JPH07327971A - Space resolution evaluating means for x-ray ct apparatus - Google Patents

Abstract

PURPOSE:To enable evaluation as to whether or not there is performance useful for discovering the malignant neoplasm of a good size after lapse of an opera tion in the case of removal whether or not there is performance useful for discovery of the kind of the tumor even if the kind of the tumor (density of the tumor) varies. CONSTITUTION:Plural pieces of spherical samples 1 varied stepwise in CT values by the prescribed common magnitude are arranged in order of the magnitude of the CT values in a hollow state in liquid having a low coefft. of X-ray absorption.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spatial resolution evaluation instrument for evaluating the spatial resolution of an X-ray CT apparatus.

[0002]

2. Description of the Related Art An X-ray CT apparatus performance evaluation instrument (phantom) checks whether a certain material, for example, Teflon or polyethylene, shows a CT value of the material on an actually scanned image.

In the CT scanner, the F. O. V (image constituting area) is divided into a matrix, and each element (pixel) constituting the matrix is filled with a color on a gray scale according to a CT value to reconstruct the image.

Here, the intensity of X-rays that have passed through the subject is measured by a detector and processed by a computer to obtain CT values, water = 0, air = −1000, and also Teflon. It is set to a specific value.

The performance evaluation instrument is a scanner whose CT value is adjusted so that the CT value of water becomes 0. For example, when scanning Teflon, it is confirmed that the CT value is the specific value of Teflon on the image. Used to confirm.

3A and 3B are views showing a conventional performance evaluation instrument of this type. FIG. 3A is a side view and FIG. 3B is a front view. In FIG. 3, a Teflon performance evaluation instrument 33, a polyethylene performance evaluation instrument 34, etc. are inserted into the hole 32 of the instrument body 31 for use. Reference numeral 31a is a mounting hole provided in the instrument body 31 for attaching the instrument to the X-ray CT apparatus side. The illustrated performance evaluation tool has a diameter of 50 mm,
It was useful in assessing the general performance of CT scanners.

[0007]

In recent years, early detection of malignant neoplasms such as cancer has been demanded, but malignant neoplasms gradually grow into large tumors and eventually become unresectable. Generally, it is said that a malignant neoplasm can be removed in a spherical 5 mm state and the postoperative course is good. Also, the density (X-ray absorption coefficient) varies depending on the type of tumor.

[0008] With the conventional performance evaluation instrument, it is evaluated whether or not it has useful performance for finding a malignant neoplasm having a good size after surgery after removal, and the type of tumor (tumor density = X
Even if the linear absorption coefficient) is different, there is a problem that it is not possible to evaluate whether or not there is a useful performance for the discovery.

The object of the present invention is to evaluate whether or not there is a useful performance for finding a malignant neoplasm of good size after surgery after removal, and to find it even if the tumor type is different. An object of the present invention is to provide a spatial resolution evaluation instrument for an X-ray CT apparatus capable of evaluating whether or not it has various performances.

[0010]

The above object is to provide a plurality of spherical samples having a predetermined common size in a hollow state in a liquid having a low X-ray absorption coefficient and having stepwise different CT values. This is achieved by arranging the CT values in order of magnitude.

[0011]

By using the spherical sample of a predetermined size, it is possible to evaluate whether or not it has a useful performance for finding a malignant neoplasm of a size (predetermined size) which has a good postoperative course when removed.
By arranging multiple spherical samples with a common size and different CT values (density), it is useful for discovering different tumor types (tumor density = X-ray absorption coefficient) It is possible to evaluate whether there is performance. Stages in the growth process of malignant neoplasms (early stage, middle stage, end stage, etc.) by arranging multiple spherical samples with a common size and different CT values in order It is possible to evaluate whether or not there is a useful performance for the judgment of.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a spatial resolution evaluation instrument of an X-ray CT apparatus according to the present invention, in which (a) is a side sectional view,
(B) is the figure which looked at the AA line cross section in (a) figure from the arrow direction.

