上海交通大学：《生物与机器人学》课程教学资源_Medical Robotics and Computer-Integrated Surgery

199 52.Medical Robotics and Computer-Integrated Surgery Russell H.Taylor,Arianna Menciassi,Gabor Fichtinger,Paolo Dario The growth of medical robotics since the mid- 52.1 Core concepts....1200 1980s has been striking.From a few initial efforts 52.1.1 Medical Robotics, in stereotactic brain surgery,orthopaedics,endo- Computer-Integrated Surgery, and Closed-Loop Interventions......1200 scopic surgery,microsurgery,and other areas,the 52.1.2 Factors Affecting the Acceptance field has expanded to include commercially mar- of Medical Robots.......... ..1200 keted,clinically deployed systems,and a robust 52.1.3 Medical Robotics System m and exponentially expanding research community. Paradigms:Surgical CAD/CAM u This chapter will discuss some major themes and and Surgical Assistance...............1202 illustrate them with examples from current and past research.Further reading providing a more 52.2 Technology.............. .1204 comprehensive review of this rapidly expanding 52.2.1 Mechanical Design Considerations..1204 field is suggested in Sect.52.4. 52.2.2 Control Paradigms 1205 Medical robots may be classified in many ways: 52.2.3 Virtual Fixtures by manipulator design (e.g.,kinematics,actua- and Human-Machine tion);by level of autonomy (e.g.,preprogrammed Cooperative Systems................1206 52.2.4 Safety and Sterility........ ....1207 versus teleoperation versus constrained cooper- 52.2.5 Imaging and Modeling ative control),by targeted anatomy or technique of Patients...... .1208 (e.g.,cardiac,intravascular,percutaneous,la- 52.2.6 Registration. 1208 paroscopic,microsurgical);or intended operating environment(e.g.,in-scanner,conventional op- 52.3 Systems,Research Areas, erating room).In this chapter,we have chosen to and Applications............ .1209 focus on the role of medical robots within the con- 52.3.1 Nonrobotic Computer-Assisted text of larger computer-integrated systems includ- Surgery:Navigation ing presurgical planning,intraoperative execution, and Image Overlay Devices .1209 and postoperative assessment and follow-up. 52.3.2 Orthopaedic Systems .1209 First,we introduce basic concepts of computer- 52.3.3 Percutaneous Needle integrated surgery,discuss critical factors affecting Placement Systems...... ..1210 the eventual deployment and acceptance of 52.3.4Telesurgical Systems .1212 medical robots,and introduce the basic system 52.3.5 Microsurgery Systems.113 52.3.6 Endoluminal Robots. paradigms of surgical computer-assisted plan- .1213 52.3.7 Sensorized Instruments ning,registration,execution,monitoring,and and Haptic Feedback 1214 assessment(CAD/CAM)and surgical assistance.In 52.3.8 Surgical Simulators subsequent sections,we provide an overview of and Telerobotic Systems the technology of medical robot systems and dis- for Training..... 1215 cuss examples of our basic system paradigms, 52.3.9 0ther Applications with brief additional discussion topics of remote and Research Areas 1216 telesurgery and robotic surgical simulators.We conclude with some thoughts on future research 52.4 Conclusion and Future Directions...........1217 directions and provide suggested further reading. Reference5.… 1218

1199 Medical Robo 52. Medical Robotics and Computer-Integrated Surgery Russell H. Taylor, Arianna Menciassi, Gabor Fichtinger, Paolo Dario The growth of medical robotics since the mid- 1980s has been striking. From a few initial efforts in stereotactic brain surgery, orthopaedics, endo￾scopic surgery, microsurgery, and other areas, the field has expanded to include commercially mar￾keted, clinically deployed systems, and a robust and exponentially expanding research community. This chapter will discuss some major themes and illustrate them with examples from current and past research. Further reading providing a more comprehensive review of this rapidly expanding field is suggested in Sect. 52.4. Medical robots may be classified in many ways: by manipulator design (e.g., kinematics, actua￾tion); by level of autonomy (e.g., preprogrammed versus teleoperation versus constrained cooper￾ative control), by targeted anatomy or technique (e.g., cardiac, intravascular, percutaneous, la￾paroscopic, microsurgical); or intended operating environment (e.g., in-scanner, conventional op￾erating room). In this chapter, we have chosen to focus on the role of medical robots within the con￾text of larger computer-integrated systems includ￾ing presurgical planning, intraoperative execution, and postoperative assessment and follow-up. First, we introduce basic concepts of computer￾integrated surgery, discuss critical factors affecting the eventual deployment and acceptance of medical robots, and introduce the basic system paradigms of surgical computer-assisted plan￾ning, registration, execution, monitoring, and assessment (CAD/CAM) and surgical assistance. In subsequent sections, we provide an overview of the technology of medical robot systems and dis￾cuss examples of our basic system paradigms, with brief additional discussion topics of remote telesurgery and robotic surgical simulators. We conclude with some thoughts on future research directions and provide suggested further reading. 