Calibration for OCT-NIRAF multimodality probe

Patent metadata

Field	Value
Publication number	US-11147453-B2
Application number	US-201715724003-A
Country	US
Kind code	B2
Filing date	Oct 3, 2017
Priority date	Oct 3, 2017
Publication date	Oct 19, 2021
Grant date	Oct 19, 2021

Abstract

A multimodality system includes first and second modalities, a catheter, and a processor. The catheter collects fluorescent light from a plurality of locations of a sample which has been irradiated with excitation light of the second modality; a detector detects intensity of the fluorescent light received from the plurality of locations as a function of an angle α formed between the normal to the sample surface and the optical axis of the excitation light. A processor calculates the angle α at each of the plurality of locations based on radiation of the first modality incident on the sample, and corrects the intensity of the detected fluorescent light using a calibration factor g(α). The calibration factor g(α) is a function of the angle α calculated at two or more of the plurality of locations. The angle α is composed of a transversal angle α t and an axial angle α a .

First claim

What is claimed is:

1. An apparatus, comprising:
a catheter extending from a proximal end to a distal end along a catheter axis, the catheter configured to simultaneously direct a radiation of first wavelength and a radiation of second wavelength from its distal end thereof towards a sample as a light beam transverse to the catheter axis, and configured to simultaneously collect at its distal end thereof, from a plurality of locations of the sample, backscattered radiation of first wavelength in response to irradiation with the radiation of first wavelength and a radiation of third wavelength emitted in response to irradiation with the radiation of second wavelength;
a first detector and a second detector operatively coupled to the catheter, the first detector configured to detect an intensity of the radiation of third wavelength and the second detector configured to detect an intensity of the backscattered radiation of first wavelength collected by the catheter from each of the plurality of locations of the sample; and
a processor operatively coupled to the first detector and the second detector, and configured to:
acquire data from the first detector about the intensity of the radiation of third wavelength and data from the second detector about the intensity of the backscattered radiation of first wavelength,
based on the data about the intensity of the backscattered radiation of first wavelength, calculate an angle α at which the radiation of second wavelength is incident on each of the plurality of locations of the sample,
adjust the intensity of the radiation of third wavelength detected by the first detector, using a calibration factor g(α), and
generate an image using data corresponding to the adjusted intensity of the radiation of third wavelength,

wherein the calibration factor g(α) is a function of the angle α calculated for each of the plurality of locations,
wherein the processor adjusts the intensity of the radiation of third wavelength by multiplying the detected intensity of the radiation of third wavelength by the calibration factor g(α) obtained from the backscattered radiation of first wavelength at each of the plurality of locations,
wherein the processor calculates the angle α by combining values of an axial rotation angle α a measured along an axial plane of the sample, and a transversal angle α t measured along a transversal plane of the sample, wherein the axial plane is perpendicular to the catheter axis and the transversal plane is parallel to the catheter axis, and
wherein the transversal angle α t is measured along the transversal plane of the sample between a line normal to the sample surface and the light beam transverse to the catheter axis along which the radiation is directed from the catheter to the sample, and the axial rotation angle α a is measured along the axial plane of the sample between a line normal to the sample surface and the light beam transverse to the catheter axis along which the radiation is directed from the catheter to sample.

2. The apparatus according to claim 1 , further comprising;
a patient interface unit (PIU) operatively connected to the proximal end of catheter,
wherein the PIU includes a fiber optic rotary joint (FORA a rotational motor and translation stage,
wherein the catheter includes a double clad fiber and a coil disposed in a protective sheath,
wherein the FORJ is configured to provide uninterrupted transmission of the radiation of first wavelength and the radiation of second wavelength from one or more light sources to the catheter and transmission of the collected radiation of third wavelength and backscattered radiation of first wavelength respectively to the first detector and the second detector while rotating the double clad fiber within the catheter during a pullback operation.

3. The apparatus according to claim 2 ,
wherein the processor calculates the transversal angle α t using sequential readings of the backscattered radiation of first wavelength backscattered from the plurality of locations and detected by the second detector along a pullback path of the catheter without changing the axial rotation angle, and
wherein the processor calculates the axial rotation angle α a using sequential readings of the backscattered radiation of first wavelength backscattered from the plurality of locations and detected by the second detector as the catheter is simultaneously rotated and pulled back.

4. The apparatus according to claim 1 ,
wherein the processor calculates the angle α using the following formula
α=tan −1 [sqrt(tan 2 (θ offset )+tan 2 (α a ))]

where
α t is the transversal angle between the line normal to the sample surface and the light beam transverse to the catheter axis projected on the plane parallel to the catheter axis, and α a is the axial rotation angle between the line normal to the sample surface and the light beam transverse to the catheter axis projected on the plane perpendicular to the catheter axis,
the transversal angle α t is calculated using sequential readings of the backscattered radiation of first wavelength backscattered from at least two transversal locations of the sample detected by the second detector along a pullback path of the catheter while the axial rotation angle is fixed, and
the axial rotation angle α a is calculated using sequential readings of the backscattered radiation of first wavelength backscattered from at least two rotational locations detected by the second detector as the catheter is simultaneously rotated and pulled back.

5. The apparatus according to claim 1 ,
wherein the processor further calculates the angle α using the following formula
α=tan −1 [sqrt(tan 2 (θ offset )+tan 2 (α a ))]

where
θ offset is an angle formed between the line normal to the catheter and the light beam transverse to the catheter axis projected on the plane parallel to the catheter axis, and
α a is the axial rotation angle between the line normal to the sample surface and the light beam transverse to the catheter axis projected on the plane perpendicular to the catheter axis,
the axial rotation angle α a is calculated using sequential readings of the backscattered radiation of first wavelength backscattered from at least two rotational locations and detected by the second detector as the catheter is simultaneously rotated and pulled back.

6. The apparatus according to claim 1 ,
wherein the processor further calculates the angle α using the following formula
α=αt

where
α t is the transversal angle between the line normal to the sample surface and the light beam transverse to the catheter axis projected on the plane parallel to the catheter axis, and
the transversal angle α t is calculated using sequential readings of the backscattered radiation of first wavelength backscattered from the plurality of locations and detected by the second detector from along a pullback path of the catheter.

7. The apparatus according to claim 4 ,
wherein the sample is a bodily lumen, and
wherein the processor calculates the transversal angle α t using the following formulas:
α t =|φ−θ offset |α t =|tan −1 ( h/D )−θ offset |α t =|tan −1 (( d−d prev_a )cos)θ offset )/ D )−θ offset |α t =|tan −1 (( d−d prev_a )cos)θ offset )/δ)−θ offset |,

where
φ is an angle formed between the lumen surface and a line parallel to the catheter axis at a current measurement location,
θ offset is an angle formed between the line normal to the catheter and the light beam transverse to the catheter axis,
d is a current distance between the catheter and the lumen surface measured at the angle θ offset at the current measurement location,
d prev_a is a previous distance between the catheter and the lumen surface measured at the angle

Assignees

• Canon Usa Inc

Inventors

• Yamada Daisuke
• Chen Jeffrey
• Elmaanaoui Badr

Classifications

• G01N2021/6465

  Angular discrimination · CPC title

• A61B5/6852

  Catheters · CPC title

• G01N2201/127

  Calibration; base line adjustment; drift compensation · CPC title

• G01B9/0203

  With imaging systems · CPC title

• G01B9/02091

  Tomographic interferometers, e.g. based on optical coherence · CPC title