JP2773358B2 - Bone mineral analyzer - Google Patents
Bone mineral analyzerInfo
- Publication number
- JP2773358B2 JP2773358B2 JP2050700A JP5070090A JP2773358B2 JP 2773358 B2 JP2773358 B2 JP 2773358B2 JP 2050700 A JP2050700 A JP 2050700A JP 5070090 A JP5070090 A JP 5070090A JP 2773358 B2 JP2773358 B2 JP 2773358B2
- Authority
- JP
- Japan
- Prior art keywords
- energy
- ray
- tube
- bone mineral
- living body
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 210000000988 bone and bone Anatomy 0.000 title claims description 27
- 229910052500 inorganic mineral Inorganic materials 0.000 title claims description 24
- 239000011707 mineral Substances 0.000 title claims description 24
- 238000009826 distribution Methods 0.000 claims description 17
- 230000005540 biological transmission Effects 0.000 claims description 8
- 238000005259 measurement Methods 0.000 description 8
- 238000010521 absorption reaction Methods 0.000 description 3
- 238000001228 spectrum Methods 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 2
- 210000004872 soft tissue Anatomy 0.000 description 2
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000000968 intestinal effect Effects 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 210000000056 organ Anatomy 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000008855 peristalsis Effects 0.000 description 1
Landscapes
- Analysing Materials By The Use Of Radiation (AREA)
- X-Ray Techniques (AREA)
- Apparatus For Radiation Diagnosis (AREA)
- Measuring And Recording Apparatus For Diagnosis (AREA)
Description
この発明は、生体の骨に含まれる塩を定量するための
骨塩定量装置に関する。The present invention relates to a bone mineral quantifying device for quantifying a salt contained in a bone of a living body.
【従来の技術】 骨塩定量装置として、従来より、連続Ｘ線をフィルタ
を通して単色化して生体に照射するようにしておき、Ｘ
線管の管電圧を変化させるとともにそれにともなってフ
ィルタをその管電圧に適したものに切り換え、その各々
で測定した透過Ｘ線強度から骨塩量を算出するという構
成のものが知られている。 また、連続Ｘ線を生体に照射し、生体を透過したＸ線
を計測する際に、ある範囲のエネルギー幅のＸ線だけを
測定して線吸収係数を求め骨塩量を算出するという構成
のものも知られている。2. Description of the Related Art Conventionally, as a bone mineral quantifying device, continuous X-rays are monochromatic through a filter and irradiated to a living body.
There is known a configuration in which the tube voltage of a tube is changed, the filter is switched to a filter suitable for the tube voltage, and the amount of bone mineral is calculated from the transmitted X-ray intensity measured at each tube. In addition, when a living body is irradiated with continuous X-rays and the X-rays transmitted through the living body are measured, only the X-rays having a certain range of energy width are measured to obtain a line absorption coefficient and calculate a bone mineral amount. Things are also known.
しかしながら、管電圧の切り換えに応じてフィルタを
切り換えるものでは、フィルタ切り換えに時間がかか
り、その切り換え中に生体内部で臓器や空気が移動して
しまうことが原因となって、骨塩量を精度高く求めるこ
とが難しいという問題がある。また、Ｘ線管電圧の各々
に応じて最適フィルタを決定する作業は面倒で、ある程
度の試行錯誤が必要な点も問題である。 また、連続Ｘ線を生体に照射し、その透過Ｘ線のある
エネルギー幅の範囲のものだけを測定するものでは、２
回の曝射で１つの骨塩量しか求めていないため、精度の
高い骨塩量を求めることができないという問題がある。 この発明は、フィルタ切り換えの問題を解消し、精度
の高い骨塩量を求めることができる、骨塩定量装置を提
供することを目的とする。However, when the filter is switched according to the switching of the tube voltage, it takes a long time to switch the filter, and the organs and air move inside the living body during the switching. There is a problem that it is difficult to find. Further, it is troublesome to determine an optimum filter according to each of the X-ray tube voltages, and there is a problem that a certain amount of trial and error is required. In the case of irradiating a living body with continuous X-rays and measuring only those within a certain energy range of the transmitted X-rays, 2
Since only one amount of bone mineral is obtained by one irradiation, there is a problem that a highly accurate amount of bone mineral cannot be obtained. SUMMARY OF THE INVENTION It is an object of the present invention to provide a bone mineral quantifying device capable of solving the problem of filter switching and obtaining a highly accurate bone mineral amount.