52.1 Core Concepts ....................................... 1200 52.1.1 Medical Robotics, Computer-Integrated Surgery, and Closed-Loop Interventions ...... 1200 52.1.2 Factors Affecting the Acceptance of Medical Robots......................... 1200 52.1.3 Medical Robotics System Paradigms: Surgical CAD/CAM and Surgical Assistance ................. 1202 52.2 Technology .......................................... 1204 52.2.1 Mechanical Design Considerations .. 1204 52.2.2 Control Paradigms ........................ 1205 52.2.3 Virtual Fixtures and Human–Machine Cooperative Systems ..................... 1206 52.2.4 Safety and Sterility ....................... 1207 52.2.5 Imaging and Modeling of Patients .................................. 1208 52.2.6 Registration................................. 1208 52.3 Systems, Research Areas, and Applications .................................. 1209 52.3.1 Nonrobotic Computer-Assisted Surgery: Navigation and Image Overlay Devices ............ 1209 52.3.2 Orthopaedic Systems .................... 1209 52.3.3 Percutaneous Needle Placement Systems ....................... 1210 52.3.4 Telesurgical Systems ..................... 1212 52.3.5 Microsurgery Systems.................... 1213 52.3.6 Endoluminal Robots ..................... 1213 52.3.7 Sensorized Instruments and Haptic Feedback .................... 1214 52.3.8Surgical Simulators and Telerobotic Systems for Training ................................. 1215 52.3.9Other Applications and Research Areas ...................... 1216 52.4 Conclusion and Future Directions ........... 1217 References .................................................. 1218 Part F 52

1200 Part F Field and Service Robotics 52.1 Core Concepts 52.1.1 Medical Robotics, Figure 52.1 illustrates this view of computer- Computer-Integrated Surgery, integrated surgery (CIS).The process starts with and Closed-Loop Interventions information about the patient,which can include medical images [computed tomography (CT).magnetic reso- A fundamental property of robotic systems is their abil- nance imaging (MRD),positron emission tomography ity to couple complex information to physical action (PET),etc.],lab test results,and other information.This in order to perform a useful task.This ability to re- patient-specific information is combined with statisti- place,supplement,or transcend human performance has cal information about human anatomy,physiology,and had a profound influence on many fields of our soci- disease to produce a comprehensive computer represen- ety,including industrial production,exploration,quality tation of the patient,which can then be used to produce control,and laboratory processes.Although robots have an optimized interventional plan.In the operating room, Part often been first introduced to automate or improve dis- the preoperative patient model and plan must be reg- crete processes such as welding or test probe placement istered to the actual patient.Typically,this is done by F-52 or to provide access to environments where humans identifying corresponding landmarks or structures on the cannot safely go,their greater long-term impact has of- preoperative model and the patient,either by means of ten come indirectly as essential enablers of computer additional imaging (X-ray,ultrasound,video),by the use integration of entire production or service processes. of a tracked pointing device,or by the robot itself.If the Medical robots have a similar potential to funda- patient's anatomy has changed,then the model and plan mentally change surgery and interventional medicine are updated appropriately,and the planned procedure is as part of a broader,information-intensive environment carried out with assistance of the robot.As the interven- that exploits the complementary strengths of humans and tion continues,additional imaging or other sensing is computer-based technology.The robots may be thought used to monitor the progress of the procedure,to update of as information-driven surgical tools that enable hu- the patient model,and to verify that the planned proce- man surgeons to treat individual patients with greater dure has been successfully