Endoscopic irradiation

Figure 7. Target light geometries used commonly for different clinical applications, (a) surface irradiation, (b) interstitial irradiation, (c) intraluminal (endoscopic), (d) intracavity or intraoperative.

Figure 8. Representative clinical applications using diffusing fiber light delivery, (a) multiple interstitial cylindrical fibers used to treat brain tumors (courtesy Dr T. Origitano, Chicago, USA), (b) cylindrical diffusing fibers being placed into the instrument channel of an endoscope for esophageal PDT (courtesy Dr. N. Marcon, Toronto, Canada), (c) three cylindrical diffusers in an umbrella configuration for endometrial irradiation (courtesy Drs B. Tromberg and Y. Tadir, Irvine, USA), (d) transcomeal irradiation of the retina from a laser diode coupled into a fundus camera (courtesy QLT Inc, Canada).

Figure 9. Balloon applicators for light distribution in hollow cavities (a) brain tumor cavity irradiation post-resection, (b) with centered diffusing fiber for treatment of the esophagus the balloon is collapsed for passage through the endoscope instrument channel (courtesy Drs M. Panjepour and G. Overholt, Knoxville, USA).

For other endoscopic applications, the inadiation may be onto the tumor surface using a forward directed fiber, by placing the fiber tip interstitially into the tumor mass, or (for bladder) by irradiating the whole tissue surface. In the last case, it is important to note that, since the bladder acts as an integrating sphere , the actual surface irradiance may be several times higher than the irradiance from the primary beam. 

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