Abstract: A system and method for controlling thermal output of a medical device is disclosed. A thermal controller receives operational parameters for an impending use of a medical device and predicts a thermal output of the medical device from the operational parameters. The thermal controller compares the predicted thermal output to a desired limit on thermal output and, if the predicted thermal output exceeds the desired limit on thermal output, dynamically controls power consumption by the medical device to maintain an actual thermal output substantially at or below the desired limit on thermal output during use of the medical device.

Abstract: An anode assembly (50) includes a thermally conductive bearing encasement (52) covering a portion of a bearing (64). An anode (56) rotates on the bearing (64) and has a target (58) with an associated focal spot (60). The thermally conductive bearing encasement (52) is configured and expansion limited to prevent displacement of the focal spot (60) of greater than a predetermined displacement during operation of the anode (56).

Abstract: An RF birdcage coil for use in MRI systems is disclosed. A number of slotted or nonconductive channels are provided in the conductive material of the RF coil to minimize the size of the conductive paths available for eddy currents. Furthermore, blocking capacitors are applied between the legs and the end segments of the conductive elements to isolate the end segments from the legs at low frequency harmonics, such as those associated with eddy currents, while acting substantially as a short circuit at high operational frequencies. Preferably, the blocking capacitors are constructed by providing the legs of a plurality of I-beams on a first side of a dielectric material, and the end segments on an opposing side. The blocking capacitor results from overlapping the conductive material forming the leg and end segment on opposite sides of the dielectric material.

Abstract: An RF birdcage coil for use in MRI systems is disclosed. A number of slotted or nonconductive channels are provided in the conductive material of the RF coil to minimize the size of the conductive paths available for eddy currents. Furthermore, blocking capacitors are applied between the legs and the end segments of the conductive elements to isolate the end segments from the legs at low frequency harmonics, such as those associated with eddy currents, while acting substantially as a short circuit at high operational frequencies. Preferably, the blocking capacitors are constructed by providing the legs of a plurality of I-beams on a first side of a dielectric material, and the end segments on an opposing side. The blocking capacitor results from overlapping the conductive material forming the leg and end segment on opposite sides of the dielectric material.

Abstract: An apparatus for supporting a patient support bridge member in an MR system where a first end of the bridge is supported by an upright support member on a first side of an MR imaging bore and the bridge extends through the bore so that a second end of the bridge extends out a second side of the bore, the apparatus including a bracket mounted to an MR main magnet on the second side of the bore and extending upwardly to contact and support the bridge there above.

Abstract: Apparatus is provided for reducing the level of acoustic noise or energy which is received by an imaging subject located within the bore of an MR imaging system. The apparatus comprises a bridge fixed within the bore to support the subject during MR data acquisition, and further comprises a curved frame, usefully formed of fiberglass, which is removably insertable in the bore for placement upon the bridge. The frame, when in place upon the bridge, defines a space within the bore which is disposed to receive the imaging subject. The frame is covered by a layer of material, such as open cell foam, which is capable of absorbing substantial amounts of acoustic energy present in the bore. At the same time, the material is highly transmissive to RF signals required for MR data acquisition and avoids spurious RF signal generation which would add noise to MR data.

Abstract: A method and apparatus for cooling MRI system components including components that reside inside an RF shield such as an RF coil, a receiver coil, a patient support table and a patient enclosure wall wherein the cooling system employs a liquid coolant essentially devoid of protons and to that end, essentially devoid of hydrogen atoms.

Abstract: Apparatus which provides a barrier for vibrational energy between an MR imaging system and an associated horizontal support surface includes a stiff platform of substantial mass, which is disposed to carry the entire weight of the MR imaging system. The apparatus further includes a number of vibration isolation elements positioned to support the platform and the MR imaging system upon the horizontal support surface. Each of the isolation elements comprises an enclosure containing pressurized air which is disposed to dampen vibrations, in order to oppose the transmission of vibrations between the platform and the support surface. An air pressure regulator is coupled to respective isolation elements to maintain specified air pressure levels therein, in order to support the platform in selected spaced-apart orientation with respect to the horizontal support surface.

Abstract: In an MR imaging system provided with a main magnet having a bore and with a gradient coil assembly located within the bore, RF coil apparatus is provided for reducing noise in the imaging volume of the MR system. The RF coil apparatus comprises a tubular RF coil form provided with an inner surface, an RF coil attached to the inner surface of the RF coil form, and mounting structure extending between the RF coil form and gradient coil assembly. The mounting structure supports the RF coil and RF coil form upon the gradient coil assembly, in spaced-apart relationship therewith. The apparatus further compises an inner tubular member which is selectively constructed to oppose transmission of acoustic signals from the RF coil to the imaging volume.

Abstract: In an MR system, a mounting assembly is provided at each end of the bore of the main magnet for supporting a cylindrical gradient coil assembly within the bore. Each mounting assembly comprises first and second brackets, the first bracket being provided with a concave bearing surface having a specified curvature. The first bracket is fixably joined to the main magnet proximate to the lower side of the bore, and the second bracket is provided with a convex bearing surface which is selectively similar to the curvature of the concave bearing surface of the first bracket. The second bracket is attached to a lower portion of the gradient coil, so that the convex bearing surface extends longitudinally outward from the gradient coil assembly. A vibration attenuator is positioned between the convex and concave bearing surfaces of each mounting assembly, the vibration attenuator acting to transmit a static force between the two bearing surfaces to support the gradient coil assembly within the bore.

Abstract: Vibration and noise isolation for a magnetic resonance imager (MRI) superconducting magnet cryocooler includes a bellows between the cryocooler and its vacuum sleeve in the magnet, a mass suspended along the axis of, but at a distance from, the cryocooler, elastomeric blocks parallel to the axis, and braided copper wires connecting the vacuum sleeve and the heat shields of the MRI. Motion limiters and bellows flexures are provided for dynamic loads which might be encountered during transport of the magnet.

Abstract: An arrangement is provided for supporting the inner and outer gradient coils of one or more gradient coil sets, the coils of each gradient coil set providing one of the orthogonal gradient magnetic fields for an MR imaging system. The arrangement includes an inner cylindrical coil form disposed to supportably carry an inner gradient coil of a coil set, an outer cylindrical coil form in coaxial spaced-apart relationship with the inner coil form disposed to supportably carry an outer gradient coil of the coil set, and a stiffening cylinder positioned between the inner and outer coil forms to divide the space therebetween into first and second volumes. A thermally conductive adhesive material, such as an epoxy containing alumina particulate material, is inserted into the first and second volumes to bond both the inner and outer coil forms to the stiffening cylinder, in order to hold the inner and outer gradient coils respectively carried by the coil forms in rigid fixed relationship with respect to one another.