上記の目的を達成するため、この発明による骨塩定量
装置においては、Ｘ線管と、生体透過前及び透過後のＸ
線を検出したエネルギー分布を測定する手段と、Ｘ線管
の管電圧を複数のものに切り換える手段と、この管電圧
切り換えに応じて管電流と上記エネルギー分布測定手段
におけるしきい値とを切り換える手段と、しきい値で定
まるエネルギー範囲を複数の狭い幅のエネルギーバンド
に分けたときの各エネルギーバンドの生体透過前及び透
過後Ｘ線データの組合せを複数用いて骨塩量を算出する
手段とが備えられる。To achieve the above object, the bone mineral quantifying apparatus according to the present invention comprises an X-ray tube, and
Means for measuring the energy distribution of the detected X-ray, means for switching the tube voltage of the X-ray tube to a plurality of means, and means for switching the tube current and the threshold value in the energy distribution measuring means in response to the tube voltage switching And means for calculating the amount of bone mineral using a plurality of combinations of X-ray data before and after transmission through a living body of each energy band when the energy range determined by the threshold is divided into a plurality of narrow energy bands. Be provided.
測定されるＸ線のエネルギー範囲を複数の狭い幅のエ
ネルギーバンドに分けてそれらのＸ線強度データを測定
することにより、単色Ｘ線を用いて得たときと同様の測
定データが得られる。そして、これら複数のエネルギー
バンドのデータが、１回のＸ線曝射中にＸ線管の管電圧
を切る換えることにより得られる。３つのエネルギーバ
ンドについての生体透過前後のデータから骨塩量の算出
がなされる。３つのエネルギーバンドについての生体透
過前後のデータは、何組も取り出すことができるので、
骨塩量の算出結果も複数得られ、それらの平均値を求め
ることなどにより、精度の高い骨塩量を求めることがで
きる。By dividing the energy range of the measured X-rays into a plurality of narrow energy bands and measuring the X-ray intensity data, the same measurement data as obtained by using monochromatic X-rays can be obtained. The data of the plurality of energy bands is obtained by switching the tube voltage of the X-ray tube during one X-ray irradiation. The amount of bone mineral is calculated from the data before and after penetration into the living body for the three energy bands. Since any number of sets of data before and after permeation through the living body for the three energy bands can be extracted,
A plurality of calculation results of the amount of bone mineral can be obtained, and a highly accurate amount of bone mineral can be obtained by calculating an average value of the results.
