Effects of different insertion methods on reducing needle deflection.

Needle steering in medical procedures has attracted considerable attention in recent years. For example, in prostate brachytherapy, it is desired to insert a flexible beveled-tip needle with minimum deflection. To date, different methods of insertion which incorporate needle rotation about its insertion axis have been proposed in order to reduce needle deflection and target displacement. In this paper, needle deflection resulting from different methods of insertion are compared with our "model-based" method which estimates the amount of needle deflection using Euler-Bernoulli beam equations. Experiments are performed in gelatin phantoms and animal tissue. The results show that the proposed "model-based" method reduces the amount of needle deflection more than other methods. In this paper, some factors for choosing the appropriate method of insertion are also discussed.