Tracker Assembly Research Articles

A Patient-Specific Reference Tracker for Noninvasive Electromagnetic Navigation of Endoscopic Skull Base Surgery.

Owing to the possibility of nonrigid head fixation, electromagnetic navigation (EM) is a mainstay for endoscopic skull base surgery. The currently available dynamic reference trackers (RTs) are invasive or inaccurate. To investigate the feasibility and stability of this innovative oral tracker (OT), which is adhesive to the hard palate in comparison with a commercially available skin adhesive tracker (ST). A prospective series of 31 patients with intrasellar lesions who underwent surgery between 2019 and 2021 using a pure endoscopic transsphenoidal approach were evaluated. A patient-specific palatal mold was designed from preoperative computed tomography data. The OT was cast using a biocompatible algin with an integrated EM tracker assembly. In comparison with a skull-mounted RT, which served as a gold standard, the deviations of OT vs those of the ST with the RT were continuously assessed. The OT showed significantly lower deviations from the RT than the ST during the surgical steps: start of endoscopic surgery (OT vs ST: 0.62 mm, IQR 0.36-0.89 vs 1.65 mm, IQR 1.35-2.32, P < .001), drilling phase (OT vs ST: 0.81 mm, IQR 0.51-1.32 vs 1.89 mm, IQR 1.6-2.74, P < .001), and end of endoscopic surgery (OT vs ST: 1.1 mm, IQR 0.68-1.64 vs 1.9 mm, IQR 1.6-2.72, P < .001). The OT showed significantly higher intraoperative stability than the ST. Therefore, this noninvasive and patient-specific tool could be used to achieve accurate EM guidance during endoscopic skull base surgeries.

Application of Beidou Satellite Navigation System in Finding Separated Children

The Beidou satellite navigation system is currently one of the most advanced navigation systems on an international scale. The purpose of this work is to design a system framework based on the Beidou navigation system for the positioning and tracking of children. The novel system designed in this work includes a Beidou satellite system, a tracker assembly mounted on the sole of a child’s shoe, a guardian’s cell phone terminal and a monitoring computer terminal. In particular, the present work creates a new tracker assembly that is communicatively connected to the guardian’s mobile phone terminal and the monitoring computer terminal through the Beidou satellite system, respectively. This paper designs and implements an effective monitoring and tracking of children’s location based on Beidou navigation, which is worth promoting and applying

Construction and commissioning of the SuperNEMO detector tracker

The SuperNEMO detector will search for neutrinoless double beta decay at the Modane Underground Laboratory; the detector design allows complete topological reconstruction of the decay event enabling excellent levels of background rejection and, in the event of a discovery, the ability to determine the nature of the lepton number violating process.In order to demonstrate the feasibility of the full experiment, we are building a Demonstrator Module containing 7kg of 82Se, with an expected sensitivity of |mββ|<0.2−0.4eV after 2.5yr.The demonstrator tracker is currently being assembled in the UK; the main challenge in the tracker design is the high radiopurity required to limit the background. For this reason the cell wiring is automated and every step of the tracker assembly happens in a clean environment. All components are carefully screened for radiopurity and each section of the tracker, once assembled, is sealed and checked for Radon emanation.We present the detector design, the current status of the construction and present the first results from the surface commissioning of one section of the Demonstrator Module tracker.

