WO2009107658A1 - X線ctスキャンシミュレータ及びx線ct装置 - Google Patents
X線ctスキャンシミュレータ及びx線ct装置 Download PDFInfo
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- WO2009107658A1 WO2009107658A1 PCT/JP2009/053407 JP2009053407W WO2009107658A1 WO 2009107658 A1 WO2009107658 A1 WO 2009107658A1 JP 2009053407 W JP2009053407 W JP 2009053407W WO 2009107658 A1 WO2009107658 A1 WO 2009107658A1
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment
- A61B6/02—Devices for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
- A61B6/03—Computerised tomographs
- A61B6/032—Transmission computed tomography [CT]
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment
- A61B6/58—Testing, adjusting or calibrating apparatus or devices for radiation diagnosis
- A61B6/582—Calibration
- A61B6/583—Calibration using calibration phantoms
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- the present invention relates to an X-ray computed tomography (CT), and more particularly to a technique for obtaining an image corresponding to imaging conditions by simulation.
- CT computed tomography
- X-ray CT systems have made it possible to collect a wide range of data in a short period of time by increasing the number of X-ray detectors and increasing the scanner rotation speed.
- the exposure dose per examination is increasing, and reduction of exposure by low-dose imaging is regarded as important.
- simple low-dose imaging alone causes an increase in image noise, and an image suitable for diagnosis may not be acquired.
- Patent Document 1 a technique for simulating an image obtained under an arbitrary shooting condition designated by an operator before shooting has been proposed. According to this technique, an image obtained under the designated photographing condition can be presented to the operator before photographing. Therefore, the operator can determine whether or not an image suitable for diagnosis can be acquired according to the designated photographing condition.
- An object of the present invention is to provide an X-ray CT scan simulator and an X-ray CT apparatus capable of displaying a lesion assumed by an operator on a simulation image and capable of highly accurate simulation including the assumption of a new lesion occurrence. There is.
- an X-ray CT scan simulator assumes an image storage device that stores a reference image, a target noise value setting device that sets a noise target value of a desired image, and an operator.
- a simulated lesion setting device for setting a simulated lesion condition; a simulation image generating device for generating a simulation image including a simulated lesion using the reference image based on the set target noise value and simulated lesion condition; and And an image display device for displaying a simulation image including a simulated lesion.
- the X-ray CT apparatus an X-ray source that irradiates a subject with X-rays, an X-ray detector that is disposed opposite to the X-ray source and detects X-rays transmitted through the subject, A tomographic image of the subject is reproduced based on a rotating device that is mounted with the X-ray source and the X-ray detector and rotates around the subject, and transmitted X-ray doses in a plurality of directions detected by the X-ray detector.
- an X-ray CT apparatus comprising: an image reconstructing apparatus to be configured; an imaging condition input apparatus for inputting the X-ray irradiation conditions and image reconstruction conditions; and an image display apparatus for displaying the tomographic image.
- a target noise value setting device for setting a noise target value of a desired image
- a simulated lesion setting device for setting conditions of a simulated lesion assumed by an operator
- the set target noise value Include simulated lesions using the reference image based on simulated lesion conditions
- simulation image generating device for generating a simulation image, further wherein the image display device and displaying a simulation image including the simulated lesion.
- the lesion assumed by the operator can be displayed on the simulation image, and a highly accurate simulation including the assumption of occurrence of a new lesion is possible.
