JP2018080961A - Calibrator of X-ray CT system - Google Patents
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- 239000010979 ruby Substances 0.000 claims abstract description 50
- 229910001750 ruby Inorganic materials 0.000 claims abstract description 50
- 238000012937 correction Methods 0.000 claims abstract description 12
- 238000000034 method Methods 0.000 claims abstract description 4
- 239000004925 Acrylic resin Substances 0.000 claims description 4
- 229920000178 Acrylic resin Polymers 0.000 claims description 4
- 238000005259 measurement Methods 0.000 abstract description 9
- 229910052790 beryllium Inorganic materials 0.000 description 3
- ATBAMAFKBVZNFJ-UHFFFAOYSA-N beryllium atom Chemical compound [Be] ATBAMAFKBVZNFJ-UHFFFAOYSA-N 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000013016 damping Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
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Abstract
Description
Ｘ線ＣＴ装置による内部形状評価の精度向上を目的として複数のルビー球からなる校正器に関するものである。 The present invention relates to a calibrator composed of a plurality of ruby balls for the purpose of improving the accuracy of internal shape evaluation by an X-ray CT apparatus.
産業用Ｘ線ＣＴ装置を計測に利用するため、欧州、主にドイツにおいて、三次元計測器メーカーによる三次元計測を目的としたＸ線ＣＴ装置が開発されている。
一方、日本において、Ｘ線ＣＴ装置を「ものづくり」に生かした取り組みの件数では、日本は世界一であるといわれているが、製品のクラックや内部欠陥の良／不良、可／否の判定を行う検査機としての用途が主流であり、寸法精度にかかわる三次元計測を目的とした使い方はまれである。
In order to use an industrial X-ray CT apparatus for measurement, an X-ray CT apparatus for three-dimensional measurement by a three-dimensional measuring instrument manufacturer has been developed in Europe, mainly in Germany.
On the other hand, in Japan, it is said that Japan is the world's best in the number of initiatives that make use of X-ray CT equipment for “manufacturing”. The main use is as an inspection machine, and it is rarely used for the purpose of three-dimensional measurement related to dimensional accuracy.
そのため、日本国内の企業、大学、公設試に導入済みのＸ線ＣＴ装置では、現在規格化が進んでいる計測関係において、Ｘ線ＣＴ装置による寸法計測が行えなくなる恐れがある。
ところで、従来技術としてＸ線ＣＴ装置の校正器として特許文献１，２が挙げられる。
特許文献1において、ベリリウム成型体と、該ベリリウム成型体を内包し、Ｘ線ＣＴ装置から得られる投影イメージにおいて前記ベリリウム成型体と異なるコントラストで示される外装体とを有することを特徴とするＸ線ＣＴ装置の校正及び評価用の標準ゲージが示されている。特許文献１においては、Ｘ線ＣＴ装置から得られる投影イメージから、試料の内部形状を含む形状寸法を精度良く校正することを目的とした標準ゲージでは、試料の形状等に対応して、成形された標準ゲージの確認が、三次元計測機により、適切に出来ない場合があることを課題とする。
For this reason, in an X-ray CT apparatus that has already been introduced to Japanese companies, universities, and public trials, there is a risk that dimension measurement by the X-ray CT apparatus cannot be performed in a measurement standard that is currently being standardized.
By the way, Patent Documents 1 and 2 are cited as calibrators of X-ray CT apparatuses as conventional techniques.
In Patent Document 1, an X-ray comprising: a beryllium molded body; and an exterior body including the beryllium molded body and having a contrast different from that of the beryllium molded body in a projection image obtained from an X-ray CT apparatus. A standard gauge for calibration and evaluation of CT apparatus is shown. In Patent Document 1, a standard gauge for the purpose of accurately calibrating a shape dimension including an internal shape of a sample from a projection image obtained from an X-ray CT apparatus is formed according to the shape of the sample. It is an issue that confirmation of standard gauges cannot be performed properly with a three-dimensional measuring machine.
そして、発明者達は、以前、特許文献２において、円筒体または円柱体の外円周に、異なる外径の球を複数個配置した構造の校正器を用いて、接触式三次元計測機により必要に応じていつでも、各部の寸法の実測が可能であるＸ線ＣＴ装置の校正器の提案を行った。 The inventors previously used a calibrator having a structure in which a plurality of spheres having different outer diameters are arranged on the outer circumference of a cylindrical body or a cylindrical body in Patent Document 2, using a contact-type three-dimensional measuring machine. We have proposed a calibrator for X-ray CT equipment that can measure the dimensions of each part whenever necessary.
