Method and apparatus for controlling shape filter in CT scanning device

Patent metadata

Field	Value
Publication number	US-10463322-B2
Application number	US-201514836982-A
Country	US
Kind code	B2
Filing date	Aug 27, 2015
Priority date	Aug 29, 2014
Publication date	Nov 5, 2019
Grant date	Nov 5, 2019

Abstract

The disclosure includes: judging whether a center line of an object to be scanned is deviated from a rotation axis of a gantry of a CT scanning device; determining a first distance by which the center line of the object to be scanned is deviated from the rotation axis in a case that the center line of the object to be scanned is deviated from the rotation axis; determining according to the first distance a second distance by which the shape filter is to be translated in each projection angle; and controlling the shape filter to make it translate by the second distance in each corresponding projection angle.

First claim

What is claimed is:

1. A method for controlling a shape filter in a CT scanning device, wherein the CT scanning device comprises a tube, the shape filter and a detector, the tube and the detector are able to rotate around a rotation axis of a gantry of the CT scanning device, and the shape filter is able to be translated relative to the tube, and wherein the method comprises:
judging whether a center line of an object to be scanned is deviated from the rotation axis;
determining a first distance by which the center line of the object to be scanned is deviated from the rotation axis in a case that the center line of the object to be scanned is deviated from the rotation axis;
determining, according to the first distance, a second distance by which the shape filter is to be translated in each projection angle; and
controlling the shape filter to make it translate by the second distance in each corresponding projection angle,
wherein determining according to the first distance the second distance by which the shape filter is to be translated comprises:
obtaining the second distance x 0 according to the following formula:

k
⁡

(

x
0

)

=

-
r

+

h
·
cos

⁢

⁢
α

-
h

·
sin

⁢

⁢
α

,

wherein r is a vertical distance from the tube to the rotation axis, h is the first distance; α is an angle between a first connection line and a second connection line, the first connection line is a connection line between the tube and a rotation center point and the second connection line is a connection line between a center point of the object to be scanned and the rotation center point, wherein the rotation center point is an intersection of the rotation axis and a scanning plane, the center point of the object to be scanned is an intersection of the center line of the object to be scanned and the scanning plane, and the scanning plane is a plane which is perpendicular to the rotation axis and is through the tube; and k(x 0 ) is a slope function of a ray with the strongest intensity after passing through the shape filter, x 0 is a variable in the slope function.

2. The method according to claim 1 , wherein judging whether the center line of the object to be scanned is deviated from the rotation axis comprises:
performing lateral film scanning on the object to be scanned to obtain a scan result;
determining a channel of the detector corresponding to a ray passing through the center line of the object to be scanned according to the scan result; and
judging whether a distance between the determined channel of the detector and a central channel of the detector is less than a preset threshold, determining that the center line of the object to be scanned is not deviated from the rotation axis in a case that the distance between the determined channel of the detector and the central channel of the detector is less than the preset threshold or determining that the center line of the object to be scanned is deviated from the rotation axis in a case that the distance between the determined channel of the detector and the central channel of the detector is not less than the preset threshold.

3. The method according to claim 2 , wherein determining the channel of the detector corresponding to the ray passing through the center line of the object to be scanned according to the scan result comprises:
collecting M×N pieces of data as follows:
rawdata={ p 00 ,p 01 ,p 02 , . . . ,p ij , . . . },i= 0,1,2,3, . . . , M− 1, j= 0,1,2,3 . . . , N− 1; and

calculating the X m -th channel of the detector corresponding to the ray passing through the center line of the object to be scanned according to the following formula:

X
m

=

∑

i
,
j

⁢

p
ij

·
j

∑

i
,
j

⁢

p
ij

,

wherein M is the number of lateral sections selected for the object to be scanned, N is the number of channels of the detector, and p ij is a value representing intensity of a ray passing through the i-th lateral section and collected by the j-th channel of the detector.

4. The method according to claim 3 , wherein determining the first distance by which the center line of the object to be scanned is deviated from the rotation axis comprises: determining the first distance by which the center line of the object to be scanned is deviated from the rotation axis in a perpendicular direction; and
determining the first distance by which the center line of the object to be scanned is deviated from the rotation axis in the perpendicular direction comprises:
calculating the first distance h according to the following formula:

h
=

r
·

tan
(

X
m

-

N
-
1

2

N

·
β

)

,

Assignees

• Shenyang Neusoft Medical Sys

Inventors

• Pang Ling
• Han Junlong
• Lou Shanshan

Classifications

• A61B6/547

  involving tracking of position of the device or parts of the device · CPC title

• A61B6/4035 Primary

  the source being combined with a filter or grating · CPC title

• A61B6/032

  Transmission computed tomography [CT] · CPC title

• A61B6/542

  involving control of exposure · CPC title