executed.After the procedure safety,improved efficacy,and reduced morbidity than is complete,further imaging,modeling,and computer- would otherwise be possible.Further,the consistency assisted assessment is performed for patient follow-up and information infrastructure associated with medical and to plan subsequent interventions,if any should be robotic and computer-assisted surgery systems have the required.Further,all the patient-specific data generated potential to make computer-integrated surgery as impor- during the planning,execution,and follow-up phases tant to health care as computer-integrated manufacturing can be retained.These data can subsequently be an- is to industrial production. alyzed statistically to improve the rules and methods used to plan future procedures. Information 52.1.2 Factors Affecting the Acceptance of Medical Robots Patient-specific information (images,lab results Model Plan Medical robotics is ultimately an application-driven genetics.text Acton research field.Although the development of medical records,etc.) robotic systems requires significant innovation and can lead to very real,fundamental advances in technology, medical robots must provide measurable and significant General information (anatomic atlases. Patient-specific evaluation advantages if they are to be widely accepted and de- statistics,rules) ployed.The situation is complicated by the fact that these advantages are often difficult to measure,can take an extended period to assess,and may be of varying im- Statistical analysis portance to different groups.Table 52.1 lists some of the more important factors that researchers contemplating Fig.52.1 Fundamental information flow in computer-integrated the development of a new medical robot system should surgery consider in assessing their proposed approach

1200 Part F Field and Service Robotics 52.1 Core Concepts 52.1.1 Medical Robotics, Computer-Integrated Surgery, and Closed-Loop Interventions A fundamental property of robotic systems is their abil￾ity to couple complex information to physical action in order to perform a useful task. This ability to re￾place, supplement, or transcend human performance has had a profound influence on many fields of our soci￾ety, including industrial production, exploration, quality control, and laboratory processes. Although robots have often been first introduced to automate or improve dis￾crete processes such as welding or test probe placement or to provide access to environments where humans cannot safely go, their greater long-term impact has of￾ten come indirectly as essential enablers of computer integration of entire production or service processes. Medical robots have a similar potential to funda￾mentally change surgery and interventional medicine as part of a broader, information-intensive environment that exploits the complementary strengths of humans and computer-based technology. The robots may be thought of as information-driven surgical tools that enable hu￾man surgeons to treat individual patients with greater safety, improved efficacy, and reduced morbidity than would otherwise be possible. Further, the consistency and information infrastructure associated with medical robotic and computer-assisted surgery systems have the potential to make computer-integrated surgery as impor￾tant to health care as computer-integrated manufacturing is to industrial production. Information Statistical analysis Patient-specific evaluation Model Plan Action Patient-specific information (images, lab results, genetics, text records, etc.) General information (anatomic atlases, statistics, rules) Fig. 52.1 Fundamental information flow in computer-integrated surgery Figure 52.1 illustrates this view of computer￾integrated surgery (CIS). The process starts with information about the patient, which can include medical images [computed tomography (CT), magnetic reso￾nance imaging (MRI), positron emission tomography (PET), etc.], lab test results, and other information. This patient-specific information is combined with statisti￾cal information about human anatomy, physiology, and disease to produce a comprehensive computer represen￾tation of the patient, which can then be used to produce an optimized interventional plan. In the operating room, the preoperative patient model and plan must be reg￾istered to the actual patient. Typically, this is done by identifying corresponding landmarks or structures on the preoperative model and the patient, either by means of additional imaging (X-ray, ultrasound, video), by the use of a tracked pointing device, or by the robot itself. If the patient’s anatomy has changed, then the model and plan are updated