つぎにこの発明の一実施例について図面を参照しなが
ら説明する。第１図において、Ｘ線管１から発生したＸ
線は、コリメータ２で整形され生体３に照射されるとと
もに基準Ｘ線検出器４に入射して検出される。この基準
Ｘ線検出器４の出力は基準エネルギー分布測定測８に送
られてエネルギー分析される。他方、生体３を透過した
Ｘ線はコリメータ２で整形された後、透過Ｘ線検出器５
に入射し、その出力が透過後エネルギー分布測定器９に
送られてエネルギー分析される。 この生体３を透過した後のＸ線エネルギー分布は、検
出器５の特性に合わせて測定される。つまりたとえばNa
Iの場合透過Ｘ線の最大エネルギーからＩのＫ吸収端の
エネルギー（28KeV）の範囲が波高分析しきい値設定装
置10によって設定され、その範囲で測定される。また、
エネルギー幅設定・組合せ設定装置11は、その範囲を単
色Ｘ線と見なせる程度に狭い複数のエネルギー幅なバン
ドに分け、その各エネルギーバンドでの生体３の透過前
と透過後のＸ線強度についての測定を基準エネルギー分
布測定器８及び透過後エネルギー分布測定器９に行わせ
る。 管電圧設定装置６と管電流設定装置７とにより、Ｘ線
管１の管電圧と管電流とが切り換えられ、それに連動し
て波高分析しきい値設定装置10におけるしきい値設定条
件が変更される。管電圧が低いと生体３内で吸収される
ことが多くなるので、管電圧が低いとき管電流を多く
し、管電圧が高いとき少なくして、生体３を透過したＸ
線のフォトン数をおよそ同程度にして統計的誤差を小さ
くするようにしている。そのため、管電圧V1,V2,V3（V1
＞V2＞V3）としてＸ線等からＸ線を発生した場合の、生
体３を透過する前のエネルギースペクトルは第２図のよ
うになる。管電圧・管電流の切り換えシーケンスはたと
えば第３図のようにし、管電圧が高いとき管電流を少な
くしている。このときの管電圧の切り換えは1/100秒程
度の短時間で行うことができる。 第３図のようにして管電圧をV1,V2,V3に切り換え（同
時に管電流を切り換え）てＸ線を照射した場合、生体３
を透過したＸ線のエネルギー分布は第４図A,B,Cのよう
になる。これらエネルギー分布のそれぞれについて、最
大エネルギーE1,E2,E3から検出器４、５の特性に応じた
エネルギー範囲（上記の例では28KeV）を、単色Ｘ線と
見なせるエネルギー幅（たとえば5KeV）を持つ複数のエ
ネルギーバンドE1〜E24に分割する。 このとき各エネルギーバンドEi（ｉ＝１、２、…、2
4）について測定れた透過Ｘ線強度をIEi、透過前のＸ線
強度をIoEiとすると、 の関係が成り立つ。ここで はそれぞれ軟組織１、２、骨の質量減衰係数をし召し、
Ms1,Ms2,Mbmは軟組織１、２、骨の単位面積当りの質量
数（g/cm2）を表す。この式からｉを３つ選んで方程式
を３つたてれば、３つの未知数Ms1,Ms2,Mbmを求めるこ
とができる。３つのｉに対するデータIEi,IoEiの組合せ
は、エネルギー幅設定・組合せ設定装置11により設定さ
れ、それらのデータが骨塩量計算装置12に送られて、上
記の連立方程式が解かれ、骨塩量（Mbm）の算出がなさ
れる。この場合、３つのｉの組合せを複数とすることに
より、連立方程式自体を複数とし、その解を複数求めて
たとえば平均値を得るなどにより骨塩量の算出精度を向
上させることができる。 こうして算出された骨塩量は、ある画素についてのも
のであるから、画像表示用制御装置13に送られてその画
素に対応して記憶される。つぎにスキャン装置15により
Ｘ線管１、コリメータ２、検出器４、５のＸ線発生・検
出系を生体３に対してX,Y方向に移動させてスキャン
し、同様に第３図のように管電圧・管電流を切り換えて
各エネルギーバンドでの測定を行い、その位置での画素
についての骨塩量を求めてその画素に対応して記憶す
る。これを繰り返すことにより骨塩量の２次元分布が得
られ、これが画像表示装置14によって表示される。 なお、上記の実施例では、透過Ｘ線検出器５とは別に
基準Ｘ線検出器４を用いて生体３に透過する前のＸ線を
検出しているが、生体３がＸ線ビーム上にない状態でＸ
線検出器５及びエネルギー分布測定器９を用いて測定す
るようにすれば、Ｘ線検出器４及び基準エネルギー分布
測定器８を省略することもできる。また、第３図では管
電圧を小さい方から大きい方に変化させた後、スキャン
して再び小さい方から大きい方へと変化させることを繰
り返しているが、大きい方から小さい方へと切り換えた
り、あるいはつねに大きな方から小さい方または小さい
方から大きい方へと一方向に切り換えるのでなく、大き
い方から小さい方への切り換えと小さい方から大きい方
への切り換えとを交互に行うようにしたり、その順序は
任意に選ぶことが可能である。また、管電圧、管電流及
びしきい値の変化は、１サイクルの間では連続的にする
こともできる。Next, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, X-rays generated from an X-ray tube 1 are shown.
