Radiation ct apparatus

Patent metadata

Field	Value
Publication number	US-2016133031-A1
Application number	US-201414536043-A
Country	US
Kind code	A1
Filing date	Nov 7, 2014
Priority date	Nov 7, 2014
Publication date	May 12, 2016
Grant date	—

Abstract

A radiation CT apparatus that can gain a clear tomogram without a rotation axis runout and without fail through a single CT scan and a simple operation is provided. When the data on the projection with radiation collected through a CT scan is first reconstructed through an arithmetic operation by a reconstruction arithmetic operation unit 13 , temporary coordinates that have been set in advance as the coordinates of the projected rotation axis so as to construct a tomogram along a predetermined sliced surface are used, this tomogram is displayed on the screen for changing the rotation axis coordinates that include the temporary coordinates, and the coordinates of the projected rotation axis are shifted by any amount in any direction through an operation on the screen so that a reconstruction arithmetic operation is again carried out in the reconstruction arithmetic operation unit 13.

First claim

What is claimed is:

1 . A radiation CT apparatus, comprising: a rotational table on which an object to be examined is placed, the rotational table being provided between a radiation source and a radiation detector, which are provided so as to face each other, so as to rotate around a rotation axis that is perpendicular to the direction of the radiation axis; and a reconstruction arithmetic operation means for constructing a tomogram of the object along a sliced surface that is perpendicular to said rotation axis through an arithmetic operation using data of the projected object with radiation collected by taking in the output of said radiation detector for each of the minute rotational angles gained when the rotational table is rotated while irradiating the object on the rotational table with radiation from said radiation source, characterized in that
said reconstruction arithmetic operation means comprises: a screen display means for changing the rotation axis coordinates that constructs a tomogram along a predetermined sliced surface using temporary coordinates that have been set in advance as the coordinates of said rotation axis projected over said radiation detector in the first reconstruction arithmetic operation after collecting data on said object projected with radiation, and at the same time displays a screen for changing the coordinates of the projected rotation axis that include said tomogram and the temporary coordinates; and an instruction input means for instructing said reconstruction arithmetic operation means to perform another arithmetic operation by shifting the coordinates of the projected rotation axis by any amount in any direction relative to said temporary coordinates through an operation on the screen, wherein said reconstruction arithmetic operation means carries out another reconstruction arithmetic operation by changing the coordinates of the projected rotation axis in accordance with the instructions.

2 . The radiation CT apparatus according to claim 1 , characterized in that said radiation source generates radiation in a cone-beam form, said radiation detector is a two-dimensional detector, and said reconstruction arithmetic operation means constructs a number of tomograms along a number of sliced surfaces that are perpendicular to said rotation axis through a reconstruction arithmetic operation, and at the same time carries out a first reconstruction arithmetic operation using said temporary coordinates on one tomogram along a predetermined sliced surface and carries out the reconstruction arithmetic operation on the tomograms along the other sliced surfaces after receiving the instructions to that effect.

3 . The radiation CT apparatus according to claim 1 , characterized in that: said reconstruction arithmetic operation means carries out the first reconstruction arithmetic operation after collecting data on said object projected with radiation as a reconstruction arithmetic operation for a tomogram using two coordinates that are shifted from said temporary coordinates by a predetermined amount to the two sides with the temporary coordinates in between as the coordinates of the projected rotation axis together with a reconstruction arithmetic operation for a tomogram using the temporary coordinates; and said screen display means for changing the rotation axis coordinates displays these three tomograms together with the coordinates of the projected rotation axis that are used for the respective arithmetic operations.

4 . The radiation CT apparatus according to claim 3 , characterized in that it is possible to change the settings for the amount of shift from said temporary coordinates of projection for the two coordinates that are shifted from the temporary coordinates to two sides with the temporary coordinates in between.

5 . The radiation CT apparatus according to claim 1 , characterized by further comprising an image evaluation arithmetic operation means for finding an evaluation value concerning the definition of each image through an arithmetic operation in terms of a tomogram gained through a reconstruction arithmetic operation using said temporary coordinates, a tomogram gained through a reconstruction arithmetic operation using two coordinates that are shift from the temporary coordinates to the two sides by a predetermined amount with the temporary coordinates in between, and a tomogram gained through a reconstruction arithmetic operation according to an instruction by said instruction input means, and said screen display means for changing the rotation axis coordinates displays the evaluation values gained through arithmetic operations together with the respective tomograms.

6 . The radiation CT apparatus according to claim 1 , characterized in that: a tomogram constructed through a reconstruction arithmetic operation using said temporary coordinates and tomograms respectively constructed through a reconstruction arithmetic operation respectively using two projection coordinates that shift from the temporary coordinates to the two sides with the temporary coordinates in between are displayed on a display in such a state as to be aligned with the tomogram constructed through a reconstruction arithmetic operation using said temporary coordinates in the center; and said instruction input means is formed so as to give an instruction when either tomogram on the two sides is clicked, and at the same time, the direction of the shifting of the coordinates is set by clicking either tomogram, left or right, of said tomograms on the two sides, and the amounts of shifting of the coordinates are respectively set in accordance with the distances of the click points on said tomograms on the two sides from the center.

7 . The radiation CT apparatus according to claim 1 , characterized in that said temporary coordinates are any of the following coordinates (A) to (C):
(A) coordinates calculated by using projection data collected when a phantom for calibrating the position of the projected rotation axis is placed on said rotational table; (B) coordinates calculated through interpolation or extrapolation calculation from the projection coordinates in a positional relationship between said radiation source, the radiation detector, and the rotational table when an image of the object is taken using a number of coordinates that have been calculated using projection data collected and stored when a phantom for calibrating the position of the projected rotation axis is placed on said rotational table in each of the number of positional relationships between said radiation source, the radiation detector, and the rotational table; and (C) designed coordinates that have been set from the beginning.

8 . A radiation CT apparatus, comprising: a rotational table on which an object to be examined is placed, the rotational table being provided between a radiation source and a radiation detector, which are provided so as to face each other, so as to rotate around a rotation axis that is perpendicular to the direction of the radiation axis; and a reconstruction arithmetic operation means for constructing a tomogram of the object along a sliced surface that is perpendicular to said rotation axis through an arithmetic operation using data of the projected object with radiation collected by taking in the output of said radiation detector for each of the minute rotational angles gained when the rotational table is rotated while irradiating the object on the rotational table with radiation from said radiation source, characterized by further comprising:
a screen display means for changing the rotation axis coordinates which designates data on an object projected with radiation of which the tomogram is constructed through a reconstruction arithmetic operation, and

Assignees

• Shimadzu Corp

Inventors

• Keyaki Yasuyuki

Classifications

• G06T12/20

  Inverse problem, i.e. transformations from projection space into object space · CPC title

• G06T12/10 Primary

  Image preprocessing, e.g. calibration, positioning of sources or scatter correction · CPC title

• G01N23/046 Primary

  using tomography, e.g. computed tomography [CT] · CPC title

• G06T11/005 Primary

  Physics · mapped topic

• G06T2207/10081

  Computed x-ray tomography [CT] · CPC title