Fluctuating Magnetic Field Surveys and Vibration Measurement Surveys are usually required to confirm the proposed location of a new MRI scanner installation meets the site requirements specified by the scanner manufacturers.
At the planning stage of a new hospital, department or new MRI installation the scanner supplier and model type is rarely known. It is therefore essential that the site requirements of ALL potential suppliers are assessed.
Magnetic field fluctuations are measured in all three axes (X,Y,Z) using a fluxgate sensor over the frequency range DC (0 Hz) to 1000 Hz. The sensor has a range of ±10 µT and a typical noise level of <10 pT RMS.
Site vibration is measured on the floor of the MRI examination room (or as close to as site conditions allow) over the frequency range of 0.2 Hz to 5 kHz. The sensitivity of the vibration measuring sensor and FFT analyser is 9.78 V/g and the resolution 0.000001 g.
A full survey must be carried out over a reasonable period representative of normal usage, typically not less than 4 hours, and any unusual site activity such as by construction equipment must be avoided during this time to give realistic results.
Following the survey EEP will produce a comprehensive report providing the results, including the largest fluctuations during the measurement period in time domain, and the amplitude spectrum. The results can then be compared to ALL available scanners.