JPH01136636A - X-ray ct apparatus - Google Patents

X-ray ct apparatus

Info

Publication number
JPH01136636A
JPH01136636A JP62295303A JP29530387A JPH01136636A JP H01136636 A JPH01136636 A JP H01136636A JP 62295303 A JP62295303 A JP 62295303A JP 29530387 A JP29530387 A JP 29530387A JP H01136636 A JPH01136636 A JP H01136636A
Authority
JP
Japan
Prior art keywords
scanner
measurement
rotation
data
measuring
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.)
Pending
Application number
JP62295303A
Other languages
Japanese (ja)
Inventor
Yasushi Miyazaki
靖 宮崎
Atsushi Moriya
淳 森谷
Isao Horiba
堀場　勇夫
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Healthcare Manufacturing Ltd
Original Assignee
Hitachi Medical Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Hitachi Medical Corp filed Critical Hitachi Medical Corp
Priority to JP62295303A priority Critical patent/JPH01136636A/en
Publication of JPH01136636A publication Critical patent/JPH01136636A/en
Pending legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
    • G01N23/04—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material
    • G01N23/046—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material using tomography, e.g. computed tomography [CT]
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2223/00—Investigating materials by wave or particle radiation
    • G01N2223/40—Imaging
    • G01N2223/419—Imaging computed tomograph

Landscapes

  • Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Pulmonology (AREA)
  • Radiology & Medical Imaging (AREA)
  • Theoretical Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)
  • Apparatus For Radiation Diagnosis (AREA)

Abstract

PURPOSE:To make the rotational speed of a scanner constant and to simplify and miniaturize the constitution of a scanner control system to enhance maintenance, in changing over a measuring mode, by setting the number of rotations of the scanner to more than one and shifting the phase of measurement at every rotation. CONSTITUTION:After the rotational speed of a scanner 28 becomes stable, an X-ray control block 22 operates an X-ray tube 27 to start the radiation of X-ray and a data measuring block 24 starts the measurement of data at a measuring interval DELTAt. During the measurement by the scanner, the rotational angular velocity omega of the scanner and the data measuring interval DELTAt are constant regardless of a measuring mode and have the relation of DELTAbeta=omega.DELTAt with respect to a measuring angle interval DELTAbeta. The output pulse of an angle-of-rotation detection circuit is inputted to the data measuring block 24 at the first time of rotation and projection data is measured once per two pulses. At the second of rotation, the scanner measurement is finished when projection data is measured 2pi/DELTAbeta times, and the rotation of the scanner 28 and the radiation of X-rays are respectively stopped. The measured projection data is successively transmitted to an image processing block 26 to be subjected to image reconstitution processing.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、スキャナ制御系システムの簡素化、小型化に
好適なＸ＆ＩＣＴ装置に関するものである。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an X&ICT device suitable for simplifying and downsizing a scanner control system.

〔従来の技術〕[Conventional technology]

ＸｍＣＴ装置は、数種類の計測モードを有し、各計測モ
ードは計測する投影データ数が異なるもので、そのモー
ドは撮影目的に応じて適宜選択される。The XmCT apparatus has several types of measurement modes, and each measurement mode differs in the number of projection data to be measured, and the mode is appropriately selected depending on the purpose of imaging.

従来装置においては、スキャナが１回転する間に計測す
る投影データ数を変えるため、投影データの計測間隔（
時間間隔）は一定で、スキャナの回転速度を変えること
により、回転方向の計測間隔（角度間隔）を変えていた
。In conventional devices, in order to change the number of projection data measured during one rotation of the scanner, the measurement interval of projection data (
The measurement interval (time interval) was constant, and the measurement interval (angular interval) in the rotation direction was changed by changing the rotation speed of the scanner.

〔発明が解決しようとする問題点〕[Problem that the invention seeks to solve]

従来装置においては、スキャナ回転速度を変えるため、
制御用モータの速度を計測モード毎に変える必要があり
、スキャナ制御系システムが複雑で大型化し、保守性も
劣るという問題点があった。In conventional equipment, in order to change the scanner rotation speed,
It is necessary to change the speed of the control motor for each measurement mode, resulting in a complicated and large scanner control system, as well as poor maintainability.

