Kerr, William

Pierce, S. Gareth

Rowe, Philip

University of Strathclyde Institutional Repository

Strathprints Institutional RepositoryKerr, William and Rowe, Philip and Pierce, Stephen Gareth (2015) Measurement of the geometry of the distal femur using robotic 3D ultrasound. In: 15th Annual Meeting of CAOS-International. UNSPECIFIED, pp. 1-3. , This version is available at http://strathprints.strath.ac.uk/57781/Strathprints is  designed  to  allow  users  to  access  the  research  output  of  the  University  of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may  not  engage  in  further  distribution  of  the  material  for  any  profitmaking  activities  or  any commercial gain. You may freely distribute both the url (http://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge. Any  correspondence  concerning  this  service  should  be  sent  to  Strathprints  administrator: strathprints@strath.ac.ukMEASUREMENT OF THE GEOMETRY OF THE DISTAL FEMUR USING ROBOTIC 3D ULTRASOUND.  William Kerr BSc1*, Philip Rowe PhD2, Stephen Gareth Pierce PhD3 1,2,3*University of Strathclyde, Glasgow, G4 0NW, United Kingdom, william.kerr@strath.ac.uk  INTRODUCTION Currently, Computed Tomography (CT) is the gold standard method of preoperative imaging for guided knee arthroplasty systems, such as the Makoplasty 5RFKH2¶/RXJKOLQKendoff, Musahl, & Pearle, 2009). However, this method is costly (Fred, 2004) and applies a potentially dangerous dose of ionising radiation to the patient (Albert, 2013). Ultrasound imaging has the potential to provide an alternative to CT in this capacity by offering comparable accuracies, while reducing cost and eliminating the risk of ionising radiation. A system was developed which allows for imaging of the bony surface of the distal femur using imaging methods usually found in non-destructive testing (Holmes, Drinkwater, & Wilcox, 2005). This serves to establish a proof of concept for a full 3D knee imaging scheme.  MATERIALS AND METHODS An artificial human distal femur made from fibre strengthened epoxy (Sawbones, VA, USA) and a bovine distal femur were submerged in a water bath and imaged using a 128 element 5MHz linear probe. The transducer was driven by a Diagnostic Sonar Ltd. (Livingston, Scotland) FlawInspecta phased array driver, which allowed for Full Matrix Capture (FMC). Following a cuboidal path, the probe was manoeuvred around the specimen by a Kuka KR5 Arc HW 6 axis robot. Bespoke probe mounts and calibration parts were manufactured to determine the probe position and orientation relative to the robot¶VFRRUGLQDWHV\VWHP. Measurement with a Faro (FL, USA) Quantum touch probe found the parts to be within 0.1mm of the desired dimensions. Using synchronised probe position and ultrasonic data capture, 337 ultrasonic data acquisitions were performed for the human distal femur and 1090 for the bovine distal femur - both using FMC. The data were post-processed using the Total Focussing Method (TFM) and the Synthetic Aperture Focussing Method (SAFT), which provided 2D images. Contour extraction was performed on each image and the resulting points were translated and transformed using the associated positional data, providing 3D point clouds representing the surface. Using Geomagic Studio 12, wrapping algorithms were applied to the point clouds, returning 3D surface models. Both distal femurs were laser scanned using a Faro Quantum, providing accurate reference models for accuracy analysis.  RESULTS The ultrasound-derived models were of a relatively high level of accuracy, achieving sub-millimetre mean error for both specimens, as shown in Table 1. This was achieved not with TFM, but rather a small aperture variety of SAFT. However, both data sets returned relatively large maximum errors. In the human model, this was presented as a circular feature, as can be seen in Figure 1. The human distal femur featured a drilled hole at this point, the representation of which was present in the point cloud, but was lost due to the wrapping function during 3D model production. The standard deviation was small for the human distal femur, but over 1mm for the bovine distal femur. Large errors in the bovine model corresponded to incomplete regions in the reference model, caused by line of sight issues during laser capture. These gaps likely account for the large standard deviation.   Figure 1: Result of matching resultant 3D models with the reference models. Part (a) shows the composite distal femur comparison, while part (b) displays the bovine distal femur.    Mean Error (mm) Maximum Error (mm) Standard Deviation (mm) Composite Human Distal Femur 0.8201 7.6845 0.6401 Bovine Distal Femur 0.8797 10.4124 1.0157 Table 1: The results of the comparison between resultant 3D models with the reference models.   