Biomedical Engineering Reference
In-Depth Information
Standards should be kept in every use site for easy reference
by users and operators during laser use; knowledge of the
guidance in the ANSI standards should be included in all edu-
cation and training programs.
laser-generated airborne contaminants, electrical damage,
toxic dyes, and system failures.
Each wavelength, system, delivery device, and applica-
tion must be assessed for associated hazards, since they
are all different and will require different management and
procedures.
Once the hazards are identifi ed, risk must be assessed. Risk is
often defi ned as the level of potential for exposure to, or injury
resulting from, identifi ed hazards. Risk levels may differ for
each member of the laser team and for each person involved
with the laser equipment. The level of risk may also vary with
clinical applications of a system, depending on the delivery
device, power parameters, and target tissues.
While all in the laser treatment room have the risk of eye
exposure and damage if they are unprotected, there are going
to be varied risks for physician, assistant, nurse practitioner,
patient, patient support person, technician, offi ce manager,
LSO, scrub nurse, sales representative, biomedical engineer,
and manager. Therefore, the LSO must understand each
person's level of interaction with the system and their job
responsibilities, before developing appropriate policies and
procedures.
For example, a photothermal laser such as a 1064-nm
Nd:YAG creates enough heat to cause fl ammability hazards.
Users of such a laser will need to follow procedures to prevent
fi re, including eliminating dry materials or alcohol-containing
solutions from the target zone, correctly placing an appropri-
ate fi re extinguisher, having an open container of water avail-
able, preventing specular refl ections, observing the path of the
beam for interference of any kind, and removing sources of
oxygen or other fl ammable gases.
Should a laser, based on its science, be assessed to have min-
imal hazards, the user may modify standards and procedures
to refl ect that individual level of hazard. This is the reason
it is so important for users to write their own facility poli-
cies and procedures, and not simply adopt generic documents
obtained from manufacturers, course materials, or other
institutions. An example of how the same laser used in two
different practice settings may require different safety mea-
sures as follows.
risk management step 2: identification
of hazards and risks
In order to assess the presence of potential hazards, risk of
exposure to those hazards, and what appropriate control mea-
sures are required to prevent that risk, it is necessary for all
personnel (nurses, technicians, physician assistants, private
scrubs, and physicians) in a laser practice to have a thorough
understanding of laser science.
So how does laser science education relate to safety stan-
dards? Follow this simple formula for the rationale behind
the requirement for comprehensive education and training
for all—beyond the basics of vendor-taught operational
inservice.
Tissue interaction depends on the knowledge of the
wavelength (absorption, selective photothermolysis,
etc.).
●
Wavelength depends on knowing what the medium
is [neodymium (Nd):YAG, CO
2
, erbium (Er):YAG,
holmium (Ho):YAG, etc.].
●
Medium determines the delivery system (fi ber, hand-
piece, scanner, etc.).
●
Delivery system affects application (open surgical,
endoscopic, cutaneous, etc.).
●
Application indicates risks/hazards (fi re, ocular,
plume, etc.).
●
Risks and hazards determine the control measures
(policies and procedures for each hazard identifi ed).
●
Control measures are found in ANSI standards!
●
It is impossible to provide a safe laser environment without
understanding the science. Therefore, everyone who may work
within a laser treatment room must have that knowledge.
Safety is only ensured when everyone has equal training,
responsibility, and understanding of what occurs when a laser
is switched on. And since not all lasers have the same hazards,
this understanding must be specifi c to the user's equipment
and the practice in which it is used.
Laser science includes the following:
Setting A: A suite on the top fl oor of an offi ce build-
ing overlooking a park land sets up a green diode
laser, emitting at 532 nm. Window barriers do not
have to be installed to cover the windows on the out-
side facing wall, because the laser beam, even if trans-
mitted accidentally through the window, cannot
strike anything that could be harmed.
●
1. Properties of laser light that make it different from
ambient or white light
2. Characteristics of each laser wavelength
3. Absorbing chromophores of each wavelength
4. Dosimetry (power, pulse parameters, fl uence, en-
ergy density, etc.)
5. Spot size and delivery systems
6. Application techniques
Setting B: A suite on the ground fl oor of a busy pro-
fessional building, with a window facing directly
across from another window in the adjacent suite,
sets up the same laser. In this case, appropriate win-
dow coverings must be installed to prevent acciden-
tal transmission of the beam through to the adjacent
suite. The specifi cations for appropriate window
coverings will be addressed further on in this text.
●
Once these properties are well understood, the clinician can
anticipate potential hazards. Hazards are all of those poten-
tially dangerous conditions that are associated with an unan-
ticipated interaction or exposure of tissues or materials, to
laser energy. These include both direct beam hazards such as
tissue burns, eye damage, endotracheal tube fi re, drape fi re,
and explosion of gases, or indirect non-beam hazards (those
that are secondary to the actual beam interaction) such as
Clinically relevant risk assessment provides safety in a sen-
sible and appropriate manner often at lower cost to the user,
and always, at greater levels of protection for all concerned.
