MPM-A - Special Session: Magnetic Field Effects & Safety for Health Physicists Centennial Ballroom 300A 14:30 - 17:50
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| Chair(s): Peter Sprenger and John Metyko
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MPM-A.1
14:30 NMR/MRI Physics Primer ME Jafari*, Morristown Medical Center
Abstract: An overview of the basic principles of NMR/MRI signal acquisition and image formation is presented. Topics covered include basic properties of magnetism, magnetic characteristics of the nucleus, creation of the magnetic resonance signal, magnetization properties of tissues, and basic image acquisition pulse sequences. Learning objectives:
1. Identify the magnetic properties of matter and the nucleus that make spectroscopy and magnetic resonance imaging possible.
2. Summarize how the magnetic resonance imaging signal is created.
3. Understand the terms Free Induction Decay, T1, T2, and T2*relaxation.
4. Recognize the concepts used in Spin Echo, Inversion Recovery, and Gradient Echo pulse sequences
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MPM-A.2
14:50 Static Magnetic Field Sources recognized and not so much KL Barat*, Laser Safety Solutions
Abstract: There are numerous devices used in scientific research and medical setting that are static magnetic sources. For some of these devices it is clear they are magnetic sources, such as bend or steering magnetics, while others are common but have no obvious indication that they are sources of magnetic fields. Two examples of the latter are Faraday Rotators and Ion Gauges. Both of which emit high magnetic fields but only to a limited distance. The goal of this presentation is to make people aware of these sources and precautions to take. Some of these sources will have a magnetic field that extends for meters. While other emit limited magnetic fields, but of considerable strength. On items such as a bend magnetic, the expectation of establishing a 5 Gauss demarcation line is as well as exclusion zones is expected. While other sources that present fields but are not obvious sources little or no attention is addressed to their 5 Gauss lines. Taking steps to make users aware of their potential exposure, through labeling or education is the diligent safety step needed by safety staff. It is my hope people will find this presentation informational and raise awareness.
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MPM-A.3
15:10 Magnetic Resonance Safety E Kanal*, University of Pittsburgh Medical Center
Abstract: Magnetic Resonance Imaging (MRI) is unique among medical imaging modalities in that it uses three, not one, energy sources to which the patient is exposed in order to generate the diagnostic information contained within MR image. Further, each of these energy sources is spatially distributed in a unique and heterogeneous pattern over the patient, and each energy source has its own unique potential adverse effect(s) and/or safety considerations. Thus, assessing the safety of exposing a patient in/on whom there may be an implanted device, implant, and/or foreign body to an MR imaging examination requires a rather comprehensive and broad understanding of the potential safety issues underlying the MR imaging process and a multifactorial, in-depth analysis of the multiple variables involved. In this presentation we will introduce and explain the forces used in the MR imaging process and clarify how they are spatially distributed. The specific risk(s) are associated with each of these energies relative to a patient in whom there might be an implanted device and/or foreign body will be highlighted. Finally, the presentation will introduce a standardized process whereby these potential MR-related safety risks may be assessed and compared against the potential benefits of proceeding with the requested MR imaging examination to assist in the formulation of a scan/no scan clinical decision-making process.
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MPM-A.4
16:10 BREAK
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MPM-A.5
16:30 MR Suite Design & Shielding T Kellogg*, ETS-Lindgren
Abstract: Despite the magnetic fields generated by a MRI cause no long-term negative affects to patients or staff, the importance of MRI safety for the staff and patients cannot be overstated. The absolute safety of the patients and staff is instrumental to patient throughput and ensuring positive patient outcome in addition to protecting a facility’s capital investment.
This presentation will provide an overview MR suite design with a focus on shielding design and construction along with accessories intended to enhance safety procedures, protecting staff, patients and the equipment. The presentation will begin with an overview of methods and solutions utilize in the design and construction of MRI suites. An example will be shared of an existing MRI suite from design through completed construction. The presentation will then provide an overview of safety accessories that have been developed to enhance MR safety along with some best practices for utilizing those accessories.
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MPM-A.6
16:50 STATIC MAGNETIC FIELD MEASUREMENTS: Overview of Instruments and Techniques FF McWilliams, MIT
; DL Haes*, Consultant
Abstract: While performing static magnetic (aka “DC”) field measurements may appear to be simple, obtaining accurate and reproducible measurements of levels can be challenging. The user of any DC magnetic field measurement instrumentation must have a thorough understanding of the types and limitations of the instruments, along with the adapting to the changing environmental circumstances. There are safety considerations to contemplate prior to making field measurements, both with the surveyor and the instrumentation chosen. The presentation provides information relative to DC magnetic field measurement survey types and units, in addition to established exposure limits to be used for comparison to field survey values. The DC magnetic field surveys discussed in this presentation involve determining the magnitude and extent of fringing fields, and NOT direct bore measurement. Instrumentation examples and techniques to be used are included with sample field work in both Nuclear Magnetic Resonance imaging (NMR) and Magnetic Resonance Imaging (MRI) system settings. To conclude, specific example safety program elements are discussed to assist the safety professional in enhancing their static magnetic field safety program.
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MPM-A.7
17:10 Effects of Magnetic Fields on Pacemakers/Defibrillators ME Jafari*, Morristown Medical Center
Abstract: As the population ages, a greater number of patients have a Cardiac Implantable Electronic Device (CIED), such as a pacemaker or Implantable Cardioverter Defibrillator (ICD). An MRI scan may be medically necessary for these patients, however the magnetic fields and radiofrequency pulses used in the procedure may affect the functionality and programming of the device. Topics covered in this presentation include types of CIEDs, the effect of the magnetic field on ECG waves, potential risks to patients with these devices (arrhythmias, device heating, pacing and tachycardia inhibition, activation of tachycardia therapy, etc.) and recommended practices for scanning. Several case examples will be given. Learning objectives:
1. Describe the two basic types of CIEDs and what they do.
2. Understand the difference between MRI Conditional and Non-Conditional CIEDs and potential risks from scanning them.
3. Explain steps that must be taken to safely scan these devices.
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MPM-A.8
17:30 Preclinical 7T MRI, micro-PET, and micro-CT in a BSL3 MR Amurao*, Washington University in St. Louis
; DJ Szatkowski, Washington University in St. Louis; SH Cook, Washington University in St. Louis; J Quirk, Washington University in St. Louis; K Boschert, Washington University in St. Louis
Abstract: The use of a pre-clinical high-field 7-Tesla MRI scanner requires the careful implementation of MR Safety best practices, with a special focus on the unique hazards presented by the static magnetic field and the spatial field gradient. When housed in a Biosafety Level 3 (BSL3) facility, the presence of highly pathogenic in-vitro and in-vivo (animal-model) biological agents require special considerations for implementation. Additional layers of complexity arise when radioactive materials and radiation producing equipment are used in the same space. In this presentation, we report the planning and operational experiences involved with a pre-clinical multi-modality advanced imaging facility (7T MRI, micro-PET, micro-CT) in a BSL3 facility at Washington University in St. Louis. This unique mixed hazard environment offers unique tradeoffs, insights, and lessons learned in the effort to ensure adherence to regulations and safety principles encompassing MR-safety, Biosafety and Radiation safety.
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