# US 9,651,701 B2 · Ferromagnetic incident detecting and logging arrangement > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,651,701 B2 - Document ID: US9651701B2 - Status: Granted - Kind: B2 - Application number: 14/882,919 - Filed: 2015-10-14 - Published: 2016-05-12 - Granted: 2017-05-16 - Earliest claimed: 2014-11-06 - Assignees: Kopp Development Inc. - Applicants: Kopp Development Inc. - Inventors: Keith Kopp - Web page: https://patentgrep.com/patent/US9651701B2 ## CPC - G01V 3/08: operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices (with electromagnetic waves G01V3/12) - G01P 13/00: Indicating or recording presence, absence, or direction, of movement (electric switches H01H; counting moving objects G06M7/00) - G01R 33/288: {Provisions within MR facilities for enhancing safety during MR, e.g. reduction of the specific absorption rate [SAR], detection of ferromagnetic objects in the scanner room} - G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02) - G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G}) - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## 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. ## Claims ### Claim 1 An arrangement for association with an operable MRI apparatus located within a room that has an access opening and with the MRI apparatus providing a residual magnetic field that extends to a location of the access opening, and for detecting presence of ferrous material and discriminating out far field magnetic disturbance, the arrangement including: a detector configured to passively monitor the residual magnetic field at the location of the access opening, the detector including an array of magnetic field sensors arranged about the periphery of the access opening in a spaced arrangement such that each sensor is associated with a different portion of the access opening, the magnetic field changing in response to a presence of ferrous material at the access opening, the magnetic field also changing in response to a far field magnetic disturbance, each of the sensors being configured to output a signal having a value indicative of the sensed magnetic field at the associated portion of the access opening; 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; and 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. ### Claim 2 (depends on 1) An arrangement as set forth in claim 1, the arrangement further including a recording system configured to record incident information associated with a determination that a ferrous-indicating limit is exceeded. ### Claim 3 (depends on 2) An arrangement as set forth in claim 2, wherein the recording system including a portion configured to record an image of the location of the access opening associated with a determination that a ferrous-indicating limit is exceeded. ### Claim 4 (depends on 2) An arrangement as set forth in claim 2, wherein the processor is configured to determine whether an incident occurs upon the ferrous-indicating limit being exceeded and the recording system includes an incident detection monitor configured to cause the recording system to record the incident information upon the processor determining an incident occurrence. ### Claim 5 (depends on 2) An arrangement as set forth in claim 2, wherein the detector includes an alarm configured to provide an alarm indication in response to the processor providing the safety response, and the recording system includes a camera configured to capture an image area that includes the location of the access opening and at least a portion of the alarm that provides the alarm indication. ### Claim 6 (depends on 2) An arrangement as set forth in claim 2, wherein the recording system is operatively coupled to the detector. ### Claim 7 (depends on 6) An arrangement as set forth in claim 6, wherein the detector includes an alarm configured to provide an audible alarm indication in response to the processor providing the safety response, and the recording system for recording system is operatively coupled to the alarm. ### Claim 8 (depends on 7) An arrangement as set forth in claim 7, wherein the operative coupling between the alarm and the recording system is an audible sound coupling. ### Claim 9 An arrangement as set forth in 1, wherein the corrector includes: a summer configured to sum all of signal values to provide a summed value, a divider configured to divide the summed value by a total number of the magnetic field sensors to provide an average signal value, and a subtracter configured to subtract the average value respectively from each signal values to provide the respective corrected signal values. ### Claim 10 An arrangement as set forth in 1, wherein the access opening is a doorway having a movable door thereat, the arrangement including a direction sensing arrangement configured to determine movement direction of the door. ### Claim 11 An arrangement as set forth in 10, wherein the processor is configured to modifying the safety response as a function of the determined movement direction of the door. ### Claim 12 An arrangement as set forth in 10, wherein the direction sensing arrangement includes at least one photoelectric emitter-detector device. ### Claim 13 An arrangement as set forth in 1, wherein the access opening permits movement of an object there through, the arrangement including a direction sensing arrangement configured to determine movement direction of the object. ### Claim 14 An arrangement as set forth in 13, wherein the processor is configured to modifying the safety response as a function of the determined movement direction of the object. ### Claim 15 An arrangement as set forth in 13, wherein the direction sensing arrangement includes at least one photoelectric emitter-detector device. ### Claim 16 An arrangement as set forth in 13, wherein the object is a person. ### Claim 17 An arrangement as set forth in 1, wherein the access opening permits an object to be present at the access opening, the arrangement including a presence sensing arrangement configured to determine presence of the object at the access opening. ### Claim 18 An arrangement as set forth in 17, wherein the processor is configured to modifying the safety response as a function of the determined presence of the object. ### Claim 19 An arrangement as set forth in 17, wherein the presence sensing arrangement includes at least one photoelectric emitter-detector device. ### Claim 20 An arrangement as set forth in 17, wherein the object is a person.