IEEE/ASME TRANSACTIONS ON MECHATRONICS, VOL. 16, NO. 6, DECEMBER 2011 1011 Toward a Robot-Assisted Breast Intervention System Vishnu Mallapragada, Nilanjan Sarkar, Senior Member, IEEE, and Tarun K. Podder, Member, IEEE Abstract—Minimally invasive breast biopsies have several ad- vantages, such as low morbidity and decreased cost. However, suc- cess of these procedures is critically dependent on precise place- ment of the biopsy probe at the tumor location. In addition, during manual image-guided breast interventions, freehand ultrasound (US) imaging is challenging and coordinating image acquisition with probe insertion and breast stabilization simultaneously re- quires high level of skill. To address these problems, a novel robotic breast intervention device is presented in this paper. This system assists the clinician by: 1) ensuring accurate placement of the in- strument at the tumor location and 2) autonomously acquiring real-time images of the tumor. Experimental results on breast phan- toms demonstrate the efficacy of this device. This system has the potential to increase targeting accuracy while at the same time reducing the level of skill required to perform minimally invasive breast interventional procedures. Index Terms—Autonomous ultrasound (US) imaging, robot- assisted intervention, tumor manipulation. I. INTRODUCTION B REAST cancer is the most common cancer among Amer- ican women and is the third leading cause of cancer death in women [1]. Approximately 182 000 new breast cancer cases will be diagnosed next year with an estimated death of more than 40 000 women [1]. New minimally invasive procedures such as percutaneous core needle biopsy, radiofrequency ablation, in- terstitial laser ablation, and cryotherapy offer treatment options that are psychologically and cosmetically more acceptable to patients than traditional surgery [2]. These procedures also have numerous benefits such as low morbidity, decreased cost [3], short operating time, quick recovery of patient, etc. Early detection of breast cancer has been proven to reduce mortality by about 20%–35% [4]. Histopathological examina- tion is considered to be the “Gold Standard” for definitive di- agnosis of cancer, but requires tissue samples that are collected through biopsy. Of the two major approaches for breast biopsy, needle biopsy, and open excisional biopsy, needle biopsy is more attractive because it is less traumatic, produces little or no scar, Manuscript received September 1, 2009; revised November 25, 2009 and April 6, 2010; accepted May 18, 2010. Date of publication September 23, 2010; date of current version September 7, 2011. Recommended by Technical Editor D. Stoianovici. V. Mallapragada is with Stryker Medical, Kalamazoo, MI 49048 USA (e-mail: vishnu.goutham@gmail.com). N. Sarkar is with the Departments of Mechanical Engineering and Computer Engineering, Vanderbilt University, Nashville, TN 37235 USA (e-mail: nilanjan. sarkar@vanderbilt.edu). T. K. Podder is with the Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, PA 19107 USA (e-mail: tarun.podder@ jeffersonhospital.org). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TMECH.2010.2068575 allows quicker recovery, and is less costly. Despite many bene- fits of needle biopsy, there are significant technical challenges concerning accurate steering and precise placement of a biopsy needle at the target (in this paper, the word target is used to refer to a tumor, lesion, or just a suspected region of tissue) in the breast. During these procedures, a hollow core needle is percu- taneously inserted into the soft, inhomogeneous breast tissue in order to sample a target. In such procedures, it is critical to po- sition the needle tip precisely at the target. Precise placement of the needle at the target is challenging because of several reasons, such as tissue heterogeneity, tissue deformation, target mobility, patient movement, and poor maneuverability of the needle The current state-of-the-art minimally invasive procedure is highly dependent on the skill of the clinician and requires ex- traordinary level of hand–eye coordination [5]. Quality discrep- ancy has been noted in many studies and appears to be related to surgeon volume and/or specific breast surgery or surgical on- cology training [6]. It is concluded in [7] that breast-focused surgeons are more competent than the 50% of surgeons who do the occasional case. To overcome the aforementioned limitations, a new paradigm for image-guided minimally invasive procedures is presented [8], [9]. To demonstrate the efficacy of this paradigm, a novel robot-assisted breast intervention device is developed. Sonog- raphy is the most widely used imaging technique because of its real-time capability and cost-effectiveness [10]. Therefore, the robot-assisted breast intervention system presented in this pa- per is designed for ultrasound (US)-guided percutaneous breast biopsy. The biopsy instrument used for experimental valida- tion is a 10-gauge vacuum-assisted hollow core biopsy needle. The specific subsystems of this device are as follows. 1) A robotic manipulation mechanism: a mechanism to compensate for needle–target misalignment for providing access to mobile targets. 2) A US imaging system: an image acquisition system for dynamic tracking of the location of a target in real time using a 2-D US probe. These two subsystems are then integrated for a semiautomated modality of breast interventions. This device will potentially enhance clinical efficacy of image-guided breast interventions. The rest of the paper is organized as follows. Section II presents the design of the robotic system. Section III de- scribes the overall control architecture of the system. Section IV presents experimental results on breast phantoms (soft plastic material that mimics breast tissue). Section V summarizes the conclusions of this paper. II. SYSTEM DESIGN A. Design of a Robotic Manipulation Mechanism Currently available commercial biopsy instruments do not compensate for target movement. Freehand US-guided biopsy 1083-4435/$26.00 © 2010 IEEE