3D-NAVIGATION FOR INTERSTITIAL STEREOTACTIC BRACHYTHERAPY

Aim: The aim of this paper is to describe the adaption of 3D-navigatio n for interstitial brachytherapy. The new method leads to prospective and therefore improved planning of the therapy (position of the needle and dose distribution) and to the possibility of a virtual simulation (control if vessels or nerves are on the pathway of the needle). Mate rial and Methods: The EasyGuide Neuro(R) navigation system (Philips) w as adapted in the way, that needles for interstitial brachytherapy wer e made connectable to the pointer and correctly displayed on the scree n. To determine the positioning accuracy, several attempts were perfor med to hit defined targets on phantoms. Two methods were used: ''free navigation'', where the needle was under control of the navigation sys tem, and the ''guided navigation'' where an aligned template was used additionally to lead the needle to the target. In addition a mask syst em was tested, whether it met the requirements of stable and reproduci ble positioning. The potential of applying this method in clinical pra ctice was tested with an anatomical specimen. Results: About 91% of al l attempts lied within 5 mm. There were even better results on the mor e rigid table (94% < 4 mm). No difference could be seen between both a pplication methods (''free navigation'' and ''navigation with template ''), they showed the same accuracy. Conclusions: The accuracy of the p hantom experiments and the confirmation by the experiment with the ana tomical specimen showed that excellent results can be expected in clin ical practice using rigid tables and patient supporting systems.