- Configuration diagram of the X-ray CT apparatus of the present invention Configuration diagram of the X-ray CT scan simulator of the present invention The figure which shows the processing flow which shows the method of creating the simulation image The figure which shows an example of the condition setting screen for the simulated lesion Outline explanatory diagram of approximate model calculation method Explanatory drawing of how to create reference projection data Explanatory diagram of relationship between distribution of slice thickness direction of simulated lesion and X-ray path
- 1 X-ray CT device 100 scan gantry section, 101 X-ray tube, 102 rotating disk, 103 collimator, 104 opening, 105 bed, 106 X-ray detector, 107 data collection device, 108 gantry control device, 109 bed control device , 110 X-ray control device, 120 console, 121 input device, 122 image calculation device, 123 storage device, 124 system control device, 125 display device, 2 X-ray CT scan simulator, 200 simulation image generation device, 201 object model Calculation means, 202 image noise calculation means, 203 addition noise amount calculation means, 204 reference projection data creation means, 205 noise projection data creation means, 206 simulated lesion projection data creation means, 207 projection data addition means, 208 image reconstruction means, 209 simulation image creation means, 210 image storage device, 220 condition setting device, 230 simulation image display device, 400 Simulated lesion condition setting screen, 410 reference image display area, 411 reference image, 412 simulated lesion coordinate setting cursor, 420 simulated lesion condition setting area,
- FIG. 1 is an overall configuration diagram of an X-ray CT apparatus 1 to which the present invention is applied.
- the X-ray CT apparatus 1 includes a scan gantry unit 100 and a console 120.
- the scan gantry unit 100 includes an X-ray tube 101, a rotating disk 102, a collimator 103, an X-ray detector 106, a data collection device 107, a bed 105, a gantry control device 108, a bed control device 109, An X-ray control device 110.
- the X-ray tube 101 is an apparatus that irradiates a subject placed on a bed 105 with X-rays.
- the collimator 103 is a device that controls the radiation direction of X-rays emitted from the X-ray tube 101.
- the X-ray detector 106 is a device that is arranged opposite to the X-ray tube 101 and detects X-rays transmitted through the subject, and generates an electrical signal corresponding to the transmitted X-ray dose.
- the rotating disk 102 includes an opening 104 into which a subject placed on a bed 105 enters, and is equipped with an X-ray tube 101 and an X-ray detector 106, and rotates around the subject.
- the data collection device 107 is a device that converts the X-rays detected by the X-ray detector 106 into a predetermined signal.
- the gantry control device 108 is a device that controls the rotation of the rotary disk 102.
- the bed control device 109 is a device that controls the vertical movement of the bed 105.
- the X-ray control device 110 is a device that controls the output to the X-ray tube 101.
- the console 120 includes an input device 121, an image calculation device 122, a display device 125, a storage device 123, and a system control device 124.
- the input device 121 is a device for inputting a subject's name, examination date / time, imaging conditions, simulated lesion conditions, and the like, and is specifically a keyboard, a pointing device, or the like.
- the image computation device 122 is a device that performs CT processing on the measurement data sent from the data collection device 107 and performs CT image reconstruction.
- the display device 125 is a device that displays the CT image created by the image calculation device 122.
- the storage device 123 is a device that stores data collected by the data collection device 107 and image data of a CT image created by the image calculation device 122.
- the system control device 124 is a device that controls these devices, the gantry control device 108, the bed control device 109, and the X-ray control device 110.
- the X-ray tube 101 is controlled by the X-ray control device 110, and emits X-rays based on the imaging conditions (X-ray tube voltage, X-ray tube current, etc.) input from the input device 121.
- the X-ray detector 106 has a plurality of X-ray detection elements arranged in the circumferential direction of the rotating disk 102 (for example, 1000), or two-dimensionally in the circumferential direction of the rotating disk 102 and the rotational axis direction of the rotating disk 102. The X-rays irradiated from the X-ray tube 101 and transmitted through the subject are detected by each detection element.
- the rotating disk 102 is controlled by the gantry control device 108 and rotates based on imaging conditions (scanning speed, etc.) input from the input device 121.
- the bed 105 is controlled by the bed control device 109 and operates based on the imaging conditions (such as a helical pitch) input from the input device 121.
- X-ray projection data from various directions is collected by the data collection device 107 by irradiating and detecting X-rays while rotating the rotating disk 102 around the subject.
- the X-ray projection data collected by the data collection device 107 is sent to the image calculation device 122.
- the image calculation device 122 reconstructs the X-ray projection data to obtain a CT image.
- the reconstructed CT image is displayed on the display device 125, and is stored in the storage device 123 as image data together with the imaging conditions.
- the X-ray CT scan simulator 2 Prior to imaging with the X-ray CT apparatus 1, a configuration diagram of an X-ray CT scan simulator 2 that simulates an image obtained by imaging is shown in FIG.
