lasers in dermatology by qingyunliuliu

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									               Lasers in Dermatology



                                 Port Wine Stain




Pulsed Dye   Ruby   Erbium YAG
How does laser help in dermatology ?
 When a laser beam is directed at the skin, it is absorbed by the water, naturally
  occurring pigments like melanin and hemoglobin. It is also absorbed by artificial
  pigments introduced by means of tattooing.


 Lasers causes very precise tissue destruction of the lesion in focus and leaves the
  skin tissue in the immediate surrounding undamaged. It is this precision that has
  generated tremendous interest among dermato-surgeons to use it as an operative
  tool.

 Fine tuning of laser therapy requires knowledge of the exact relationship of the
  elements of the skin:

    - magnifier: to look at that edema fluid is playing a part in paling the pink skin color
    - high frequency ultrasound: skin depth (thickness of the epidermis) and relative
                                  water component in the upper dermis

 Difficulties of laser therapy: the size, shape, depth and distribution of the chromophore
                                 (pigment & hemoglobin) and its surrounding tissue are
                                 variables that influence the pattern and degree of
                                 response to laser therapy
Continue


 Intracelluar and extracellular water content influence the quality of the thermal effect
  produced by IR laser:

               - protein denaturation (40 deg.), coagulation (60 deg.)
               - vaporization (100 deg.), carbonization(300 deg.)

 The variability of the upper dermis is dependent on its water content.

 Patient satisfaction is not proportional to the amount of destruction. A full
  assessment of the lesion by contemporary technology is required.
Skin Anatomy


                                                                  (Melanin)


                                                               (Hemoglobin)




       Epidermis (Basal) layer:
       keratocytes & melanocytes (produce melanin & skin color)

       Dermis layer:
       Elastin & collagen fibers, blood vessels, nerves & receptors
Absorption Spectra of Skin


   OxyHb:542 & 574 nm
   DeoxyHb: 545 nm
                                                 deeply pigmented skin




                             lightly pigmented skin
With Respect To Pigmentation

 Normal Situation:
  most pigment is produced by the melanocyte in the basal layer of the epidermis and
  pump melanin into the epidermal cells




 Abnormal Situation:
  sometimes, melanin passing into the dermis, where it is taken up by macrophages
  and can remain at various depths within the dermis for years




 Differentiation Between Normal and Abnormal Melanin Location:
  Using Wood’s lamp (UV light), it is easy to detect whether the melanin is in the most
  superficial layers of the skin or whether it resides at a deeper level
With Respect To the Vascular

 Pinkness is due to hemoglobin in a blood vessel, which if it is compressed empties
  and this result in blanching.


 Most of the skin color comes from the horizontal subpapillary plexus of venules.
  However, in the case of the capillary loop disease (port wine stain, psoriasis), the
  vessels are located in the uppermost dermis and contribute most of the color.


 Skin color depends on the thickness of the epidermis and the amount of tissue fluid
 lying between the vessel and the epidermis


 Blue light reflected from the deeper layers of the skin passes through the epidermis
 with greater facility than red light. This is why some deep element like veins or blue
 nevi appear to be blue - whereas in fact they have red blood and reddish - brown
 pigment.
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 Blood that has leaked outside the blood vessel, known as purpura, does not blanch
 on pressure.

 Similarly, the loop of vasculature surrounded by epidermis will not always empty on
 compression

 Blood vessel in the skin: 100-300 um in diameter, larger than this in disease state.


Vascular Lesion Treatment:

  Lasers produce a yellow light , which is selectively absorbed by the red color in the
  veins. The energy is transformed into heat, causing temperature rise of above ~70
  degree to destroys the veins selectively, without damaging the normal surrounding
  skin.
Laser-Tissue Interaction

Laser Light:

 Spatially and temporally coherent

 Monochromatic: selectivity of target particular chromorphore

 Irradiance (W/cm^2) =
               laser power output (W) / laser beam cross-sectional area (cm^2)

 Fluence = (J/cm^2) =
[laser power output(w) * exposure time (sec)] / laser beam cross-sectional area (cm^2)


 Photothermolysis (heat damage): destroy specific celluar and subcelluar structure
                                      (denaturing, coagulation, vaporization, charring)
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Requirements:
 Appropriate wavelength


 Time to heat the target < thermal relaxation time (cooling time)


 Thermal relaxation time decreased with decreasing target size


 Penetration depth of laser through skin increase directly with the wavelength of the
  light:
        - longer wavelength > deeper penetration
        - vascular laser: <1.2mm at 565nm
        - Q-switched Nd:YAG: ~2mm
Laser Systems in Dermatology

                                                          Penetration depth




    CW, pulsed (pulse duration: microsecond & nanosecond)
    Q-switched: it has photooptical shutters that allow extremely short bursts of high-
     energy(~10^9 W > temperature rise 300 degree) laser light in the nanosecond
     range
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Argon Laser
 The Argon laser emits blue-green light at 488 nm and 514 nm. These wavelengths of light are preferentially absorbed
 by oxyhaemoglobin and, to a lesser extent, by melanin in the skin. The light energy absorbed by erythrocytes within
 blood vessels is converted to heat, leading to red cell destruction and thrombosis of small vessels.