今回、発明者達が特許文献２にて提案したＸ線ＣＴ装置の校正器を利用して、Ｘ線ＣＴ装置で断面画像を計測する上で問題になるビームハードニング（線質硬化）の軽減対策を行い校正器のルビー球径の誤差の低減を目指した。 This time, using the calibrator of the X-ray CT apparatus proposed by the inventors in Patent Document 2, beam hardening (wire quality hardening), which is a problem when measuring cross-sectional images with the X-ray CT apparatus, is reduced. Measures were taken to reduce the error of the ruby ball diameter of the calibrator.
Ｘ線の透過性の良好な材料であり、外径５８ｍｍ、厚さ５ｍｍの、アクリル樹脂製の円筒体２ａ、円筒体２ｂ、円筒体２ｃからなり、これ等の円筒体の下端面から、所定の間隔をあけて平行に配置される仮想２平面上の同一径上に各ルビー球の中心を置き、異なる外径（大球３、中球４、小球５）から採用された４個のルビー球を１セットとなし、２セットを用意して、上下２段に１セットずつ配置して構成されてなるＸ線ＣＴ校正器を用いて、Ｘ線ＣＴ装置のボリュームデータ(複数の断層画像情報)から求めた径の値と接触式三次元計測機による校正器のルビー球の径の計測値（真値）の各比を求め、各比の平均値の逆数を適切な係数と定義し、各比とこの適切な係数との積の（最大値―最小値）の値を誤差と定義し、本願発明による補正を行わない場合のルビー球の径の真値に対する径の誤差0.6910％が本願発明による補正によりルビー球の径の真置に対する径の誤差0.4568％より0.2342％以上改善するＸ線校正器による補正方法である。 It is a material with good X-ray permeability, and consists of a cylindrical body 2a, a cylindrical body 2b, and a cylindrical body 2c made of acrylic resin having an outer diameter of 58mm and a thickness of 5mm. The center of each ruby sphere is placed on the same diameter on two virtual planes that are arranged in parallel with an interval of 4 and adopted from four different outer diameters (large sphere 3, middle sphere 4, small sphere 5) One set of ruby spheres, two sets are prepared, and the X-ray CT calibrator is configured by arranging one set in the upper and lower two stages. Information) and the ratio of the measured value (true value) of the ruby ball diameter of the calibrator with the contact-type CMM, and the reciprocal of the average value of each ratio is defined as an appropriate coefficient. The value of the product of each ratio and this appropriate coefficient (maximum value – minimum value) is defined as the error, and is corrected according to the present invention. In the correction method by the X-ray calibrator, the error of 0.6910% with respect to the true value of the diameter of the ruby sphere when not performed is improved by 0.2342% or more from the error of the diameter with respect to the true position of the ruby sphere of 0.4568% by the correction of the present invention. is there.
Ｘ線ＣＴ装置のボリュームデータ(複数の断層画像情報)から求めた径の値と接触式三次元計測機による校正器のルビー球の径の計測値（真値）の各比を求め、各比の平均値の逆数を適切な係数と定義し、各比とこの適切な係数との積の（最大値―最小値）の値を誤差と定義し、本願発明による補正を行わない場合のルビー球の径の真値に対する径の誤差（0.6910％）が本発明によりルビー球の径の真置に対する径の誤差（0.4568％）より（0.2342％）以上改善できる。 Obtain each ratio of the diameter value obtained from the volume data (multiple tomographic image information) of the X-ray CT device and the measured value (true value) of the ruby sphere diameter of the calibrator by the contact type three-dimensional measuring machine. Ruby sphere when the inverse of the average value is defined as an appropriate coefficient, the value of the product of each ratio and this appropriate coefficient is defined as the error (maximum value-minimum value), and correction according to the present invention is not performed The diameter error (0.6910%) with respect to the true value of the diameter of the sphere can be improved by 0.2342% or more from the diameter error (0.4568%) with respect to the true position of the ruby ball.
