about lasers used in medicine

1. Lasers in surgery
aditya kalyan

2. LASER
Light Amplification by Stimulated
Emission of Radiation

3. History
 Maiman ,1960, Ruby
 1962, Leon Goldman .
 Dr.Goldmans experiment was the first use of lasers in
the medical history
 Early 1980s, John Parrish and Rox Anderson -
Selective Photo Thermolysis - Risk of scarring &
damage to normal tissue

4. Common Components of Lasers

6. Production of Laser

10. Laser output
2 Modes
 Continuous mode (Watts)
 Pulsed mode (Joules)
Output depends upon the Medium

11. Properties
 Collimation

12.  Monochromacity
 Coherence

13. Effect of Laser on tissues

14. When a laser beam projected to tissue

15.  Biological activity of laser light is due to
Absorption phenomenon by chromophores
 Photons energy of laser light is transferred to
blood, tissues or bone in the form of heat.
 Laser can transfer photon energy to chemical bond
energy of the molecules in human body, like DNA.

16.  There are generally three interaction
mechanisms involved.
1) Photocoagulation
2) Photovaporization
3) Photoablation
 Thermal effects depend on Energy density.

17. Photocoagulation
 A Laser heating of tissues above 50 oC & below
100oC induces disordering of proteins and other
bio-molecules
 Shrink in mass – water expelled
 Heated region loses its mechanical integrity
 Cells in the photocoagulated region die and a region
of dead tissue called photocoagulation burn
develops

18. Applications
 Destroy tumors
 Treating Retinal disorders caused by diabetes
 Hemostatic laser surgery - bloodless incision,
excision:
Blood vessel subjected to photocoagulation
develops a pinched point due to shrinkage of
proteins in the vessel’s wall, helps seal off the flow.

19. Photovaporisation
 With very high power densities,lasers will quickly
heat the tissues to above 100o C
 water in tissues boils and evaporates.
 Since 70% of the body tissue is water, the boiling
change the tissue into a gas.
 Results in complete removal of the tissue.
 Hemostatic incision or excision, Skin
Rejuvenation, Resurfacing.

21. Photoablation
 When using high power lasers of ultraviolet
wavelength, chemical bonds are broken,without
causing local heating.
 Thermal component is relatively small and zone of
thermal interaction is limited
 Results in clean cut incision

22. Selective absorption
 A given color of light is strongly absorbed by one
type of tissue,while transmitted by another.
 Lasers’ pure color is responsible.
 Oxyhemoglobin in blood: Absorption of
UltraViolet, blue and green light
 Melanin a pigment in skin, hair, moles etc:
Absorption of visible and near Infrared light
 Water in tissues: Transparent to visible light

23. 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

25. Excimer Laser
 Excited Dimer
 Noble gas halide
 Photoablative effect-Cool Laser
 Ophthalmologic sugeries like LASIK,
PRK.

26. Argon Laser
 Tissue depth penetration only 1mm-
Superficial coagulation
 Precise cutting with minimal damage to
adjacent tissue
 Absorbed best in Red,Black tissue
 Retinal photocoagulation
 Arterial Recanalisation

28. Dye Laser
 Pulsed Lasers
 Organic Dyes like Kiton Red,Rhodamine.
 Tunable Lasers
 Dye can be replaced-Different wavelengths
with same laser
 Port-wine stains,Pigmented lesions

30. Co2 Lasers
 Most effective Laser Scalpel
 0.1mm zone of Histologic Necrosis
 Cutting & Vapourising Instrument
 Seals lymphatics as it cuts through,decreasing
spread of malignant cells
 Loss of tissues through Evaporisation
 Skin resufacing- Laser Facelifts

31. Nd:YAG Laser
 Most widely used in medical field
 High penetration capacity of >5mm
 Photocaogulation
 Endoscopic Laser
 To arrest bleeding GI varices
 Debulking GIT & Pulmonary tumours
 Coagulates Bladder tumour

32. Ho:YAG
 Treats tissue in a liquid-filled environment
(e.g., saline, blood)
 Endoscopic Laser
 Orthopaedic Laser used in Arthoscopy
Er:YAG
 Shallow penetration
 Extreme surgical precision

33. Diode Laser
 Semiconductor devices that emit Laser light as
electric current passes through them
 Tunable laser
 Fiberoptic delivery system
 Photocoagulation for general surgery
 Hair removal

