Study recruites 16-20 voluuntering patients with symmetrical actinic damage on face or scalp. Treatment sites are randomized to receive either hexylaminolaevulinate 0.2% or methylaminolaevulinate ( 16% MAL) as photosensitizers (0.25mm-thick layer). A web-based validated program (Research Randomizer) generated a randomized list to define the treatment sides. The randomization results were kept blinded from the investigators who conducted the follow-up visits, from the pathologist, and the patients. Pre-treatment procedures include application of sunscreen for 15 minutes and curettage of the treatment area. Illumination is performed using 2 hours daylight-exposure. Efficacy is assessed clinically, and histologically at 3 and 12 months by blinded observers. Pain during and after treatments and adverse reactions at one week are recorded.