laser in urology in different urology diseases

2. By

3. Laser Physics

4. .
The word "laser " is an acronym for
Light
Amplification by
Stimulated
Emission of
Radiation
Lasers are devices that produce intense beams of monochromatic,
coherent radiation

5. Laser Physics
Comparison of a Laser and an ordinary light source
Coherent
(in space and time) Non coherent
intensity
Monochromatic Polychromatic
I I
intensity
Collimated beam Divergent beam
laser Ordinary lamp

6. Effects of Laser:
1. Thermal effect.
2. Mechanical effect.
3. Photochemical effect.
4. Tissue welding effect.

7. Thermal effect:
Light energy is absorbed & transmitted into heat:
• 40-60 C ---------- Denaturation of protien
• 70 C -------------- Shrinkage of blood vessels
• 100 C ------------- Cellular dehydration
• 250 C ------------- Carbonization
• 300 C ------------- Vaborization

8. Mechanical effect:
When high power density is directed to a stone
Photochemical effect:
Selective activation of specific drug or molecule which may be given
systematically & uptake by selected tissues
Tissue welding effects:
Focusing light at particular wave length to induce collagen cross linkage.

9. Laser types and
clinical applications

10. Ruby laser
•The laser produces red light at a wavelength of 694 nm.
•The ruby laser is less efficient than more modern lasing materials.
•Used in a for removal of pigmented lesions and tattoos, with little
scarring.

11. CO2 laser
•The CO2 laser emits in the invisible far infrared portion, at
10,600 nm.
•It usually is coupled with a visible helium-neon beam for
guidance.
•Its beam is highly absorbed by water.
•Therefore, it vaporizes water-dense tissues to a superficial
depth of less than 1 mm.

12. Neodymium:yttrium-aluminum-
garnet laser
•ND:YAG is used commonly today because of its efficiency
•The Nd:YAG laser emits a beam at 1064 nm (near infrared)
•Deep penetration of as much as 10 mm because this frequency is
outside the absorption peaks of both hemoglobin and water
•It has good hemostatic (coagulates blood vessels as much as 5
mm in diameter) and cutting properties and also is suitable for
lithotripsy

13. Potassium-titanyl phosphate
crystal laser
•(KTP) laser, yields a green visible light beam of 532
•It is used for incisions, resection, and ablation

14. Alexandrite laser
•This is a tunable laser
•The wavelength range is from 380-830 nm
•This light is absorbed well by melanin; therefore, it can be
used for cutaneous lesions
•It is used for lithotripsy of pigmented stone
•This laser also can be used for tissue welding

15. Semiconductor diode laser
*Smaller, more efficient, and potentially cheaper than most
other lasers now in use.
*Their wavelength can be tuned.
*These lasers currently are used for tissue coagulation and
thermal treatment of solid organs, including the prostate.

16. Holmium:YAG laser
*Holmium:YAG (Ho:YAG) is a somewhat recent edition
*This laser energy is delivered most commonly in a pulsatile manner
*It is ideal for lithotripsy of all stone types
*The absorption depth in tissue is 1-2 mm, as long as it is used in a
water-based medium
*It also may be used for incisions.

17. Current laser applications

18. Laser therapy for
benign prostatic hyperplasia
•Laser prostatectomy
•The 2 main tissue effects are
ocoagulation
ovaporization

19. Coagulation:
•Coagulation occurs when somewhat diffusely focused laser
energy heats tissue to 100°C.
•Proteins denature, and necrosis ensues.
•This results in subsequent sloughing of necrotic tissue.
•This process often initially results in edema, which increases
prostate volume transiently (may require short-term Foley).

20. Vaporization
•Vaporization occurs when greater laser energy is focused
(increased power density) and tissue temperatures reach as high
as 300°C.
•This causes tissue water to vaporize and results in an
instantaneous debulking of prostatic tissue.

21. Types of laser :
1-Potassium-titanyl phosphate laser
(KTP, or Greenlight)
• Commonly used for its vaporization effects.
• This procedure is associated with significantly less bleeding and
fluid absorption than standard TURP.
• The KTP procedure is a safe and effective treatment option in
seriously ill patients or those receiving oral anticoagulants
• Drawbacks to the KTP procedure include the lack of tissue obtained
for postoperative pathological analysis.

22. 2- Neodymium:YAG
•Nd:YAG is used most commonly for its coagulative effect
•The procedure is termed visual laser ablation of the prostate
(VLAP)
•The postoperative course may be complicated by irritative voiding
symptoms because of the disrupted urethral epithelium

23. 3- Ho:YAG
*The Ho:YAG laser have been used to incise or enucleate prostate
adenomas down to the capsule
*The Ho:YAG is ideally suited for this task because it creates
precise incisions, cuts by vaporizing tissue with adequate
hemostasis, and leaves minimal collateral damage
*Advantages of this method include the availability of a specimen
for histologic examination, less postoperative catheter time, and
the ability to excise large adenomas

24. Ablative Therapy for
Renal Tumors

25. Ablative Therapy for Renal Tumors:
Laser Interstitial Thermal Therapy (LITT)
• LITT has relied on neodymium : yttrium-aluminum-garnet (Nd :
YAG) lasers and diode lasers.
• Treatment temperatures of greater than 55° C are achieved, and
tissue necrosis results.

26. Laser lithotripsy:

27. Holmium:YAG laser
holmium laser lithotripsy occurs primarily through a
photothermal mechanism that causes stone vaporization
Advantages
• The holmium:YAG laser can transmit its energy through a flexible fiber.
• the holmium:YAG laser is safer and more efficient , the holmium laser
may be safely activated at a distance of 0.5 to 1 mm from the ureteral wall.
• Mean perforation and stricture rates are generally in the range of 1% to
2%.

