The present invention presents devices, kits, systems and methods that can be used to deliver and activate a photosensitizing composition in a cavity. For example, a device (100) of the present invention includes a member (10) having a base portion (11), an insert portion (13) adapted for insertion into the cavity, and a pocket (12) adapted for communication with a waveguide (14) which is connected to a light source (20) for delivering light to the device (100), wherein the pocket (12) includes a light dispersing section (18) that is adapted for light communication with distal end (16) of the waveguide (14) and desired illumination pattern for photodisinfection of the cavity is provided by at least one of the elements selected from the group consisting of: surface finish of the light dispersing section (18), geometry of the light dispersing section (18), surface finish of the member (10), geometry of the member (10), and a combination thereof. The present invention can be used for humans, other animals, and inanimate objects.