US 12,663,387 B2Granted

Electromagnetic imaging calibration method

AssigneeEMvision Medical Devices Ltd

InventorsAmin Abbosh, Konstanty Bialkowski

Life of this patent

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Abstract

A method of calibrating an electromagnetic medical imaging apparatus having a vector network analyser (VNA) coupled via transmission lines to an array of antennas disposed about an imaging domain; measure scattering parameters Scal for a known calibration object at a known location within the imaging domain; process the measured scattering parameters Scal to calculate calibration terms; rearranging at least some of the transmission lines in preparation for imaging a subject; with the rearranged transmission lines, measure scattering parameters for one-port calibration standards to determine matrices YA and YB; calculate a thru error term aM for calibrating scattering parameters for the subject; with the rearranged transmission lines, measure scattering parameters of the subject and calibrate the measured scattering parameters of the subject. Y A = [ - Δ A t 11 e A 00 t 11 - e A 11 t 11 1 t 11 ] ⁢ Y B = [ 1 t 22 - e B 11 t 22 e B 00 t 22 - Δ B t 22 ] ; ⁢ where ⁢ t 11 = e A 01 ⁢ e A 10 , t 22 = e B 01 ⁢ e B 10 , Δ A = ( e A 00 ⁢ e A 11 - e A 01 ⁢ e A 10 ) , and ⁢ Δ B = ( e B 00 ⁢ e B 11 - e B 01 ⁢ e B 10 ) ;

Claims12

Dependent claims

using the apparatus to measure scattering parameters Scal for a known calibration object at a known location within the imaging domain, wherein each of the antennas of the array of antennas is connected to the VNA via a corresponding transmission line and a corresponding inline calibration module disposed between the transmission line and the antenna, wherein the measurements are performed for each of at least four configurations of the inline calibration module, the at least four configurations including a measurement configuration in which the inline calibration module is configured to electrically connect the transmission line to the corresponding antenna, and at least three calibration configurations in which the inline calibration module is configured to implement respective different calibration standards;
processing the measured scattering parameters Scal to calculate calibration terms e00, e01 e10, and e11 for ports A and B;
rearranging at least some of the transmission lines in preparation for imaging a subject disposed within the imaging domain;
with the rearranged transmission lines, measuring scattering parameters for one-port calibration standards to determine matrices YA and YB for respective ports A and B, according to:
Y
A
=
[
-
Δ
A
t
11
e
A
00
t
11
-
e
A
11
t
11
1
t
11
]
⁢
Y
B
=
[
1
t
22
-
e
B
11
t
22
e
B
00
t
22
-
Δ
B
t
22
]
;
where
⁢
t
11
=
e
A
01
⁢
e
A
10
,
t
22
=
e
B
01
⁢
e
B
10
,
Δ
A
=
(
e
A
00
⁢
e
A
11
-
e
A
01
⁢
e
A
10
)
,
and
⁢
Δ
B
=
(
e
B
00
⁢
e
B
11
-
e
B
01
⁢
e
B
10
)
;
calculating a thru error term αM for calibrating scattering parameters for the subject, according to:
α
M
=
±
det
⁢
T
cal
⁢
det
⁢
Y
B
det
⁢
Y
A
where Tcal is the transmission matrix for the known calibration object;
with the rearranged transmission lines, measuring scattering parameters for the subject disposed within the imaging domain;
and
calibrating the measured scattering parameters of the subject according to:
T
subject
⁢
_
⁢
cal
=
α
M
-
1
⁢
Y
A
-
1
⁢
T
subject
⁢
Y
B
where Tsubject_cal and Tsubject are calibrated and uncalibrated transmission matrices for the subject, respectively.

164 more elements

A computer-readable storage medium having stored thereon executable instructions that, when executed by at least one processor of an electromagnetic medical imaging apparatus, cause the at least one processor to:

