This slide presentation has been prepared for Temple University Health System and is intended only for use by it s faculty, staff and students. All questions pertaining to this presentation should be directed to EHRS.
LASER SAFETY TRAINING FOR TUHS EMPLOYEES by Dr. Eyas Amr Senior Laser Safety Officer Environmental Health & Radiation Safety Temple University
UNDERSTANDING LASER SAFETY In order to understand laser safety the following questions need to be answered: What is a laser? What are the potential hazards? How can these hazards be prevented?
WHAT IS A LASER? L ight A mplification by Stimulated Emission of Radiation The light emitted by a laser is non-ionizing electromagnetic radiation, that is, ultraviolet, visible, or infrared light
WHAT IS A LASER? Stimulated Emission Incident Photon Excited Atom Incident Photon Stimulated Photon same wavelength same direction in phase
LASER BASICS - Laser light differs from ordinary light in 3 ways: - Monochromatic - Directional - Coherent - These three properties allow a laser to focus a lot of energy onto a small area
DEFINITIONS: Monochromatic - one single color or wavelength. Directional - Collimated, traveling in one direction Coherent all the individual waves of light are moving precisely together through time and space, i.e. they are in phase.
LASER BASICS -DESIGN Feedback mechanism ACTIVE (LASING) MEDIUM Solid (Crystal) Gas Semiconductor (Diode) Liquid (Dye) EXCITATION MECHANISM Optical Electrical Chemical OPTICAL RESONATOR HR Mirror and Lasing Output medium Coupler The Active Medium contains atoms which can emit light by stimulated emission. The Excitation Mechanism is a source of energy to excite the atoms to the proper energy state. The Optical Resonator reflects the laser beam through the active medium for amplification. Output coupler
Laser Temporal Outputs
The Electromagnetic Spectrum
The Electromagnetic Spectrum Region Ultraviolet (UV) UV-C UV-B UV-A Visible (Light) Near Infrared Far Infrared Wavelength 100 to 400 nm 100 to 280 nm 280 to 320 nm 320 to 400 nm 400 to 700 nm 700 to 1400 nm 1400 nm to 1 mm
LASER Classification Lasers and laser systems are assigned one of the four broad classes (1 to 4) depending on the potential for causing potential damage. Class 1: "safe" if not disassembled. Example: Laser printers, CD-Rom players/drives Class 1M: is safe for all conditions of use except when passed through magnifying optics such as microscopes and telescopes. Examples: Fiber-optic communication systems.
LASER Classification Class 2: dangerous if viewed more than 0.25 seconds, but still does not pose significant eye hazards. Example: Supermarket scanners Class 2M: is safe because of the blink reflex if not viewed through optical instruments. Eye is protected by blink reflex if not viewed by optical instruments. Example: level and orientation instruments for civil engineering applications
LASER Classification Class 3R: is considered safe if handled carefully, with restricted beam viewing. Direct intrabeam viewing is potentially hazardous. Visible continuous lasers in Class 3R are limited to 5 mw. Example: alignment lasers. Class 3B: eye hazards if beams are viewed directly or specular reflections are viewed. Example: research
LASER Classification Class 4: eye hazards if beams are viewed directly or specular reflections and sometimes even from diffuse reflections. The power output for class 4 is above 500 mw. Skin burns from direct beam exposure. Example: research lasers, manufacturing, and medical lasers
Viewing Laser Radiation Figures 1, 2, 3 below illustrate the different ways laser radiation can be viewed and therefore the different types of exposures an individual may encounter. Figure 1. Intrabeam viewing of direct (primary) beam. This type of viewing is most hazardous. Note that the diagram also illustrates that a laser beam may diverge as it propagates.
Viewing Laser Radiation Figure 2. Intrabeam viewing of a specularly reflected (secondary) beam from a flat surface reflector.
Viewing Laser Radiation Figure 3. Diffuse viewing of a diffusely reflected (secondary) beam from a rough surface in which a collimated beam is reflected in all directions.