 Tunable Dye Laser 577 nm
 By increasing the wavelength of light from 577 nm to 585 nm the penetration depth is increased from 0.5mm to 1.2
 mm in port wine stained skin while maintaining the same degree of vascular selectivity.

 Pulsed Tunable Dye Laser
 By using microsecond impulses it is possible to confine thermal injury to targetted blood vessels without heat diffusion
 to surrounding tissue.

 Carbon Dioxide Laser
 Carbon dioxide laser therapy removes tattoo pigment after vapourisation of the epidermis and superficial dermis and is
 used also for skin resurfacing. Although effective, this laser has a high incidence of scarring and pigmentary
 disturbances in inexperienced hands.

 Ruby laser
 Q-switching whereby high energy levels (5-10J/sqcm) are delivered in ultrashort pulse widths (10-80ns) of Ruby,
 Nd:YAG and Alexandrite lasers, has offered significant advances in the treatment of tattoos. Ruby lasers emit light at
 694 nm. The Ruby laser can also be used to treat green tattoos.

 Alexandrite Laser
 The Alexandrite laser, with a wavelength of 755 nm produces slower results than the Ruby and Nd:YAG Q-switched
 lasers, but may be of value in the treatment of tattoo pigments of other colours.

 Nd:YAG lasers
 Nd :YAG lasers emit light at 1064 nm. Frequency doubling of Nd:YAG laser light produces green light of wavelength 532
 nm. This green light can produce fading of red tattoo pigments.
Some Conditions Treated By Skin Lasers

 Use of effectiveness of the CO2 laser



                                         Effectiveness of Q-switched laser treatment
                                                     of pigmented lesion




                                           effectiveness of flashlamp-pumped dye laser
                                                    treatment of vascular lesion
Clinical Examples of Laser Treatments
               Hair Removal                     Port Wine Stain
                              Wrinkle Removal
 Facial Vein




                              Tattoo



   Acne
               Telangiectasia:
Nevus of Ota   모세혈관확장증           Rosacea:장미여
                                 드름,딸기코
PORT WINE STAIN ?
 A vascular birthmark consisting of superficial and deep dilated capillaries in the skin
  which produce a reddish to purplish discoloration of the skin.
 0.3 % (3/1000)
 Port-Wine Stains occur most often on the face but can appear anywhere on the
  body. Early stains are usually flat and pink in appearance. As the child matures, the
  color may deepen to a dark red or purplish color.

Treatment:
 Early Attempt: cosmetic cover-up, skin grafting, radiation, dermabrasion,
   cryosurgery, tattooing, & electrotherapy.
 Laser: Pulsed dye laser (585 nm), 450 msec, 7 or 10 mm spot size, 6~15 (J/cm^2).




                  before                            after
Imaging Method For PWS Evaluation



Imaging system                       Head positioning
                                         device




                 Image acquisition
                     method
Quantitative Evaluation of Port Wine Stain




Before            E.I.: 15.8, 26.1




After             E.I.: 15.5, 20.6
Lasers in Gynaecology
Comparison of Lasers Used in Gynaecology
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 CO2 Laser (10.6um)
          - colposcopic procedure and laparotomy.
          - minimal depth of thermal injury.
          - less coagulating power and non-contact laser.
          - It cannot be transmitted down a fiber, so it cannot be use for operative
            hysteroscopy.
          - Recently, use of hallow fiber to deliver laser.
 Nd:YAG Laser (1064nm)
           - primary endoscopic instrument
          - used for deep coagulation
          - need aiming beam (He-Ne)
          - use of contact sapphire tip to increase its precision


 Argon & KTP (potassium titanyl phosphate) Laser
          - similar to Nd:YAG in use
          - best used as color selective photocoagulator
Use of Lasers




