Abstract
Abstract: :
Purpose: To evaluate the insertion and positioning technique for a newly developed ocular brachytherapy device (TheraSightTM Ocular Brachytherapy System, Theragenics Corporation®,Buford, GA). The device consists of a high dose rate 103Pd applicator, a sterile sheath, and an articulating arm designed to stabilize the system after insertion and positioning. The TheraSightTM System is an investigational device developed for the treatment of exudative macular degeneration and ocular tumors and has not yet been tested in clinical studies. Methods: A fresh human cadaver was used to evaluate the size of incision required, the ease of insertion, and the reliability of positioning against the external sclera in the posterior pole. A three–clock–hour conjunctival peritomy at the limbus was performed and the superotemporal quadrant was bluntly dissected. Muscle hooks were used to gently retract the lateral and superior rectus muscles. The applicator and its sterile sheath were then inserted without difficulty. Indirect ophthalmoscopy with transillumination was used to localize the device under the macula using visualization of the device contour as well as transillumination of three lights on the tip, one of which was designed to be visible only on retraction of a lid that shields the radioactive portion of the applicator. Positioning was also verified by ultrasonography. Insertion and positioning procedures were documented photographically. Results: Indirect ophthalmoscopy confirmed localization under the macula by transillumination. Ultrasonography demonstrated a slight indentation of the posterior eye wall when the device was correctly positioned flush against the sclera. A space between the device and the sclera could be visualized on ultrasonography when it was not flush. The articulating arm was effective at stabilizing the device after it was positioned. Conclusions: The TheraSightTM ocular brachytherapy device can be inserted into the correct position without difficulty. Correct positioning of the device can be confirmed using transillumination with indirect ophthalmoscopy, as further verified by ultrasonography.
Keywords: age–related macular degeneration • tumors • radiation therapy