs. wavelength
UV VISIBLE Near-IR Mid-IR
(0.2-0.4) (04.-0.7) (0.8- 2.1) (2.7-3.2) um
(0.05-0.5) mm (0.5-2.0)
(2.0-6.0)
(0.2-0.5) 0.05 mm
Water 3 absorption peaks: 1.45, 1.93, 2.94 um
Pain Relief Sports Injuries
Lasers in beauty therapy
Lasers application in beauty therapy are based on:
• selective absorption of absorbing components.
• photo-vaporization process for removal of the treated components.
• pulsed lasers are used.
Nd YAG Laser – superficial pigmented lesions
Nevi: biopsy if suspicious Q-switched Nd:YAG 532, 694, 755nm
lasers respond within 1-3 treatments
Melasma: Q-switched Nd:YAG laser hormonal control bleaching agents sun avoidance tend to recur
Rosacea: topicals (antibiotics, tretinoin) oral abx IPL KTP laser
Laser -- deep pigmented lesions • Deep lesions-deeper, therefore treated
better with longer wavelength (goes deeper): can use ruby, alexandrite, and
Nd:YAG – blue nevi:
• 1064 nm Nd:YAG laser – nevus of ota and ito: Q-switched
1064nm Nd:YAG laser • multiple treatments • recurrence is unusual
Laser removal of port-wine stain
Yellow laser is absorbed by the presence of hemoglobin in blood vessels.
Laser skin rejuvenation
IR lasers are used to remove extremely thin layer of skin (<0.1 mm). In the absence of pigment in general, they take advantage of the presence of water in the skin to provide an ability to remove skin and body tissue.
SKIN TIGHTENING
MEDICAL: Laser treatment may be the answer to skin cancer. Trials show that as well as removing cancer cells, laser treatment also
stimulates the immune system. …skin cancer has a tendency to form metastases that create new types
of cancer that are virtually incurable using existing forms of treatment…
SKIN CANCER CURE
Laser hair removal
1. dermis
2. epi-dermis
3. sebacecusglands
4. follicle
5. root
6. Papilla
7. Blood vessel
hair
(1)(2)
(3)(4)
(5)(6)
(7)
Skin-hair structure
Laser -- hair removal
Goal = ablation of hair unit Wavelengths between 600 and 1000 nm most
effective Generally want spot size larger than the depth of
the target being treated--5mm to 1 cm for hair Optimal situation is dark hair with light skin Thermal relaxation time is key: epidermis: 3- 10 ms, hair follicle : 80-100 ms. Use pulse duration < 10 millisecond targets hair
on white skin. May need longer for darker skinned individuals.
Laser hair removal
selective absorption : absorbing component being melanin pigment in hair and follicle, it is best worked with a red light ruby laser. White hair can not be treated with any laser due to the lack of absorbing component.
Home use hand-held LED
4- color LEDs :
IR (940 nm) Yellow (580 nm)
Red (660 nm) Blue (470 nm)
Hair growth
Laser-comb Red-LED (630-695 nm)
Dental lasers (1) Hard tissue (dentin, carries) a) Biolase “water-laser” (Er:YSGG at 2.78 um) b) Lin/ITRI, mid-IR diode laser (2.7-3.0 um) (2) Diode laser (soft tissue) at 808, 940, 980 nm (3) Teeth whitening Nd:YAG (1064) + dye (4) Velcope Blue-light (or LED) to detect cancer tissue
Dental LASER
. Designed for a wide range of endodontic, periodontic and dental surgery procedures,
Picasso allows for clean cutting and hemostasis in soft tissue procedures, cuts gum tissue with precision, helps sterilize canals in endodontics, treats periodontal disease, and aids in tooth whitening.
Laser applications in dentistry
Laser applications in dentistry
Alternative to mechanical drills and CW lasers
Reduced thermal stress
And micro cracks in enamel
AMD Dental LASER
Lasers in ophthalmology
For cornea and lens, UV light emitted by the excimer laser is strongly absorbed by water and proteins, so their energy can be absorbed by transparent cornea and lens, permitting laser surgery on these areas.
• Cataracts: a milky structure in the lens of the eye. Photo-vaporization by using UV laser to remove the obaque regions.
• Correction of myopia: over focusing of the lens. Excimer laser removal of surface of cornea to make it flatten.
Excimer Lasers
Noble gas:Halide. Emit (UV) light that triggers a photochemical reaction on the target tissue.
