Bioengineering Laser

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BioengineeringLaser Ultraviolet Safety Update

• John Saunderson
• Radiation Protection Adviser
• TPRH ext. 6690

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Classifications of LightThe visible the
invisible

• The Electromagnetic Spectrum
• from 100 nm to 1000 ?m

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Ultraviolet Hazards

• Erythema (sunburn)
• appears 2 to 4 h after exposure
• peaks after 8-24 h
• may take several days to resolve
• v. high doses give blistering

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Ultraviolet Hazards

• Photokeratitis
• inflammation of cornea - severe pain
• 30 min to 24 h to appear
• clears up after 2 days
• Conjunctivitis
• inflammation of inside of eyelids
• gritty eye
• aversion to light
• lacrimation (tears)
• blepharospasm (spasm of eyelid muscles) .

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Ultraviolet Hazards

• Photokeratitis
• Conjunctivitis

• Cataracts
• loss of transparency of lens
• sunlight has a role - UVB main culprit .

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Ultraviolet
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Patient with plaque psoriasis
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UV treatment of psoriasis
Erythema
clearance of psoriasis
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1
UVA
UVC
0.1
UVB
Relative effect
0.01
0.001
0.0001
250
275
300
325
350
375
400
Wavelength / nm
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Relative Spectral Power of UV Therapy lamps
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P soralenU ltra-V ioletA
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• PUVA treatment for psoriasis

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Typical UV Therapy Equipment
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Max. Permissible Exposuresin any 8 hour period
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Bioengineering Staff safety

• Keep away from primary beam
• Wear appropriate UV safe eyewear
• If necessary, wear UV-opaque clothing
• Consider safety of others .

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Lasers
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40 W bulb vs 5 mW laser

• Bulb gives approx. 2 W of light
• So bulb 400 x more light than laser
• Light from bulb diverges, light from laser 1 mm
  dia.
• At 1 m laser 50,000 x brighter than bulb.

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Horses for Courses
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Visible light
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• CO2 laser

IRA
IRB
IRC
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• Carbon dioxide
• surgical laser

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Incident beam
Focal point
Mirror
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• CO2 laser

NdYAG laser ?
IRA
IRB
IRC
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• KTP / NdYAG laser

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• CO2 laser

NdYAG laser ?
Argon laser ?
VIBGYOR
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Ophthalmic Argon Laser
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Ophthalmic Laser Photocoagulator
Fibre optic laser input
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Run V/T
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Laser Safety Classes

• Class 1 - Totally safe
• Class 2 - Safe for accidental viewing
• Class 3A - Safe unless viewed with optical
  instruments
• Class 3B - Hazardous to eyes. Eye protection
  needed
• Class 4 - Even diffuse reflections may be
  hazardous to eyes. Eye protection needed.
• Direct beam specular reflections hazardous to
  eyes. Eye protection needed
• Direct beam specular reflections hazardous to
  skin. Skin protection needed
• Fire hazard.

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New laser safety classes

• Class 1 - unchanged
• Class 1M - safe under reasonably foreseeable
  conditions if optical instruments are not used
• Class 2 - unchanged
• Class 2M - visible, safe if no optical
  instruments
• Class 3R - eye hazard
• Class 3B - eye hazard (some current class 3B
  products will qualify for class 1M or 2M)
• Class 4 - Unchanged

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Laser Safety Structure

• Controlled Area
• Local Rules.

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Local Rules (How to work safely)

• Specific to each laser
• What are hazards?
• Controlled area - limit area of hazard - signs
• Users Laser Protection Supervisor
• Safety precautions (e.g. eyewear, blinds)
• Methods of safe working, etc.
• Adverse incident procedure, LPA, etc.

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Laser Safety Structure

• Controlled Area
• Local Rules
• Laser Protection Supervisor
• Eye Clinic - Pat Savage
• Eye Hospital - Denise Oliver
• Laser Protection Adviser
• Authorised Operators and Assistants

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MDA One Liners - Eye risk? August 2002 (Issue
17)

• MDA has become aware of the use of inappropriate
  filters for lasers used in ophthalmic surgery.
  This can lead to permanent eye damage for the
  operator.
• When connecting a laser to a protective system
  with filters, ensure that the wavelengths of
  laser radiation for which the filter offer
  protection match the output wavelength of the
  laser. If a fault is suspected with the filters,
  the procedure should be discontinued and the
  filters examined by a trained engineer.

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Example

• Laser
• 520-575 nm Green, 2 W
• 568-575 nm Yellow, ?1 W
• 670 nm Red (aim), lt 5 mW
• Goggles labelled
• 560-570 nm ODgt4
• 570-580 nm ODgt5
• 580-650 nm ODgt6

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Example

• Laser
• 520-575 nm Green, 2 W
• 568-575 nm Yellow, ?1 W
• 670 nm Red (aim), lt 5 mW
• Goggles labelled
• 560-570 nm ODgt4
• 570-580 nm ODgt5
• 580-650 nm ODgt6

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MDA One Liners - Hind Sight? March 2000 (Issue
8)

• Two separate incidents reported to MDA involving
  faulty laser equipment resulted in permanent
  retinal damage (one to a patient and one to the
  operator). In both cases, the operator had
  noticed that the equipment was behaving unusually
  but carried on with the procedure.
• Abnormal performance of any equipment should be
  questioned immediately.

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Laser Eyewear Labelling

• DI 1060 L7 X Z
• 620 TO 700 nm OD 2
• CARBON DIOXIDE, O.D. 10 _at_ 10600 NM
• DIR 690 - 1290 L4
• D 1064 L7, IR 1064 L8, DIR 1350 - 1400 L7, DIR gt
  1400 - 1580 L5, DI 2090 - 2100 L5, DI 2900 - 2940
  L5
• D continuous wave laser, I pulsed laser (0.1
  ms - 100 ms)
• R giant pulsed laser (1 ns - 10 ?s), M
  mode-coupled pulse laser (lt 1 ns)

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Laser Eyewear Labelling

• DI 1060 L7 X Z
• 620 TO 700 nm OD 2
• CARBON DIOXIDE, O.D. 10 _at_ 10600 NM
• DIR 690 - 1290 L4
• D 1064 L7, IR 1064 L8, DIR 1350 - 1400 L7, DIR gt
  1400 - 1580 L5, DI 2090 - 2100 L5, DI 2900 - 2940
  L5

D continuous wave laser, I pulsed laser (0.1
ms - 100 ms) R giant pulsed laser (1 ns - 10
?s), M mode-coupled pulse laser (lt 1 ns)
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Ultima 2000 Argon Laser

• Argon ion visible lines (8 UV lines and 2 IR
  lines ignored)
• Blue 454.6 nm, 457.9 nm, 465.8 nm, 476.5 nm,
  488.0 nm, 496.5 nm,
• Green 501.7 nm, 514.5 nm, 528.7 nm.

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Run V/T 2
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f i n
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Uses of Light in Medicine

• Visual examination
• Phototherapy
• Photochemotherapy
• Lasers - thermal effects
• Infrared physiotherapy
• Infrared imaging
• Luminescence (e.g. chemi, thermo)
• Scintigraphy (nuclear med. scans)

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