Method and apparatus for ferrous object and/or magnetic field detection for MRI safety

• US 7,696,751 B2
• Filed: 12/07/2006
• Issued: 04/13/2010
• Est. Priority Date: 12/08/2005
• Status: Expired due to Fees

• Current Assignee: Invivo Corporation (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Ciesla, Jeanette, Molyneaux, David A., Tsalikis, Dimitris
• Primary Examiner(s): Shrivastav; Brij B
• Application Number:
  US11/635,417
• Publication Number:
  US 20070132581A1
• Time in Patent Office: 1,223 Days
• Field of Search: 324300-345, 600407-445
• US Class Current: 324/301
• CPC Class Codes: 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

Abstract

A method and apparatus for ferrous object and/or magnetic field detection are provided. Embodiments can improve magnetic resonance imaging (MRI) safety and increase the safety of MRI facilities. Embodiments can detect a given magnetic field strength around a MRI machine and alert users to the field'"'"'s presence. In an embodiment, the magnetic field warning system can rely on a single badge that warns its user. In another embodiment, the badge can utilize an RFID system. The RFID system can turn the badge on when it enters the MRI room and off when it leaves the MRI room. In another embodiment, a badge with a rechargeable battery and charger can be utilized with or without an RFID tag. The subject badges or other detection devices can be worn by a person, located on or near a ferrous object, embedded in clothing, or located in other positions convenient to a user.

Claims

1. An apparatus for magnetic field detection, comprising:

a magnetic field detector comprising one or more magnetic field sensors for detecting a threshold magnitude magnetic field;

a user interface for generating an alert to a user upon detection of the threshold magnitude magnetic field;

a power supply;

wherein the magnetic field detector, the power supply, and the user interface are utilized in a single package, wherein the one or more magnetic field sensors comprise three magnetic field sensors, wherein the three magnetic field sensors detect magnetic fields in three perpendicular directions.

2. The apparatus according to claim 1, wherein the three magnetic field sensors comprise three linear Hall effect sensors.

3. An apparatus for magnetic field detection, comprising:

a magnetic field detector comprising one or more magnetic field sensors for detecting a threshold magnitude magnetic field;

a user interface for generating an alert to a user upon detection of the threshold magnitude magnetic field;

a power supply;

wherein the magnetic field detector, the power supply, and the user interface are utilized in a single package, wherein the one or more sensors comprise one or more sensors selected from the following type of sensors;

a giant magnetoresistive (GMR) sensor, a flux gate sensor, an anisotropic magnetoresistors (AMR) sensor, an induction magnetic field sensor, a SQUID magnetic field sensor, and a linear Hall effect sensor.

4. The apparatus according to claim 3, wherein the one or more magnetic field sensors comprise a first magnetic field sensor that does not consume power from the power supply, wherein the first magnetic field sensor turns on a second magnetic field sensor once the first threshold magnitude magnetic field is detected by the first magnetic field sensor.

5. The apparatus according to claim 4, wherein the first magnetic field sensor is a Reed switch.

6. The apparatus according to claim 3, further comprising a RFID tag utilized in the single package.

7. The apparatus according to claim 6, further comprising an RFID tag reader for reading the RFID tag when the single package enters a specified area and a means for activating the power supply upon reading the RFID tag.

8. The apparatus according to claim 7, further comprising a panel structure proximate the specified area, wherein a first warning is provided by the panel structure upon the RFID tag reader reading the RFID tag when the single package enters the specified area.

9. The apparatus according to claim 7, further comprising a means for deactivating the power supply upon the RFID tag reader reading the RFID tag when the single package exits the specified area.

10. The apparatus according to claim 9, wherein the specified area is an MRI facility.

11. The apparatus according to claim 3, wherein the alert to the user comprises visual and/or audible alarms.

12. The apparatus according to claim 3, wherein upon detection of the threshold magnitude magnetic field, the user interface also sends a signal to effect the closing and/or locking doors or other apparatus to prevent or reduce access to an MRI scanner.

13. The apparatus according to claim 3, wherein the single package is worn by the user as a badge.

14. The apparatus according to claim 13, wherein the badge is shaped as a nametag.

15. The apparatus according to claim 14, wherein the badge has dimensions no greater than 3.times.2 inches for its front face.

16. The apparatus according to claim 3, wherein power consumption of the single package is less than 400 mW.

17. The apparatus according to claim 3, wherein the single package is embedded in clothing.

18. The apparatus according to claim 3, wherein the single package is located on or near a ferrous object.

19. An apparatus for magnetic field detection, comprising:

a magnetic field detector comprising one or more magnetic field sensors for detecting a threshold magnitude magnetic field;

a user interface for generating an alert to a user upon detection of the threshold magnitude magnetic field;

a power supply;

wherein the magnetic field detector, the power supply, and the user interface are utilized in a single package, wherein the magnetic field sensors detect a second threshold magnitude magnetic field, wherein the second threshold magnitude is larger than the first threshold magnitude magnetic field, wherein the user interface generates a second alert upon detection of the second threshold magnitude magnetic field.

20. An apparatus for magnetic field detection, comprising:

a magnetic field detector comprising one or more magnetic field sensors for detecting a threshold magnitude magnetic field;

a user interface for generating an alert to a user upon detection of the threshold magnitude magnetic field;

a power supply;

wherein the magnetic field detector, the power supply, and the user interface are utilized in a single package, wherein the one or more magnetic field sensors comprise six Hall effect sensors, wherein two Hall effect sensors are positioned on an x-axis, two Hall effect sensors are positioned on a y-axis, and two Hall effect sensors are positioned on a z-axis, wherein one of the two Hall effect sensors for each axis provides a measurement for a positive magnetic field along the axis and the other one of the two Hall effect sensors for each axis provides a measurement for a negative magnetic field along the axis.