The rays are shaped by the collimator 2 and irradiated onto the living body 3, and are incident on the reference X-ray detector 4 and detected. The output of the reference X-ray detector 4 is sent to the reference energy distribution measurement 8 for energy analysis. On the other hand, the X-ray transmitted through the living body 3 is shaped by the collimator 2 and then transmitted through the transmitted X-ray detector 5.
And its output is transmitted to an energy distribution measuring device 9 after transmission to be analyzed for energy. The X-ray energy distribution after passing through the living body 3 is measured according to the characteristics of the detector 5. So, for example, Na
In the case of I, the range from the maximum energy of the transmitted X-ray to the energy at the K absorption edge of I (28 KeV) is set by the peak value analysis threshold value setting device 10 and measured in that range. Also,
The energy width setting / combination setting device 11 divides the range into a plurality of energy width bands narrow enough to be regarded as monochromatic X-rays, and determines the X-ray intensity before and after transmission of the living body 3 in each energy band. The measurement is performed by the reference energy distribution measuring device 8 and the transmitted energy distribution measuring device 9. The tube voltage and the tube current of the X-ray tube 1 are switched by the tube voltage setting device 6 and the tube current setting device 7, and the threshold setting condition in the peak value analysis threshold setting device 10 is changed in conjunction with the switching. You. When the tube voltage is low, the amount of absorption in the living body 3 increases. Therefore, the tube current is increased when the tube voltage is low, and reduced when the tube voltage is high.
The number of photons in the line is about the same to reduce the statistical error. Therefore, the tube voltages V1, V2, V3 (V1
FIG. 2 shows an energy spectrum before transmitting through the living body 3 when X-rays are generated from X-rays or the like as>V2> V3). The switching sequence of the tube voltage and the tube current is, for example, as shown in FIG. 3, and when the tube voltage is high, the tube current is reduced. Switching of the tube voltage at this time can be performed in a short time of about 1/100 second. When the tube voltage is switched to V1, V2, V3 (and the tube current is switched at the same time) as shown in FIG.
The energy distribution of the X-ray transmitted through is shown in FIGS. 4A, 4B, and 4C. For each of these energy distributions, an energy range (28 KeV in the above example) corresponding to the characteristics of the detectors 4 and 5 from the maximum energies E1, E2 and E3 is set to a plurality of energy widths (for example, 5 KeV) that can be regarded as monochromatic X-rays. Energy bands E1 to E24. At this time, each energy band Ei (i = 1, 2,..., 2
If the transmitted X-ray intensity measured in 4) is I Ei and the X-ray intensity before transmission is Io Ei , Holds. here Is the mass attenuation coefficient of soft tissue 1, 2 and bone, respectively.