34. KTP Laser
 Fiberoptic delivery system
 Cholecystectomy

35. Applications
Vascular Malformations of GIT
 Diffuse gastric antral vascular ectasia
 Colonic vascular malformation
 Argon & Nd:YAG lasers
 Photocoagulation therapy
 80% success rate in contolling recurrent
blood loss & subsequent transfusions

37. Upper GIT Carcinoma
 Early Gastric cancer
 Endoscopic laser therapy (Nd:YAG) can
eliminate cancers completely
 3 Requirments:Lesion <4cm with no
lymphnode metastasis,Followup,operator
 Advanced carcinoma it is a palliative
procedure to relieve obstruction,dysphagia
or bleeding

38.  Destroy neoplastic tissues & recanalise
lumen
 Relief of dysphagia 92%,perforation 10%
 Outpatient basis

39. Colorectal Cancer
 Laser therapy with Nd:YAG indicated in
 Patients with Metastatic or unresectable
local disease
 In Obstruction,Haemorrhage for Palliative
therapy

40. Liver
 Fibrotic Liver Resection
 Controlled resection of liver without
bloodloss possible
 Nd:YAG Laser with tissue contact tip
 Insitu ablation of Intrahepatic
malignancies (metastases)
 Palliation in HCC

41. Bile duct stones
 Laser Lithotripsy
 Coumarin pulsed dye laser
 For Bileduct stones that can’t be extracted
easily
 Break stones into small fragments which
pass spontaneously
 Light energy to Acoustic energy

42. Haemorrhoidectomy
 CO2 or Nd:YAG Laser with contact tip
 Like scalpel precisely cut through pile mass,
melt them & subsequent sloughing
Neurosurgery-Nd:YAG
 AV malformations
 Highly Vascular Meningiomas
 Lesions at inoperable sites like Base of
skull,midbrain,floor of fourth ventricle

43. Laparoscopic Surgery
 CO2 Laser
 Argon laser & Nd:YAG with contact tips
 Endometriosis
 Cholecystectomy (KTP/Nd:YAG)
 Lymphadenectomy (KTP)
 Posterior trunca vagotomy in peptic ulcer disease

44. Vascular Applications
 Laser Endarterectomy – Argon laser
 Smart Laser- Reflective Fluorescent spectral data
 Combination of Helium laser for fluorescence
excitation & Holmium laser for plaque ablation are
tried
 Laser Angioplasty – Co2,Argon,Nd:YAG
Laser angioplasty .av i

45.  Laser assisted balloon angioplasty done in
localised lesions of common iliac & superficial
femoral artery
 Prosthetic graft stenosis – Argon laser Angioplasty

46. Urology
 Renal stones - Laser lithotripsy
 Coumarin-based pulsed dye laser
 Light energy is delivered through Flexible quartz
fibers, directed Endoscopically onto a calculus
 Mechanism of action occurs via plasma
formation between the fiber tip and the calculus,
which develops an acoustic shockwave that
disrupts the stone along fracture lines
 Endoscopic extraction

47. BPH
 Photovaporisation - Tissue water is vaporized
resulting in an instantaneous debulking of
prostatic tissue.
 KTP or Greenlight is commonly used for its
vaporization effects on prostate tissue.
 Less bleeding and fluid absorption than standard
TURP
 Lack of tissue obtained for postoperative
pathological analysis

48. Urothelial stricture Disease
 Nd:YAG, KTP, and Ho:YAG lasers have all been
used experimentally to vaporize fibrous strictures
Urothelial malignancies
 Transitional cell carcinoma of bladder,
ureter, and renal pelvis
Skin lesions
 CO2 Lasers - Condyloma acuminata, Haemangioma
of external genetalia,early penile carcinoma.

49. Advantages
 Bloodless field
 Excellent Haemostasis
 Excellent Healing
 Allow precise Microsurgery
 Less postoperative pain & oedema
 Lower infection rate
 Outpatient procedure

50. Precautions

53. Laser Plume
 High Filtration surgical masks
 Smoke Evacuation units

54.  Drapes, Towels – Wet
 Fire Extinguisher, Water/Saline
 Water/Saline saturated fire retardant materials
 Laser safety officer- Hazard zone, Minimal access

55. Disadvantages
 Atmospheric contamination: Laser Plume
 Mutagenic,Teratogenic or vector for viral infection.
 Interstitial pneumonia
 Bronchiolitis
 Reduced mucociliary clearance, inflammation

56.  Misdirection of laser energy
 perforation of viscous or large blood vessels
 Eye damage
 Skin damage
 Fire and explosion:
 Gas embolism:
 laparoscopic or Hysteroscopic laser surgery

57. THANK YOU