Which of the following apply to the clinical application of ultraviolet radiation?

• A. Guide of dosage is the erythemal response of the patient
• B. Standard skin burner distance is 30 inches
• C. No erythemal dose should be administered until reaction from previous exposures has subsided
• D. All of the above

Answer: (D)

Managing ultraviolet therapy safely relies on controlling dose, standardizing exposure, and allowing proper recovery between treatments. The dose is guided by the patient’s erythemal response, so the clinician tailors exposure to achieve thedesired effect without causing excessive burns, often starting near the minimal erythemal dose and adjusting in subsequent sessions. The distance from the UV source matters because irradiance changes with distance, and using a standard skin burner distance (such as 30 inches in many clinical protocols) helps keep the exposure consistent across patients and visits. It’s also important that no erythemal dose is administered until any previous reaction has subsided, to avoid cumulative damage and give the skin time to recover. Taken together, these practices reflect how UV therapy is applied safely and effectively, so all of the above apply.