CT-guided procedures: evaluation of a phantom system to teach accurate needle placement

Aim: To evaluate the use of a phantom system to help teach the basic techniques of accurate CT-guided needle placement, thereby avoiding the risks associated with teaching on patients.

Materials and Methods: Gelatine phantoms with five, 1.9 cm embedded spherical wooden targets were constructed. Four trainee operators performed 15 simulated biopsy procedures on the targets (series one) and repeated identical procedures 2 weeks later (series two). Statistical analysis of accuracy of needle placement and subject confidence were performed. 

Results: Significant sequential improvement in axial plane angular error was noted with the average error decreasing by 0.33 degrees after every five procedures performed (95% CI: -0.58 to -0.08, p = 0.01). Operator confidence indicated significant improvement both within each series and from series one to series two (95% CI: 0.08 to 1.17, p = 0.025 and 95% CI: 0.00 to 0.58, p = 0.05) respectively. However, variability in operator performance made statistically significant improvement in other variables unproven. 

Conclusion: Despite the study comprising a relatively small number of participants and procedures, it clearly demonstrated the effectiveness of teaching operators to perform CT-guided procedures using a phantom system. Needle placement accuracy significantly improved, with a reduction in axial angular error, and improved operator confidence without the risks associated with training on patients. Three of the operators in this study had never performed a CT-guided procedure previously, and their proficiency, after a relatively short but intense period of training, was impressive. The use of phantoms should be considered routinely for basic training of CT-guided needle placement.