Results of needle steering using (a) an 18 G biopsy needle and (b) a 20 G brachytherapy needle. Measured needle tip positions at the end of each insertion are shown in blue. The three target loci (T1, T2, T3) are marked in red, requiring 90, 100, and 110 mm depth of insertions respectively. Higher targeting accuracy was obtained in 18 G biopsy needle trials.