つぎに、本発明に係るＸ線ＣＴ装置の校正器の実施例について図面を参照して具体的に説明する。 Next, an embodiment of the calibrator of the X-ray CT apparatus according to the present invention will be specifically described with reference to the drawings.
Ｘ線ＣＴ装置では、連続Ｘ線を使用しているため、Ｘ線がワークを透過する際、高いエネルギーをもつＸ線よりも、低いエネルギーをもつＸ線のほうが、より多く吸収される。そのため、Ｘ線のエネルギー分布は少しずつ高い方へシフトしていく。エネルギーが高いという状態を専門用語で硬い（ｈａｒｄ）と表現するため、ビームハードニング（線質硬化 ｂｅａｍｕ ｈａｒｄｅｎｉｎｇ）と呼ばれる。このビームハードニングはアーチファクトと呼ばれるノイズを発生させ断面画像の画質を低下させる。
これを補正するのがビームハードニング補正（ｂｅａｍ ｈａｒｄｅｎｉｇ ｃｏｒｒ-ｅｃｔｉｏｎ：以下、ＢＨＣ）である。後述するように、ＢＨＣでは、ワークと同一密度で、厚みの異なる補正用試料の投影データの輝度値から連続Ｘ線の減衰を近似曲線から単色Ｘ線の減衰を求めるものである。
Since the X-ray CT apparatus uses continuous X-rays, when the X-rays pass through the workpiece, X-rays having low energy are absorbed more than X-rays having high energy. For this reason, the energy distribution of X-rays gradually shifts higher. Since the state of high energy is expressed as hard in technical terms, it is called beam hardening (beam hardening). This beam hardening generates noise called artifacts and degrades the image quality of a cross-sectional image.
This is corrected by beam hardening correction (hereinafter referred to as BHC). As will be described later, in the BHC, the attenuation of continuous X-rays is obtained from the brightness value of the projection data of the correction sample having the same density as the workpiece and different thickness, and the attenuation of monochromatic X-rays is obtained from the approximate curve.
図５は、本発明に係る、Ｘ線ＣＴ装置の校正器１、の全体図であり、図５において、Ｘ線ＣＴ装置の校正器１は、左方から、それぞれ、校正器大１ａ、校正器中１ｂ、校正器小１ｃとし、正面上方からの斜視図を示す。これ等の校正器１ａ、校正器１ｂ、校正器１ｃは、Ｘ線の透過性の良好な材料であり、外径５８ｍｍ、厚さ５ｍｍの、アクリル樹脂製の円筒体２（第１の円筒体２ａ、第２の円筒体２ｂ、第３の円筒体２ｃ）からなり、これ等の円筒体２の下端面から、所定の間隔をあけて平行に配置される仮想２平面上で、かつ、それぞれ、同一径の円周上に各ルビー球（３，４，５）の中心を置き、異なる外径のルビー球（大球３、中球４、小球５）のルビー球から採用された４個のルビー球を１セットとなし、２セットのルビー球を用意して、上下２段に１セットずつルビー球を配置して構成されてなるＸ線ＣＴ校正器１ａ，１ｂ，１ｃである。 FIG. 5 is an overall view of the calibrator 1 of the X-ray CT apparatus according to the present invention. In FIG. 5, the calibrator 1 of the X-ray CT apparatus is calibrated from the left, the calibrator size 1a and the calibration, respectively. A perspective view from above the front is shown with the inside 1b and the small calibrator 1c. These calibrator 1a, calibrator 1b, and calibrator 1c are materials having good X-ray transmission, and are made of acrylic resin cylinder 2 (first cylinder) having an outer diameter of 58 mm and a thickness of 5 mm. 2a, the second cylindrical body 2b, and the third cylindrical body 2c) on the virtual two planes arranged in parallel with a predetermined distance from the lower end surface of these cylindrical bodies 2, and respectively The center of each ruby ball (3, 4, 5) is placed on the circumference of the same diameter, and is adopted from the ruby balls of different outer diameters (large ball 3, medium ball 4, small ball 5) 4 The X-ray CT calibrators 1a, 1b, and 1c are configured by forming one set of ruby spheres and preparing two sets of ruby spheres and arranging one set of ruby spheres on the upper and lower stages.
