Needles and liver phantoms in interventional radiology: Design considerations

Liver carcinoma is in the top five leading causes of cancer death worldwide. Patients often require radiologic interventions in which needles are inserted, for example when taking biopsies, accessing blood vessels or bile ducts, and ablating tumors. Accurate and precise needle placement in interventional radiology is important, but also challenging. Challenges include several factors, such as anatomical obstructions along the insertion path, patient motion, and unwanted needle bending upon insertion. Incorrect needle placement may prolong procedure time, increase radiation dose for the patient and may cause complications. Proposed approaches to improve needle placement in interventional radiology include, but are not limited to, steerable needles and liver phantoms. Although steerable needles are technically feasible to produce, these prototypes are often general-purpose. Currently, there is a lack of (analyzed) clinical and experimental data that provide insight into needle placement, and that would clarify the right design requirements for novel needles in interventional radiology. Another gap exists in the development of liver phantoms, which can be used in a validation set-up for novel needles and/or a training model for medical doctors. Current phantom development focusses mostly on medical imaging properties. However, matching needle-tissue interaction forces and simulating breathing motion are also crucial for a phantom to be of use in a realistic validation set-up. Therefore, the objectives of this thesis are to define relevant design considerations for novel needles, and to develop a high fidelity liver phantom that features respiratory motion and that mimics needle-tissue interaction forces upon insertion. Accomplishing this will improve and advance needle placement in interventional radiology.