The authors have developed magnetic resonance imaging-guided breast biopsy robot (MRSON), which is an automated magnetic resonance (MR) guided breast needle biopsy robot that works in an intragantry space with (3+1) degrees of freedom. This robot utilizes a bendable superelastic Nitinol biopsy needle. The MRSON’s needle path is normally parallel to the X -axis of the Cartesian coordinates. However, in some cases, parallel biopsy needle paths are not feasible based on obstacles that are present in front of the target tumor (i.e., compressor grid walls, visible blood vessels, or nontarget tumors). Therefore, a deflected needle path planning method for MRSON was developed in this article to avoid obstacles and accurately perform biopsies. The novelty of the proposed method lies in using a grid with 20×12 holes, through which the robot introduces the biopsy needle and actively deflects the needle against the grid to generate a deflected needle path leading to the target lesion without requiring additional actuators. To calculate the deflection amount and needle insertion depth, the deflected needle is modeled by an $\epsilon$ -second-order polynomial, and feasible needle paths are determined through geometry-based analysis. A path-ranking algorithm is then applied to select the best path among all feasible needle paths. Furthermore, to handle with any target lesion movement and coordinate misalignment between the robot and MR image coordinates, a Jacobian-based needle path adjustment method is proposed and verified through numerical simulations. The proposed deflected needle path planning method was verified through 28 in vitro accuracy test and four in vitro validation tests with a linear obstacle, which revealed a root-mean-square targeting error of 2.3 mm.

Sarcopenia is defined as muscle mass and strength loss with aging. As places, such as South Korea, Japan, and Europe have entered an aged society, sarcopenia is attracting global attention with elderly health. However, only few developed devices can quantify sarcopenia diagnosis modalities. Thus, the authors developed a sarcopenia detection system with 4 degrees of freedom to scan the human thigh with ultrasound probe and determine whether he/she has sarcopenia by inspecting the length of muscle thickness in the thigh by ultrasound image. To accurately measure the muscle thickness, the ultrasound probe attached to the sarcopenia detection system, must be moved angularly along the convex surface of the thigh with predefined pressure maintained. Therefore, the authors proposed an angular thigh scanning method for the aforementioned reason. The method first curve-fits the angular surface of the subject’s thigh with piecewise arcs using D information from a fixed RGB-D camera. Then, it incorporates a Jacobian-based ultrasound probe moving method to move the ultrasound probe along the curve-fitted arc and maintains radial interface force between the probe and the surface by force feedback control. The proposed method was validated by in-vitro test with a human thigh mimicked ham-gelatin phantom. The result showed the ham tissue thickness was maintained within approximately 26.01 ± 1.0 mm during 82$°$ scanning with a 2.5 N radial force setting and the radial force between probe and surface of the phantom was maintained within 2.50 ± 0.1 N.