即ち、一方の異なる外径（大球３、中球４、小球５）から採用された４個のルビー球の１セットを、円筒体の下端面より所定の高さ寸法に位置する同一仮想平面上で、かつ、それぞれ、同一径の円周上に各ルビー球の中心を配置すると共に、該円筒体の外側壁面から所定寸法の位置に前記各ルビー球の中心を接着し得るように、各球の直径と同じ直径のボールエンドミルにより座面加工を施して、前記一方の４個のルビー球の１セットを固着形成し、更に、前記一方の４個のルビー球の１セットの位置より上方に位置し、且つ、前記仮想平面に平行な他の仮想平面上に他方の異なる外径（大球３、中球４、小球５）から採用された４個のルビー球の中心を配置すると共に、該円筒体の外側壁面から所定寸法の位置に各ルビー球の中心を接着し得るように、各球の直径と同じ直径のボールエンドミルにより座面加工を施して、他方の４個のルビー球の１セットを固着形成してなるＸ線ＣＴ装置の校正器１である。 That is, one set of four ruby spheres adopted from one different outer diameter (large sphere 3, middle sphere 4, small sphere 5) is the same virtual position located at a predetermined height from the lower end surface of the cylindrical body. The center of each ruby sphere is arranged on a plane and on the circumference of the same diameter, respectively, and the center of each ruby sphere can be bonded to a position of a predetermined dimension from the outer wall surface of the cylindrical body. The bearing surface is processed by a ball end mill having the same diameter as each of the balls, and one set of the four ruby balls is fixedly formed. Further, from the position of the one set of the four ruby balls, The center of four ruby spheres adopted from the other different outer diameters (large sphere 3, medium sphere 4, small sphere 5) is arranged on another virtual plane parallel to the virtual plane. At the same time, the center of each ruby ball is bonded to the position of a predetermined dimension from the outer wall surface of the cylindrical body. So that the, is subjected to the seating surface processing by a ball end mill of the same diameter as the diameter of each sphere is a calibrator 1 of the other four ruby sphere fixing formed X-ray CT apparatus comprising a set of.
ルビー球（３，４，５）は、前記の円筒体２よりもＸ線透過性が低く、真球加工が容易な、例えば、ルビーやジルコニア等がよく、本実施例では、ルビー球を採用した。そして、ルビー球は、大球３の直径は６mm、中球４の直径は3.5 mm、小球５の直径は2.5 mmとした。
Ｘ線ＣＴ装置の校正器である。１セット４個のルビー球を２段にセットした理由は、上下の対角線上の計測データも参照したいためである。
Ruby spheres (3,4,5) have lower X-ray transparency than the cylindrical body 2 and are easy to process true spheres, for example, rubies and zirconia are good. In this embodiment, rubies are used. did. In the ruby sphere, the diameter of the large sphere 3 is 6 mm, the diameter of the middle sphere 4 is 3.5 mm, and the diameter of the small sphere 5 is 2.5 mm.
It is a calibrator of an X-ray CT apparatus. The reason why one set of four ruby balls is set in two stages is that it is desired to refer to the measurement data on the upper and lower diagonal lines.
今回の実施例１では、Ｘ線ＣＴ装置の校正器（１ａ，１ｂ，１ｃ）の代表図面の斜視図を図１０に、代表図面の上面図を図１１に、代表図面の正面図を図１２に、代表図面の右側面図を図１３に示す。校正器１（１ａ，１ｂ，１ｃ）の円筒体２（２ａ，２ｂ，２ｃ）の外径を５８mmとし、厚さ５mmのアクリル樹脂製とした。円筒体２の中心軸に直角で、円筒体２の外周より２mm大きい半径の水平な円周上に球の中心位置を定め、計４個の球を９０度の間隔で配置した。前記したように、ルビー球において、大球３の直径は６mm、中球４の直径は3.5 mm、小球５の直径は2.5 mmであり、そして、そのＸ線ＣＴ装置によるＸ線透過の輝度値は図６の通りである。 In the first embodiment, a perspective view of a representative drawing of the calibrator (1a, 1b, 1c) of the X-ray CT apparatus is shown in FIG. 10, a top view of the representative drawing is shown in FIG. 11, and a front view of the representative drawing is shown in FIG. FIG. 13 is a right side view of the representative drawing. The cylindrical body 2 (2a, 2b, 2c) of the calibrator 1 (1a, 1b, 1c) was made of acrylic resin having an outer diameter of 58 mm and a thickness of 5 mm. The center position of the sphere was determined on a horizontal circumference having a radius of 2 mm larger than the outer periphery of the cylindrical body 2 and perpendicular to the central axis of the cylindrical body 2, and a total of four spheres were arranged at intervals of 90 degrees. As described above, in the ruby sphere, the diameter of the large sphere 3 is 6 mm, the diameter of the middle sphere 4 is 3.5 mm, the diameter of the small sphere 5 is 2.5 mm, and the brightness of X-ray transmission by the X-ray CT apparatus. The values are as shown in FIG.