Diameter 5 mm made of different materials
Holding plates 2 and 3 made of acrylic material
Hold it between. On the mutually opposing surface sides of the holding plates 2 and 3,
The conical holes 4 for positioning and supporting the spherical samples 1 are processed at the same positions, and the conical holes 4 of the holding plate 3 are formed.
The countersunk side of the machined surface of the machine is a countersunk screw 8
Has been applied.

The plate 5 and the plate 7 are joined by three rods 6, and the holding plate 2 is fixed to the plate 5 with a screw. The spherical sample 1 is held and fixed by tightening the push screw 9 and pressing the holding plate 3 to the holding plate 2 side.

The assembly consisting of the spherical sample 1, the holding plates 2 and 3, the plates 5 and 7, the rod 6 and the screw 9 is located on the bottom side (right side in the drawing) inside the cylindrical case 12 having a bottom. It is fixed by inserting a screw 11 with the O-ring 10 interposed therebetween. The opening side (left side in the drawing) of the case 12 is covered with a lid 14 with a packing 13 sandwiched between the lid 14 and the screw 1
It is closed by fixing at 5.

After the above assembly is completed, the case 12 is filled with a liquid having a low X-ray absorption coefficient, here, water. The O-ring 10 and the packing 13 are provided to prevent water leakage. The water inlet is not shown.

Also, a mounting hole 14a provided in the lid 14
Is provided to attach the spatial resolution evaluation instrument 17 of the present invention to the X-ray CT apparatus side. As shown in FIG. 2, the instrument mount 22 provided on the bed 21 of the X-ray CT apparatus. The mounting portion 22a is inserted into the mounting portion 22a.
Fixed to. Reference numeral 23 in FIG. 2 indicates a scan plane (X-ray center line).

The materials of the spherical sample 1 are arranged in the order of acrylic, urethane, MC nylon, and polycarbonate from the top in FIG. 1, and the CT values (X-ray absorption coefficient) of each are 125, 115, 105, 95. It is designed to change gradually. The CT value of water around the spherical sample 1 is zero.

A gap 16 is provided between the holding plates 2 and 3 because the presence of the holding plates 2 and 3 does not affect the X-ray absorption coefficient of the spherical sample 1. Further, the reason why the conical hole 4 is used as the hole for supporting the spherical sample 1 is to make the positioning and supporting thereof simple and reliable. Further, the pressing screw 9 presses the holding plate 3 toward the holding plate 2 to hold and fix the spherical sample 1, and also prevents the holding plate 3 from falling.
It functions as a more secure fall prevention.

In the above embodiments, water was used as the liquid having a low X-ray absorption coefficient, but the liquid is not limited to this, and other colloids such as agar and jelly may be used.

[0021]

As described above, according to the present invention, it is evaluated whether or not there is a useful performance for the detection of a malignant neoplasm having a good size after surgery after removal, and the type of tumor ( Even if the tumor density = X-ray absorption coefficient) is different, it is possible to evaluate whether or not there is a useful performance for the discovery.
Moreover, there is also an effect that it is possible to evaluate whether or not there is a useful performance for judging the stage (early, middle, end, etc.) in the growth process of the malignant neoplasm.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a spatial resolution evaluation instrument of an X-ray CT apparatus according to the present invention.

FIG. 2 is an explanatory view of the attachment of the above instrument to an X-ray CT apparatus.

FIG. 3 is a diagram showing a performance evaluation tool of a conventional X-ray CT apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spherical sample 2 Holding plate 3 Holding plate 4 Conical hole 5 Plate 6 Rod 7 Plate 8 Counterbore 9 Push screw 10 O-ring 11 Screw 12 Case 13 Packing 14 Lid 14a Mounting hole 15 Screw 16 Gap 17 Inventive spatial resolution evaluation tool 21 Bed top plate 22 Instrument mount 22a Mount 23 Scan plane (X-ray center line)

Claims (1)

[Claims] 1. A plurality of spherical samples having a predetermined common size and having different CT values stepwise in a hollow state in a liquid having a low X-ray absorption coefficient are arranged in the order of the CT values. Spatial resolution evaluation tool for X-ray CT system.