M s1 , M s2 , and M bm represent mass numbers (g / cm 2 ) per unit area of soft tissue 1, 2, and bone. If three i are selected from this equation and three equations are obtained, three unknowns M s1 , M s2 , and M bm can be obtained. The combination of the data I Ei and Io Ei for the three i is set by the energy width setting / combination setting device 11, and the data is sent to the bone mineral density calculation device 12, where the above simultaneous equations are solved, The amount of salt (M bm ) is calculated. In this case, by using a plurality of combinations of three i, a plurality of simultaneous equations can be obtained, and a plurality of solutions thereof can be obtained, for example, an average value can be obtained, thereby improving the accuracy of calculating the amount of bone mineral. Since the bone mineral amount calculated in this way is for a certain pixel, it is sent to the image display control device 13 and stored corresponding to that pixel. Next, the X-ray tube 1, the collimator 2, and the X-ray generation / detection system of the detectors 4 and 5 are moved in the X and Y directions with respect to the living body 3 by the scanning device 15 and scanned, as shown in FIG. Then, the tube voltage and tube current are switched to perform measurement in each energy band, and the amount of bone mineral for the pixel at that position is obtained and stored in correspondence with the pixel. By repeating this, a two-dimensional distribution of the amount of bone mineral is obtained, and this is displayed by the image display device 14. In the above embodiment, X-rays before transmission through the living body 3 are detected using the reference X-ray detector 4 separately from the transmission X-ray detector 5, but the living body 3 is detected on the X-ray beam. X without
If the measurement is performed using the ray detector 5 and the energy distribution measuring device 9, the X-ray detector 4 and the reference energy distribution measuring device 8 can be omitted. In addition, in FIG. 3, after changing the tube voltage from the smaller one to the larger one, scanning is repeated to change the tube voltage again from the smaller one to the larger one. Alternatively, instead of always switching in one direction from the larger to the smaller or from the smaller to the larger, the switching from the larger to the smaller and the switching from the smaller to the larger are performed alternately. Can be arbitrarily selected. Further, changes in the tube voltage, the tube current, and the threshold value can be made continuous during one cycle.
この発明の骨塩定量装置によれば、フィルタの切り換
えを行う必要がないため、フィルタ切り換えのための時
間と労力がかからず、精度の高い骨塩測定が可能とな
る。すなわち、管電圧は非常に高速に切り換えることが
できるため、異なるエネルギーバンドについてのデータ
を、腸のぜん動運動などに影響されずに厳密に同一部位
に関して測定することができるので、骨塩量計測の精度
が向上する。また検出器自体の特性を考慮してエネルギ
ー分布測定のしきい値を定めることができるので、検出
器による測定誤差が少なくなり、この点でも精度が向上
する。さらに、１回のＸ線照射でデータの組合せを複数
求めることができるので、複数の骨塩量算出ができ、そ
れらの平均値などを求めることにより、精度を向上させ
ることができる。According to the bone mineral quantifying device of the present invention, since there is no need to switch the filter, time and labor for switching the filter are not required, and highly accurate bone mineral measurement can be performed. In other words, since the tube voltage can be switched at a very high speed, data on different energy bands can be measured strictly at the same site without being affected by intestinal peristalsis and the like. The accuracy is improved. Further, since the threshold value of the energy distribution measurement can be determined in consideration of the characteristics of the detector itself, the measurement error by the detector is reduced, and the accuracy is improved in this respect as well. Further, since a plurality of data combinations can be obtained by one X-ray irradiation, a plurality of bone mineral amounts can be calculated, and the accuracy can be improved by obtaining an average value thereof.
第１図はこの発明の一実施例のブロック図、第２図は生
体透過前のＸ線エネルギースペクトルを示すグラフ、第
３図は管電圧・管電流の切り換えシーケンスを示すタイ
ムチャート、第４図A,B,Cは透過Ｘ線エネルギースペク
トル及び各エネルギーバンドを示すグラフである。 １……Ｘ線管、２……コリメータ、３……生体、４……
基準Ｘ線検出器、５……透過Ｘ線検出器、６……管電圧
設定装置、７……管電流設定装置、８……基準エネルギ
ー分布測定器、９……透過後エネルギー分布測定器、10
……波高分析しきい値設定装置、11……エネルギー幅設
定・組合せ設定装置、12……骨塩量計算装置、13……画
像表示用制御装置、14……画像表示装置、15……スキャ
ン制御装置。FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a graph showing an X-ray energy spectrum before passing through a living body, FIG. 3 is a time chart showing a switching sequence of tube voltage and tube current, and FIG. A, B and C are graphs showing a transmission X-ray energy spectrum and each energy band. 1 ... X-ray tube, 2 ... collimator, 3 ... living body, 4 ...
