A simple standardization of esophageal photodynamic therapy light dosimetry is proposed. Calculations of the effect on local treatment dose of using non-centered diffusing fibers have been made and the methods of calculating light energy dose to the treatment area within a centering balloon are discussed. A requirement for centering devices and standard units of Joules per cm² of treatment area are indicated.

Key words: Photodynamic therapy, PDT, Dosimetry, Esophagus.