This very short wavelength is capable of high resolution and microscopic surgery-note the letters etched into the human hair at right.
The most common medical application is the Argon:Fluorine (Ar:F) laser at 193 nm, used for PRK and LASIK vision correction. The laser beam is delivered through an operating microscope integrated with the laser housing and operating table.
Excimer laser radiation shows great promise for cardiac revascularization and lithotripsy, but is currently limited by the lack of durable UV-capable fiberoptic delivery devices.
Focusing Elements in EYE
• Refractive indicies within the eye
Cornea 1.37
Aqueous Humour 1.33
Crystalline Lens 1.38 (outer layers) 1.41 (inner layers)
Vitreous Humour 1.33
Lasers in Ophthalmology For retina operation, visible laser can be used. Visible light is transparent to the cornea and crystalline lens, and can be focused with eye’s lens on the retina. The most popular visible laser is the green argon laser. • Treatment of glaucoma: Argon laser is focused
externally on iris to make incision, creating drainage holes for excess aqueous humors to release pressure,
• Retina tear: photocoagulation burn to repair retina tears due to trauma to the head.
• Diabetic retinopathy: inadequate blood supply to the retina due to diabetes. Small photocoagulation burn by green argon laser to repair the retina due to vessels leakage.
Laser-Assisted in situ Keratomileusis LASIK , Developed in 1995
LASIK Operation
ADVANTAGES FOR THE LASER AS A MEDICAL CUTTING TOOL
Lasers & Medicine
Reduces pain and trauma for the patient
Speeds healing — thereby shortening costly hospital stays
Improves the accuracy of certain surgical procedures
ADVANTAGES FOR THE LASER AS A MEDICAL CUTTING TOOL
Lasers & Medicine
Reduces pain and trauma for the patient
Speeds healing — thereby shortening costly hospital stays
Improves the accuracy of certain surgical procedures
Touch less Brain and Spine Surgery
Laser Brain Surgery
This image cannot currently be displayed.
Lasers & Medicine
• Greater accuracy of incisions • Lasers can be inserted inside the body with little risk or discomfort
• Incisions can be guided by computers • The laser is extremely precise, and can be tuned to work on a micro-level, barely visible to the human eye
DATA KNIFE
ANGIOPLASTY
Cleaning Arteries
ANGIOLOGY Laser Guided Angioplasty
ANGIOLOGY Laser Guided Angioplasty
Early Cancer Diagonosis
Computed Tomography Laser Mammography (CTLM): Imaging Diagnostic Systems (Ft.
Lauderdale, FL)
• No X ray • No Dye Injections • Checks Blood circulation
Breast Cancer CTLM (Computed Tomography Laser Mammography )
808nm laser diodes: At this wavelength, haemoglobin absorb
the light, with little absorbance from water and fat.
This technology works well with dense breast tissue, which is a challenge for mammography.
High sensitivity, because it detects blood flow. Angiogenesis extends around a tumor. For example, a 3.0mm tumor can have a 4-6cm area of angiogenesis.
Lung Cancer •
408nm laser-diode excitation• charge-coupled detector (CCD) that detects
autofluorescence
Diagnostic Application Fluorescence Spectroscopy
Goal: Noninvasive tissue characterization to replace or guide physical biopsy, e.g. early diagnosis of lung cancer.
Single optical fiber
Laser
Camera Filters
Imaging bundle
Wavelength Em
issi
on in
tens
ity
Normal mucosa
Image
Image 2
Early carcinoma
© Deb Newberry 2008
New Technology Could Combine Detection and Treatment
Immediate sensing as a tumor is removed! Sandia National Laboratories
Fundamental Research Cell Biology
CONFOCAL MICROSCOPY
Cytometry
Optical manipulation of plasmid-coated particles and insertion into the cell through a small pore punctured by a short-pulsed laser. Plasmids produce a green fluorescent
protein once inside the cell.
Drawing is not to scale. (Image courtesy of the Gwangju Institute of Science and Technology
Optical tweezers, ultrafast laser pair to gently insert DNA into living cells
Seeing inside a HeLa Cell
Warning Signs
Laser Safety
Lasers are no Toy Guns
Absorption of the eye
Personal Protective Equipment
Thank You
CAUTION: Do not look a laser with remaining eye!
Thank you for your attention !! and
Thank you for your PATIENCE !!
Mobile 91 9888410066