# US 2016/0253443 A1 · CT Simulation Optimization for Radiation Therapy Contouring Tasks

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- Number: US 2016/0253443 A1
- Document ID: US20160253443A1
- Status: Published application
- Kind: A1
- Application number: 15/054,215
- Filed: 2016-02-26
- Published: 2016-09-01
- Earliest claimed: 2015-02-26
- Assignees: Washington University In St.Louis
- Applicants: Washington University in St.Louis
- Inventors: Hua Li; Sasa Mutic; Mark Anastasio
- Web page: https://patentgrep.com/patent/US20160253443A1

## CPC

- G06T 7/0002: {Inspection of images, e.g. flaw detection}
- G16H 30/40: for processing medical images, e.g. editing
- G16H 70/60: relating to pathologies
- G06T 2207/10081: Computed x-ray tomography [CT]
- G16H 50/50: for simulation or modelling of medical disorders
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G16H: HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA

## Abstract

A method for optimizing a CT simulation protocol for different size patients for contouring and segmentation of organs and tumors. The method scanning different size phantoms, cadavers, or patients with a CT scanning x-ray tube to create a set of images and to create data sets for each different size phantoms, cadavers, or patients and then calculating an image quality index (IQI) as a benchmark for contouring accuracy. Finding an optimal IQI that characterizes patients of different sizes and using the optimal IQI to determine the accuracy of the contouring and segmentation of A CT simulation protocol for a patient.

## Claims

### Claim 1

A method for optimizing a CT simulation protocol for different size patients for contouring and segmentation of organs and tumors comprising:
a. scanning different size phantoms, cadavers, or patients with a CT scanner to create a set of CT images, wherein CT scanning parameters are varied to create data sets for each different sized phantoms, cadavers, or patients and wherein radiation output of the CT scanner is recorded;
b. calculating image quality indices (IQI) based on the data sets,
c. selecting an optimum IQI from the IQI indices based on quality of CT images in the CT image set and on minimizing radiation output that produces the CT images; and
d. creating a CT simulation protocol for a particular patient including CT scanning parameters, wherein the CT scanning parameters for the CT simulation protocol for the particular patient result in the optimal IQI.

### Claim 2 (depends on 1)

The method of claim 1, wherein using the CT simulation protocol on additional patients over time produces additional CT images and data sets that are used to further define the optimal IQI.

### Claim 3 (depends on 1)

The method of claim 1, wherein the IQI is calculated based on the data sets and wherein the IQI is calculated in accordance with the following formula:
IQI
2
=
∫
∫
∫
NEQ

(
k
x
,
k
y
,
k
z
)

W
task
2

(
k
x
,
k
y
,
k
z
)


k
x


k
y


k
z
=
∫
∫
∫
MTF
2

(
k
x
,
k
y
,
k
z
)

W
task
2

(
k
x
,
k
y
,
k
z
)
NNPS

(
k
x
,
k
y
,
k
z
)


k
x


k
y


k
z
wherein:
a. the expression MTF2(kx, ky, kz) is a transfer function that carries information of intrinsic CT scan properties;
b. the expression W2task(kx, ky, kz) is a task function defined based on segmentation requirements; and
c. the expression NNPS(kx, ky, kx) is the normalized noise power spectrum to background signal level.

### Claim 4 (depends on 1)

The method of claim 1, wherein the IQI is calculated based on the data sets and wherein the IQI is calculated in accordance with the following formula:
IQI
2
=
K
2

∫
∫
∫
MTF
2

(
k
x
,
k
y
,
k
z
)


Δ


f
2

(
k
x
,
k
y
,
k
z
)

NNPS

(
k
x
,
k
y
,
k
z
)


k
x


k
y


k
z
wherein:
a. the expression MTF2(kx, ky, kz) is a transfer function that carries information of intrinsic CT scan properties;
b. the expression Δf represents the Fourier-domain difference of contrast of a target to its background; and
c. the expression NNPS(kx, ky, kz) is the normalized noise power spectrum to background signal level.

### Claim 5 (depends on 1)

The method of claim 1, wherein the CT scanning parameters for acquiring the CT images include collimator setting, rotation time, pitch, resolution, filter, slice thickness, x-ray tube current, x-ray tube potential, and radiation output.

### Claim 6 (depends on 1)

The method of claim 1, with automatic tube current modulation enabled on the CT scanning x-ray tube, adjusting the rotation time, pitch, and effective amperage, to match the maximum amperage/slice of the CT simulation protocol.

### Claim 7 (depends on 1)

The method of claim 1, with automatic tube current modulation disabled on the CT scanning x-ray tube, adjusting the rotation time, pitch, and amperage, to match the amperage/slice of the CT simulation protocol.