Methodology on Co-Registration of MRI and Optoelectronic Motion Capture Marker Sets: In-Vivo Wrist Case Study

S kin-surface mounted markers provide incomplete spatial information of the underlying-bone. A new methodology is developed combining optoelectronic motion capture MOCAP and imaging modalities to co-register the positions of underlying-bone and external markers. Skin surface-mounted markers, utilized in MR imaging, were coated with reflective material to collect spatial data in passive infra-red optoelectronic MOCAP system. Two-link jig mechanisms were designed to mount-on marker sets; these were rotated in increments through 180° of angular rotation at pre-determined angles. The rotations were recorded within the MOCAP system and 3T MRI scanner under a 3D STIR short tau-inversion recovery sequence. A 3D in-silico model was built for the co-registration of marker centroids' on a 1 to 1 scale. Differences were calculated from the co-registered data obtained from these two systems using the same set of markers. Root mean square error RMSE and angular rotation was less than 1.5 mm in translation and 1° respectively in-vitro. Concordance Correlation Coefficients CCC was calculated as 0.9788 to 1 . Mean-Difference plots showed good agreement. Next, adduction/abduction movements of the natural wrist joint were investigated in six healthy subjects. MOCAP data was collected for three sets of motions, and MRI scans were repeated twice to derive within-subject repeatability data. Within-subject, the maximum RMSE for wrist angular rotations was 1.28° and 1.30° respectively in vivo. Pearson correlation coefficient was calculated for adduction and abduction as 0.70 and 0.71 respectively. Paired Student-t test identified systematic differences. The used methodology established the way to analyze the relationship between the bone and external marker

Vehicle internal design improvement guidelines by using the computational pregnant occupant model 'expecting'

New interior designs for vehicles may improve the safety of pregnant occupants without compromising the safety of non-pregnant occupants. The objective of this study is to investigate the implications of the steering wheel unit orientation by using ‘Expecting’, the Computational Pregnant Occupant Model developed at Loughborough University. Three steering column angles and three steering wheel angles are modelled in a subcompact mini-car interior in MADYMO. A standard 3-point seat belt and an airbag are used as restraint systems. The strain values at the placental location of the uterus of ‘Expecting’ for frontal impacts with 15, 30, 45 kph are predicted for various steering wheel unit configurations and the resulting distance between the steering wheel unit and the abdomen and sternum of ‘Expecting’. Recommendations are made to improve safety

Evidence-based cross validation for acoustic power transmission for a novel treatment system

Introduction: The novel Trans-Fusimo Treatment System (TTS) is designed to control Magnetic Resonance guided Focused Ultrasound (MRgFUS) therapy to ablate liver tumours under respiratory motion. It is crucial to deliver the acoustic power within tolerance limits for effective liver tumour treatment via MRgFUS. Before application in a clinical setting, evidence of reproducibility and reliability is a must for safe practice. Materials and methods: The TTS software delivers the acoustic power via ExAblate-2100 Conformal Bone System (CBS) transducer. A built-in quality assurance application was developed to measure the force values, using a novel protocol to measure the efficiency for the electrical power values of 100 and 150W for 6s of sonication. This procedure was repeated 30 times by two independent users against the clinically approved ExAblate-2100 CBS for cross-validation. Results: Both systems proved to deliver the power within the accepted efficiency levels (70–90%). Two sample t-tests were used to assess the differences in force values between the ExAblate-2100 CBS and the TTS (p > 0.05). Bland-Altman plots were used to demonstrate the limits of agreement between the two systems falling within the 10% limits of agreement. Two sample t-tests indicated that TTS does not have user dependency (p > 0.05). Conclusions: The TTS software proved to deliver the acoustic power without exceeding the safety levels. Results provide evidence as a part of ISO13485 regulations for CE marking purposes. The developed methodology could be utilised as a part of quality assurance system in clinical settings; when the TTS is used in clinical practice

Methodology on Quantification of Sonication Duration for Safe Application of MR Guided Focused Ultrasound for Liver Tumour Ablation

Background and objective Magnetic Resonance Guided Focused Ultrasound (MRgFUS) for liver tumour ablation is a challenging task due to motion caused by breathing and occlusion due the ribcage between the transducer and the tumour. To overcome these challenges, a novel system for liver tumour ablation during free breathing has been designed. Methods The novel TRANS-FUSIMO Treatment System (TTS, EUFP7) interacts with a Magnetic Resonance (MR) scanner and a focused ultrasound transducer to sonicate to a moving target in liver. To meet the requirements of ISO 13485; a quality management system for medical device design, the system needs to be tested for certain process parameters. The duration of sonication and, the delay after the sonication button is activated, are among the parameters that need to be quantified for efficient and safe ablation of tumour tissue. A novel methodology is developed to quantify these process parameters. A computerised scope is programmed in LabVIEW to collect data via hydrophone; where the coordinates of fiber-optic sensor assembly was fed into the TRANS-FUSIMO treatment software via Magnetic Resonance Imaging (MRI) to sonicate to the tip of the sensor, which is synchronised with the clock of the scope, embedded in a degassed water tank via sensor assembly holder. The sonications were executed for 50 W, 100 W, 150 W for 10 s to quantify the actual sonication duration and the delay after the emergency stop by two independent operators for thirty times. The deviation of the system from the predefined specs was calculated. Student's-T test was used to investigate the user dependency. Results The duration of sonication and the delay after the sonication were quantified successfully with the developed method. TTS can sonicate with a maximum deviation of 0.16 s (Std 0.32) from the planned duration and with a delay of 14 ms (Std 0.14) for the emergency stop. Student's T tests indicate that the results do not depend on operators (p > .05). Conclusion The evidence obtained via this protocol is crucial for translation- of-research into the clinics for safe application of MRgFUS. The developed protocol could be used for system maintenance in compliance with quality systems in clinics for daily quality assurance routines

Spine modelling for lifting

Mathematical modelling is widely used in the field of biomechanics. The traditional approach to investigate spine related injuries is to check the strength of the components of-the spine. Spinal stability approach focuses on the force polygons formed by the body weight, muscle forces, ligament forces and external load. This force polygon is expected to stay within the boundaries of the spine to ensure stability. Proving the possibility of one force polygon within the spine boundaries proves the stability of the spine. Results show that there is a difference between male and female postures during the full span of lifting activities. Application of individual muscle forces provides greater control of stability at each vertebral level. By considering the elongation of the laments and the force requirements of the muscle groups, it is possible to diagnose soft tissue failure.EThOS - Electronic Theses Online ServiceGBUnited Kingdo