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RADIO RANGING LANDMARK SYSTEM

IP.com Disclosure Number: IPCOM000204146D
Publication Date: 2011-Feb-15
Document File: 6 page(s) / 243K

Publishing Venue

The IP.com Prior Art Database

Abstract

The landmark system comprises two subsystems, a transmit subsystem and a receive subsystem. The transmit subsystem comprises at least four transmit units, whose positions have already been identified at system installation. The receive subsystem comprises a single receive unit, which is placed on the patient or on the receive coil around the patient to identify the place to scan. By using radio ranging, e.g. pseudo-random coding or carrier phase, the distance between the receive unit to each of the four transmit units may be obtained. The position of the receive unit may be calculated subsequently.

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RADIO RANGING LANDMARK SYSTEM

FIELD OF INVENTION

The invention generally relates to imaging systems and more particularly to magnetic resonance imaging systems.

BACKGROUND OF THE INVENTION

Prior art MR systems employ laser light for land marking patients. One of the limitations associated with the method includes the risk the method poses on the safety issue of the patient if and when the patient opens his eyes.

Another limitation associated with the method includes the need for the healthcare professional to push two buttons to place the patient in isocenter. The healthcare professional needs to open laser light, move the table to place the laser light perpendicular to the place of scanning, press “landmark” and “move to scan” buttons to get the patient ready for scanning.

BRIEF DESCRIPTION OF THE INVENTION

The invention provides a method of designing a landmark system without laser light by employing radio ranging. 

DETAILED DESCRIPTION OF THE INVENTION

The landmark system comprises two subsystems, a transmit subsystem and a receive subsystem. The transmit subsystem comprises at least four transmit units (red color in the figure), whose positions have already been identified at system installation.

The receive subsystem comprises a single receive unit (green color in the figure), which is placed on the patient or on the receive coil around the patient to identify the place to scan.

By using radio ranging, e.g. pseudo-random coding or carrier phase, the distance between the receive unit to each of the four transmit units may be obtained. The position of the receive unit i.e. (x, y, z), may be obtained by solving the following equations:

Where

(xi, yi, zi), i=1,2,3,4, is the position of one of the transmit units,

ri, i=1,2,3,4, is the distance obtained from radio ranging (allowing error from timing difference ),

c is the propagation speed of the wireless wave,

 is the timing difference between transmit and receive system (each of the four transmit units use a single reference timing clock).

Since the position of the center of ROI (the receive unit) is known, the healthcare professional may simply press “move to scan” button to move the patient to isocenter directly. 

       
   
 
   

(x,y,z)

 
 

                                Figure 1.  The landm...