The present invention provides improved light delivery catheters for use in therapeutic methods, such as PDT, that require illumination of target tissue within a blood vessel or other hollow body organ. An improved catheter includes an optical fiber that transmits light from a light source at the proximal end of the catheter shaft to a light treatment zone. An occlusion balloon on the distal end of the catheter shaft adjacent to the light treatment zone receives fluid via an inflation lumen in the catheter shaft. An infusion lumen connects with a plurality of infusion ports at the light treatment zone to deliver infusion fluid to the hollow body organ so that blood can be flushed from the region between the light treatment zone and target tissue.