An Ultrasound Probe Holder for Image-Guided Surgery

Automating image-guided therapy and registering a medical image to a patient require knowledge of the locations of both the medical image source (e.g., ultrasound) and the surgical tool with respect to a global coordinate system that is known relative to the patient. Also, sturdiness of the medical instrumentations is essential. A novel compact stabilizer-tracker integrated assembly is designed to serve as a holder that can be used to support, manipulate in six degrees-of-freedom, and firmly lock-in-place ultrasound imaging probes and other instruments for use in image-guided surgery as well as to provide the position and orientation of the probe in 3D space with respect to a known reference origin. The stabilizer’s configuration allows a clinician to easily manipulate an ultrasound probe in 3D space, and demonstrate improved sturdiness when locked. A reliable validation technique using forward kinematics was used to evaluate the performance of the holder. Performance tests show that the tracker assembly can acquire the position and orientation of the ultrasound probe with an average displacement accuracy of 0.66mm and roll, pitch, and yaw angular accuracies of 0.24deg, 0.38deg, and 0.19deg, respectively. The improved sturdiness demonstrated by the compact-sized stabilizer and the high accuracy of the tracking mechanism make the integrated holder mechanism well suited for use in image-guided robot-assisted brachytherapy. It is anticipated that this will lead to improvement in accuracy and clinical outcomes for the procedure. The novel tracker can also be used to acquire the positions and orientations of other passive mechanisms of complex designs.

Module production for the CMS Tracker: Problems and achieved quality

The construction of the CMS Inner Tracker is nearing completion. The various components are being mounted on the large structures and by the end of 2006 the tracker assembly will be finished at CERN. The basic elements of the strip tracker are the silicon sensor modules. In total about 15,000 modules of various geometries have been built by a large collaboration of institutes. This paper will explain the design and the semi-automatic assembly procedures. The major problems which appeared during this production are discussed. The final section gives an overview of the obtained results.

Design and clinical evaluation of an image-guided surgical microscope with an integrated tracking system

A new image-guided microscope system using augmented reality image overlays has been developed. With this system, CT cut-views and segmented objects such as tumors that have been previously extracted from preoperative tomographic images can be directly displayed as augmented reality overlays on the microscope image. The novelty of this design stems from the inclusion of a precise mini-tracker directly on the microscope. This device, which is rigidly mounted to the microscope, is used to track the movements of surgical tools and the patient. In addition to an accuracy gain, this setup offers improved ergonomics since it is much easier for the surgeon to keep an unobstructed line of sight to tracked objects. We describe the components of the system: microscope calibration, image registration, tracker assembly and registration, tool tracking, and augmented reality display. The accuracy of the system has been measured by validation on plastic skulls and cadaver heads, obtaining an overlay error of 0.7 mm. In addition, a numerical simulation of the system has been done in order to complement the accuracy study, showing that the integration of the tracker onto the microscope could lead to an improvement of the accuracy to the order of 0.5 mm. Finally, we describe our clinical experience using the system in the operation room, where three operations have been performed to date.

The detector control system for the ATLAS semiconductor tracker assembly phase

The ATLAS Semiconductor tracker (SCT) consists of 4088 silicon microstrip modules, with a total of 6.3 million readout channels. These are arranged into 4 concentric barrel layers and 2 endcaps of 9 disks each. The coherent and safe operation of the SCT during commissioning and subsequent operation is an essential task of the Detector Control System (DCS). The main building blocks of the SCT DCS, the cooling system, the power supplies and the environmental system, are described. First results from DCS testing are presented.

Test of CMS tracker silicon detector modules with the ARC system

The CMS Silicon Strip Tracker will be equipped with 16000 silicon microstrip detector modules covering a surface of approximately 200m2. The APV Readout Controller system was developed at RWTH Aachen, III. Physikalisches Institut in order to perform full readout tests of hybrids and modules at each production step. From the experience derived from initial module production, an automated fault finding algorithm has been developed which uses the full correlations between different electrical tests. The results of a recent production of over 250 Tracker Outer Barrel and 25 Tracker End Cap modules at UCSB demonstrate that the testing protocols are sufficient to find all known faults and that electrical module components produced have a high quality. The results are typical of all CMS tracker assembly and bonding sites.