Reference X-ray detector, 5: transmitted X-ray detector, 6: tube voltage setting device, 7: tube current setting device, 8: reference energy distribution measuring device, 9: post-transmission energy distribution measuring device, Ten
…… Crest height analysis threshold value setting device, 11 …… Energy width setting / combination setting device, 12 …… Bone mineral density calculation device, 13 …… Image display control device, 14 …… Image display device, 15 …… Scan Control device.
フロントページの続き (56)参考文献 特開 昭63−115540（ＪＰ，Ａ) 特開 昭58−41531（ＪＰ，Ａ) 実開 昭61−193364（ＪＰ，Ｕ) (58)調査した分野(Int.Cl.6，ＤＢ名) A61B 6/00 - 6/03Continuation of the front page (56) References JP-A-63-115540 (JP, A) JP-A-58-41531 (JP, A) Japanese Utility Model Showa 61-193364 (JP, U) (58) Fields investigated (Int) .Cl. 6 , DB name) A61B 6/ 00-6/03
Claims (1)
検出してエネルギー分布を測定する手段と、Ｘ線管の管
電圧を複数のものに切り換える手段と、この管電圧切り
換えに応じて管電流と上記エネルギー分布測定手段にお
けるしきい値とを切り換える手段と、しきい値で定まる
エネルギー範囲を複数の狭い幅のエネルギーバンドに分
けたときの各エネルギーバンドでの生体透過前及び透過
後のＸ線強度データの組合せを複数用いて骨塩量を算出
する手段とを備えることを特徴とする骨塩定量装置。1. An X-ray tube, means for detecting X-rays before and after passing through a living body and measuring an energy distribution, means for switching a tube voltage of the X-ray tube to a plurality of tubes, and switching the tube voltage Means for switching between the tube current and the threshold value in the energy distribution measuring means in accordance with the above, and before passing through the living body in each energy band when the energy range determined by the threshold value is divided into a plurality of narrow width energy bands. Means for calculating the amount of bone mineral using a plurality of combinations of X-ray intensity data after transmission.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2050700A JP2773358B2 (en) | 1990-02-28 | 1990-02-28 | Bone mineral analyzer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2050700A JP2773358B2 (en) | 1990-02-28 | 1990-02-28 | Bone mineral analyzer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03251234A JPH03251234A (en) | 1991-11-08 |
| JP2773358B2 true JP2773358B2 (en) | 1998-07-09 |
Family
ID=12866178
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2050700A Expired - Lifetime JP2773358B2 (en) | 1990-02-28 | 1990-02-28 | Bone mineral analyzer |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2773358B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011093058A1 (en) * | 2010-01-27 | 2011-08-04 | Canon Kabushiki Kaisha | Radiation imaging apparatus, and control method and program of the apparatus |
| JP2015091394A (en) * | 2015-01-14 | 2015-05-14 | キヤノン株式会社 | Radiation imaging device, control method thereof and program |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4728116B2 (en) * | 2005-12-15 | 2011-07-20 | 日本電信電話株式会社 | X-ray absorption spectroscopy apparatus and method |
| JP5582514B2 (en) * | 2008-02-29 | 2014-09-03 | ジーイー・メディカル・システムズ・グローバル・テクノロジー・カンパニー・エルエルシー | X-ray CT system |
-
1990
- 1990-02-28 JP JP2050700A patent/JP2773358B2/en not_active Expired - Lifetime
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011093058A1 (en) * | 2010-01-27 | 2011-08-04 | Canon Kabushiki Kaisha | Radiation imaging apparatus, and control method and program of the apparatus |
| JP2011152280A (en) * | 2010-01-27 | 2011-08-11 | Canon Inc | Radiographic apparatus, and control method and program thereof |
| US9492134B2 (en) | 2010-01-27 | 2016-11-15 | Canon Kabushiki Kaisha | Radiation imaging apparatus, and control method and program of the apparatus |
| JP2015091394A (en) * | 2015-01-14 | 2015-05-14 | キヤノン株式会社 | Radiation imaging device, control method thereof and program |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03251234A (en) | 1991-11-08 |
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