OBT Safety Protocols & Quality Assurance 2 — Questions and Answers
Question 1: Which laser classification requires engineering controls and administrative controls but does NOT require protective eyewear for casual viewing of the beam?
- Class 1
- Class 2 (Correct answer)
- Class 3R
- Class 3B
Correct answer: Class 2
Class 2 lasers emit visible light at ≤1 mW and rely on the natural aversion response (blink reflex) to protect eyes, so casual viewing does not require eyewear.
Question 2: What does the term 'nominal hazard zone' (NHZ) define in optical beam therapy safety planning?
- The safe operating distance from the power supply unit
- The area within which the beam irradiance exceeds the maximum permissible exposure (Correct answer)
- The region where electrical hazards exceed OSHA thresholds
- The footprint of the treatment room requiring lead shielding
Correct answer: The area within which the beam irradiance exceeds the maximum permissible exposure
The NHZ is the spatial region in which the level of direct, reflected, or scattered laser radiation exceeds the applicable maximum permissible exposure (MPE).
Question 3: During a quality assurance check, a practitioner measures the output power of a therapeutic laser and finds it is 15% below the manufacturer's specified value. What is the most appropriate next step?
- Continue treatment at a higher dose to compensate
- Document the variance and take the device out of service for calibration (Correct answer)
- Recalibrate the device using the built-in user adjustment
- Repeat the measurement with a different power meter brand
Correct answer: Document the variance and take the device out of service for calibration
A >10% output deviation typically exceeds acceptable tolerance; the device should be removed from service and sent for professional calibration before further patient use.
Question 4: Optical density (OD) of laser protective eyewear is defined as:
- The thickness of the lens material in millimeters
- The logarithm (base 10) of the attenuation factor at a given wavelength (Correct answer)
- The percentage of light transmitted through the lens
- The maximum continuous power the lens can withstand before damage
Correct answer: The logarithm (base 10) of the attenuation factor at a given wavelength
OD = log₁₀(H₀/H), where H₀ is the incident exposure and H is the transmitted exposure, so OD 4 means 10⁴ attenuation.
Question 5: Which standard is most commonly referenced in the US for safe use of lasers in health care facilities?
- ANSI Z136.3 (Correct answer)
- IEC 60825-1
- ISO 11553-1
- OSHA 29 CFR 1910.132
Correct answer: ANSI Z136.3
ANSI Z136.3 is the American National Standard specifically addressing safe use of lasers in health care environments.
Question 6: A treatment room door is opened unexpectedly while a Class 4 therapeutic laser is in use. The immediate correct action is to:
- Redirect the beam away from the door
- Activate the key-switch lockout to prevent accidental emission
- Terminate the emission immediately using the emergency stop or shutter (Correct answer)
- Instruct the entering person to don eyewear before proceeding
Correct answer: Terminate the emission immediately using the emergency stop or shutter
Immediate beam termination via the emergency stop or shutter is the required first response to any uncontrolled access during Class 4 laser operation.
Question 7: What is the primary purpose of a Laser Safety Officer (LSO) in a clinical optical beam therapy setting?
- To perform all laser treatments directly on patients
- To purchase and maintain all laser equipment
- To evaluate, authorize, and oversee the control measures for laser hazards (Correct answer)
- To file adverse-event reports with the FDA on behalf of the facility
Correct answer: To evaluate, authorize, and oversee the control measures for laser hazards
The LSO is responsible for evaluating laser hazards, establishing control measures, and ensuring that all personnel follow applicable safety standards.
OBT Safety Protocols & Quality Assurance 2
Which laser classification requires engineering controls and administrative controls but does NOT require protective eyewear for casual viewing of the beam?