Laser Exposure Limits Maximum Permissible Exposure (MPE): is defined as the level of laser radiation to which a person may be exposed without hazardous effect or adverse biological changes in the eye or skin. The MPE of a specific laser is determined based on the wavelength and exposure duration.
Laser Exposure Limits Nominal Hazard Zone (NHZ) is the space within which level of the direct, reflected, or scattered radiation during normal operation exceeds the applicable MPE. Exposure levels beyond the boundary of the NHZ are below the appropriate MPE level.
TWO TYPES of LASER HAZARDS - Non-beam related - Beam related hazards
NON-BEAM RELATED HAZARDS Hazards associated with the generation of the laser beam - Electrical - Chemical
NON-BEAM RELATED HAZARDS - Electrical - High voltage many lasers require high voltage to generate the laser beam - Accidental exposure can result in electrical shock or death - Chemical - Dye lasers use hazardous dyes to generate the laser beam - These dyes can be toxic or carcinogenic and require proper disposal
BEAM RELATED HAZARDS Hazardous effects related to unintentional direct contact with the laser beam -Skin related -Eye related -Interaction hazards
INTERACTION HAZARDS - Laser Generated Airborne Contaminates (LGAC) - Fire and explosion
LGAC (Plume) - Plume - smoke from vaporization - Creates a visibility problem - Can cause nausea - Potential health hazard
LGAC (Plume) Types of LGAC -Carbon - Aerosolized blood - Bacteria - Viral particulates -Gases including benzene, toluene and formaldehyde
FIRE AND EXPLOSION Can occur if the laser beam comes into contact with combustible or volatile materials, such as: - gauge pads - surgical drapes - gowns - alcohol - anesthetic gases - plastic trach tubes - rectal gases
BEAM RELATED EFFECTS - Skin related - most skin damage caused by the laser is temporary - Eye related most eye damage caused by the laser is usually permanent
SKIN RELATED - Thermal burn - Laser effects on tissue are dependent on 4 factors: - power density of laser beam - wavelength - duration of exposure - effects of circulation and conduction
Skin Hazards UV-C (200-280 nm): erythema (sunburn), skin cancer UV-B (280-315 nm): accelerated skin aging, increased pigmentation UV-A (315-400 nm): pigment darkening, photosensitive reactions Visible (400-780 nm): photosensitive reactions, skin burn Infrared (900 nm - 1 mm): skin burn
EYE RELATED - Injury can result from exposure to a: - direct beam - mirror reflection (surgical instruments) - diffuse beam (tissue reflection) - Damage is dependent on: - intensity - lens of the eye can focus beam onto the retina (dye laser) - wavelength - absorbed by different parts of the eye (CO2 - cornea, sclera) - duration - fraction of second, before you can blink (aversion response)
The human eye can focus even a low-power laser beam to a tiny spot on the retina increasing its energy up to 100,000 times
Eye Hazards The image below shows the site of damage dependence on the wavelength of the incident or reflected laser beam
Eye Hazards Visible (400-700 nm) and Near-Infrared wavelengths (700-1400 nm) are focused by the cornea and lens and are absorbed by the retina. This may result in a fovea burn which may be considered one of the most serious types of laser injuries. Mid-Infrared and Far-Infrared (1400 nm - 1mm) wavelengths and Mid-Ultraviolet (180-315 nm) are absorbed by water on the surface of the eye. Near-Ultraviolet (315-390 nm) wavelengths are absorbed in the cornea and lens structures.
