Derivation of Optimal Insertion Speed for Organs to Satisfy Efficiency and Accuracy

While administering cancer vaccines, an extra-fine needle punctures into the affected area. Reportedly, needle insertion speeds affect the insertion reaction force, causing needle deflections. Additionally, longer insertion times increase the effect of respiratory fluctuations on the needle insertion speeds, leading to a reduction in needle deflections. This study focused on deriving the optimal speed for the liver, kidney, fat, and muscle of pigs to enable efficient and accurate insertion. Insertion tests were conducted to analyze the dependence of needle deflections on the insertion speed ranging from 2 to 20 mm/s and insertion angles of 0°, 15°, 30°, and 45°. Subsequently, a diagram of the relationship among insertion speeds, insertion angles, and needle deflections was created for each organ; this illustration, suggests that it is possible to determine the optimal insertion speed. In future, it is necessary to derive the optimal insertion speed for organs not used in this study. It is desirable to use insertion planning in combination with organ segmentation techniques using computed tomography (CT) images to optimal insertion speed.