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Result : Searchterm 'Radio Frequency Coil' found in 1 term [] and 8 definitions [], (+ 14 Boolean[] results
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Radio Frequency CoilInfoSheet: - Coils - 
Intro, 
Overview, 
etc.MRI Resource Directory:
 - Coils -
 
A coil is a large inductor with a considerable dimension and a defined wavelength, commonly used in configurations for MR imaging. The frequency of the radio frequency coil is defined by the Larmor relationship.
The MRI image quality depends on the signal to noise ratio (SNR) of the acquired signal from the patient. Several MR imaging coils are necessary to handle the diversity of applications. Large coils have a large measurement field, but low signal intensity and vice versa (see also coil diameter). The closer the coil to the object, the stronger the signal – the smaller the volume, the higher the SNR. SNR is very important in obtaining clear images of the human body. The shape of the coil depends on the image sampling. The best available homogeneity can be reached by choice of the appropriate coil type and correct coil positioning. Orientation is critical to the sensitivity of the RF coil and therefore the coil should be perpendicular to the static magnetic field.

RF coils can be differentiated by there function into three general categories:
Transmit Receive Coil
Receive Only Coil
Transmit Only Coil
The RF signal is in the range of 10 to 100 MHz. During a typical set of clinical image measurements, the entire frequency spectrum of interest is of the order 10 kHz, which is an extremely narrow band, considering that the center frequency is about 100 MHz. This allows the use of single-frequency matching techniques for coils because their inherent bandwidth always exceeds the image bandwidth. The multi turn solenoid, bird cage coil, single turn solenoid, and saddle coil are typically operated as the transmitter and receiver of RF energy. The surface and phased array coils are typically operated as a receive only coil.

See also the related poll result: '3rd party coils are better than the original manufacturer coils'
 
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    • Volume Coil
    • Signal to Noise Ratio
    • Gradient Coil
    • Device
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Further Reading:
  Basics:
Radio-frequency Coil Selection for MR Imaging of the Brain and Skull Base1
   by radiology.rsnajnls.org    
  News & More:
High-field MRI Coils – that work, superbly, even at 750 MHz
   by www.dotynmr.com    
MRI Resources 
DICOM - NMR - Services and Supplies - Implant and Prosthesis - MRI Technician and Technologist Jobs - Shoulder MRI
 
CoilForum -
related threadsInfoSheet: - Coils - 
Intro, 
Overview, 
etc.MRI Resource Directory:
 - Coils -
 
A coil consists of one or more loops of conductive wire, looped around the core of the coil. Coils are part of the hardware of MRI machines and are used to create a magnetic field or to detect a changing magnetic field by voltage induced in the wire. A coil is usually a physically small antenna.
The perfect coil produces a uniform magnetic field without significant radiation.
Different types of MRI coils are used in MR systems:
Gradient coils are used to produce controlled variations in the main magnetic field (B0) to provide spatial localization of the signals and to apply reversal pulses in some imaging techniques.
MR imaging radio frequency coils to receive and/or transmit the RF signal.
Shim coils provide auxiliary magnetic fields in order to compensate for inhomogeneities in the main magnetic field of the MRI machine.
See also Gradient Coil, Radio Frequency Coil, Hardware and Coil Loading.

See also the related poll result: '3rd party coils are better than the original manufacturer coils'
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• View the DATABASE results for 'Coil' (193).Open this link in a new window


• View the NEWS results for 'Coil' (11).Open this link in a new window.
 
Further Reading:
  News & More:
DOTmed Industry Sector Report: MRI Coil Sales & Service Companies
Thursday, 13 December 2007   by www.dotmed.com    
High-field MRI Coils – that work, superbly, even at 750 MHz
   by www.dotynmr.com    
MRI coil optimized for imaging of infants gets FDA clearance
Tuesday, 17 April 2012   by www.medcitynews.com    
ScanMed Introduces a Groundbreaking New Orbit and Mandible Array to the MRI Market
Wednesday, 26 March 2014   by www.digitaljournal.com    
MRI Resources 
Fluorescence - Intraoperative MRI - Brain MRI - MRI Physics - Safety Products - Veterinary MRI
 
B1Forum -
related threads
 
(B1, B1) A conventional symbol for the radio frequency field strength (another symbol historically used, is H1). In MRI, , B1 labels the field produced by the radio frequency coil.
The B1 field is often conceived of two vectors rotating in opposite directions, usually in a plane transverse to B0. At the Larmor frequency, the vector rotating in the same direction as the precessing spins will interact strongly with the spins.
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• View the DATABASE results for 'B1' (1346).Open this link in a new window