               Less thermal effect


   Pulse power and duration are      Depending on the kind of
   controlled to obtain desired      treatment desired, beam focused
   effect                            can be changed
Laparoscopy (개복술) & Laparotomy (복강경 수
              술) with Lasers
Endometriosis (자궁내막증)
- A common condition affecting women in the productive age group leading to
 infertility(불임), pain and dysmenorrhoea (월경통)
- CO2 laser is more effective but has disadvantages due to water absorption
- Argon laser may have benefit because of its color spectrum
- Related to pregnancy rate: 62% for mild, 52% for moderate, 42% for severe


Treatment Methods
- Excision of endometriomas
- Vaporization of the endometriotic implants
- Ovarian cystectomy
- Uterosacral nerve ablation & presacral neurectomy
Fibroids & Other Conditions of Uterus

Myomectomy (근종절제술):
- Removal of subserous and interstitial fibroids
- Suited for fibroid size less than 8-10 cm & numbering 4 or less
Continue
Laparoscopic Myolysis (근육용해)
- Involves multiple punctures of the fibroid with the laser fiber so that the
 vasculature is desiccated and a reduction in size is achieved.
- Concentric puncture: 5 mm apart at 30-50 W
- Fibroids of 3-10 cm in size & less than 4 in number
- 30 - 40% reduction in size of myoma (근종) after surgery


Hysterectomy (자궁절제술)
- Laser may be used as a cutting and coagulating tool during laparoscopic assisted
 vaginal hysterectomy (LAVH)
- Nd:YAG laser


Metroplasty (자궁절제술)
- Laser may be used during metroplasty for bicornuate uterus
- Incision of the uterus with laser
Tubal Disease
Tubal disease is one of the most frequently cause of female infertility accounting for
40% of cases.
Ectopic Pregnancy (자궁외 임신)
- Laparoscopic linear salpingostomy (난관개구술) is ideal for an unruptured ectopic
 pregnancy in the distal tube
- Salpingectomy (난관절제술) is indicated with large, ruptured ectopic pregnancies or
 when conservation of the tube is not a priority
- CO2, Nd:YAG, Argon laser
- advantages of laser: precise cutting and haemostasis (지혈)
Proximal tubal disease
Distal tubal disease
Ovarian Cysts (난소주변낭)
Ovarian Drilling:
- Polycystic ovarian syndrome is a common cause of anovulation (무배란) and
 infertility in women. Women with this syndrome do not ovulate regularly and have
 ovaries that contain multiple small cystic structures, usually about 2-9 mm in
 diameter. This gives the ovaries a characteristic "polycystic" (many cysts) appearance
 on ultrasound – see images below.
- Polycystic ovarian may be treated by drilling multiple holes in the ovarian stroma to
 decrease androgen production by destruction of ovarian cysts
- CO2 & Nd:YAG
Ovarian Cystectomy
Hysteroscopic Procedures with Laser
Endometrial Laser Ablation (ELA): 자궁속막
- New technique for treatment of dysfuntional uterine bleeding & menorrhagia
 associated with fibroids
- Nd:YAG laser: contact or non-contact technique
Hysteroscopic Resection of Myoma (hysteroscopy: 자궁경검사)
- Suitable for patients with one or two submucous fibroids, less than 6 cm in diameter
- Nd:YAG laser
Hysteroscopic Resection of Septum (사이막)
- Nd:YAG laser in the hysteroscopic resection of septate uterus (자궁사이막증)
- Resectocope(절제경) is most commonly used followed by scissors and laser
Continue
Hysteroscopic Myolysis
- Suited for large submucous fibroids with largest portion inside the myometrium(자궁
  근육층) which cannot be dealt with by hysteroscopic resection alone
Colposcopy with Lasers

Cervical Intraepithelial Neoplasia (자궁목 상피종양) (CIN)

-   Laser vaporization
-   laser excision
-   photodynamic therapy
-   CO2 laser

Vaginal Intraepithelial Neoplasia (처녀막상피종양) (VAIN)

- CO2 laser

Vulvar Intraepithelial Neoplasia (외음성상피종양)(VIN)

- CO2 laser excision is preferred to ablation treatment than laser vaporization
- Photodynamic therapy
Assisted Reproductive Techniques (ART)

- Laser works without actually physically touching the cell and does not have any
  traceable toxic effect.

- Immobilization of sperms prior to intracytoplasmic sperm injection

- Zona drilling(투명대 천공) & thinning for “assisted hatching” with improved
  implantation and pregnancy rate is one of the microsurgical techniques widely used to
  facilitate sperm penetration
Future Trends of Lasers in Gynaecology

- Free electron laser

- Better laser delivery system

- Newer delivery system for CO2 laser

- Other wavelength of laser

- PDT

- Diagnostic Aids:
  endoscopic holography: 3-D endoscopic picture of the tissue with aids of
                         laser

								
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