本発明の目的は、スキャナ制御系システムを簡素化、小
型化し、保守性も向上したＸ線ＣＴ装置を提供すること
にある。An object of the present invention is to provide an X-ray CT apparatus whose scanner control system is simplified and miniaturized, and whose maintainability is improved.

〔問題点を解決するための手段〕[Means for solving problems]

本発明は、計測モードをスキャナ回転速度で切換えるの
ではなく、スキャナを一定角速度ωで複数回回転させ、
各回転毎のデータ取込の位相をずらせて投影データを計
測することにより切換えるものである。The present invention does not switch the measurement mode depending on the scanner rotation speed, but instead rotates the scanner multiple times at a constant angular velocity ω,
Switching is performed by measuring projection data while shifting the phase of data acquisition for each rotation.

例えば、Ｘ線源の初期位置をβＯ（ｒａｄ〕、データの
計測間隔をΔ直５ｅｃ）とし、２回転で投影データを計
測するものとする。この場合、まず１回転目ではＸ線源
が次式（１）に示した位置βにあるときに投影データを
計測する。For example, it is assumed that the initial position of the X-ray source is βO (rad), the data measurement interval is Δdirect 5ec, and the projection data is measured in two rotations. In this case, in the first rotation, projection data is measured when the X-ray source is at the position β shown in the following equation (1).

ｎ＝β０＋ω・ｎΔｔ　　・・（１） ただし、ｎ＝ｏ、１，２．　　・・ さらに、２回転目では計測間隔Δｔの１／２だけ計測の
位相をずらして計測する。その結果、回転方向の計測間
隔Δβの］−／２だけ位相がずれ、２回転目ではＸ線源
が次式（２）に示した位置βにあるときに投影データを
計測する。n=β0+ω・nΔt (1) However, n=o, 1, 2. ...Furthermore, in the second rotation, the measurement phase is shifted by 1/2 of the measurement interval Δt and the measurement is performed. As a result, the phase is shifted by ]−/2 of the measurement interval Δβ in the rotational direction, and in the second rotation, projection data is measured when the X-ray source is at the position β shown in the following equation (2).

β＝β０＋Δβ／２＋ω・ｎΔｔ　・・・・・（２）た
だし、ｎ＝ｏ、１．２・・ Δβ＝ω・Δを 以」二の２回転分の投影データは、スキャナ回転速度ω
／２．計測間隔Δｔにより計測した場合と同様にΔβ／
２の間隔で計測サンプル軸」二に並ぶ。β=β0+Δβ/2+ω・nΔt (2) However, n=o, 1.2... After Δβ=ω・Δ, the projection data for 2 rotations is the scanner rotation speed ω
/2. As in the case of measurement using the measurement interval Δt, Δβ/
Line up the measurement sample axes at intervals of 2.

これにより、計測モードの切換えは、スキャナの回転回
数を複数回にすることと、各回転毎の計測の位相をずら
すことにより可能であり、スキャナ回転速度は一定で切
換えられる。Thereby, the measurement mode can be switched by rotating the scanner a plurality of times and by shifting the measurement phase for each rotation, and the scanner rotation speed can be switched at a constant rate.

〔作用〕[Effect]

以上のように計測モードの切換えは、スキャナの回転回
数を複数回にし、かつ各回転毎の計測の位相をずらすこ
とにより可能となり、スキャナ回転速度は一定とし得、
スキャナ制御系システムの構成が簡素化、小型化され、
保守性も向」ニする。As described above, switching the measurement mode is possible by rotating the scanner multiple times and shifting the measurement phase for each rotation, and the scanner rotation speed can be kept constant.
The configuration of the scanner control system has been simplified and downsized,
Maintainability is also improved.

