Feasibility of Locating Tumours in Lung via Kinesthetic Feedback Greig L. McCreery Ana Luisa Trejos Michael D. Naish Rajni V. Patel Richard A. Malthaner Abstract Background Localizing lung tumours during Minimally Invasive Surgery is difficult since restricted access pre- cludes manual palpation, and pre-operative imaging cannot map directly to the intra-operative lung. This study analyzes the force sensing performance that would allow an instrumented kinesthetic probe to localize tumours based on stiffness variations of the lung parenchyma. Methods Agar injected into ex-vivo porcine lungs produced a model approximating commonly encountered tumours. Force-deformation data were collected from multiple sites at various palpation depths and velocities, before and after the tumours were injected. Results Analysis showed an increase in force after the tumours were injected, ranging from 0.07 to 0.16 N at 7 mm, p< 10 -4 . A 2 mm/s palpation velocity minimized exponential stress decay at constant depths, facilitating easier comparisons between measurements. Conclusion A sensing range of 0 to 1 N, with 0.01 N resolution should allow a kinesthetic palpation probe to resolve local tissue stiffness changes that suggest an underlying tumour. 1 Introduction Minimally Invasive Surgery (MIS) is a surgical method which, due to its numerous advantages over conventional open surgery, is being adapted to many surgical techniques. Some of the advantages include a lower chance of infection, and reduced tissue trauma and post-operative pain [1]. Economic advantage has also been cited as a benefit of MIS, due to reduced recovery time in hospital and a faster return to work [2, 3]. These advantages are a result of the much smaller incisions, typically less than 10 mm in length, that are necessary to gain access to the surgical site. Irrespective of the advantages, some tasks in MIS are currently more difficult to perform than in the corresponding open procedure, possibly resulting in longer operative time and thereby offsetting some of the cost-savings and potential wait-time improvements. Some of the difficulties in MIS arise