use the apparatus to measure scattering parameters Scal for a known calibration object at a known location within an imaging domain, wherein each antenna of an array of antennas is connected to a vector network analyser (VNA) via a corresponding transmission line and a corresponding inline calibration module disposed between the transmission line and the antenna, wherein the measurements are performed for each of at least four configurations of the inline calibration module, the at least four configurations including a measurement configuration in which the inline calibration module is configured to electrically connect the transmission line to the corresponding antenna, and at least three calibration configurations in which the inline calibration module is configured to implement respective different calibration standards;
process the measured scattering parameters Scal to calculate calibration terms e00, e01, e10 and e11 for a port A and a port B;
rearrange at least some of the transmission lines in preparation for imaging a subject disposed within the imaging domain;
with the rearranged transmission lines, measure scattering parameters for one-port calibration standards to determine matrices YA and YB for respective ports A and B, according to:
Y
A
=
[
-
Δ
A
t
11
e
A
00
t
11
-
e
A
11
t
11
1
t
11
]
⁢
Y
B
=
[
1
t
22
-
e
B
11
t
22
e
B
00
t
22
-
Δ
B
t
22
]
;
where
⁢
t
11
=
e
A
01
⁢
e
A
10
,
t
22
=
e
B
01
⁢
e
B
10
,
Δ
A
=
(
e
A
00
⁢
e
A
11
-
e
A
01
⁢
e
A
10
)
,
and
⁢
Δ
B
=
(
e
B
00
⁢
e
B
11
-
e
B
01
⁢
e
B
10
)
;
calculate a thru error term αM for calibrating scattering parameters for the subject, according to:
α
M
=
±
det
⁢
T
cal
⁢
det
⁢
Y
B
det
⁢
Y
A
where Tcal is the transmission matrix for the known calibration object;
with the rearranged transmission lines, measure scattering parameters for the subject disposed within the imaging domain;
and
calibrate the measured scattering parameters of the subject according to:
T
subject
⁢
_
⁢
cal
=
α
M
-
1
⁢
Y
A
-
1
⁢
T
subject
⁢
Y
B
where Tsubject_cal and Tsubject are calibrated and uncalibrated transmission matrices for the subject, respectively.

164 more elements

An electromagnetic medical imaging apparatus including:

an array of antennas disposed about an imaging domain;
a vector network analyser (VNA) connected to the antennas via respective transmission lines and inline calibration modules disposed between the antennas and the transmission lines;
at least one processor configured to perform the steps of:
receiving from the VNA, measurements of scattering parameters Scal for a known calibration object at a known location within the imaging domain, wherein the measurements are performed with the transmission lines in a first arrangement and for each of at least four configurations of the inline calibration modules, the at least four configurations including a measurement configuration in which the inline calibration module is configured to electrically connect the transmission line to the corresponding antenna, and at least three calibration configurations in which the inline calibration module is configured to implement respective different calibration standards;
processing the measured scattering parameters Scal to calculate calibration terms e00, e01, e10, and e11 for ports A and B;
receiving from the VNA measurements of scattering parameters for one-port calibration standards, wherein the measurements are performed with at least some of the transmission lines in a second arrangement different to the first arrangement in preparation for imaging a subject disposed within the imaging domain;
processing the scattering parameters for the one-port calibration standards to determine matrices YA and YB for respective ports A and B, according to:
Y
A
=
[
-
Δ
A
t
11
e
A
00
t
11
-
e
A
11
t
11
1
t
11
]
⁢
Y
B
=
[
1
t
22
-
e
B
11
t
22
e
B
00
t
22
-
Δ
B
t
22
]
;
where
⁢
t
11
=
e
A
01
⁢
e
A
10
,
t
22
=
e
B
01
⁢
e
B
10
,
Δ
A
=
(
e
A
00
⁢
e
A
11
-
e
A
01
⁢
e
A
10
)
,
and
⁢
Δ
B
=
(
e
B
00
⁢
e
B
11
-
e
B
01
⁢
e
B
10
)
;
calculating a thru error term αM for calibrating scattering parameters for the subject, according to:
α
M
=
±
det
⁢
T
cal
⁢
det
⁢
Y
B
det
⁢
Y
A
where Tcal is the transmission matrix for the known calibration object;
with the rearranged transmission lines, measuring scattering parameters for the subject disposed within the imaging domain;
and
calibrating the measured scattering parameters of the subject according to:
T
subject
⁢
_
⁢
cal
=
α
M
-
1
⁢
Y
A
-
1
⁢
T
subject
⁢
Y
B
where Tsubject_cal and Tsubject are calibrated and uncalibrated transmission matrices for the subject, respectively.

167 more elements

Dependencies are inferred from the claim text.

Facts

Application: 18/722,413Filed 22 Dec 2022
Priority: AU 202190420822 Dec 2021
Published: US 2024/0402099 A15 Dec 2024
Granted: 23 Jun 2026
Term ends: Not estimatedThe source records don’t support an estimate.

Classification16 codes

A61B 5/0507
Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves: using…
G01N 23/046
And forming images of the material: using tomography, e.g. computed tomography [CT]
G01R 27/28
Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom: measuring attenuation, gain, phase…
G01R 35/005
Testing or calibrating of apparatus covered by the other groups of this subclass: calibrating; Standards or reference devices, e.g. voltage or…