Magnetic Resonance Imaging | An Introduction | Site Info: The Project.

00-f5 Title and Logo 00-f6

Site Info: The Project.

 guide Contents
 siteinfo Site Info

Site Information

 The Editor
 The Team

 The Project


 Terms of Use



a b c d e f g h i j k l m n o p q r s t u v w x y z


Q → Quality factor.

Quadrature coil: analogous to quadrature detection in that the in phase and 90° out of phase components are used to improve the efficiency of the RF pulse and the S/N ratio.

Quadrature detector: a phase sensitive detector or demodulator that detects the com­po­nents of the signal in phase with a reference oscillator and 90° out of phase with the reference oscillator.

Quality factor (Q): applies to any electrical circuit component; most often the coil Q is limiting. Inversely related to the fraction of the energy in an oscillating system lost in one oscillation cycle. Q is inversely related to the range of frequency over which the sys­tem will exhibit resonance. It affects the signal-to-noise ratio, because the detected sig­nal in­crea­ses proportionally to Q while the noise is proportional to the square root of Q. The Q of a coil will depend on whether it is unloaded (no patient) or loaded (patient).

Quench, quenching: loss of superconductivity of the current carrying coil that may oc­cur unexpectedly in a superconducting magnet. As the magnet becomes resistive, heat will be released that can result in rapid evaporation of liquid helium in the cryostat.

Missing terms? Send us an e-mail. We'll add them ...

spaceholder 600 spaceholder 600