title: Weather conditions and daylight-mediated photodynamic therapy: protoporphyrin IX-weighted daylight doses measured in six geographical locations.
abstract: BACKGROUND
  Photodynamic therapy (PDT) is an attractive therapy for nonmelanoma skin cancers and actinic keratoses (AKs). Daylight-mediated methyl aminolaevulinate PDT (daylight-PDT) is a simple and painless treatment procedure for PDT. All daylight-PDT studies have been performed in the Nordic countries. To be able to apply these results in other parts of the world we have to compare the daily protoporphyrin IX (PpIX) light dose in other countries with the PpIX light doses found in Nordic countries.
  
  
  OBJECTIVE
  To calculate where and when daylight-PDT of AKs was possible in six different geographical locations using ground stations measuring PpIX-weighted daylight doses.
  
  
  METHODS
  PpIX-weighted daylight doses were measured using a dosimeter with a customer-specific photodiode with a detector sensitivity that mimics the PpIX absorption spectrum and measures in 'PpIX doses'. The dosimeters were built into ground stations that were placed in six geographical locations measuring from July to December 2008. Temperature data for each location were obtained from the internet. The maximal ultraviolet (UV) index for Copenhagen was obtained for the measuring period of the dosimeters.
  
  
  RESULTS
  If the PpIX light dose should be above 8Jcm(-2) and the maximum temperature of the day at least 10°C, it was possible to treat patients on nearly all days until the middle of September in Reykjavik and Oslo, until the last week of October in Copenhagen and Regensburg, until the middle of November in Turin and all year in Israel.
  
  
  CONCLUSIONS
  Where and when to perform daylight-PDT depends on the PpIX light dose and outdoor temperature. The PpIX light dose was influenced by the geographical location (latitude), weather condition and time of year. The UV index was not more suitable than temperature and weather to predict if the intensity of daylight would be sufficient for daylight-PDT.
authors.affiliation: Department of Dermatology, Bispebjerg Hospital, University of Copenhagen, Bispebjerg Bakke 23, 2400 Copenhagen NV, Denmark.
authors.forename: S R
authors.initials: SR
authors.lastname: Wiegell
authors.forename: S
authors.initials: S
authors.lastname: Fabricius
authors.forename: J
authors.initials: J
authors.lastname: Heydenreich
authors.forename: C D
authors.initials: CD
authors.lastname: Enk
authors.forename: S
authors.initials: S
authors.lastname: Rosso
authors.forename: W
authors.initials: W
authors.lastname: Bäumler
authors.forename: B T
authors.initials: BT
authors.lastname: Baldursson
authors.forename: H C
authors.initials: HC
authors.lastname: Wulf
mesh_terms: D000622:Aminolevulinic Acid / Q000031:analogs & derivatives / Q000627:therapeutic use; D004307:Dose-Response Relationship, Radiation; D005060:Europe; D062306:Geography, Medical; D006801:Humans; D007557:Israel; D055623:Keratosis, Actinic / Q000188:drug therapy*; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000627:therapeutic use; D011524:Protoporphyrins / Q000032:analysis*; D011874:Radiometry; D012111:Residence Characteristics; D012621:Seasons; D012878:Skin Neoplasms / Q000188:drug therapy*; D013472:Sunlight; D013696:Temperature; D014466:Ultraviolet Rays; D014887:Weather
chemical_list: D017319:Photosensitizing Agents; D011524:Protoporphyrins; C475457:methyl 5-aminolevulinate; D000622:Aminolevulinic Acid; C028025:protoporphyrin IX