28. • The holmium laser is one of the safest, most effective, and most
versatile intracorporeal lithotripters.
• The ability of the holmium laser to fragment all stones regardless of
composition
• Production of significantly smaller fragments as compared with other
lithotrites.
• The holmium laser produces a weak shockwave, which reduces the
likelihood of retropulsion of the stone
• The required eye protection for the holmium laser does not
compromise the ureteroscopic view of the stone or the fiber.

29. Disadvantages:
• The major disadvantage of the holmium laser is the initial
high cost of the device and the cost of the laser fibers.
• However, the laser fibers are reusable, so that the effective
cost of the holmium laser device and reusable fibers may be
lower than others.

30. • The fracture of a laser fiber inside of an endoscope can result
in a catastrophic failure of the scope, as when this occurs the
fiberoptic bundles that transmit images and light are generally
destroyed.
• A potential side effect of holmium laser lithotripsy is the
production of cyanide when uric acid stones are treated, which
has been reported in vitro. However, a review of clinical
experience suggests no significant cyanide toxicity from
holmium laser lithotripsy.

31. Technique:

32. Non–muscle-invasive
bladder cancer

33. Type of laser:
• The Neodymium : yttrium-aluminum-garnet (Nd : YAG)
laser has the best properties for use in bladder cancer by
deep tissue coagulation.
• The Neodymium : yttrium-aluminum-garnet (Nd : YAG)
laser has the best properties for use in bladder cancer.

34. Indication:
• Tumors up to 2.5 cm in size.
• Because there is no tissue available for pathologic
inspection, the optimal candidate for laser therapy is the
patient with recurrent, low-grade lesions whose biology
is already known.
• Additional information regarding tumor grade may be
obtained with a cold cup biopsy if necessary.

35. Complication:
• The most significant complication of laser therapy is forward
scatter of laser energy to adjacent structures, resulting in
perforation of a hollow, viscous organ such as overlying bowel.
• This is rare but most commonly occurs with the (neodymium :
YAG laser) because of its deeper tissue penetration than with
(holmium : YAG) and KTP lasers.

36. How to avoid:
• Limiting energy to 35 W precludes exceeding 60° C on the
outer bladder wall, minimizing the risk of perforation.
• Treatment should be under direct visualization and should
discontinue as soon as protein denaturation is evident by the
white appearance of the treated tissue.

37. Laser Therapy for
penile cancer:

38. Indication:
• Laser therapy has been extensively evaluated as a form of
conservative treatment of penile squamous cell carcinoma:
o Tis and
o small T1 squamous cell carcinoma of the penis, and for
o patients with manageable T2 tumors who refuse more aggressive
surgical treatment.
The lasers most commonly reported for this purpose are:
• The carbon dioxide (CO2),
• Neodymium:yttrium-aluminum-garnet (Nd:YAG), and
• Potassium titanyl phosphate (KTP).

39. The carbon dioxide (CO2):
• The laser energy is absorbed by intracellular water, resulting in
vaporization to a skin depth of 0.01 mm.
• For these reasons, it has been most often used as monotherapy
for treatment of dysplastic lesions and squamous cell carcinoma
in situ.
• a local recurrence rate of up to 33% has been reported.

40. Neodymium:yttrium-aluminum-garnet (Nd:YAG):
• The laser most commonly reported in the treatment of squamous cell
carcinoma has been the Nd : YAG laser.
• It has a depth of penetration of 3 to 6 mm and therefore is considered to
potentially be more appropriate for treating small superficial penile lesions.
• When the Nd : YAG laser is used alone for carcinoma in situ and T1
squamous cell carcinoma, the local recurrence rate has been approximately
20%.
• The Nd : YAG laser has also been used in combination with surgical excision,
with the hope of improving treatment efficacy.

41. Potassium titanyl phosphate (KTP):
• The KTP (532-nm wavelength) laser has also been used
successfully in the treatment of superficial penile carcinoma.
• It has an intermediate depth of penetration relative to the CO2
and Nd : YAG lasers, and better hemostasis than the CO2 laser.

42. Disadvantages:
• Difficulty in determining the exact depth of laser coagulation;
• Inability to treat larger lesions; and
• Potentially difficult healing in patients who are obese, immunocompromised,
or receiving anticoagulation therapy.
• Postoperative healing generally requires 8 to 12 weeks for the Nd : YAG and
KTP lasers, but overall cosmetic results are generally good.
• Erectile function after combined CO2 and Nd : YAG laser treatment of
penile squamous cell carcinoma was unaltered in 72% of patients in one
study.
• As with any form of conservative treatment, careful long-term surveillance
is essential

43. Lasers for
urethral stricture:

44. Types of lasers that have been used:
• carbon dioxide,
• argon,
• KTP,
• Nd : YAG,
• holmium : YAG

45. Lasers for the ablation of
skin lesions

46. •Lasers offer minimal scarring and superior cosmetic results
when compared with other forms of cutaneous lesion
resection
oCondyloma acuminata
oCutaneous hemangiomas (highly indicated)

48. •Laser energy is applied in a constructive manner to
reapproximate tissues
•The results are very promising thus far, with good tensile
strength, watertight seals, and minimal scar formation

49. This technology may be particularly helpful in laparoscopic
surgery:
*Vasovasotomy for vasectomy
*Hypospadias repair
*Pyeloplasty
*augmentation cystoplasty
*urinary diversion. Proposed future
*laparoscopic ureteroureterostomy
*laparoscopic Pyeloplasty
*laparoscopic Ureteroneocystostomy
*laparoscopic bladder and bowel anastomoses