Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1999-11-24
2003-09-30
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C324S248000, C324S261000
Reexamination Certificate
active
06628978
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a biomagnetism measurement device and a method of biomagnetism measurement which are suitable for measuring a magnetic field (for example, a magnetic field being caused by a nerve activity or myocardial activity of a heart) occurring from a portion to be measured of a living body (a patient to be inspected) by making use of a super conducting quantum interference device (hereinbelow abbreviated as SQUID) which serves as a highly sensitive magnetism sensor.
BACKGROUND ART
Since the SQUID which is developed in association with a growth of technology with regard to superconducting devices functions as a highly sensitive magnetism sensor, a technology which measures a magnetic field distribution caused by a living body making use of the SQUID and uses the same as medical diagnosis data is now being established in a medical measurement field.
FIG. 16
shows an arrangement diagram when such biomagnetism measurement device is applied for a cardio magnetism measurement system.
The cardio magnetism measurement is performed in a magnetically shielded room
1
so as not to be affected by environmental magnetic noises. A patient
2
to be inspected lies down on a bed
3
, and is positioned close to and immediately below a bottom of a dewar (vessel)
4
so that a portion to be measured (a center position of a heart) meets with a center position of the dewar
4
(which includes magnetism sensors formed by integrating detection coils and the SQUIDs and is constituted by a cylindrical container filled with liquid He) supported by a gantry
5
.
For He being evaporated, liquid He is continuously supplemented to a liquid He tank
6
by an automatic supply device
7
disposed outside the magnetically shielded room
1
.
Outputs of the magnetism sensors are inputted to an FLL circuit
8
wherein voltage outputs proportional to the detected magnetic field intensities are obtained. The output voltages are amplified and of which frequency band are selected via an amplifier and filter circuit
9
, and are taken in by a computer
10
after being A/D converted, wherein signal processing is performed and the processed data are outputted therefrom.
A dewar
4
for the biomagnetism measurement, for example, as disclosed in G. L. Romani, et al., Rev. Sci. Instrom, 53. pp. 1815-1845(1982), is configurated in a cylindrical shape or a combination of cylinders of different diameters and is disposed vertically because of easy production from its structural point of view.
Further, in a system for measuring a cardio magnetism most of the bottom faces of such cylindrical shaped dewars are configurated in flat, because a chest wall of a living body is nearly flat. In case of cardio magnetism measurement, after a patient to be inspected lay on the patient's back on the bed
3
which is constituted to be movable freely (permitted position adjustment) in backward and forward, right and left and upward and downward with respect to the dewar
4
, it was necessary to meet the heart portion (center position of the heart) in the chest wall area of the patient
2
to be inspected with the center position of the bottom face of the dewar
4
and to come close thereto by adjusting respective movable portions in the bed
3
.
However, if the measurement portion of the patient to be measured touches the bottom face of the dewar
4
which causes noises, therefore, it is necessary to place the measurement portion away therefrom to some extent, however, if the measurement portion is placed away excessively, the sensitivity of the sensors reduces, therefore, a positioning operation has to be repeated many times for determining an optimum position visually.
FIG. 17
shows a conventional common method of positioning a measurement portion with respect to a dewar
4
.
In the conventional cardio magnetism measurement device the bed
3
for placing the patient
2
to be inspected thereon is disposed on a traveling stand
12
which is movable in back and forth direction along back and forth transferring use trails
11
via an elevation means
13
and a right and left direction moving means
14
.
The traveling stand
12
is either manually driven or electrically driven by a motor, and moves in the back and forth direction on the back and forth transferring use rails
11
. At the retreated state of the traveling stand
12
, the traveling stand
12
positions the bed
3
at a measurement preparation position, in that a position away from the dewar
4
, where the patient
2
gets on and off the bed
3
as well as the posture of the patient
2
is corrected for the measurement, and at the advanced state the traveling stand
12
positions the bed
3
at a measurement position where the patient
2
is placed immediately under the dewar
4
.
The elevation means
13
is disposed between the traveling stand
12
and the right and left direction moving means
14
. The elevation means
13
elevates and deelevates the right and left direction moving means
14
(the bed
3
) by a hydraulic expansion and contraction means constituted by a hydraulic cylinder and piston. Through manipulation of an elevation use hydraulic pump handle
17
pressurized oil is supplied in the hydraulic cylinder to elevate the right and left direction moving means
14
, and when pushing a relief valve
18
, the pressure oil in the hydraulic cylinder is discharged to deelevate the right and left direction moving means
14
.
The right and left direction movement means
14
supports the bed
3
in such a manner to permit the bed
3
to move in right and left direction. When rotating a right and left transferring handle
16
, the bed
3
is caused to move in right or left direction through a combination of a pinion and rack or a ball screw mechanism.
In order to place the patient
2
in a measurable condition in which the chest (the heart portion) of the patient
2
comes close to and immediately below the center of the bottom portion of the bewar
4
, at first the traveling stand
12
is retreated along the back and forth direction transferring rails
11
to move the bed
3
to the measurement preparation position, thereafter, the patient
2
is laid on the bed
3
on the patient's back and the posture thereof is corrected. At this instance, the elevation means
14
deelevates the bed
3
to the lowest position or a predetermined height suitable for getting on and off the bed
3
.
Thereafter, the traveling stand
12
is advanced along the back and forth transferring use rails
11
and moves the bed
3
to the measurement position under the dewar
4
to perform position matching of the heart center of the patient
2
with the bottom center of the dewar
4
.
In order to match the heart center of the patient
2
with the bottom center of the dewar
4
, it is necessary to perform the matching while observing a pin point marking of the heart of the patient
2
(usually the heart center position is estimated which is shifted by predetermined distances in X and Y axis directions from the position of a xiphoid process which is determined in advance through palpation, and this estimated position is determined as the pin point marking position). With this positioning method, because of the narrow space between the patient
2
and the dewar
4
, the chest of the patient
2
is hidden behind the dewar
4
which causes insufficient confirmation of the positions of the dewar
4
and the pin point marking. For this reason, the setting is conventionally performed under insufficient matching, therefore, correlation between the sensor positions in the dewars
4
and the measurement portion is hardly taken which causes the position matching difficult. In particular, when many number (multi-channels) of magnetism sensors are arranged in the dewar
4
, it was difficult to correlate the magnetism sensors for respective channels with the measurement portion.
The correlation between the magnetism sensors and the measurement portion is very important in data processing (position calibration) for the heart diagnosis. Further, it is possible to
Kandori Akihiko
Kondo Shoji
Sasabuchi Hitoshi
Suzuki Hiroyuki
Tsukada Keiji
Hitachi , Ltd.
Mattingly Stanger & Malur, P.C.
Qaderi Runa Shoh
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