It has sometimes been said, perhaps unfairly, that radiosurgery has been a treatment looking for a successful application. This volume, the second in the series on radiosurgery, attempts, in some parts more successfully than others, to refute that suggestion. The technique was first established by Lexsell, using a collimated cobalt source (“the gamma knife”). In the United Kingdom, the Stereotactic Radiosurgery Centre in Sheffield has been treating patients since 1985. The published results for treatment of arteriovenous malformations have been good and its place in the non-operative management of cerebral arteriovenous malformations is now secure. Radiosurgery has now become the treatment of choice for appropriately sized and located malformations. However, increasingly refined techniques of endarterial obliteration for vascular lesions have also been developing apace in parallel, and it seems likely that the combined use of both techniques will in future make it increasingly rare for us to have to undertake surgery for these often demanding lesions.

The main drawback of the “gamma knife” technique of radiosurgery has been the enormous capital outlay required for the equipment. In the United Kingdom there is only one machine and this has perhaps inhibited a wider application of the technique in the management of intracranial malignancy. The greater availability of machines in the United States, and the commercial pressures to retain the appropriate return on investment, has led to a wider range of applications in the United States and the results of some of these are published in this book. The development of fractionated stereotactic radiotherapy using relocatable stereotactic frame and alinear accelerator has shown that it is possible to achieve good results with this technique and some of these are also published here. In the United Kingdom we are beginning to identify a much wider range of applications for this technique and, in the not too distant future, we should expect a whole range of reports of its use in malignant brain tumours, recurrences, melanomas, and other metastatic lesions. However, for the moment the literature is rather sparse and it remains to be seen whether the technique in future will also become the treatment of choice for these rather dismal conditions.

The place of radiotherapy in general, and stereotactic techniques in particular, for benign lesions, such as acoustic neuromas and meningiomas, in my view remains uncertain despite some rather encouraging results published here. At this stage it is perhaps sensible to proceed with caution until the long term effects are clearer. With regard to the future, the rapid advances in imaging techniques using MRI, the various new variants of CT, and the PET machine, offer the tantalising possibility of being able to identify both the anatomical and functional pathology to be targeted for treatment. With the merging of these exciting new technologies it may at last be possible to make some real progress in improving the outcomes for CNS tumours.