DISCUSSION Robotically controlled ultrasound systems have been employed to image and reconstruct bony surfaces of the femur before, but were intended only for registration of real world position with CT data (Torres, Sanches, Goncalves, & Martins, 2012). Others have employed optically tracked systems that require prior knowledge of the geometry of the bone (Barratt et al., 2008; Krysztoforski, Krowicki, Swiatek-Najwer, Bedzinski, & Keppler, 2011). The presented system, on the other hand, requires no previous information. While a number of biomedical ultrasound research efforts have employed non-commercial ultrasound systems (Jensen, Nikolov, Gammelmark, & Pedersen, 2006),  most employ conventional systems, which do not allow for wide ranging imaging strategies (Jensen et al., 2005). The system used herein allows for FMC capture and, as such, provides the ability to test a number of imaging methods post capture. One such method is TFM, which is seen as the gold standard in classical beamforming (Fan, Caleap, Pan, & Drinkwater, 2014). It, along with SAFT, is used heavily in ultrasonic NDT research, but has found little uptake in biomedical imaging. The mean accuracy of the system met the target of 1mm error often reported for CT (Viceconti, Zannoni, Testi, & Cappello, 1999). However, both surface models suffered from high maximum errors and, in the case of the bovine distal femur, a high standard deviation. It is believed that with a more accurate reference model, the standard deviation, maximum error and, to a lesser extent, mean error would be reduced in the bovine distal femur. Additionally, filling of the hole in the human distal femur - an abrupt feature not expected in vivo - would reduce the error associated with the wrapping algorithm¶V hole filling. Finally, it is believed that improvements to the robot calibration procedure would further reduce errors. Despite the relative success of this study in showing the principle of functionality of the system, the conditions under which the data were recovered were unrealistic. As such, future work will look to incorporate the problem of soft tissue penetration in FMC and issues involving line of sight in intact knee joints.      REFERENCES Albert, J. M. (2013). Radiation risk from CT: Implications for cancer screening. American Journal of Roentgenology, 201(July), 81 ?87. doi:10.2214/AJR.12.9226 Barratt, D. C., Chan, C. S. K., Edwards, P. J., Penney, G. P., Slomczykowski, M., Carter, T. J., & Hawkes, D. J. (2008). Instantiation and registration of statistical shape models of the femur and pelvis using 3D ultrasound imaging. Medical Image Analysis, 12(3), 358 ?74. doi:10.1016/j.media.2007.12.006 Fan, C., Caleap, M., Pan, M., & Drinkwater, B. W. (2014). A comparison between ultrasonic array beamforming and super resolution imaging algorithms for non-destructive evaluation. Ultrasonics, 54(7), 1842 ?1850. doi:10.1016/j.ultras.2013.12.012 Fred, H. L. (2004). Drawbacks and Limitations of Computed Tomography. Texas Heart Institute Journal, 31(4), 345 ?348. Holmes, C., Drinkwater, B. W., & Wilcox, P. D. (2005). Post-processing of the full matrix of ultrasonic transmit ?receive array data for non-destructive evaluation. NDT & E International, 38(8), 701 ?711. doi:10.1016/j.ndteint.2005.04.002 :ĞŶƐĞŶ ?: ? ? ?,Žůŵ ?K ? ?:ĞŶƐĞŶ ?> ?: ? ?ĞŶĚƐĞŶ ?, ? ?EŝŬŽůŽǀ ^ ?/ ? ?dŽŵŽǀ ? ?' ? ? ?'ĂŵŵĞůŵĂƌŬ ?< ?> ?(2005). Ultrasound Research Scanner for Real-time Synthetic Aperture Data Acquisition. IEEE Transactions on Utrasonics, Ferroelectrics, and Frequency Control, 52(5), 881 ?891. Jensen, J. A., Nikolov, S. I., Gammelmark, K. L., & Pedersen, M. H. (2006). Synthetic aperture ultrasound imaging. Ultrasonics, 44 Suppl 1, e5 ?15. doi:10.1016/j.ultras.2006.07.017 Krysztoforski, K., Krowicki, P., Swiatek-Najwer, E., Bedzinski, R., & Keppler, P. (2011). Noninvasive ultrasonic measuring system for bone geometry examination. The International Journal of Medical Robotics and Computer Assisted Surgery, 7(January), 85 ?95. doi:10.1002/rcs ZŽĐŚĞ ?D ? ?K ?>ŽƵŐŚůŝŶ ?W ?& ? ?<ĞŶĚŽĨĨ ? ? ?DƵƐĂŚů ?s ? ? ?WĞ ƌůĞ ? ? ? ? ? ? ? ? ? ?ZŽďŽƚŝĐĂƌŵ-assisted unicompartmental knee arthroplasty: preoperative planning and surgical technique. American Journal of Orthopedics (Belle Mead, N.J.), 38(2 Suppl), 10 ?5. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/19340377 Torres, P. M. B., Sanches, M. J., Goncalves, P. J. S., & Martins, J. M. M. (2012). Robotic 3D Ultrasound. In Proceedings of RECPAD 2012, 18th Portuguese Conference on Pattern Recognition (pp. 2 ?3). Viceconti, M., Zannoni, C., Testi, D., & Cappello, A. (1999). CT data sets surface extraction for biomechanical modeling of long bones. Computer Methods and Programs in Biomedicine, 59, 159 ?166. doi:10.1016/S0169-2607(98)00107-2 DISCLOSURES None.   

Measurement of the geometry of the distal femur using robotic 3D ultrasound

Pierce, Stephen Gareth

Name not available

http://strathprints.strath.ac.uk/57781/1/Kerr_etal_CAOS2015_measurement_geometry_distal_femur_using_robotic_3D_ultrasound.pdf

Measurement of the geometry of the distal femur using robotic 3D ultrasound

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