For interstitial radiotherapy there is a marked tendency toward the replacement of radioactive needles by radioactive wires (most commonly 182Ta and 192Ir). The wires have the advantages of flexibility, malleability, and safe fixing in the tissues. In addition, there is a possibility for afterloading (3, 5, 6, 8, 12, 13). The disadvantages inherent in the use of radioactive wire are: (a) The large diameter of the guides and plastic tubes leads to a considerable tissue injury during implantation. (b) The lack of wires overloaded at one or both ends necessitates the crossing of the implant ends, while needles without this disadvantage (dumbbell and Indian club needles) are already in use (1, 4, 10, 11). (c) When hairpins are employed (8, 14), the dose of the points is unevenly distributed (2). In our department we tried to fabricate a linear radioactive source which combines the advantages of the needles overloaded at one or both ends with those of the radioactive wire. We constructed linear sources of wire...