# US 2019/0244355 A1 · Determining respiratory phase from fluoroscopic images

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- Number: US 2019/0244355 A1
- Document ID: US20190244355A1
- Status: Published application
- Kind: A1
- Application number: 15/891,669
- Filed: 2018-02-08
- Published: 2019-08-08
- Earliest claimed: 2018-02-08
- Assignees: APN Health, LLC
- Applicants: APN Health, LLC
- Inventors: Donald Brodnick; Shivani Kohut
- Web page: https://patentgrep.com/patent/US20190244355A1

## CPC

- G06T 7/0016: {involving temporal comparison}
- A61B 5/08: Measuring devices for evaluating the respiratory organs
- A61B 5/0816: {Measuring devices for examining respiratory frequency (measuring frequency of electric signals G01R23/00)}
- A61B 5/082: {Evaluation by breath analysis, e.g. determination of the chemical composition of exhaled breath (A61B5/083, A61B5/091 take precedence)}
- A61B 6/485: {involving fluorescence X-ray imaging}
- A61B 6/486: {involving generating temporal series of image data}
- A61B 6/487: {involving fluoroscopy}
- A61B 6/50: specially adapted for specific body parts; specially adapted for specific clinical applications
- A61B 6/5217: {extracting a diagnostic or physiological parameter from medical diagnostic data}
- A61B 6/541: {involving acquisition triggered by a physiological signal}
- A61B 8/543: {involving acquisition triggered by a physiological signal}
- A61B 34/20: Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
- G06T 5/20: using local operators
- G06T 5/70: Denoising; Smoothing
- A61B 5/7285: {for synchronizing or triggering a physiological measurement or image acquisition with a physiological event or waveform, e.g. an ECG signal}
- A61B 6/503: {for diagnosis of the heart}
- A61B 6/5247: {combining images from an ionising-radiation diagnostic technique and a non-ionising radiation diagnostic technique, e.g. X-ray and ultrasound}
- A61B 2017/00699: {correcting for movement caused by respiration, e.g. by triggering}
- A61B 2017/00703: {correcting for movement of heart, e.g. ECG-triggered}
- G06T 2207/10064: Fluorescence image
- G06T 2207/20021: Dividing image into blocks, subimages or windows
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

A method of determining respiratory phase of a living body from a sequence of digitized fluoroscopic images of a living-body region exhibiting respiratory displacement. The method employs programmable computing apparatus and includes the steps of: (1) in each living-body-region image in the sequence, defining one or more zones with each image having identical image-to-image zone locations, sizes, and shapes; (2) for each image, computing an average pixel intensity for each zone to form a sequence thereof for each zone; (3) for each zone, modifying the average pixel intensities by (a) computing the mean value of the sequence of average pixel intensities for such zone, (b) subtracting the mean from each average pixel intensity in the zone, and (c) summing the absolute values of the modified average pixel intensities to form a zone-sequence sum A; (4) for each zone, computing absolute-value first differences for each sequential pair of average pixel intensities and summing the differences to form a zone-sequence first-difference sum B; (5) selecting the zone having the highest ratio A/B; and (6) using the sequence of modified average pixel intensities of the selected zone to determine respiratory phase.

## Claims

### Claim 1

A method of determining respiratory phase of a living body from a sequence of digitized fluoroscopic images of a living-body region exhibiting respiratory displacement, the method employing programmable computing apparatus and comprising the steps of:
in each living-body-region image in the sequence, defining one or more zones with each image having identical image-to-image zone locations, sizes, and shapes;
for each image, computing an average pixel intensity for each zone to form a sequence thereof for each zone;
for each zone, modifying the average pixel intensities by:
computing a mean value of the sequence of average pixel intensities for the zone;
subtracting the mean value from each average pixel intensity in the zone; and
summing absolute values of the modified average pixel intensities to form a zone-sequence sum A for the zone;
for each zone, computing absolute-value first differences for each consecutive pair of average pixel intensities and summing the differences to form a zone-sequence first-difference sum B;
selecting the zone having the highest ratio A/B; and
using the sequence of modified average pixel intensities of the selected zone to determine respiratory phase.

### Claim 2 (depends on 1)

The method of determining respiratory phase of claim 1 further including applying a smoothing filter to the sequence of average pixel intensities for the selected zone.

### Claim 3 (depends on 2)

The method of determining respiratory phase of claim 2 wherein the smoothing filter is a moving-average filter.

### Claim 4 (depends on 3)

The method of determining respiratory phase of claim 3 wherein the moving-average filter is a one-second moving-average filter.

### Claim 5 (depends on 3)

The method of determining respiratory phase of claim 3 wherein the moving-average filter depends on a measured cardiac rate of the living body.

### Claim 6 (depends on 1)

The method of determining respiratory phase of claim 1 wherein the one or more zones completely cover each image.

### Claim 7 (depends on 1)

The method of determining respiratory phase of claim 1 wherein the sizes of all of the zones within an image are identical.

### Claim 8 (depends on 1)

The method of determining respiratory phase of claim 1 wherein the shapes of all of the zones within an image are identical.

### Claim 9 (depends on 1)

The method of determining respiratory phase of claim 1 wherein the forming for each zone of its sequence of average pixel intensities includes applying a scale factor to the average pixel intensities and using the same scale factor for each zone.

### Claim 10 (depends on 1)

The method of determining respiratory phase of claim 1 wherein the forming for each zone of its zone-sequence first-difference sum B further includes the addition of a constant to the zone-sequence first-difference sum B.

### Claim 11 (depends on 1)

The method of determining respiratory phase of claim 1 further including the steps of extrapolating respiratory phase estimates forward in time beyond a most recent phase determination and gating the generation or capture of the sequence of digitized fluoroscopic images of a living-body region based on the extrapolated phase estimates.

### Claim 12 (depends on 1)

The method of determining respiratory phase of claim 1 wherein the zones are non-overlapping zones.