PREVENTION - The potential laser hazards discussed must be eliminated or controlled for the safe use of lasers in the medical arena
CONTROL MEASURES There are 3 basic control measures: - Engineering - Personal protection - Administrative
ENGINEERING There are control measures that are built into the laser system, such as: - enclosing the electrical system, within a cabinet - enclosing the beam within fiber optics or mechanical arms
PERSONAL PROTECTION - Eyewear - Barriers - Fire protection - Smoke evacuation & filtration
EYE PROTECTION Eyewear - Each laser requires specific eyewear that is capable of absorbing laser light of that specific wavelength Proper Optical Density (OD) and Proper Wavelength (λ)
EYE PROTECTION
EYE PROTECTION - Everyone in the laser OR must wear eye protection including the patient
EYE PROTECTION -Patient the patient s eye s can be protected by: - covering with moist towels - goggles - intra-ocular shields -The surgeon must have eye protection, even during microscopic and endoscopic procedures. -Lens filters that fit over the eyepiece can be used
SKIN PROTECTION Barriers - Clothing - Gloves - Fire resistant gowns - Fire resistant surgical drapes - Moist gauze and drapes around surgical area
SKIN PROTECTION Clothing Offers some protection from skin exposure to laser beams, unfortunately most OR s use flammable gowns and drapes thus increasing the potential for fire hazards - all gauze and drapes around the surgical area should be moistened with sterile saline. - commercially available nonflammable gowns and drapes designed for laser surgery should be used when possible
FIRE PROTECTION - Adequate fire extinguisher available - Sterile saline or water near by -A fire resistant endotracheal tube should be used for all oral and tracheal procedures -For lower bowel procedures the rectum may be packed with a wet sponge -Moist gauze and drapes used around surgical area -Non explosive anesthetic gases must be used
SMOKE EVACUATION & FILTRATION Commercially available smoke evacuators filter out the smallest particles (0.1 µ) found in the laser plume - to be completely effective the smoke evacuator suction tube must be placed as close as possible to the site of laser ablation (less than 2 cm)
SMOKE EVACUATION & FILTRATION Filtration -HEPA (high efficiency particulate air) Filter -99.99% efficient at filtering 0.3 micron particles -Bacterial filter -ULPA (ultra-low penetration) Filter -99.999% efficient at filtering 0.12 micron particles -Viral filter
ADMINISTRATIVE CONTROLS - Controlled entry - Education - Standards
CONTROLLED ENTRY - Closing doors and covering windows - Door interlocks automatically switches laser to standby if doors are opened - Posting of Laser in Use signs outside all entries
EDUCATION All personnel that may be exposed to the laser shall be required to attend regular in-services on operating the laser and laser safety
STANDARDS Each medical facility should develop their own set of operating standards. An important source of Suggested Standards to be followed is provided by the federal government in the American National Standards For The Safe Use Of Lasers and the American National Standards For The Safe Use Of Lasers In The Health Care Facility
Temple University Procedures & Policies Institutional Departmental
Institutional Procedures & Policies Temple University Laser Safety Manual Located on Environmental Health and Radiation Safety website http://www.temple.edu/ehrs/safety/lasersafety/lasersafetypolicies.asp Educational & research laser use Laser use in Temple health care facilities Laser Registration form http://www.temple.edu/ehrs/safety/laser-safety/
Institutional Procedures & Policies All Departments / Divisions must have policies & procedures addressing safety precautions for personnel It is suggested for personnel to have a baseline eye exam Medical staff shall be credentialed (written record)
Safety Precautions (based on ANSI) Trained laser tech/nurse present to oversee laser safety Record all activity & report any incidents Post laser signs PPE (eyewear, masks) worn by all present Use of audible/visible alarms Laser key removed after use (also OSHA)
Safety Precautions (based on ANSI) All laser system repairs documented Rental lasers Shall be inspected by Tech Support Tech from outside must provide credentials Provide record of maintenance & repair
Laser Safety Survey of TUHS Clinical and OR Laser Use Areas All Health Care areas will be surveyed by EHRS The survey might take place during a laser procedure The survey questions are based on Institutional Procedures & Policies and Nursing Services/OR Policies The following questions are typical of the type that will be asked during a survey
End of Training Session