[3D navigation for interstitial stereotaxic brachytherapy].

AIM

The aim of this paper is to describe the adaption of 3D-navigation 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).

MATERIAL AND METHODS

The EasyGuide Neuro navigation system (Philips) was adapted in the way, that needles for interstitial brachytherapy were made connectable to the pointer and correctly displayed on the screen. To determine the positioning accuracy, several attempts were performed to hit defined targets on phantoms. Two methods were used: "free navigation", where the needle was under control of the navigation system, and the "guided navigation" where an aligned template was used additionally to lead the needle to the target. In addition a mask system was tested, whether it met the requirements of stable and reproducible positioning. The potential of applying this method in clinical practice was tested with an anatomical specimen.

RESULTS

About 91% of all attempts lied within 5 mm. There were even better results on the more rigid table (94% < 4 mm). No difference could be seen between both application methods ("free navigation" and "navigation with template"), they showed the same accuracy.

CONCLUSIONS

The accuracy of the phantom experiments and the confirmation by the experiment with the anatomical specimen showed that excellent results can be expected in clinical practice using rigid tables and patient supporting systems.