Faraday shields are used in MRI rooms to prevent stray radio waves from entering the room and affecting the imaging process.
Sometimes called a Faraday cage, the Faraday shield is a metallic device designed to block and focus electrical fields. Often constructed as a sheet of metal, this device is used in a variety of applications ranging from telecommunications to medical equipment.
The concept of the Faraday shield was developed by Michael Faraday, a physicist with a special interest in the control of electric fields. Beginning in 1836, Faraday constructed and explained the function of Faraday shields. The earliest of these Faraday cages or shields were in the form of a metal casing, often using metal mesh to create an enclosed space for the transmission of currents or waves. Faraday saw the shield as a way to prevent multiple electromagnetic waves from splitting up and interfering with each other. The Faraday shield would allow multiple pieces of machinery to be operated closely together without electrical interference.
Shields were installed on telecommunication towers to help prevent radio waves from spreading and interfering with other equipment.
In modern construction, this shield is essentially a set of parallel wires that are connected to a common conductor at one end. The conductor is grounded and helps form a layer that helps focus the electrostatic field. At the same time, the device helps prevent interference from other electrical waves from interfering with the flow of energy within the casing.
Over time, Faraday shielding applications were developed for many industries. The concept of shielding revolutionized the idea of wiring buildings for electrical services, ensuring the safe operation of several devices at the same time. Communications is an example of an industry that benefited from the Faraday shield from the start. Shields were installed on switches and transmission towers to help prevent radio waves from spreading and interfering with other equipment. The Faraday shield continued to expand its presence with the advent of television and still plays an essential role in modern technologies such as wireless communications and computer networks.
The medical profession also uses this device. One of the most common applications is with MRI equipment. Shields are used in many MRI rooms to prevent stray radio waves from entering the room and affecting the imaging process. This allows the equipment to provide a clear image that can lead to more accurate diagnosis and treatment.