図６に示すように、球径とＸ線吸収量は比例しないことから、ビームハードニングが発生していることが分かる。各校正器（１ａ，１ｂ，１ｃ）に使用しているルビー球（大球３、中球４、小球５）の球径の差を利用し、ＢＨＣを行った。 As shown in FIG. 6, since the spherical diameter and the X-ray absorption amount are not proportional, it can be seen that beam hardening occurs. BHC was performed using the difference in the diameter of the ruby balls (large sphere 3, medium sphere 4, small sphere 5) used in each calibrator (1a, 1b, 1c).
図１において、ＢＨＣの考え方を示す。ＢＨＣでは、同じ密度で、厚みの違う補正用試料の投影データの輝度値をもとに近似曲線を作成し、近似曲線から単色Ｘ線の同一密度のワークに厚みに対する減衰を求めるものである。
本事例では、校正器に使用されるルビー球（大球３、中球４、小球５）を利用し、投影データの輝度値から近似曲線を作成し、単色Ｘ線の減衰を求め補正を行った。近似曲線および単色Ｘ線の減衰を図８に示す。
FIG. 1 shows the concept of BHC. In the BHC, an approximate curve is created based on the brightness value of the projection data of the correction samples having the same density and different thicknesses, and attenuation with respect to the thickness is obtained from the approximate curve to a work having the same density of monochromatic X-rays.
In this example, using the ruby spheres (large sphere 3, medium sphere 4, and small sphere 5) used for the calibrator, an approximate curve is created from the brightness value of the projection data, and the attenuation of the monochromatic X-ray is obtained and corrected. went. The approximate curve and monochromatic X-ray attenuation are shown in FIG.
図７に示すように、１〜８まで番号を割り当てる。Ｘ線ＣＴ装置の校正器を構成するルビー球のボリュームデータから求めた径と、接触式三次元計測機によるＸ線ＣＴ装置の校正器のルビー球の計測結果（ここでは真値という。）と、を形状比較した。各ルビー球の真値に対する径の割合の校正前の結果を表１に、校正後の結果を表２にそれぞれ示す。ＢＨＣを行わない結果を図３に、ＢＨＣを行った結果を図４にそれぞれ示す。 As shown in FIG. 7, numbers 1 to 8 are assigned. The diameter obtained from the volume data of the ruby sphere constituting the calibrator of the X-ray CT apparatus, the measurement result of the ruby sphere of the calibrator of the X-ray CT apparatus by the contact type three-dimensional measuring instrument (herein referred to as a true value). The shapes were compared. The results before calibration of the ratio of the diameter to the true value of each ruby ball are shown in Table 1, and the results after calibration are shown in Table 2. FIG. 3 shows the result without BHC, and FIG. 4 shows the result with BHC.
Ｘ線ＣＴ装置については、図９のように検出器とＸ線源の焦点との距離ＳＤＤ（Source to detector Distance）ワークの中心とＸ線源の焦点との距離ＳＲＤ（Source to Rotation center Distance ）の比断面画像の倍率が決まるが、ＳＤＤ/ＳＲＤの位置決め精度は機械的誤差要因でありビームハードニングとは直接的な関係はない。
機械的誤差要因であるＳＤＤ/ＳＲＤの位置決め精度による誤差では、ルビー球の径は一律な縮小・拡大による補正が可能であるが、ビームハードニングではルビー球の径、ルビー球の同一平面上の並びにより、ルビー球おのおので誤差の大きさは異なる。
For the X-ray CT apparatus, as shown in FIG. 9, the distance between the center of the detector and the focus of the X-ray source SRD (Source to Rotation center Distance) between the center of the work and the focus of the X-ray source as shown in FIG. Although the magnification of the specific cross-sectional image is determined, the positioning accuracy of the SDD / SRD is a mechanical error factor and has no direct relationship with the beam hardening.
