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Method and an apparatus for calculation of the weight and detection of patient positioning for specific absorption rate (SAR) adjustment for workflow automation and bringing additional safety at clinical scanners

IP.com Disclosure Number: IPCOM000028961D
Published in the IP.com Journal: Volume 4 Issue 7 (2004-07-25)
Included in the Prior Art Database: 2004-Jul-25
Document File: 3 page(s) / 176K

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

In the present clinical MR (Magnetic Resonance Imaging) or CT (Computer Tomography) scanners, the operator manually makes an entry for the patient's weight, age, positioning head first/feet first, prone/supine (see fig. 1). The software compares the weight entered by the operator with the standard values for weight (e.g. a 25 year old man can not weigh 10 kg, the approximate weight range would be 50-100 kg etc.). For high field system, for various sequences specific absorption rate (SAR) adjustments are essential. SAR is position dependent and varies with the patient positioning. E.g. if the patient changes his position by putting hands on the chest/stomach. During quality assurance check, the system asks for phantom/load. In case, the operator forgets to put phantom/load, wrong adjustments could be made. Also high potentials could lead to arcing. The operator must ensure that the arms and the legs are not touching. He advices the patient to keep a distance of at least 5 cm as skin contacts may cause large-surface current loops. However the operator does not view the patient's complete body movement during the scan.

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Method and an apparatus for calculation of the weight and detection of patient positioning for specific absorption rate (SAR) adjustment for workflow automation and bringing additional safety at clinical scanners

Idea: Sultan Haider, DE-Erlangen

In the present clinical MR (Magnetic Resonance Imaging) or CT (Computer Tomography) scanners, the operator manually makes an entry for the patient's weight, age, positioning head first/feet first, prone/supine (see fig. 1). The software compares the weight entered by the operator with the standard values for weight (e.g. a 25 year old man can not weigh 10 kg, the approximate weight range would be 50-100 kg etc.). For high field system, for various sequences specific absorption rate (SAR) adjustments are essential. SAR is position dependent and varies with the patient positioning. E.g. if the patient changes his position by putting hands on the chest/stomach.

During quality assurance check, the system asks for phantom/load. In case, the operator forgets to put phantom/load, wrong adjustments could be made. Also high potentials could lead to arcing. The operator must ensure that the arms and the legs are not touching. He advices the patient to keep a distance of at least 5 cm as skin contacts may cause large-surface current loops. However the operator does not view the patient's complete body movement during the scan.

The operator makes sure that a direct contact between the patient's body and the tunnel will be avoided. There are limitations for the sequence repetition time at fields of 1.5 Tesla or greater for spin- echo sequences with two 180 degree pulses of approximately 1 ms duration. In this case, the sequence repetition time is no longer limited by the capabilities of the measurement system, but by SAR.

The new idea presents a method and apparatus for calculation of the weight and detection of patient positioning for SAR adjustments for workflow automation and bringing additional safety at clinical scanners.

As soon as the phantom/load patient/ is kept on the table, the weight is recorded by the weighing sensory mechanism in the table. The table additionally consists of sensory mechanism to detect patient movement and informs the operator in case of an accident e.g. the patient's hairs are stuck while moving the table, the patients feel uncomfortable inside the scanner and starts moving inside the table (say forming circular loops or touching the tunnel which...