Biocompatible sensors have been demonstrated using traditional microfabrication techniques modified for polymer substrates and utilize only materials suitable for implantation or bodily contact. Sensor arrays for the measurement of the load condition of polyethylene spacers in the total knee arthroplasty (TKA) prosthesis have been developed. Arrays of capacitive sensors are used to determine the three-dimensional strain within the polyethylene prosthesis component. Data from these sensors can be used to give researchers a better understanding of component motion, loading, and wear phenomena for a large range of activities. This dissertation demonstrates both analytically and experimentally the fabrication of these sensor arrays using biocompatible polymer substrates and dielectrics while preserving industry-standard microfabrication processing for micron-level resolution. An array of sensors for real-time measurement of pressure profiles is the long-term goal of this research. A custom design using capacitive-based sensors is an excellent selection for such measurement, giving high spatial resolution across the sensing surface and high load resolution for pressures applied normal to that surface while operating at low power.

Modern image-guided surgery aids minimally-invasive, high-precision procedures that increase efficacy of treatment. This thesis investigates two research aims to improve precision and integration of intraoperative cone-beam CT (CBCT) imaging in guidance of head and neck (H&N) surgery. First, marker configurations were examined to identify arrangements that minimize target registration error (TRE). Best arrangements minimized the distance between the configuration centroid and surgical target while maximizing marker separation. Configurations of few markers could minimized TRE with more markers providing improved uniformity. Second, an algorithm for automatic registration of image and world reference frames was pursued to streamline integration of CBCT with real-time tracking and provide automatic updates per scan. Markers visible to the tracking and imaging systems are automatically co-localized and registered with equivalent accuracy and superior reproducibility compared to conventional registration. Such work helps the implementation of CBCT in H&N surgery to maximize surgical precision and exploit intraoperative image guidance.

Modern image-guided surgery aids minimally-invasive, high-precision procedures that increase efficacy of treatment. This thesis investigates two research aims to improve precision and integration of intraoperative cone-beam CT (CBCT) imaging in guidance of head and neck (H&N) surgery. First, marker configurations were examined to identify arrangements that minimize target registration error (TRE). Best arrangements minimized the distance between the configuration centroid and surgical target while maximizing marker separation. Configurations of few markers could minimized TRE with more markers providing improved uniformity. Second, an algorithm for automatic registration of image and world reference frames was pursued to streamline integration of CBCT with real-time tracking and provide automatic updates per scan. Markers visible to the tracking and imaging systems are automatically co-localized and registered with equivalent accuracy and superior reproducibility compared to conventional registration. Such work helps the implementation of CBCT in H&N surgery to maximize surgical precision and exploit intraoperative image guidance.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21338号 / 医博第4396号 / 新制||医||1031(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 坂井 義治, 教授 平井 豊博, 教授 溝脇 尚志 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Disregard for patient-specific joint-level variability may be related to decreased functional ability, poor implant longevity and dissatisfaction post-TKA. The purpose of this study was to, 1) compare pre and post-implant intraoperative passive knee adduction angle kinematic patterns and characterize the effect of surgical intervention on each pattern, 2) examine the association between passive pre and post-implant knee kinematics measured intraoperatively and dynamic knee kinematics and kinetics pre and post-TKA measured during gait, and 3) compare dynamic post-TKA kinematic and kinetic patterns between patient-specific knee recipients and traditional TKA recipient. Patients received a TKA using the Stryker Precision Knee navigation system capturing pre/post-implant kinematics through a passive range of flexion. One-week prior and 1-year post-TKA patients underwent three-dimensional gait analysis. Knee joint waveforms were calculated according to the joint coordinate system. Principal component analysis (PCA) was applied to frontal plane gait angles, moments and navigation angles. Paired two- tailed t-tests were used to compare principal component (PC) scores between pre and post-implant patterns, and a one-way ANOVA was used to test if post-implant patterns were significantly different from zero. Two-tailed Pearson correlation coefficients tested for associations between navigation and gait PCscores, and an un-paired two-tailed t-test was used to compare PCscores between patient-specific and traditional TKA groups. Six different passive kinematic phenotypes were captured pre-implant. Although some waveform patterns persisted at small magnitudes post-implant (PC1 and PC3: p<0.001), curves remained within the clinically acceptable alignment range through passive motion. A positive correlation was found between navigation adduction angle PC1 and gait adduction moment PC1 pre and post-TKA (p<0.001, r=0.79; p<0.01 r=0.67), and a negative correlation between navigation adduction angle PC1 and gait adduction angle PC1 post-TKA (p=0.03, r=-0.53). The patient-specific group showed significantly lower PC2 scores than the traditional TKA group (p=0.03), describing a lower flexion moment magnitude during early stance phase, possibly representing a functional limitation or non- confidence during gait. These results were an important first step to assess patient- specific approaches to TKA, suggesting possible applications for patient-specific intraoperative kinematics to aid in surgical decision-making and influence functional outcomes.