appropriately, and the planned procedure is carried out with assistance of the robot. As the interven￾tion continues, additional imaging or other sensing is used to monitor the progress of the procedure, to update the patient model, and to verify that the planned proce￾dure has been successfully executed. After the procedure is complete, further imaging, modeling, and computer￾assisted assessment is performed for patient follow-up and to plan subsequent interventions, if any should be required. Further, all the patient-specific data generated during the planning, execution, and follow-up phases can be retained. These data can subsequently be an￾alyzed statistically to improve the rules and methods used to plan future procedures. 52.1.2 Factors Affecting the Acceptance of Medical Robots Medical robotics is ultimately an application-driven research field. Although the development of medical robotic systems requires significant innovation and can lead to very real, fundamental advances in technology, medical robots must provide measurable and significant advantages if they are to be widely accepted and de￾ployed. The situation is complicated by the fact that these advantages are often difficult to measure, can take an extended period to assess, and may be of varying im￾portance to different groups. Table 52.1 lists some of the more important factors that researchers contemplating the development of a new medical robot system should consider in assessing their proposed approach. Part F 52.1

Medical Robotics and Computer-Integrated Surgery 52.1 Core Concepts 1201 Table 52.1 Assessment factors for medical robots or computer-integrated surgery systems [52.1] Assessment factor Important to whom Assessment method Summary of key leverage New treatment Clinical researchers, Clinical and trials Transcend human sensory-motor limits options patients preclinical (e.g.,in microsurgery).Enable less invasive procedures with real-time image feedback (e.g..fluoroscopic or MRI-guided liver or prostate therapy).Speed up clinical research through greater consistency and data gathering Quality Surgeons. Clinician Significantly improve the quality of surgical technique (e.g.. patients judgment; in microvascular anastomosis),thus improving results and revision rates reducing the need for revision surgery Time and cost Surgeons, Hours, Speed operating room(OR)time for some interventions.Reduce hospitals, hospital costs from healing time and revision surgery.Provide effective insurers charges intervention to treat patient condition Less Surgeons, Qualitative Provide crucial information and feedback needed to reduce Part invasiveness patients judgment: the invasiveness of surgical procedures,thus reducing recovery times infection risk,recovery times,and costs(e.g..percutaneous spine surgery) Safety Surgeons. Complication Reduce surgical complications and errors,again lowering patients and revision costs,improving outcomes and shortening hospital stays surgery rates (e.g.,robotic total hip replacement(THR),steady-hand brain surgery) Real-time Surgeons Qualitative Integrate preoperative models and intraoperative images to feedback assessment, give surgeon timely and accurate information about the quantitative patient and intervention(e.g.,fluoroscopic X-rays without comparison of surgeon exposure,percutaneous therapy in conventional plan to MRI scanners).Assure that the planned intervention has in observation. fact been accomplished revision surgery rates Accuracy or Surgeons Quantitative Significantly improve the accuracy of therapy dose pattern precision comparison of delivery and tissue manipulation tasks (e.g.,solid organ plan to actual therapy,microsurgery,robotic bone machining) Enhanced Surgeons, Databases, Exploit CIS systems'ability to log more varied and detailed documentation clinical anatomical information about each surgical case than is practical in and follow-up researchers atlases. conventional manual surgery.Over time,this ability. images,and coupled with CIS systems'consistency,has the potential to clinical significantly improve surgical practice and shorten research observations trials Broadly,the advantages offered by medical robots These capabilities can both enhance the ability of an av- may be grouped into three areas.The first is the poten- erage surgeon to perform procedures that only a few tial of a medical robot to significantly improve surgeons' exceptionally gifted surgeons can perform unassisted technical capabiliry to perform procedures by exploiting and can also make it possible to perform interventions the complementary strengths of humans and robots sum-that would otherwise be completely infeasible. marized in Table 52.2.Medical robots can be constructed A second,closely related capability is the poten- to be more precise and geometrically accurate than an tial of medical robots to promote surgical safery both unaided human.They can operate in hostile radiolog-by improving a surgeon's technical performance and by ical environments and can provide great dexterity for means of active assists such as no-fly zones or virtual minimally invasive procedures inside the patient's body.fixtures (Sect.52.2.3)to prevent surgical instruments