〔実施例〕〔Example〕

以下、図面を参照して本発明の詳細な説明する。第１図
は本発明によるＸ線ＣＴ装置の原理を説明するための図
で、投影データの計測タイミングと計測時のＸ線源Ｘの
位置との関係の一例を示したものである。第２図は本発
明によるＸ線ＣＴ装置の一実施例を示すブロック図であ
る。Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram for explaining the principle of the X-ray CT apparatus according to the present invention, and shows an example of the relationship between the measurement timing of projection data and the position of the X-ray source X at the time of measurement. FIG. 2 is a block diagram showing an embodiment of the X-ray CT apparatus according to the present invention.

本実施例では、最も短いスキャン時間Ｔｓ［ｓｅｃ］＝
３− の整数９倍、すなわちｎ−Ｔｓ（ｓｅｃ）　（ｎ＝１＋
　２＋３・・・）の計測モードが用意されており、その
うちのｎ　＝　２の場合について説明する。In this embodiment, the shortest scan time Ts [sec]=
3- integer 9 times, that is, n-Ts (sec) (n=1+
2+3...) measurement modes are available, of which the case where n = 2 will be explained.

まず、システム制御ブロック２１で計測モードを選択し
、スキャン・スタートを指示すると、スキャナ回転制御
ブロック２３はスキャナ２８の回転を開始させる。スキ
ャナ２８の回転速度が安定した後、Ｘ線制御ブロック２
２はＸ線管２７を作動してＸ線の曝射を開始し、データ
計測ブロック２４はデータ計測を計測間隔Δｔで開始す
る。スキャン計測中、このスキャナ回転角速度ω及びデ
ータ計測間隔Δｔは計測モードによらず一定であり、計
測の角度間隔Δβとは次式（３）の関係がある。First, when the system control block 21 selects a measurement mode and instructs to start scanning, the scanner rotation control block 23 causes the scanner 28 to start rotating. After the rotation speed of the scanner 28 has stabilized, the X-ray control block 2
2 operates the X-ray tube 27 to start emitting X-rays, and the data measurement block 24 starts data measurement at measurement intervals Δt. During scan measurement, the scanner rotational angular velocity ω and the data measurement interval Δt are constant regardless of the measurement mode, and the relationship with the measurement angular interval Δβ is expressed by the following equation (3).

Δβ＝ω・Δｔ　　　　・・（３） スキャナ回転制御ブロック２３は、回転角検出回路を備
えている。この回転角検出回路は、例えばゼブラスケー
ル（ゼブラ模様の白黒のパターンを円周」−に等間隔に
配置したもの）とフカ１−ダイオ−１−，フオｌ〜マル
等を用いてなるもので、ある角度回転する毎に第３図上
段に示すパルスを出力す一４＝ る。第３図では、計測の角度間隔の半分（Δβ／２）の
間隔毎にパルスが１つ出力される場合、すなわち、Δｔ
／２の周期を持つパルスを出力する場合を例示する。Δβ=ω·Δt (3) The scanner rotation control block 23 includes a rotation angle detection circuit. This rotation angle detection circuit is made by using, for example, a zebra scale (a zebra-like black and white pattern arranged at equal intervals around the circumference) and hooks, squares, etc. , outputs the pulse shown in the upper part of FIG. 3 every time it rotates by a certain angle. In FIG. 3, when one pulse is output at every half (Δβ/2) of the angular interval of measurement, that is, Δt
A case will be exemplified in which a pulse having a period of /2 is output.

１回転目において、データ計測ブロック２４には前記回
転角検出回路の出力パルスが入力され、２パルスに１回
の間隔で投影データを計測する（第３図下段参照）。１
パルスはΔβ／２の周期を持つことから、投影データを
計測する角度間隔はΔβとなり、計測時のＸ線管２７（
Ｘ線源Ｘ）の角度位置β（ｎ）は次式（４）のようにな
る。During the first rotation, the output pulse of the rotation angle detection circuit is input to the data measurement block 24, and projection data is measured at an interval of once every two pulses (see the lower part of FIG. 3). 1
Since the pulse has a period of Δβ/2, the angular interval at which projection data is measured is Δβ, and the X-ray tube 27 (
The angular position β(n) of the X-ray source X) is expressed by the following equation (4).

