Intra-individual Comparison of Efficacy and Safety of Metvix® Natural Daylight Photodynamic Therapy Versus Conventional Metvix® Photodynamic Therapy in Subject With Mild Actinic Keratoses

Inclusion Criteria: 1. Male or female above 18 years; 2. Subject with clinical diagnosis of mild AK on the face or the scalp with or without clinical diagnosis of moderate AK on the target areas (TAs); Exclusion Criteria: 1. Subject with clinical diagnosis of at least one severe AK on TAs 2. Subject with clinical diagnosis of other skin disease (including non-melanoma skin cancer) on the TAs; 3. Subject with pigmented AK on the TAs