SU‐FF‐T‐204: In Vivo Force‐Torque Measurement During Prostate Brachytherapy

Abstract

Purpose: The main goal of this study is to measure the needle insertion force/torque (F/T), velocity/ acceleration (V/A), and tissue/organ deformation during actual brachytherapy procedures in the operating room (OR). These in vivo data will guide the design of a Robot‐Assisted Platform for Intratumoral Delivery (RAPID) system. Method and Materials: We have acquired F/T and V/A data from actual patients and a single surgeon placing brachytherapy needles in the OR using a hand‐held adapter equipped with a 6 degree‐of‐freedom (DOF) F/T sensor (Nano25™). During this in vivo measurement, the needle progression into the soft tissue was registered using ultrasound (US) imaging technique. A 6 DOF electromagnetic (EM)‐based position sensor (miniBIRD®) was attached to the hand‐held adapter to measure 3D position and orientation of the hand‐held adapter. Results: The in vivo data reveals that maximum needle insertion force is about 18N, velocity is about 72cm/s, and acceleration is about 3000cm/s2. This relatively high acceleration may have some implications on the inertia force, which may help the surgeon in needle insertion. We observed significant transverse force (about 1.7N). From in vitro data it was observed that the force and torque during robotic needle insertion in animal soft tissues were significantly smaller as compared to that for humans. Conclusion: Additional in vivo data are being collected from different patients to study the effects of patient specific criteria such as age, height, ethnicity, body mass index (BMI), prostate specific agent (PSA) value, special anatomy, previous treatment, etc. on needle insertion force/torque and tissue deformation. Since frequent in vivo data collection and experimentation are impractical, we will use these data to determine the soft animal tissues and soft materials which have close resemblance to human tissues.

Surface-blended texturing of medical needles for friction reduction using a picosecond laser

“…The tissue with the 8 mm thickness was used for testing of the needles with micro-channels, while that with the 6 mm thickness for the needles with micro-dimples. This phantom tissue was commonly used as tissue-mimicking material during needle insertion tests due to its homogeneity [3,12]. In order to keep a constant pressure, the tissue was attached to the stage platform using double-sided tape.…”

“…Inaccurate needle placement increases the possibility of vital tissue damage, misdiagnosis, under-/overdosing with radiation, etc. [3]. Alterovitz et al [4] demonstrated that inserting and retracting a needle into soft tissues exerted forces causing the surrounding soft tissue to displace and deform and resulting in substantial placement error.…”

An experimental study on the mechanics and control of SMA-actuated bioinspired needle

“…The cutting force at the tip includes the plastic deformation from the act of cutting and the force resulting from tissue stiffness. Several studies have been conducted on modifying needle tip geometry to reduce the cutting forces [12][13][14][15]. A bevel tip needle has a smaller cutting force than a conical tip needle [15] but unlike a conical tip needle, it cannot travel in a straight path without rotating the needle about its axis.…”

High-order 3D FEM of prostate needle insertion forces

“…This was less than the displacement observed when the capsule had the same stiffness as the prostate (2.61 cm). However, in-vivo experiments conducted at our institution indicate that once the needle penetrated the capsule comparatively less force is experienced [10], [11]. The initial results emphasize the importance of capsule in the dynamics of needle insertion prior to needle penetration into the prostate parenchyma, suggesting that a more in depth analysis of the capsule material properties should be undertaken.…”

“…In-vivo needle insertion force measurements conducted at our institution established that 10N is a typical maximal needle insertion during prostate brachytherapy [10], [11]. In the model where the capsule was given the same stiffness as the prostate parenchyma, the node at the site of loading experienced an overall displacement of 2.61 cm.…”