Magnetic resonance screening portal with combination sensing

• US 20060022670A1
• Filed: 01/05/2005
• Published: 02/02/2006
• Est. Priority Date: 07/31/2004
• Status: Abandoned Application

• Current Assignee: Quantum Magnetics, Inc. (GE Aerospace), Mednovus Incorporated (Kopp Development Incorporated)
• Original Assignee: Quantum Magnetics, Inc. (GE Aerospace), Mednovus Incorporated (Kopp Development Incorporated)
• Inventors: McClure, Richard J., Kumar, Sankaran, Czipott, Peter V.
• Application Number:
  US11/031,332
• Publication Number:
  US 20060022670A1
• Time in Patent Office: Days
• US Class Current: 324/239
• 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
• CPC Class Codes: G01V 3/104 using several coupled or uncoupled coils G01V3/101 takes precedence

Abstract

A screening portal for detecting the passage of ferromagnetic threat objects, whether permanently magnetized or not, by the use of AC induction coil sensors to detect a non-magnetized object, in combination with sensors capable of detecting the passage of a permanently magnetized object.

Claims

1. A portal for detection of ferromagnetic and magnetic threat objects, comprising:

a frame having an opening for passage of a subject to be screened for threat objects;

an applied field coil adapted to establish an AC magnetic field in said opening of said frame;

a plurality of AC induction coils mounted to said frame, said induction coils being adapted to sense an induced magnetic field induced in a threat object by the presence of said applied AC magnetic field;

at least one sensor mounted to said frame, said sensor being adapted to sense a magnetic field established by a permanently magnetized threat object in said opening of said frame.

2. The portal recited in claim 1, wherein said sensor comprises a DC type sensor adapted to sense a static or slowly varying magnetic field established by said permanently magnetized threat object.

3. The portal recited in claim 2, wherein:

at least one said DC type sensor is mounted on a first vertical member of said portal frame on a first side of said opening; and

at least one said DC type sensor is mounted on a second vertical member of said portal frame on a second side of said opening.

4. The portal recited in claim 2, wherein at least one said DC type sensor is mounted on a horizontal member of said frame above said opening.

5. The portal recited in claim 1, wherein said sensor comprises a large induction coil adapted to sense a slowly varying magnetic field established by movement of said permanently magnetized threat object through said opening of said frame.

6. The portal recited in claim 1, wherein:

a first vertical array of said AC induction coils are mounted on a first vertical member of said portal frame on a first side of said opening; and

a second vertical array of said AC induction coils are mounted on a second vertical member of said portal frame on a second side of said opening.

7. The portal recited in claim 6, wherein:

a first said applied field coil is mounted adjacent to said first vertical member of said portal frame;

a second said applied field coil is mounted adjacent to said second vertical member of said portal frame; and

said first and second applied field coils have horizontal axes extending across said opening of said frame.

8. The portal recited in claim 1, wherein a horizontal array of said AC induction coils are mounted on a horizontal member of said frame above said opening.

9. A method for detection of ferromagnetic and magnetic threat objects, comprising:

providing a frame having an opening, at least one applied field coil, and a plurality of AC induction coils;

establishing an AC magnetic field in said opening of said frame with said at least one applied field coil;

passing a subject to be screened for threat objects through said opening;

sensing, with said induction coils, a magnetic field induced in a threat object by the presence of said applied AC magnetic field; and

sensing, with at least one sensor mounted to said frame, a magnetic field established by a permanently magnetized threat object in said opening of said frame.

10. The method recited in claim 9, wherein said at least one sensor comprises a DC type sensor, said method further comprising sensing, with said DC type sensor, a static or slowly varying magnetic field established by said permanently magnetized threat object.

11. The method recited in claim 10, further comprising:

providing at least one said DC type sensor on a first vertical member of said frame on a first side of said opening; and

providing at least one said DC type sensor on a second vertical member of said frame on a second side of said opening.

12. The method recited in claim 10, further comprising providing at least one said DC type sensor on a horizontal member of said frame above said opening.

13. The method recited in claim 9, wherein said at least one sensor comprises a large induction coil, said method further comprising sensing, with said large induction coil, a slowly varying magnetic field established by movement of said permanently magnetized threat object through said opening of said frame.

14. The method recited in claim 9, further comprising:

providing a first vertical array of said AC induction coils on a first vertical member of said frame on a first side of said opening; and

providing a second vertical array of said AC induction coils on a second vertical member of said frame on a second side of said opening.

15. The method recited in claim 14, further comprising:

providing a first said applied field coil adjacent to said first vertical member of said frame;

providing a second said applied field coil adjacent to said second vertical member of said frame; and

extending horizontal axes of said first and second applied field coils across said opening of said frame.

16. The method recited in claim 9, further comprising providing a horizontal array of said AC induction coils on a horizontal member of said frame above said opening.