Treatment with gamma knife versus stereotactic linear accelerator. Clinical results and the cost-effectiveness

Introduction: The principles of radiosurgery were developed in 1951 by Leksell, Their technical realization led to the development of the gamma knife and stereotactically modified linear accelerator. Methods: In addition to the gamma knife, we present the different principles of convergent beam irradiation (radiosurgery with linear accelerator), the further development to fractionated stereotactic conformal radiotherapy, and the necessary quality-assurance steps. Results: The greatest uncertainties in the precision of radiosurgery result from medical imaging (CT 0.7x0.7x1mm; DSA 1-5mm; MR angiography < 2 mm). The focusing accuracy of the gamma knife (+/- 0.3 mm) can also be achieved today by linear accelerators using a stereotactic floorstand. For the same indication and the same dosage for the target volume, there are no clinical differences between the gamma knife and the linear accelerator (AVM: 80% complete obliteration; metastases: 85% local tumor control; AN: 90% tumor control), However, there are greater differences in costs, There is no constellation where the gamma knife is just as expensive or more cost-effective than the linear accelerator treatment, The most cost-effective solution is modification of an available linear accelerator, resulting in treatment costs per patient of 9,201.25 DM (50 patients/year). year). Conclusion: There seem to be no methodological, physical, clinical or cost reasons for using a gamma knife, especially because the trend is going towards fractionated conformation radiotherapy instead of the application of high single doses.