1：Experimental Design and Method Selection:

A single treatment with hybrid 1,470-nm/2,940-nm fractional laser was offered to patients with clinically identifiable AKs who had previously failed traditional treatment modalities.

2：Sample Selection and Data Sources:

Patients of Fitzpatrick skin Type I to IV with AKs off the face were included.

3：List of Experimental Equipment and Materials:

Hybrid 1,470-nm diode/2,940-nm Er:YAG fractional laser (Halo; Sciton, Palo Alto, CA), topical 7% lidocaine/7% tetracaine anesthetic ointment.

4：Experimental Procedures and Operational Workflow:

Patients received a single laser treatment with settings ranging from 1,470 nm (depth 250–400 mm, density 15%–40%) and 2,940 nm (depth 20 mm, density 8%–20%). Postoperatively, patients applied a bland moisturizer, sunscreen of SPF 30, and avoided sun exposure for at least 1 week.

5：Data Analysis Methods:

Clinical examination and standard photography of the treatment area were performed at follow-up visits.