Open-type magnetocardiograph with cylindrical magnetic shield

Seki, Yusuke; Kandori, Akihiko; Suzuki, Daisuke; Ohnuma, Mitsuru
June 2005
Applied Physics Letters;6/13/2005, Vol. 86 Issue 24, p243902
Academic Journal
We have developed an open-type magnetocardiograph (MCG) with a cylindrical magnetic shield—having an auxiliary magnetic shield—and 64 gradiometers based on low-transition temperature (Tc) superconducting quantum interference devices (SQUIDs). A revolving door is applied to the magnetic shield with the aim of providing easy access to a subject and easy operation. The cryostat attached to the MCG contains 64 low-Tc SQUIDs and is about 1 m in height, so there must be an opening through the cylindrical surface of the magnetic shield. The properties of the magnetic shield were simulated using finite-element-method simulations and experiments. The results of the simulations indicated that the auxiliary magnetic shield recovers enough of the shielding performance of a magnetic shield with an opening that it performs like a magnetic shield without an opening. The shielding factor of the developed magnetic shield is above 46 dB in the vicinity of the magnetic shield. Accordingly, the open-type MCG can clearly measure magnetocardiograms.


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