β（ｎ）＝β。＋ｎ・Δβ　　・・・・・（４）（ただ
し、ｎ＝ｏ、１，２．・・（２ｇ／八βへ−１β０　”
　Ｏｒ以下、同様） ここで、１回転目の計４Ｉす位置を第１図中、「・」印
で示す。β(n)=β. +n・Δβ...(4) (However, n=o, 1, 2...(2g/8β to -1β0"
(Same hereafter) Here, the total 4I positions of the first rotation are indicated by "-" marks in FIG.

投影データを２π／Δβ回計測したところからスキャナ
２８は２回転目に入る。この時点でデータｉｔ　ａｔｑ
ブロック２４は４π／Δβ個のパルスが入力されている
。ここでデータ計測ブロック２４は、入力されるパルス
の１パルス分を読飛ばすことにより計測の位相をΔｔ／
２だけ遅らせ、再びΔｔの間隔で計測を開始する。その
結果、２回転目の計測時のＸ線管２７（Ｘ線源Ｘ）の角
度位置β（ｎ）はΔβ／２だけずれ、次式（５）のよう
になる。After measuring the projection data 2π/Δβ times, the scanner 28 starts its second rotation. At this point the data it atq
The block 24 receives 4π/Δβ pulses. Here, the data measurement block 24 changes the measurement phase by Δt/by skipping one pulse of the input pulses.
After a delay of 2, the measurement is started again at intervals of Δt. As a result, the angular position β(n) of the X-ray tube 27 (X-ray source

β（ｎ）＝β０＋Δβ／２＋ｎ・Δβ　・・・・・・（
５）したがって、２回転目の計測位置は第１−図中、「
×」印で示す位置になる。β(n)=β0+Δβ/2+n・Δβ ・・・・・・(
5) Therefore, the measurement position for the second rotation is “
It will be at the position indicated by the "x" mark.

２回転目では、投影データを２π／Δβ回計測したとこ
ろでスキャン計測を終了し、スキャナ２８の回転及びＸ
線の曝射を各々停止する。In the second rotation, the scan measurement ends after measuring the projection data 2π/Δβ times, and the rotation of the scanner 28 and the
Stop each line exposure.

上記のように、２回転の計測で得た４π／Δβ個の投影
データはΔβ／２の間隔で計測した投影データと同じ精
密度を持つものとなる。計測した投影データは順次画像
処理ブロック２６に転送し、検出器特性の補正等の前処
理を施した後、画像再構成処理（例えばＦＢＰ法：　Ｆ
ｉ］、ｔｅｒｅｄ　　ＢａｃｋＰｒｏｊｅｃｔｉ、ｏｎ
　　Ｍｅｔｈｏｄによる処理）を施す。再構成結果は表
示制御ブロック２５に転送され、モニタ２９で再構成画
像（断層像）として表示される。As described above, the 4π/Δβ projection data obtained by measuring two rotations has the same precision as the projection data measured at intervals of Δβ/2. The measured projection data is sequentially transferred to the image processing block 26 and subjected to preprocessing such as correction of detector characteristics, and then subjected to image reconstruction processing (for example, FBP method: F
i], tered BackProjecti, on
Processing by Method) is performed. The reconstruction result is transferred to the display control block 25 and displayed on the monitor 29 as a reconstructed image (tomographic image).

ｎ＝３、すなわちスキャナ２８を３回転させる場合も同
様に、２回転目でΔｔ／３だけ位相を遅らせ、３回転目
でさらにΔｔ／３だけ位相を遅らせて、各々計測すれば
よい。ただし、回転角検出回路の出力パルスはΔｔ／３
毎に出力されなければならない。ｎがその他の値をとる
場合も同様である。なお、ｎ＝１の場合は最初の１回転
で計測を終了するだけでよい。Similarly, when n=3, that is, when the scanner 28 is rotated three times, the phase may be delayed by Δt/3 in the second rotation, and further delayed by Δt/3 in the third rotation, and each measurement may be performed. However, the output pulse of the rotation angle detection circuit is Δt/3
must be output every time. The same applies when n takes other values. Note that in the case of n=1, it is sufficient to finish the measurement after the first rotation.

