The overall goal of this proposed work is to develop a system for delivering therapeutic ionizing xradiation along a flexible, curved path from an extracorporeal x-ray source to an internal body cavity or lumen and depositing this radiation into a desired volume of tissue. Such a device would operate in a manner comparable to the solid optical fiber methods used to transmit laser radiation into interior body cavities. It is indeed based upon similar physical principles, but utilizes reflection along the hollow fiber interior and hence is not affected by any material in contact with the capillary outside surface. A flexible conduit/catheter for transmitting x-rays is possible because of the phenomenon termed total surface specular x-ray reflection, which allows x-ray radiation incident at grazing angles along the interior surface of a hollow capillary to be transmitted without loss of energy. The possibility of using this phenomenon in a medical device does not appear to have been previously recognized. As the interior diameter of the hollow capillaries through which the x-rays are transmitted is reduced, increasingly large bending angles are permitted without loss of the transmitted intensity. Curvatures as sharp as 1 cm are possible using existing lead glasses. Such a conduit/catheter assembly can be used in conjunction with an endoscope or bronchoscope or other flexible assemblies. Radiation could also be delivered via an angiographic catheter or directly via a trochar needle into a lesion.
Three specific aims are proposed: 1) to construct such an x-ray carrying conduit/catheter assembly; 2) to measure the deliverable dose rate as a function of x-ray photon energy, capillary diameter, bending radius, and the intensity of the extracorporeal x-ray source; 3) to assess quantitatively the feasibility of this device in clinical practice, particularly with existing endoscopes and bronchoscopes, and as a treatment modality generally.
