Generally described, the present invention comprises a medical device for implantation in biological tissue and a method of making the medical device. The medical device comprises an organic compound forming at least a portion of the medical device and a beta radiation emitting element chemically bonded to the organic compound of the medical device. The beta emitter preferably causes the medical device to generate a beta radiation greater than 0.0002 .mu.Ci/cm. The beta radiation emitting element can be tritium preferably incorporated into the organic compound of the medical device by a Wilzbach process. The Wilzbach process involves an entropic exchange of the beta emitting element for elemental hydrogen in a vacuum sealed reaction chamber. On the other hand, the beta radiation emitting element may comprise Carbon 12, or other similar beta emitter, which is incorporated directly into the backbone of the organic compound prior to manufacturing the medical device from the organic compound. In another aspect of the present invention, rather than placing the medical device itself in a reaction chamber for incorporation of a beta emitting element, a mass of organic material may be placed in a reaction chamber. Again, a beta emitting element is preferably incorporated into the organic material via the Wilzbach process.