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.

Environmental Health & Radiation Safety

Temple University

byDr. Eyas Amr

Senior Laser Safety Officer

LASER SAFETYTRAINING FOR TUHS

EMPLOYEES

UNDERSTANDING LASER SAFETY

What is a laser?

What are the potential hazards?

How can these hazards be prevented?

In order to understand laser safety the following questions need to be answered:

WHAT IS A LASER?

LA

SE

R

ightmplification by

timulatedmission of

adiation

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

Stimulated Photonsame wavelength

same directionin phase

Incident Photon

LASER BASICS

- Laser light differs from ordinary lightin 3 ways:

- Monochromatic

- Directional

- Coherent

- These three properties allow a laser tofocus 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

Feedbackmechanism

Outputcoupler

Lasing medium

ACTIVE (LASING) MEDIUMSolid (Crystal)

GasSemiconductor (Diode)

Liquid (Dye)

EXCITATION MECHANISM

Optical ElectricalChemical

OPTICAL RESONATOR

HR Mirror andOutput 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.

Laser Temporal Outputs

The Electromagnetic Spectrum

The Electromagnetic Spectrum

Region Wavelength

Ultraviolet (UV) 100 to 400 nm

UV-C 100 to 280 nm

UV-B 280 to 320 nm

UV-A 320 to 400 nm

Visible (Light) 400 to 700 nm

Near Infrared 700 to 1400 nm

Far Infrared 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, tolueneand 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 thelaser 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

- Engineering

- Personal protection

- Administrative

There are 3 basic control measures:

ENGINEERING

There are control measures that are built into the laser system, such as:

- enclosing the electrical system, withina cabinet

- enclosing the beam within fiber opticsor mechanical arms

PERSONAL PROTECTION

- Eyewear

- Barriers

- Smoke evacuation & filtration

- Fire protection

EYE PROTECTION

- Each laser requires specificeyewear that is capable of absorbing laser light of that specific wavelength

Proper Optical Density (OD) and Proper Wavelength (λ)

Eyewear

EYE PROTECTION

EYE PROTECTION

- Everyone in the laser OR must wear eye protectionincluding 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, evenduring microscopic and endoscopic procedures.

-Lens filters that fit over the eyepiece can be used

SKIN PROTECTION

- Clothing- Gloves- Fire resistant gowns- Fire resistant surgical drapes- Moist gauze and drapes around surgical area

Barriers

Offers some protection from skin exposure to laser beams, unfortunately most OR’s use flammable gowns and drapes thus increasingthe potential for fire hazards- all gauze and drapes around the surgical areashould be moistened with sterile saline.

- commercially available nonflammable gownsand drapes designed for laser surgery should beused when possible

Clothing

SKIN PROTECTION

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 outthe smallest particles (0.1 µ) found in the laser plume

- to be completely effective the smoke evacuatorsuction 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 SafeUse 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 websitehttp://www.temple.edu/ehrs/safety/laser-safety/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 safetyRecord all activity & report any incidentsPost laser signsPPE (eyewear, masks) worn by all presentUse of audible/visible alarmsLaser key removed after use (also OSHA)

Safety Precautions (based on ANSI)

All laser system repairs documented Rental lasersShall be inspected by Tech SupportTech from outside must provide credentialsProvide 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