 
Further Reading:
  Basics:
Dealing with Increased MRI Field Strength
Tuesday, 1 October 2013   by www.evaluationengineering.com    
  News & More:
Implementation of Dual-Source RF Excitation in 3 T MR-Scanners Allows for Nearly Identical ADC Values Compared to 1.5 T MR Scanners in the Abdomen
Wednesday, 29 February 2012   by www.plosone.org    
Turbo-FLASH Based Arterial Spin Labeled Perfusion MRI at 7 T
Thursday, 20 June 2013   by www.plosone.org    
Mapping of low flip angles in magnetic resonance(.pdf)
Saturday, 1 January 2011   by www.hal.inserm.fr    
Searchterm 'Radio Frequency Coil' was also found in the following service: 
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News  (1)  
 
Coil LoadingInfoSheet: - Coils - 
Intro, 
Overview, 
etc.
 
The interaction of the patient with the RF coil, which causes shifts of the resonance frequency and damping of the coil’s resonance and hence reduction of the quality factor because of magnetic induction and dielectric losses in the patient.
The design and construction of a MRI coil is determined by the load on the coil. The load is either a phantom or the actual sample being imaged.
See also Radio Frequency Coil.
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• View the DATABASE results for 'Coil Loading' (2).Open this link in a new window

 
Further Reading:
  Basics:
Understanding MRI Scanner Receivers
Sunday, 19 June 2011   by www.medwow.com    
MRI Resources 
Liver Imaging - Safety Training - Bioinformatics - MRI Training Courses - RIS - MRI Physics
 
DeviceForum -
related threadsInfoSheet: - Devices -
Intro, 
Types of Magnets, 
Overview, 
etc.
 
Magnetic resonance imaging (MRI) is based on the magnetic resonance phenomenon, and is used for medical diagnostic imaging since ca. 1977 (see also MRI History).
The first developed MRI devices were constructed as long narrow tunnels. In the meantime the magnets became shorter and wider. In addition to this short bore magnet design, open MRI machines were created. MRI machines with open design have commonly either horizontal or vertical opposite installed magnets and obtain more space and air around the patient during the MRI test.
The basic hardware components of all MRI systems are the magnet, producing a stable and very intense magnetic field, the gradient coils, creating a variable field and radio frequency (RF) coils which are used to transmit energy and to encode spatial positioning. A computer controls the MRI scanning operation and processes the information.
The range of used field strengths for medical imaging is from 0.15 to 3 T. The open MRI magnets have usually field strength in the range 0.2 Tesla to 0.35 Tesla. The higher field MRI devices are commonly solenoid with short bore superconducting magnets, which provide homogeneous fields of high stability.
There are this different types of magnets:
Resistive Magnet
Permanent Magnet
Superconducting Magnet
The majority of superconductive magnets are based on niobium-titanium (NbTi) alloys, which are very reliable and require extremely uniform fields and extreme stability over time, but require a liquid helium cryogenic system to keep the conductors at approximately 4.2 Kelvin (-268.8 Celsius). To maintain this temperature the magnet is enclosed and cooled by a cryogen containing liquid helium (sometimes also nitrogen).
The gradient coils are required to produce a linear variation in field along one direction, and to have high efficiency, low inductance and low resistance, in order to minimize the current requirements and heat deposition. A Maxwell coil usually produces linear variation in field along the z-axis; in the other two axes it is best done using a saddle coil, such as the Golay coil.
The radio frequency coils used to excite the nuclei fall into two main categories; surface coils and volume coils. The essential element for spatial encoding, the gradient coil sub-system of the MRI scanner is responsible for the encoding of specialized contrast such as flow information, diffusion information, and modulation of magnetization for spatial tagging.
An analog to digital converter turns the nuclear magnetic resonance signal to a digital signal. The digital signal is then sent to an image processor for Fourier transformation and the image of the MRI scan is displayed on a monitor.

For Ultrasound Imaging (USI) see Ultrasound Machine at US-TIP.com.

See also the related poll results: 'In 2010 your scanner will probably work with a field strength of' and 'Most outages of your scanning system are caused by failure of'
Radiology-tip.comGamma Camera,  Linear Accelerator
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Radiology-tip.comUltrasound Machine,  Real-Time Scanner
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• View the DATABASE results for 'Device' (141).Open this link in a new window


• View the NEWS results for 'Device' (29).Open this link in a new window.
 
Further Reading:
  Basics:
Linear Collider Final FocusMagnet Construction
   by www.bnl.gov    
  News & More:
Selection Criteria For an MR System
   by dspace.dial.pipex.com    
MRI Resources 
Safety Products - Education - Anatomy - NMR - Safety Training - Safety pool
 
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