Daylight Photodynamic Therapy for Actinic Keratosis

Inclusion Criteria:

* Adults at least 18 years old.
* Subjects must be able to read, sign, and understand the informed consent
* Subjects have at least 4 and no more than 20 clinically typical, visible actinic keratoses in the target treatment area on the face or scalp.
* Subject must be willing to forego any other treatments for AK in the treatment area on the face or scalp, during the study period, and for 14 days prior to screening; including cryotherapy, topical 5-fluorouracil, imiquimod, and ingenol mebutate.
* Subjects who have previously received PDT must undergo at least an 8-week washout period prior to enrollment in study.
* Subject must be willing and able to participate in the study and to comply with all study requirements including concomitant medication and other treatment restrictions, and telephone interview.
* If subject is a female of childbearing potential she must have a negative urine pregnancy test result prior to study treatment initiation and must agree to use an approved method of birth control while enrolled in the study. Women who are pregnant, lactating, or planning to become pregnant during the study period are excluded from the study.

Exclusion Criteria:

* Subjects with any dermatologic disease in the treatment area that may be exacerbated by the treatment proposed or that might impair the evaluation of AKs.
* Subjects who are currently participating in another clinical study or have completed another clinical study with an investigational drug or device on the study area within 30 days prior to study treatment initiation.
* Subjects with any medical condition that, in the opinion of the investigator, makes the patient unsuitable for the trial.