Inclusion Criteria:  Age ≥ 18 years Histopathologically confirmed diagnosis of International Society for Cutaneous Lymphomas (ISCL) / European Organisation for Research and Treatment of Cancer (EORTC) mycosis fungoides stage IB or IIA  Exclusion Criteria:  Poor performance status: WHO performance status score > 2 Physically unable to maintain the posture Patient with no health coverage Patient under guardianship or curatorship Previous history of dose-limiting radiation therapy in the field Previous history of dose-limiting phototherapy Previous history of melanoma, skin squamous cell carcinoma or basal cell carcinoma or other absolute contraindication to phototherapy (including a history of lupus, xeroderma pigmentosum, or porphyria) Pregnant or breastfeeding woman Contraindication to methoxsalen (severe liver, renal or heart failure)