CDT CDT Phototherapy & Light-Based Treatments 1 — Questions and Answers
Question 1: What wavelength range is used in narrowband UVB phototherapy?
- UVA (320–400 nm)
- UVB at 311–313 nm (Correct answer)
- UVC (200–280 nm)
- Visible light (400–700 nm)
Correct answer: UVB at 311–313 nm
Narrowband UVB phototherapy uses the 311–313 nm wavelength range, which is most effective for psoriasis, vitiligo, and atopic dermatitis.
Question 2: Which condition is narrowband UVB phototherapy most commonly used to treat?
- Rosacea
- Acne vulgaris
- Psoriasis (Correct answer)
- Seborrheic dermatitis
Correct answer: Psoriasis
Narrowband UVB is most commonly used for psoriasis, and is also effective for vitiligo and atopic dermatitis.
Question 3: What does PUVA phototherapy combine?
- Pulsed ultrasound + vitamin A
- Psoralen + UVA light (Correct answer)
- Pulsed UV + antifungal
- Photodynamic agent + UVA
Correct answer: Psoralen + UVA light
PUVA combines a psoralen photosensitizer (oral or topical) with UVA light exposure to treat psoriasis, vitiligo, and cutaneous T-cell lymphoma.
Question 4: What is the Minimal Erythema Dose (MED) used to determine in phototherapy?
- Maximum safe topical steroid dose
- Safe starting UV dose for treatment (Correct answer)
- Amount of psoralen to prescribe
- Frequency of treatment sessions
Correct answer: Safe starting UV dose for treatment
The MED is the lowest UV dose producing minimal redness at 24 hours, used to calculate a safe and individualized starting phototherapy dose.
Question 5: Which protective measure is mandatory during and after PUVA therapy?
- Full-body sunscreen only
- UV-protective goggles during and for 24 hours after treatment (Correct answer)
- Antibiotic prophylaxis
- Topical corticosteroids before each session
Correct answer: UV-protective goggles during and for 24 hours after treatment
UV-protective goggles must be worn during PUVA and for 24 hours after because psoralen sensitizes the eyes to UV-induced damage.
Question 6: What is excimer laser therapy primarily used for in dermatology?
- Treating basal cell carcinoma
- Localized psoriasis and vitiligo (Correct answer)
- Acne extraction
- Wart removal
Correct answer: Localized psoriasis and vitiligo
The 308 nm excimer laser delivers targeted UVB to treat localized psoriasis and vitiligo without exposing surrounding healthy skin.
CDT CDT Phototherapy & Light-Based Treatments 1
What wavelength range is used in narrowband UVB phototherapy?