CLT Therapeutic Laser Applications 3 — Questions and Answers
Question 1: Which laser classification poses the highest risk of ocular injury during therapeutic use?
- Class 1
- Class 2
- Class 3B (Correct answer)
- Class 1M
Correct answer: Class 3B
Class 3B lasers can cause immediate eye injury from direct or specularly reflected beams and require protective eyewear during use.
Question 2: A therapist is treating trigger points in the upper trapezius. What technique best targets a discrete myofascial trigger point?
- Scanning technique over the entire muscle belly
- Stationary contact probe directly on the trigger point (Correct answer)
- Non-contact sweeping at 20 cm distance
- Grid pattern over the dermatome
Correct answer: Stationary contact probe directly on the trigger point
A stationary contact probe placed directly on the trigger point allows concentrated energy delivery to the focal point of dysfunction.
Question 3: How does therapeutic laser reduce pain through neurological mechanisms?
- By permanently blocking nociceptive nerve fibers
- By decreasing nerve conduction velocity and altering neuropeptide release (Correct answer)
- By inducing local anesthesia through tissue cooling
- By severing unmyelinated C fibers
Correct answer: By decreasing nerve conduction velocity and altering neuropeptide release
Photobiomodulation decreases nerve conduction velocity in small-diameter pain fibers and modulates release of substance P and other neuropeptides.
Question 4: When calculating treatment time, a therapist knows the device outputs 500 mW and the target fluence is 4 J/cm² over 10 cm². What is the required treatment time?
- 8 seconds
- 40 seconds
- 80 seconds (Correct answer)
- 4 seconds
Correct answer: 80 seconds
Total energy needed = 4 J/cm² × 10 cm² = 40 J; time = 40 J ÷ 0.5 W = 80 seconds.
Question 5: Which condition has the strongest evidence base for therapeutic laser efficacy according to current research?
- Acute fracture repair acceleration
- Neck pain and musculoskeletal disorders (Correct answer)
- Systemic autoimmune disease modulation
- Internal organ regeneration
Correct answer: Neck pain and musculoskeletal disorders
Neck pain and musculoskeletal conditions have the most robust clinical evidence supporting therapeutic laser effectiveness.
Question 6: What is the significance of the 'inverse square law' in laser therapy practice?
- Doubling power doubles the treatment effect
- Doubling the distance from tissue reduces irradiance to one-quarter (Correct answer)
- Wavelength decreases as distance increases
- Energy density increases with beam divergence
Correct answer: Doubling the distance from tissue reduces irradiance to one-quarter
The inverse square law states that irradiance decreases proportionally to the square of the distance, so doubling distance reduces intensity to 25%.
Question 7: Which photobiomodulation effect best explains accelerated wound closure after laser treatment?
- Thermal coagulation of wound edges
- Stimulation of fibroblast proliferation and collagen synthesis (Correct answer)
- Destruction of bacterial biofilm
- Increased local vasoconstriction
Correct answer: Stimulation of fibroblast proliferation and collagen synthesis
Laser stimulates fibroblasts to proliferate and synthesize collagen, which is essential for wound matrix formation and closure.
CLT Therapeutic Laser Applications 3
Which laser classification poses the highest risk of ocular injury during therapeutic use?