Some modifications to existing iridium-192 wire after-loading techniques.

Abstract

In view of the increasing use of iridium-192 wire in interstitial afterloading techniques, now seems an appropriate time to describe some refinements to the methods developed by Pierquin (1964), Pierquin, Chassagne and Cox (1971), and Paine (1972), which have proved useful in our hospital. The first step in these insertions takes place under anaesthetic and involves threading sterile nylon tubing through the tumour to provide a pathway for the afterloaded source. Methods for securing this “outer tubing” and for rendering its position visible on localizing films vary from centre to centre. Until recently, we have used the method described by Paine (1972). A nylon bead and a lead washer are passed over each end of each piece of outer tubing so that the bead cushions the puncture wound from the lead washer, and a piece of 25 s.w.g. tinned copper wire is threaded through the tube; the lead washer can be crimped to prevent the outer tube from slipping, and the copper wire helps to identify it on subsequent radiographs. While the patient is being returned to the ward, the radioactive iridium-192 wire is cut to the required lengths and sealed inside a fine nylon “inner tubing” which acts as a protective sheath and makes source handling much easier. The insertion is completed by passing the prepared sources into the outer tubing to replace the copper wire and by crimping the lead washers to secure the sources and to prevent slip of the outer tubing.