〔発明の効果〕〔Effect of the invention〕

以上述べたように本発明は、スキャナ回転速度を変える
ことなく、異なる角度の多数の投影データを計測するこ
とができる。したがって、高精度の再構成画像を得るた
めのスキャナ制御系システムは、従来装置の場合に比べ
て簡素化、小型化でき、保守性にも優れるという効果が
ある。As described above, the present invention can measure a large number of projection data at different angles without changing the scanner rotation speed. Therefore, the scanner control system for obtaining highly accurate reconstructed images can be simplified and downsized compared to conventional devices, and has the advantage of being superior in maintainability.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は本発明装置の原理説明図、第２図は本発明装置
の一実施例を示すブロック図、第３図は同」二装置の動
作を説明するためのタイムチャートである。 ２１・・システム制御ブロック、２２・・Ｘ線制御ブロ
ック、２３・・スキャナ回転制御ブロック、２４・・・
データ計測ブロック、２６・・・画像処理ブロック、２
７・Ｘ線管、２８・・・スキャナ。 特許出願人　　株式会社日立メデイコ 代理人弁理士　　秋　　本　　正　　実（外１名）FIG. 1 is a diagram illustrating the principle of the apparatus of the present invention, FIG. 2 is a block diagram showing an embodiment of the apparatus of the present invention, and FIG. 3 is a time chart for explaining the operation of the apparatus. 21...System control block, 22...X-ray control block, 23...Scanner rotation control block, 24...
Data measurement block, 26... Image processing block, 2
7.X-ray tube, 28...scanner. Patent applicant: Masami Akimoto, Patent Attorney, Hitachi Medeico Co., Ltd. (1 other person)

Claims (1)

【特許請求の範囲】[Claims] １、フレームと、被検体を挟む前記フレーム上の位置に
対向配置されたＸ線管装置及びＸ線検出器とを備えてな
るスキャナを回転させつつ、前記Ｘ線管装置によりＸ線
ビームを発生させて前記被検体の投影データを計測し、
Ｘ線断層像を得るＸ線ＣＴ装置において、前記スキャナ
を一定速度で複数回回転させるスキャナ定速回転手段と
、前記スキャナの各回転毎のデータ取込の位送をずらす
ことにより前記Ｘ線ビームが異なる軌跡を通り、異なる
角度の投影データを多数計測可能とするデータ計測手段
とを具備することを特徴とするＸ線ＣＴ装置。1. Generating an X-ray beam with the X-ray tube device while rotating a scanner comprising a frame, and an X-ray tube device and an X-ray detector arranged oppositely on the frame with the subject between them. and measure the projection data of the subject,
In an X-ray CT apparatus that obtains an X-ray tomographic image, the X-ray beam is 1. An X-ray CT apparatus characterized by comprising: data measuring means capable of measuring a large number of projection data at different angles through different trajectories.
JP62295303A 1987-11-25 1987-11-25 X-ray ct apparatus Pending JPH01136636A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP62295303A JPH01136636A (en) 1987-11-25 1987-11-25 X-ray ct apparatus

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP62295303A JPH01136636A (en) 1987-11-25 1987-11-25 X-ray ct apparatus

Publications (1)

Publication Number Publication Date
JPH01136636A true JPH01136636A (en) 1989-05-29

Family

ID=17818860

Family Applications (1)

Application Number Title Priority Date Filing Date
JP62295303A Pending JPH01136636A (en) 1987-11-25 1987-11-25 X-ray ct apparatus

Country Status (1)

Country Link
JP (1) JPH01136636A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011069650A (en) * 2009-09-24 2011-04-07 Shimadzu Corp Radiation tomographic image photographing system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011069650A (en) * 2009-09-24 2011-04-07 Shimadzu Corp Radiation tomographic image photographing system

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