Medical Robotics and Computer-Integrated Surgery 52.1 Core Concepts 1201 Table 52.1 Assessment factors for medical robots or computer-integrated surgery systems [52.1] Assessment factor Important to whom Assessment method Summary of key leverage New treatment Clinical researchers, Clinical and trials Transcend human sensory-motor limits options patients preclinical (e.g., in microsurgery). Enable less invasive procedures with real-time image feedback (e.g., fluoroscopic or MRI-guided liver or prostate therapy). Speed up clinical research through greater consistency and data gathering Quality Surgeons, Clinician Significantly improve the quality of surgical technique (e.g., patients judgment; in microvascular anastomosis), thus improving results and revision rates reducing the need for revision surgery Time and cost Surgeons, Hours, Speed operating room (OR) time for some interventions. Reduce hospitals, hospital costs from healing time and revision surgery. Provide effective insurers charges intervention to treat patient condition Less Surgeons, Qualitative Provide crucial information and feedback needed to reduce invasiveness patients judgment; the invasiveness of surgical procedures, thus reducing recovery times infection risk, recovery times, and costs (e.g., percutaneous spine surgery) Safety Surgeons, Complication Reduce surgical complications and errors, again lowering patients and revision costs, improving outcomes and shortening hospital stays surgery rates (e.g., robotic total hip replacement (THR), steady-hand brain surgery) Real-time Surgeons Qualitative Integrate preoperative models and intraoperative images to feedback assessment, give surgeon timely and accurate information about the quantitative patient and intervention (e.g., fluoroscopic X-rays without comparison of surgeon exposure, percutaneous therapy in conventional plan to MRI scanners). Assure that the planned intervention has in observation, fact been accomplished revision surgery rates Accuracy or Surgeons Quantitative Significantly improve the accuracy of therapy dose pattern precision comparison of delivery and tissue manipulation tasks (e.g., solid organ plan to actual therapy, microsurgery, robotic bone machining) Enhanced Surgeons, Databases, Exploit CIS systems’ ability to log more varied and detailed documentation clinical anatomical information about each surgical case than is practical in and follow-up researchers atlases, conventional manual surgery. Over time, this ability, images, and coupled with CIS systems’ consistency, has the potential to clinical significantly improve surgical practice and shorten research observations trials Broadly, the advantages offered by medical robots may be grouped into three areas. The first is the poten￾tial of a medical robot to significantly improve surgeons’ technical capability to perform procedures by exploiting the complementary strengths of humans and robots sum￾marized in Table 52.2. Medical robots can be constructed to be more precise and geometrically accurate than an unaided human. They can operate in hostile radiolog￾ical environments and can provide great dexterity for minimally invasive procedures inside the patient’s body. These capabilities can both enhance the ability of an av￾erage surgeon to perform procedures that only a few exceptionally gifted surgeons can perform unassisted and can also make it possible to perform interventions that would otherwise be completely infeasible. A second, closely related capability is the poten￾tial of medical robots to promote surgical safety both by improving a surgeon’s technical performance and by means of active assists such as no-fly zones or virtual fixtures (Sect. 52.2.3) to prevent surgical instruments Part F 52.1

