Image-guided therapies are reliant on the spatial tracking of surgical tools for navigation. Ensuring that tracking is non-intrusive and accurate is therefore important. As tracking sensors become smaller, it is important to determine their effective range in comparison to the sensors that have been previously evaluated. We tested three different electromagnetic sensor sizes in the context of a surgical navigation system. Three different sized electromagnetic sensors were tested for tracking accuracy using optical tracking as the ground truth. An algorithm was developed to calculate the error between the data collected from the electromagnetic sensors with respect to the ground-truth measurements. Contours were generated to visualize the areas where tracking error is under certain threshold values. Multiple contours from electromagnetic sensors of different sizes were generated. To reduce noise in the measurements, repeated results were averaged. Results: The 8 mm and 2 mm length sensors performed comparably, both within acceptable error in the center of the tracking system’s workspace (50 cm away from the transmitter). The accuracy of the 0.5 mm sensor was acceptable up to 40 cm away from the transmitter. A distance greater than 20 cm led to a loss of consistent accuracy from the electromagnetic sensor. The 8 mm sensor and the 2 mm sensor shared similar iso-surface volumes, establishing that the 8 mm sensor could be substituted for the 2 mm sensor, which would be clinically beneficial typically. This would allow for electromagnetic sensors to be less intrusive in the operating room when tracking surgical and percutaneous intervention tools. The 0.5 mm sensor was not able to present the clinical required accuracy ranges.
A framework has been investigated to enable a variety of comparative studies in the context of needle–based gynaecological brachytherapy. Our aim was to create an anthropomorphic phantom–based platform. The three main elements of the platform are the organ model, needle guide, and needle drive. These have been studied and designed to replicate the close environment of brachytherapy treatment for cervical cancer. Key features were created with the help of collaborating interventional radio–oncologists and the observations made in the operating room. A phantom box, representing the uterus model, has been developed considering available surgical analogies and operational limitations, such as organs at risk. A modular phantom–based platform has been designed and prototyped with the capability of providing various boundary conditions for the target organ. By mimicking the female pelvic floor, this framework has been used to compare a variety of needle insertion techniques and configurations for cervical and uterine interventions. The results showed that the proposed methodology is useful for the investigation of quantifiable experiments in the intraabdominal and pelvic regions.
In the past decades, many new trends appeared in interventional medicine. One of the most groundbreaking ones is
Image-Guided Surgery (IGS). The main benefit of IGS procedures is the reduction of the patient's pain and collateral
damage through improved accuracy and targeting. Electromagnetic Tracking (EMT) has been introduced to medical
applications as an effective tool for navigation. However, magnetic fields can be severely distorted by ferromagnetic
materials and electronic equipment, which is a major barrier towards their wider application. The focus of the study
is to determine and compensate the inherent errors of the different types of EMTs, in order to improve their accuracy.
Our aim is to develop a standardized, simple and repeatable assessment protocol; to determine tracking errors with
sub-millimeter accuracy, hence increasing the measurement precision and reliability. For initial experiments, the
NDI Aurora and the Ascension medSAFE systems were used in a standard laboratory environment. We aim to
advance to the state-of-the art by describing and disseminating an easily reproducible calibration method, publishing
the CAD files of the accuracy phantom and the source of the evaluation data. This should allow the wider spread of
the technique, and eventually lead to the repeatable and comparable assessment of EMT systems.
Hospital Acquired Infections (HAI) represent the fourth leading cause of death in the United States, and claims
hundreds of thousands of lives annually in the rest of the world. This paper presents a novel low-cost mobile
device|called Stery-Hand|that helps to avoid HAI by improving hand hygiene control through providing an
objective evaluation of the quality of hand washing. The use of the system is intuitive: having performed hand
washing with a soap mixed with UV re
ective powder, the skin appears brighter in UV illumination on the
disinfected surfaces. Washed hands are inserted into the Stery-Hand box, where a digital image is taken under
UV lighting. Automated image processing algorithms are employed in three steps to evaluate the quality of
hand washing. First, the contour of the hand is extracted in order to distinguish the hand from the background.
Next, a semi-supervised clustering algorithm classies the pixels of the hand into three groups, corresponding to
clean, partially clean and dirty areas. The clustering algorithm is derived from the histogram-based quick fuzzy
c-means approach, using a priori information extracted from reference images, evaluated by experts. Finally,
the identied areas are adjusted to suppress shading eects, and quantied in order to give a verdict on hand
disinfection quality. The proposed methodology was validated through tests using hundreds of images recorded in
our laboratory. The proposed system was found robust and accurate, producing correct estimation for over 98%
of the test cases. Stery-Hand may be employed in general practice, and it may also serve educational purposes.
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