CLT Therapeutic Laser Applications 2 — Questions and Answers
Question 1: Which wavelength range is most commonly used in low-level laser therapy (LLLT) for tissue penetration?
- 200–400 nm (UV range)
- 600–1000 nm (red to near-infrared) (Correct answer)
- 1100–1400 nm (mid-infrared)
- 1500–2000 nm (far-infrared)
Correct answer: 600–1000 nm (red to near-infrared)
Wavelengths in the 600–1000 nm range (optical window) penetrate tissue most effectively for photobiomodulation therapy.
Question 2: What is the primary chromophore targeted by 810 nm laser light in photobiomodulation?
- Melanin
- Water
- Cytochrome c oxidase (Correct answer)
- Hemoglobin
Correct answer: Cytochrome c oxidase
Cytochrome c oxidase in the mitochondrial electron transport chain is the primary chromophore absorbing 810 nm near-infrared light.
Question 3: A patient presents with a fresh acute wound (24 hours old). Which laser parameter adjustment is most appropriate?
- Increase power density to speed healing
- Use lower energy density to avoid inhibiting inflammation (Correct answer)
- Apply continuous wave mode at maximum power
- Avoid laser treatment until 72 hours post-injury
Correct answer: Use lower energy density to avoid inhibiting inflammation
In the acute inflammatory phase, lower energy densities are used to support rather than suppress the natural inflammatory response.
Question 4: The Arndt-Schulz Law as applied to laser therapy states that:
- Higher doses always produce greater therapeutic effects
- Weak stimuli excite physiological activity, moderate stimuli favor it, and strong stimuli suppress it (Correct answer)
- Laser energy is inversely proportional to tissue depth
- Coherent light is more therapeutic than non-coherent light at equal power
Correct answer: Weak stimuli excite physiological activity, moderate stimuli favor it, and strong stimuli suppress it
The Arndt-Schulz Law describes a biphasic dose-response where too little or too much energy produces suboptimal or inhibitory effects.
Question 5: When treating a patient with tendinopathy using laser therapy, which tissue structure is the primary target?
- Synovial membrane
- Periosteum
- Collagen fibers and tenocytes (Correct answer)
- Skeletal muscle fibers
Correct answer: Collagen fibers and tenocytes
Tendinopathy involves degenerated collagen and dysfunctional tenocytes, which are the primary cellular targets for photobiomodulation.
Question 6: Which of the following is a contraindication for therapeutic laser application?
- Chronic low back pain
- Post-surgical wound healing
- Direct irradiation over active carcinoma (Correct answer)
- Peripheral neuropathy
Correct answer: Direct irradiation over active carcinoma
Direct laser irradiation over active malignancies is contraindicated because laser energy may stimulate tumor cell proliferation.
Question 7: The unit 'J/cm²' used in laser therapy represents:
- Power density (irradiance)
- Pulse frequency
- Energy density (fluence) (Correct answer)
- Beam divergence angle
Correct answer: Energy density (fluence)
J/cm² represents energy density (fluence), calculated as the total energy delivered per unit area of tissue.
CLT Therapeutic Laser Applications 2
Which wavelength range is most commonly used in low-level laser therapy (LLLT) for tissue penetration?