In the error due to the positioning accuracy of SDD / SRD, which is a mechanical error factor, the diameter of the ruby sphere can be corrected by uniform reduction / enlargement, but in beam hardening, the diameter of the ruby sphere is on the same plane as the ruby sphere. Moreover, the magnitude of the error is different for each ruby ball.
ボリュームデータ(複数の断層画像情報)から求めた径と接触式三次元計測機による校正器のルビー球の径の計測結果（真値）の各比を求め、各比の平均値の逆数を適切な係数と定義する。各比とこの適切な係数の積の最大値―最小値（減法の値）を誤差と定義する。ＢＨＣを行わない場合の誤差0.6910％がＢＨＣにより誤差0.4568％と0.2342％以上改善することが分かる。 Obtain each ratio of the diameter obtained from the volume data (multiple tomographic image information) and the measurement result (true value) of the diameter of the ruby sphere of the calibrator by the contact-type three-dimensional measuring machine, and appropriately calculate the reciprocal of the average value of each ratio Is defined as a simple coefficient. The maximum-minimum value (subtraction value) of the product of each ratio and this appropriate coefficient is defined as the error. It can be seen that the error of 0.6910% when BHC is not performed is improved by 0.2342% or more by 0.4HC% by BHC.
以上、本発明の実施例を説明したが、本発明の範囲は、これに限定されるものではなく、本発明の要旨を逸脱しない範囲において種々変更を加え得ることは勿論である。 The embodiments of the present invention have been described above, but the scope of the present invention is not limited to these embodiments, and various changes can be made without departing from the scope of the present invention.
本発明はＸ線ＣＴ装置を製造、販売する産業分野または、Ｘ線ＣＴ装置を使用する産業分野や医療分野で利用することが出来る The present invention can be used in an industrial field in which an X-ray CT apparatus is manufactured and sold, or in an industrial field or a medical field in which the X-ray CT apparatus is used.
１‥Ｘ線校正器、１ａ‥第１の校正器，１ａ‥第２の校正器，１ａ‥第３の校正器，
２‥校正器の円筒体、２a‥校正器の円筒体、２b‥校正器の円筒体、２c‥校正器の円筒体、
３‥ルビー球大、
４‥ルビー球中、
５‥ルビー球小、
DESCRIPTION OF SYMBOLS 1 ... X-ray calibrator, 1a ... 1st calibrator, 1a ... 2nd calibrator, 1a ... 3rd calibrator,
2 calibrator cylinder, 2a calibrator cylinder, 2b calibrator cylinder, 2c calibrator cylinder,
3 Ruby sphere,
4 ... in the ruby ball
5 Ruby ball,
Claims (1)
A calibrator for an X-ray CT apparatus comprising a cylindrical body made of acrylic resin, and a ruby ball on the same diameter on two virtual planes arranged in parallel with a predetermined interval from the lower end surface of the cylindrical body The four ruby balls adopted from different outer diameters (large sphere 3, medium sphere 4, small sphere 5) are made into one set, and two sets are provided, one set arranged in two upper and lower tiers. Using the X-ray CT calibrator configured as described above, the diameter value obtained from the volume data (multiple tomographic image information) of the X-ray CT apparatus and the diameter of the ruby sphere of the calibrator by the contact type three-dimensional measuring machine Calculate each ratio of the measured values (true values), define the reciprocal of the average value of each ratio as an appropriate coefficient, and calculate the product of each ratio and this appropriate coefficient (maximum value – minimum value) as the error. The error of the diameter relative to the true value of the ruby ball diameter when the BHC is not performed is Correction method according to X-ray calibrator, characterized in that it improved than the error of the diameter to.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2018063243A (en) * | 2016-10-13 | 2018-04-19 | 地方独立行政法人東京都立産業技術研究センター | Calibrator for ct scanner |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2018063243A (en) * | 2016-10-13 | 2018-04-19 | 地方独立行政法人東京都立産業技術研究センター | Calibrator for ct scanner |
| JP7038399B2 (en) | 2016-10-13 | 2022-03-18 | 地方独立行政法人東京都立産業技術研究センター | Calibrator for CT equipment |
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