Fine needle insertion method for minimising deflection in lower abdomen: In vivo evaluation

Needle-tissue interaction model based needle path planning method

BACKGROUND AND OBJECTIVE

In needle insertion procedure, needle deflection and target movement will affect targeting accuracy. Existing planning algorithms rely on predetermined interaction force and parameters, which increase the targeting error for the patient-specific difference. In this paper, we proposed a needle-tissue interaction model based needle path planning method with patient-specific parameter identification algorithm, which is able to use iteration learning control and interaction model predicted information to improve targeting accuracy with the consideration of patient-specific differences.

METHODS

A 3D needle-tissue interaction deformation model has been constructed using local constraint method. The model, termed as the full computation model, predicts the needle-tissue interaction force using a Kriging-based model as well as the target movement and needle deflection simultaneously only requiring patient specific parameters. Needle paths without incorporating deformation, which is called static path, are generated by rapidly-exploring random trees algorithm first. Then, the needle-tissue interaction deformation model can calculate force and deformation of the static path and iterative learning control can correct the targeting error of moved target. In addition, the intraoperative parameter identification algorithm is proposed to identify patient-specific parameter. Simulations are carried out to verify the full computation model and needle path planning. A testbed is constructed and experiments are designed to validate the proposed method using phantom with common lesion-size obstacle markers and target markers. The deformation of tissue and needle are captured through charge coupled device camera.

RESULTS

Simulation results indicated the full computation model can simulate the needle-tissue interaction process and the proposed method can achieve needle path planning incorporating tissue deformation. Experiment results indicated the tissue deformation and needle deflection agree between model prediction and experiments. The proposed path planning method can reduce targeting error from maximum of 3.89 mm without incorporating deformation to less than 1 mm in 4 phantom experiments.

CONCLUSIONS

The full computation model based needle path planning is verified to be effective by experiments. The planning accuracy is improved based on the deformation predicted by full computation model and the desired accuracy is achieved.

Development of Needle Guide Unit Considering Buckling Bone-Perforation Control Strategy Based on Computed Tomography-Guided Needle Insertion Robot

A computed tomography (CT)-guided robotic assistance system is useful for needle insertion into metastatic carcinoma of vertebrae, which has limited pathways. However, the use of conventional needles in this procedure can result in bone fracture in the perforation area caused by the reaction force of the inserted needle. In this study, we developed a multistage retractable needle guide unit that avoids the buckling and crushing of the needle tip that commonly occur in 25-gauge ultrafine needles. First, we clarified a relationship between the shape of the guide and the termination factor when a buckling load is applied to the needle. Next, we revealed the point at which the plastic deformation of the needle occurred when the bone is drilled. Based on these results, we developed a guide unit with the reaction force set to an appropriate value. Finally, an evaluation test of bone needle insertion was conducted on porcine vertebrae with using the developed needle guide unit equipped with a 25-gauge needle. The needle penetrated the vertebra without buckling or crushing of the needle tip, which demonstrates the value of this multistage retractable needle guide unit when ultrafine needles are required. Clinical Relevance- Cancer tumors often metastasize to bones. There is a treatment called percutaneous vertebroplasty which restores the patient's quality of life by injecting poly (methyl methacrylate) (PMMA) into a bone. It helps to reinforce the bone that has become brittle due to cancer metastasis to the vertebral body or osteoporosis. This treatment often involves puncture of the vertebrae but the limited puncture pathway makes it difficult to perform the treatment manually. Therefore it is necessary to construct a system that supports accurate puncture by a robot such as the proposed method.

Robotic Cytology using Extra-Fine Needles : -Proposal of Puncture Control Strategy for Increasing Collection Amount

Fine needle aspiration cytology requires accurate needle insertion into a tumor and sufficient amount collection of samples, which highly depends on the skill of the physician. The advantage of the diagnosis is to minimize the tissue damage with the fine needle, while, when the amount of the sample sucked from the lesion is not enough for the definite diagnosis, the procedure has to be repeated until satisfying them. Although numerous research reported a robot-assisted insertion method to improve the accuracy of needle placement with fine needles, there was less research to address the efficient tissue collection. Ideally, the amount of the samples can be satisfied for the diagnosis even if an extra-fine needle (e.g. 25-gauge) is used. This paper proposes a novel needle insertion method for increasing the amount of the tissue sample with the extra-fine needle. The proposed insertion method comprises the round-trip insertion motion and trajectory rerouting with the nature of the bevel-tipped needle. The phantom study's result showed the equivalency of the aspiration amount between a physician's manual procedure with a 22-gauge needle and the proposed method with a 25-gauge needle (4.5 ± 1.0 mg vs 5.1 ± 0.7 mg). The results suggested that the proposed robotic aspiration method can increase the sampling amount with the extra-fine needle in the fine needle aspiration cytology.

Image-guided robots for low dose rate prostate brachytherapy: Perspectives on safety in design and use

BACKGROUND

Image-guided brachytherapy (BT) robots can be used to assist urologists during seed implantation, thereby improving therapeutic effects. However, safety issues must be considered in the design of such robots, including their structure, mechanical movements, function, materials and actuators. Previous reviews focused on image-guided prostate BT robot technology (e.g., imaging and robot navigation technology and robot system introduction); however, this review is the first time that safety issues have been investigated as part of a study on low-dose-rate (LDR) prostate BT robots.

METHODS

Multiple electronic databases were searched for LDR prostate BT robot articles published during the last 24 years (1996-2020), with a particular focus on two aspects of robots: safety in design and use.

RESULTS

We retrieved a total of 26 LDR prostate BT robots. BT robots were divided into ultrasound, computed tomography, magnetic resonance imaging and fusion-guided systems. The conditions associated with each system were then analysed to develop a set of requirements for the safety of prostate BT robots. Recommendations are also provided for future BT robot development.

CONCLUSIONS

The transrectal approach for prostate seed implantation is safer than the traditional transperineal approach. Research into the control of a steerable needle by the urologists and robot, the needle deflection model, and robotic automated needle changing and seed injection equipment should be pursued in a future study.