1202 Part F Field and Service Robotics Table 52.2 Complementary strengths of human surgeons and robots [52.1] Strengths Limitations Humans Excellent judgment Prone to fatigue and inattention Excellent hand-eye coordination Limited fine motion control due to tremor Excellent dexterity (at natural hmnan scale) Limited manipulation ability and dexterity Able to integrate and act on multiple information outside natural scale sources Cannot see through tissue Easily trained Bulky end-effectors(hands) Versatile and able to improvise Limited geometric accuracy Hard to keep sterile Affected by radiation.infection Robots Excellent geometric accuracy Poor judgment Untiring and stable Hard to adapt to new situations Part F52.1 Immune to ionizing radiation Limited dexterity Can be designed to operate at Limited hand-eye coordination many different scales of motion Limited haptic sensing(today) and payload Limited ability to integrate and Able to integrate multiple sources interpret complex information of numerical and sensor data from causing unintentional damage to delicate struc- ing of sutures or in placing of components in joint recon- tures.Furthermore,the integration of medical robots structions)is itself an important quality factor.If saved within the information infrastructure of a larger CIS and routinely analyzed,the flight data recorder infor- system can provide the surgeon with significantly im- mation inherently available with a medical robot can be proved monitoring and online decision supports,thus used both in morbidiry and mortaliry assessments of seri- further improving safety. ous surgical incidents and,potentially,in statistical anal- A third advantage is the inherent ability of medical yses examining many cases to develop better surgical robots and CIS systems to promote consistency while plans.Furthermore,such data can provide valuable input capturing detailed online information for every proce- for surgical simulators,as well as a database for develop- dure.Consistent execution(e.g.,in spacing and tension-ing skill assessment and certification tools for surgeons. Stereo video Fig.52.2 The daVinci telesurgical Instrument robot [52.2]extends a surgeon's ca- manipulators pabilities by providing the immediacy Surgeon interface and dexterity of open surgery in manipulators Motion controller a minimally invasive surgical envi- ronment.(Photos:Intuitive Surgical. Sunnyvale)

1202 Part F Field and Service Robotics Table 52.2 Complementary strengths of human surgeons and robots [52.1] Strengths Limitations Humans Excellent judgment Prone to fatigue and inattention Excellent hand–eye coordination Limited fine motion control due to tremor Excellent dexterity (at natural human scale) Limited manipulation ability and dexterity Able to integrate and act on multiple information outside natural scale sources Cannot see through tissue Easily trained Bulky end-effectors (hands) Versatile and able to improvise Limited geometric accuracy Hard to keep sterile Affected by radiation, infection Robots Excellent geometric accuracy Poor judgment Untiring and stable Hard to adapt to new situations Immune to ionizing radiation Limited dexterity Can be designed to operate at Limited hand–eye coordination many different scales of motion Limited haptic sensing (today) and payload Limited ability to integrate and Able to integrate multiple sources interpret complex information of numerical and sensor data from causing unintentional damage to delicate struc￾tures. Furthermore, the integration of medical robots within the information infrastructure of a larger CIS system can provide the surgeon with significantly im￾proved monitoring and online decision supports, thus further improving safety. A third advantage is the inherent ability of medical robots and CIS systems to promote consistency while capturing detailed online information for every proce￾dure. Consistent execution (e.g., in spacing and tension￾Stereo video Instrument manipulators Surgeon interface manipulators Motion controller Fig. 52.2 The daVinci telesurgical robot [52.2] extends a surgeon’s ca￾pabilities by providing the immediacy and dexterity of open surgery in a minimally invasive surgical envi￾ronment. (Photos: Intuitive Surgical, Sunnyvale) ing of sutures or in placing of components in joint recon￾structions) is itself an important quality factor. If saved and routinely analyzed, the flight data recorder infor￾mation inherently available with a medical robot can be used both in morbidity and mortality assessments of seri￾ous surgical incidents and, potentially, in statistical anal￾yses examining many cases to develop better surgical plans. Furthermore, such data can provide valuable input for surgical simulators, as well as a database for develop￾ing skill assessment and certification tools for surgeons. Part F 52.1