INTRODUCTION: Computer aided navigation is an important tool which has the capability to enhance surgical accuracy, while reducing negative outcomes. However, it is a relatively new technology and has not yet been accepted as the standard of care in all settings. OBJECTIVES: The objective of the present study is to present the development and current state of technologies in computer aided navigation in Orthopedic Spine Surgery, specifically in navigated placement of pedicle screws, to examine the clinical need for navigation, it's effect on surgical accuracy and clinical outcome and to determine whether the benefits justify the costs, and make recommendations for future use and enhancements. CONCLUSION: Computer aided navigation in pedicle screw placement enhances accuracy, reduces the probability of negative outcomes, reduces the exposure of the patient and staff to radiation, reduces operative time, and provides cost-savings. Future investigations may potentially enhance this effect further with the use of innovative augmented reality type displays.

In the past twenty years, the combination of the advances in medical imaging technologies and therapeutic methods had a great impact in developing minimally invasive interventional procedures. Although the use of medical imaging for the surgery and therapy guidance dates back to the early days of x-ray discovery, there is an increasing evidence in using the new imaging modalities such as computed tomography (CT), magnetic reso- nance imaging (MRI) and ultrasound in the operating rooms. The focus of this thesis is on developing image-guided interventional methods and techniques to support the radiation therapy treatment of gynecologic cancers. Gynecologic cancers which involves malignan- cies of the uterus, cervix, vagina and the ovaries are one of the top causes of mortality and morbidity among the women in U.S. and worldwide. The common treatment plan for radiation therapy of gynecologic cancers is chemotherapy and external beam radiation therapy followed by brachytherapy. Gynecological brachytherapy involves placement of interstitial catheters in and around the tumor area, often with the aid of an applicator. The goal is to create an optimal brachytherapy treatment plan that leads to maximal radiation dose to the cancerous tissue and minimal destructive radiation to the organs at risk. The accuracy of the catheter placement has a leading effect in the success of the treatment. However there are several techniques are developed for navigation of catheters and needles for procedures such as prostate biopsy, brain biopsy, and cardiac ablation, it is obviously lacking for gynecologic brachytherapy procedures. This thesis proposes a technique which aims to increase the accuracy and efficiency of catheter placements in gynecologic brachytherapy by guiding the catheters with an electromagnetic tracking system. To increase the accuracy of needle placement a navigation system has been set up and the appropriate software tools were developed and released for the public use as a module in the open-source 3D Slicer software. The developed technology can be translated from benchmark to the bedside to offer the potential benefit of maximizing tumor coverage during catheter placement while avoiding damage to the adjacent organs including bladder, rectum and bowel. To test the designed system two independent experiments were designed and performed on a phantom model in order to evaluate the targeting accuracy of the tracking system and the mean targeting error over all experiments was less than 2.9 mm, which can be compared to the targeting errors in the available commercial clinical navigation systems.

