The Safe Use of Lasers in Clinical Practice John Saunderson Laser Protection Adviser Hull & East Yorkshire Hospitals
Content Welcome Nature of laser radiation Laser classes & hazards Local safety systems Operational safety Q & As.
Light Amplification by the Stimulated Emission of Radiation
40 W bulb - 5% efficient 2,000 x light energy from 1 mw laser pointer At 1 metre 40 W bulb = 3.2 W/mm 2 1mW laser pointer = = 1 mw/mm 2 (300 x bulb), or = 0 W/mm 2 40 W surgical laser 40,000 x laser pointer
1 mm beam focussed to 20 microns (1000/20) 2 = 2500 power density
Absorption (log scale) 12.5 melanin Ar HbO 2 Nd:YAG Ho:YAG water CO 2 0 2000 400 1000 5000 10000 12.5 Wavelength (nm) Visible Green 532 nm Red 633 nm Invisible Nd:YAG 1064 nm CO 2 10600 nm
Continuous beam Single pulse Interrupted pulses
Laser Device Classes & Hazards Class 1 Class 1M Class 2 Class 2M Class 3R Class 3B Class 4 Applies to device as a whole.
Video
Class 1 no risk to eyes (including using optical viewing instruments) no risk to skin (either low power device or totally encased)
Class 1M no risk to the naked eye no risk to skin
Class 2 no risk to eyes for short term exposure (including using optical viewing instruments) no risk to skin (visible, so blink response protects) (may cause dazzle or flash blindness)
Class 2M no risk to naked eye for short time exposure no risk to skin
Class 3R low risk to eyes no risk to skin (risk for intentional intrabeam viewing only) (may be a dazzle hazard)
Class 3B medium to high risk to eyes low risk to skin (aversion response protects skin, or must be focussed to such a small spot that pin-prick effect only)
Class 4 high risk to eyes and skin low risk to skin (diffuse reflection may be hazardous) (possible fire hazard)
HEYH Trust CP137 Health & Safety at Work Policy - Lasers - Includes safety of class 3B and class 4 lasers
Laser Safety Structure Risk assessment Controlled Area Local Rules Laser Protection Supervisor Laser Protection Adviser Authorised Operators and Assistants
Risk Assessments
Risk Assessments
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.
Laser Protection Supervisor
Laser Protection Adviser
Authorised Users
Hull and East Yorkshire Hospitals NHS Trust L A S E R S A F E T Y AUTHORISED LASER OPERATOR ( C L I N I C A L) Laser: I have read and understand the Trust Laser Radiation Health & Safety Policy, the Local Rules & relevant sections of the manufacturer s instructions for the above laser I understand the responsibilities of Authorised Operators towards staff and patients, and undertake to use the laser in a safe manner, within my clinical competence. Name: Position: Signature: Date: If the operator is not a Consultant, this statement should be countersigned by the appropriate Clinical Coordinator or Consultant: (This statement should be kept by the Laser Protection Supervisor, and a copy sent to the Laser Protection Adviser).
Authorised Users
Incidents
Example
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.
Example Laser 520-575 nm Green, 2 W 568-575 nm Yellow, 1 W 670 nm Red (aim), < 5 mw Goggles labelled 560-570 nm OD>4 570-580 nm OD>5 580-650 nm OD>6
Example Laser 520-575 nm Green, 2 W 568-575 nm Yellow, 1 W 670 nm Red (aim), < 5 mw Goggles labelled 560-570 nm OD>4 570-580 nm OD>5 580-650 nm OD>6
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.
Laser Eyewear Labelling DI 1060 L7 X Z 620 TO 700 nm OD 2 CARBON DIOXIDE, O.D. 10 @ 10600 NM DIR 690-1290 L4 D 1064 L7, IR 1064 L8, DIR 1350-1400 L7, DIR > 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 (< 1 ns)
Wavelength Number before the L in nanometres Colour of beam May be single number (e.g. 10600) or a range (e.g. 2090 2100) Wavelength on laser should fall within range on eyewear
Optical Density Number after the L Strength of filter OD 1 only 1 / th 10 of laser light transmitted OD2-1 / th 100, OD3-1 / th 1000, etc. Local rules should say strength required. Note higher ODs may be very dark
DIR 690-1290 L4 1 / 10000 th of 690-1290 nm laser light transmitted Laser Wavelength Suitable? CO 2 10600 nm Ho:YAG 2100 nm Nd:YAG 1060 nm LaserTripter 504 nm Argon 477 or 515 nm
1047-1400 DI L7 1047-1350 R L8 > 1350-1400 R L7 >1400-1580 DI L5 2090-2100 DI L5 2900-2940 DI L5 10600 DI L5 Laser Wavelength Transmission CO 2 10600 nm 1/100,000 Ho:YAG 2100 nm 1/100,000 Nd:YAG 1060 nm 1/10,000,000 LaserTripter 504 nm? Argon 477 or 515 nm?
Other Hazards Fire Anaesthetic gas ignition Plumes
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