Medical Robotics and Computer-Integrated Surgery 52.1 Core Concepts 1203 52.1.3 Medical Robotics System Paradigms: orthopaedic joint reconstructions(discussed further in Surgical CAD/CAM Sect.52.3.2)and image-guided placement of therapy and Surgical Assistance needles (Sect.52.3.3). Surgery is often highly interactive;many decisions We call the process of computer-assisted planning,regis- are made by the surgeon in the operating room and exe- tration,execution,monitoring,and assessment surgical cuted immediately,usually with direct visual or haptic CAD/CAM,emphasizing the analogy to manufacturing feedback.Generally,the goal of surgical robotics is not CAD/CAM.Just as with manufacturing,robots can be to replace the surgeon so much as to improve his or her critical in this CAD/CAM process by enhancing the ability to treat the patient.The robot is thus a computer- surgeon's ability to execute surgical plans.The spe-controlled surgical tool in which control of the robot is cific role played by the robot depends somewhat on often shared in one way or another between the human the application,but current systems tend to exploit surgeon and a computer.We thus often speak of medical the geometric accuracy of the robot and/or its ability robots as surgical assistants. to function concurrently with X-ray or other imag- Broadly,robotic surgical assistants may be broken ing devices.Typical examples include radiation therapy into two subcategories.The first category,surgeon ex- delivery robots such as Accuray's CyberKnife [52.5] tender robots.manipulate surgical instruments under the (Accuray,Inc.,Sunnyvale,CA.),shaping of bone in direct control of the surgeon,usually through a teleop- Part F52 a) b) Stereo display Microscope C.n(任handte-Cscale frool） Tool handle Cameras Robot interface Optional HMD Steady hand robot Fig.52.3a,b The Johns Hopkins Steady Hand microsurgical robot [52.3,4]extends a surgeon's capabilities by providing the ability to manipulate surgical instruments with very high precision while still exploiting the surgeon's natural hand-eye coordination.(a)The basic paradigm of hands-on compliant guiding.The commanded velocity of the robot is proportional to a scaled difference between the forces exerted by the surgeon on the tool handle and (optionally)sensed tool-to-tissue forces.(b)A more recent version of the Steady Hand robot currently being used for experiments in microcannulation of l00μn blood vessels

Medical Robotics and Computer-Integrated Surgery 52.1 Core Concepts 1203 52.1.3 Medical Robotics System Paradigms: Surgical CAD/CAM and Surgical Assistance We call the process of computer-assisted planning, regis￾tration, execution, monitoring, and assessment surgical CAD/CAM, emphasizing the analogy to manufacturing CAD/CAM. Just as with manufacturing, robots can be critical in this CAD/CAM process by enhancing the surgeon’s ability to execute surgical plans. The spe￾cific role played by the robot depends somewhat on the application, but current systems tend to exploit the geometric accuracy of the robot and/or its ability to function concurrently with X-ray or other imag￾ing devices. Typical examples include radiation therapy delivery robots such as Accuray’s CyberKnife [52.5] (Accuray, Inc., Sunnyvale, CA.), shaping of bone in fhandle a) b) Stereo display Microscope Tool Cameras Optional HMD Steady hand robot x · f cmd tool Robot interface Cυ (fhandle – Cscale ftool) Fig. 52.3a,b The Johns Hopkins Steady Hand microsurgical robot [52.3,4] extends a surgeon’s capabilities by providing the ability to manipulate surgical instruments with very high precision while still exploiting the surgeon’s natural hand–eye coordination. (a) The basic paradigm of hands-on compliant guiding. The commanded velocity of the robot is proportional to a scaled difference between the forces exerted by the surgeon on the tool handle and (optionally) sensed tool-to-tissue forces. (b) A more recent version of the Steady Hand robot currently being used for experiments in microcannulation of 100μm blood vessels orthopaedic joint reconstructions (discussed further in Sect. 52.3.2) and image-guided placement of therapy needles (Sect. 52.3.3). Surgery is often highly interactive; many decisions are made by the surgeon in the operating room and exe￾cuted immediately, usually with direct visual or haptic feedback. Generally, the goal of surgical robotics is not to replace the surgeon so much as to improve his or her ability to treat the patient. The robot is thus a computer￾controlled surgical tool in which control of the robot is often shared in one way or another between the human surgeon and a computer. We thus often speak of medical robots as surgical assistants. Broadly, robotic surgical assistants may be broken into two subcategories. The first category, surgeon ex￾tender robots, manipulate surgical instruments under the direct control of the surgeon, usually through a teleop￾Part F 52.1