Magnetic Projectiles Research Articles

A Flexible Catheter System for Ultrasound-Guided Magnetic Projectile Delivery

Magnetic actuation is a versatiletechnology, widely applied in medical robotics for noncontact steering of flexible instruments and untethered agents. In this article, we exploit the benefits of this technology by developing a magnetically actuated flexible catheter capable of the controlled ejection and retrieval of an untethered magnetic capsule. The catheter is actuated by the advanced robotics for magnetic manipulation system. The scanning ultrasound is used for 3-D shape reconstruction of the catheter, with a mean error of 0.37 mm. We use a closed-loop position controller to steer the catheter, reporting a mean error of 0.82 mm. We develop a dynamic model of the capsule and use it to predict the trajectory of the projectile. We demonstrate the targeting of the capsule utilizing the null-space of the catheter actuation (mean residual tip displacement of 0.8 mm). Finally, we perform a delivery of a capsule to and retrieval from a target inaccessible for the catheter tip, demonstrating the capability of our instrument to reach challenging locations.

RF deflecting cavity for fast radioactive ion beams

The Facility for Rare Isotope Beams (FRIB) will be a new scientific user facility that produces rare-isotope beams for experiments from the fragmentation of heavy ions at energies of 100–200 MeV/u. During the projectile fragmentation, the rare isotope of interest is produced along with many contaminants that need to be removed before the beam reaches detectors. At FRIB, this is accomplished with a magnetic projectile fragment separator. However, to achieve higher beam purity, in particular for proton-rich rare isotopes, additional purification is necessary. RadiaBeam in collaboration with Michigan State University (MSU) has designed a 20.125 MHz radiofrequency (RF) fragment separator capable of producing a 4 MV kick with 18 cm aperture in order to remove contaminant isotopes based on their time of flight. In this paper, we will discuss the RF and engineering design considerations of this separator cavity.

Physical analysis and optimization of electromagnetic coilgun launch systems

Coilguns are one of the most widely used projectile launch systems using electromagnetic force. The ideal coilgun would propel a projectile with maximum velocity while also having a high power efficiency. The physics of coilguns is well understood; however, optimizing the coilgun design is much more difficult, as it requires the consideration of the parameters of every component of the system, such as the coil, projectile, and power supply. In this paper, electromagnetism, kinematics, and electrical circuit theory are employed to analytically describe the operations of a coilgun with permanent magnetic projectiles. These analytical equations are then implemented using mathematical programs. Coilguns with distinct design parameters and current profiles can be tested numerically to quickly find the optimal combinations to achieve the maximum velocity or power efficiency. The results are presented and measurements are utilized to verify the predictions.

WE-D-202-01: MRI Safety

While the unique physical environment hazards of Magnetic Resonance Imaging are well known and documented, adverse events including magnetic projectiles and contraindicated exposure of sensitive implants continue to occur, frequently. FDA accident report data indicates alarming increases in the rates of accidents in the MRI environment. Few understand the nature and scope of the hazards in the MRI environment as well as medical physicists, and yet physicists are infrequently consulted when physical or operational protections are being considered or deployed. New clinical accreditation recommendations and requirements from the ACR and Joint Commission, as well as new MRI suite construction requirements, place greater responsibilities upon MRI providers to protect the patients, visitors, and staff. Medical physicists are uniquely positioned to champion safety in the MRI environment and facilitate the adherence to new standards and requirements. This presentation will provide data and examples of contemporary trends of MRIsafety and accidents, outline a number of the recent standards and requirements, and provide the participants with the knowledge tools to actively shape safety at their MRI facilities. Learning Objectives: 1. Understand the contemporary state of MRIsafety through case exemplars 2. Understand the range of new accreditation, licensure and regulatory expectations for MRIsafety 3. Understand concrete, proactive steps that can be taken to improve the physical safety environment for MRI

Pulsed power generation using open and closed ferromagnetic circuits

Results are presented of an experimental study of the generation of high-voltage and high-current pulses in generators designed as open and closed ferromagnetic circuits. Experiments were carried out using a light gas gun system. The magnetic projectiles were composed of ferromagnetic disks having 1.27- and 2.54-cm diameters. It has been shown that with velocities of the magnetic projectiles of 200-380 m/s, the peak voltage of the pulses produced by the generators reach several tens of kilovolts, peak current reaches kiloampere, and the energy delivered at the load is a few Joules. Generating modules connected in series will make it possible to produce a high-energy pulse with a peak voltage of a few hundred kilovolts. It has been shown that a closed ferromagnetic circuit generator is capable of generating not only single high-voltage pulses, but also repetitive oscillations. Data are given for the effects on the amplitude of high-voltage pulses caused by the length and velocity of the ferromagnetic projectiles and the design of the generating unit for both high-voltage and high-current modes of pulsed power generation.

Translational forces on discrete metallic objects in travelling magnetic fields

Translational magnetic forces produced by a travelling field on basic shapes (block, cylinder and sphere) are calculated. The induction force on small nonferrous objects is considered and a condition for an optimum frequency deduced. Experimental evidence is given in support of the findings. The dynamic solution for the behaviour of a small magnetic object in an accelerating field is given and the problem of successfully accelerating a magnetic projectile is considered.

Search for and Localisation of Magnetic Projectiles by means of an Electro-Magnet worked with an Alternating Current

sSearch for and Localisation of Magnetic Projectiles by means of an Electro-Magnet worked with an Alternating CurrentJ. BergoniéJ. BergoniéSearch for more papers by this authorPublished Online:30 Jan 2014https://doi.org/10.1259/jrs.1915.0055SectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InEmail About"Search for and Localisation of Magnetic Projectiles by means of an Electro-Magnet worked with an Alternating Current." Journal of the Röntgen Society, 11(44), pp. 88–89 Previous article Next article FiguresReferencesRelatedDetails Volume 11, Issue 44July 1915Pages: 53-90 Copyright © 1915, the British Institute of Radiology History Published onlineJanuary 30,2014 Metrics Download PDF