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Abstract Minimally invasive surgery (MIS) techniques have seen rapid growth as methods for improved operational procedures. The main technology of MIS is based on image guided surgery (IGS) devices, namely surgical navigators, surgical robotics and image scanners. With their widespread use in various fields of surgery, methods and tools that may be used routinely in the hospital setting for “real world” assessment of the accuracy of these devices are lacking. In this thesis the concept of accuracy testing was developed to meet the needs of quality assurance of navigators and robots in a hospital environment. Thus, accuracy was defined as the difference between actual and measured distances from an origin, also including determination of directional accuracy within a specific volume. Two precision engineered accuracy assessment phantoms with assessment protocols were developed as advanced materials and methods for the community. The phantoms were designed to include a common region of surgical interest (ROSI) that was determined to roughly mimic the size of the human head. These tools and methods were utilized in accuracy assessment of two commercial navigators, both enabling the two most widely used tracking modalities, namely the optical tracking system (OTS) and the electromagnetic tracking system (EMTS). Also a study of the accuracy and repeatability of a prototype surgical interactive robot (SIRO) was done. Finally, the phantoms were utilized in spatial accuracy assessment of a commercial surgical 3D CT scanner, the O-Arm. The experimental results indicate that the proposed definitions, tools and methods fulfill the requirements of quality assurance of IGS devices in the hospital setting. The OTS and EMTS tracking modalities were nearly identical in overall accuracy but had unique error trends. Also, the accuracy of the prototype robot SIRO was in the range recommended in the IGS community. Finally, the image quality of the O-Arm could be analyzed using the developed phantoms. Based on the accuracy assessment results, suggestions were made when setting up each IGS device for surgical procedures and for new applications in minimally invasive surgery. / Tiivistelmä Mini-invasiivisen eli täsmäkirurgian tekniikoita ja teknologioita on alettu hyödyntää viime aikoina yhä enemmän. Tavoitteena on ollut parantaa kirurgisten operaatioiden tarkkuutta ja turvallisuutta. Täsmäkirurgiassa käytetyt teknologiat pohjautuvat kuvaohjattuihin kirurgisiin paikannuslaitteisiin. Kuvaohjattuihin laitteisiin kuuluvat navigaattorit, kirurgiset robotit ja kuvantalaitteet. Näiden laitteistojen kehittyminen on mahdollistanut tekniikoiden hyödyntämisen monialaisessa kirurgiassa. Paikannuslaitteistojen ja robottien yleistyminen on kuitenkin nostanut sairaaloissa esiin yleisen ongelman paikannustarkkuuden määrittämisessä käytännön olosuhteissa. Tässä väitöskirjassa esitetään kirurgisten yksiköiden käyttöön menetelmä sekä kaksi uutta fantomia ja protokollaa käytössä olevien paikannuslaitteistojen tarkkuuden määrittämiseen. Fantomit suunniteltiin sisältämään ennalta määritetty kirurginen kohdealue, mikä rajattiin käsittämään ihmisen kallon tilavuus. Fantomeita ja protokollaa hyödynnettiin kahden kaupallisen paikannuslaitteen tarkkuuden määrityksessä. Navigaattorit käyttivät optiseen ja elektromagneettiseen paikannukseen perustuvaa tekniikkaa. Lisäksi työssä kehitetyillä menetelmillä tutkittiin prototyyppivaiheessa olevan kirurgisen robotin paikannus- ja toistotarkkuutta sekä tietokonetomografialaitteen O-kaaren kuvan tarkkuuden määritystä. Kokeellisten tulosten perusteella työssä kehitetyt fantomit ja protokollat ovat luotettavia ja tarkkoja menetelmiä kirurgisten paikannuslaitteistojen tarkkuuden määrittämiseen sairaalaoloissa. Kirurgisten navigaattoreiden tarkkuuden määritystulokset osoittivat optisen ja elektromagneettisen paikannustekniikan olevan lähes yhtä tarkkoja. Prototyyppirobotin tarkkuus oli tulosten perusteella kirjallisuudessa esitettyjen suosituksien mukainen. Lisäksi O-kaaren kuvanlaatua voitiin tutkia kehitetyillä fantomeilla. Tarkkuudenmääritystulosten perusteella työssä ehdotetaan menetelmiä laitteistojen optimaalisesta käytöstä leikkaussalissa sekä laajennetaan niiden käyttömahdollisuuksia. Tuloksia voidaan hyödyntää myös paikannuslaitteistojen kehittämistyössä.