Abstract: An arrangement for association with an MRI and detecting presence of ferrous material and discriminating out far field magnetic disturbance. The arrangement includes a detector configured to monitor the magnetic field and includes an array of sensors arranged about the periphery of an opening in a spaced arrangement such that each sensor is associated with a different portion of the opening. Each of the sensors is configured to output a signal having a value indicative of the sensed magnetic field at the associated portion of the opening. The arrangement includes a corrector configured to correct each signal value from the change in response to the far field magnetic disturbance and to provide respective corrected signal values. The arrangement includes a processor configured to use the corrected signal values to determine a ferrous-indicating limit is exceeded and to provide a safety response that addresses the ferrous-indicating limit exceed condition.

Abstract: An arrangement for association with an MRI and detecting presence of ferrous material and discriminating out far field magnetic disturbance. The arrangement includes a detector configured to monitor the magnetic field and includes an array of sensors arranged about the periphery of an opening in a spaced arrangement such that each sensor is associated with a different portion of the opening. Each of the sensors is configured to output a signal having a value indicative of the sensed magnetic field at the associated portion of the opening. The arrangement includes a corrector configured to correct each signal value from the change in response to the far field magnetic disturbance and to provide respective corrected signal values. The arrangement includes a processor configured to use the corrected signal values to determine a ferrous-indicating limit is exceeded and to provide a safety response that addresses the ferrous-indicating limit exceed condition.

Abstract: A magnetic field strength threshold alarm that includes sensing means responsive to a magnetic field and actuating in response to field strength above a predetermined threshold, the sensing means being configured to be operational and able to actuate without consumption of energy; and alarm means for outputting an alarm responsive to the sensing means actuation, the alarm means being configured not to consume energy prior to actuation of the sensing means and only consuming energy subsequent to actuation of the sensing means. So, energy is not consumed by the alarm means prior to actuation. The alarm may be considered to include energy storage means for providing electrical energy, wherein the sensing means, the alarm means and energy storage means being operatively connected such that the electrical energy from the energy storage means is provided only when the sensing means is actuated.

Abstract: An apparatus for increasing the ability to detect ferromagnetic objects by increasing the magnetization of the objects. The apparatus includes at least one coil to generate a magnetic field positioned in the area of the object to be detected. The apparatus includes an electrical energy storage capacitor bank capable of quickly releasing stored energy. The apparatus includes a high speed, high current electronic switch capable of quickly transferring the stored energy from the capacitor bank to the coil thereby producing in the coil a short duration, single polarity magnetic field pulse. The apparatus includes a sample and hold circuit capable of acquiring magnetic field sensor data during periods when the pulsed magnetic field is not present. The apparatus includes a microprocessor controller to control timing and sequence of the magnetic pulse generation and the sensor data sample and hold process. The apparatus may be for portal handheld or head mounted applications.

Abstract: A magnetic field strength threshold alarm that includes sensing means responsive to a magnetic field and actuating in response to field strength above a predetermined threshold, the sensing means being configured to be operational and able to actuate without consumption of energy; and alarm means for outputting an alarm responsive to the sensing means actuation, the alarm means being configured not to consume energy prior to actuation of the sensing means and only consuming energy subsequent to actuation of the sensing means. So, energy is not consumed by the alarm means prior to actuation. The alarm may be considered to include energy storage means for providing electrical energy, wherein the sensing means, the alarm means and energy storage means being operatively connected such that the electrical energy from the energy storage means is provided only when the sensing means is actuated.

Abstract: An apparatus for increasing the ability to detect ferromagnetic objects by increasing the magnetization of the objects. The apparatus includes at least one coil to generate a magnetic field positioned in the area of the object to be detected. The apparatus includes an electrical energy storage capacitor bank capable of quickly releasing stored energy. The apparatus includes a high speed, high current electronic switch capable of quickly transferring the stored energy from the capacitor bank to the coil thereby producing in the coil a short duration, single polarity magnetic field pulse. The apparatus includes a sample and hold circuit capable of acquiring magnetic field sensor data during periods when the pulsed magnetic field is not present. The apparatus includes a microprocessor controller to control timing and sequence of the magnetic pulse generation and the sensor data sample and hold process. The apparatus may be for portal handheld or head mounted applications.

Abstract: An MRI protector for protecting personnel and the MRI apparatus from the introduction of ferrous articles into the magnetic field of the MRI has an array of Hall effect sensors oriented to scan the magnetic field of the MRI. The Hall effect sensors are oriented to scan the magnetic field at the access door of the shielded MRI room. The sensors are connected to a central processing unit (CPU) which analyses the output of the sensors and propagates a warning when the presence of ferrous articles affects the magnetic field of the MRI.

Abstract: A liquid crystal projector comprises first, second and third liquid crystal panels having corresponding light sources, namely a red light source, a green light source, and a blue light source, wherein the red light source. The light sources are preferably Semi-conductor generated light arrays. The projector further includes a dichroic prism for superimposing the red, green and blue image displays, and a projection lens for projecting a full-color image beam formed by the dichroic prism. In order to control the intensity of the light sources, a pulse modulating means is coupled to each of the Semi-conductor generated light arrays, the pulse modulating means being operable to independently switch each of the light sources between an on state and an off state at a selectable repetition rate.

Abstract: A liquid crystal projector comprises first, second and third liquid crystal panels having corresponding light sources, namely a red light source, a green light source, and a blue light source, wherein the red light source. The light sources are preferably Semi-conductor generated light arrays. The projector further includes a dichroic prism for superimposing the red, green and blue image displays, and a projection lens for projecting a full-color image beam formed by the dichroic prism. In order to control the intensity of the light sources, aa pulse modulating means is coupled to each of the Semi-conductor generated light arrays, the pulse modulating means being operable to independently switch each of the light sources between an on state and an off state at a selectable repetition rate.

Abstract: The MRI video system is a display system that provides visual stimuli to a patient who is undergoing diagnostic treatment within a magnetic resonance imagery (MRI) apparatus. The system utilizes a magnetically inert and RF shielded projector located in the close proximity to the MRI to transpose a video picture on a translucent screen inside the bore of the MRI. The patient views the screen through a prism.

Abstract: An MRI protector for protecting personnel and the MRI apparatus from the introduction of ferrous articles into the magnetic field of the MRI has an array of Hall effect sensors oriented to scan the magnetic field of the MRI. The Hall effect sensors are oriented to scan the magnetic field at the access door of the shielded MRI room. The sensors are connected to a central processing unit (CPU) which analyses the output of the sensors and propagates a warning when the presence of ferrous articles affects the magnetic field of the MRI.