Test of CMS tracker silicon detector modules with the ARC system

The CMS Silicon Strip Tracker will be equipped with 16000 silicon microstrip detector modules covering a surface of approximately 200 m 2 . The APV Readout Controller system was developed at RWTH Aachen, III. Physikalisches Institut in order to perform full readout tests of hybrids and modules at each production step. From the experience derived from initial module production, an automated fault finding algorithm has been developed which uses the full correlations between different electrical tests. The results of a recent production of over 250 Tracker Outer Barrel and 25 Tracker End Cap modules at UCSB demonstrate that the testing protocols are sufficient to find all known faults and that electrical module components produced have a high quality. The results are typical of all CMS tracker assembly and bonding sites.

The silicon-strip tracker of the Gamma ray Large Area Space Telescope

The Gamma ray Large Area Space Telescope (GLAST) is an astro-particle mission that will study the mostly unexplored, high energy ( 20 MeV – 1 TeV ) spectrum of photons coming from active sources in the universe. Construction of the GLAST silicon tracker, by far the largest ever built for a space mission, is now well on the way, as it is scheduled for launch by NASA in autumn 2006. We report on the basic technology adopted for the silicon detectors, particularly in connection to their use in space, on the first results of sensors testing and on the status of tracker assembly.

The AMS-01 silicon tracker assembly and the industrial approach to detector construction

The Alpha Magnetic Spectrometer (AMS-01) has successfully performed in a precursor flight in June 1998. The experiment is scheduled for a 3-year operation on the International Space Station (ISS) in the year 2003. For the ISS flight, the completion of the tracker as well as a major upgrade of the detector (AMS-02) is in progress. In this contribution, we present results from the AMS-01 silicon tracker construction and describe the organization of the assembly for phase 2. Given the large scale of this silicon detector, the involvement of private industries in the construction is addressed.

Automatic eye tracker for excimer laser photorefractive keratectomy.

Acute overlapping of successive laser pulses onto the cornea during photorefractive keratectomy (PRK) is important to avoid refractive distortions. Most excimer laser systems performing corneal ablation lack control of the patient's eye movements and they cannot track the target corneal zone. We developed an eye-tracker based on television monitoring of the pupil and on automatic electro-mechanical deflection of the laser turning mirror, and we applied it to the ExciMed UV200 ArF work station (Summit Technology, Inc., Waltham, Mass.). Basic components are a black and white CCD camera and two fast stepping motors. The circuitry for target discrimination and tracking, and the optical imaging system are designed specifically. The tracker assembly does not interfere with the laser beam path nor with the operator's observation. Tracking of the pupil has been successfully achieved on different color irides, with an accuracy better than 0.1 mm in a 6 x 6 mm2 tracking field. Response time is less than 100 ms. Recordings of eye movements during PRK are presented. Tracking ablations have been performed on moving test eye-balls with plastic corneas. The proposed automatic system appears to be a reliable and effective method for the compensation of patient eye movements appears to be a reliable and effective method during PRK procedures.

Study of 18-cm long single-sided AC-coupled silicon microstrip detectors

The SSC GEM silicon Central Tracker design incorporated 18-cm long single-sided AC-coupled silicon microstrip ladders. Compared to the 12-cm long ladders considered in the preliminary stages of the tracker design, the 18-cm long ladders have the advantage of reduced cost, channel count and overall power consumption, and led to a simplified tracker assembly. However, such long ships also present the challenge of maintaining satisfactory performance. The increased capacitance and series resistance contribute to lower signal-to-noise ratios, longer time walk, higher power consumption per channel and increased probability of crosstalk to neighboring channels. In this paper, an accurate method to calculate the geometric capacitance of the AC-coupled microstrips is presented and the calculated results are compared with measurements, SPICE simulations are performed to predict the noise, the extent of interstrip capacitive coupling and the dispersion of the detector signal due to the finite series resistance of the metal strips and the long length of the detector. The influence of the preamplifier current and the shaping time on the signal and noise levels is also presented. The study concludes that the 18-cm long ladders can successfully satisfy the performance goals of the GEM silicon Central Tracker.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>