- the X-ray CT scan simulator 2 includes an image storage device 210, a condition setting device 220, a simulation image generation device 200, and a simulation image display device 230.
- the image storage device 210 is a device that stores a reference image serving as a reference for a simulation image created by the X-ray CT scan simulator 2, and is specifically an HD (Hard Disk).
- the reference image is a past image obtained by CT imaging of the subject in the past or a human phantom image obtained by CT imaging of a human phantom that faithfully reproduces the internal tissue of the human body.
- Sufficient X-ray dose should be used to capture human phantom images so that clear images can be obtained.
- the human phantom image may be prepared by taking a representative FOV for each part.
- the storage device 123 may be used as the image storage device 210.
- the condition setting device 220 is a device for an operator to set a target noise value and a simulated lesion condition, and specifically, a keyboard, a pointing device, and the like.
- the target noise value is the image SD (Standard Deviation) value input by the operator, or the imaging conditions (tube voltage, tube current, slice thickness, scan time, etc.) set by the operator in the X-ray CT apparatus and the subject to be described later
- the image SD value calculated based on the approximate model may be used.
- Examples of the conditions for the simulated lesion include the coordinates, shape, and size of the simulated lesion, and the difference in CT value from the surrounding tissue.
- the input device 121 may be used as the condition setting device 220.
- the simulation image generation device 200 is a device that generates a simulation image based on the reference image, the target noise value, and the condition of the simulated lesion.
- the simulation image generation device 200 is a CPU that executes arithmetic processing described later, or a dedicated arithmetic circuit.
- the simulation image generating apparatus 200 includes an object approximate model calculating unit 201, an image noise calculating unit 202, an added noise amount calculating unit 203, a reference projection data generating unit 204, a noise projection data generating unit 205, and a simulated lesion projection.
- Data creation means 206, projection data addition means 207, image reconstruction means 208, and simulation image creation means 209 are provided.
- the simulation image generation apparatus 200 may be mounted on the image calculation apparatus 122 or the system control apparatus 124 of the X-ray CT apparatus 1, or may be mounted on another apparatus other than the X-ray CT apparatus 1, and may be connected to a LAN (Local Area Area). Communication with the X-ray CT apparatus 1 may be performed via a network.
- LAN Local Area Area
- the subject approximate model calculation means 201 calculates the approximate transmission length of the homogeneous medium (for example, water) in the relevant cross section of the subject from the reference image, and calculates the subject approximate model having the calculated approximate transmission length. A method for calculating the approximate object model will be described later.
- the homogeneous medium for example, water
- the image noise calculation unit 202 calculates an image noise value included in the reference image. A method for calculating the image noise will be described later.
- the addition noise amount calculation means 203 calculates the amount of noise to be added to the reference image in order to create an image that realizes a desired image noise value. A method for calculating the amount of noise to be added will be described later.
- the reference projection data creation unit 204 creates reference projection data based on the reference image. A method for calculating the reference projection data will be described later.
- the noise projection data creation means 205 creates noise projection data for a noise image to be added to the reference image while taking into account the value of the reference projection data. A method for calculating the noise projection data will be described later.
- the simulated lesion projection data creation means 206 creates simulated lesion projection data based on the simulated lesion conditions (coordinates, shape, size, CT value difference with surrounding tissue) set via the condition setting device 220. Is.
- the simulated lesion projection data is created as projection data that does not include noise. A method for calculating simulated lesion projection data will be described later.
- Projection data adding means 207 adds noise projection data and simulated lesion projection data to create addition image projection data.
- the image reconstruction unit 208 applies an reconstruction process (for example, the Filtered Back Projection method) to the addition image projection data, and creates an addition image to be added to the reference image.
- an reconstruction process for example, the Filtered Back Projection method
- the image calculation device 122 may be used as the image reconstruction unit 208.
- the simulation image creation means 209 creates a simulation image by adding the addition image to the reference image.
- the created simulation image is an image that satisfies the image noise value set via the condition setting device 220 and the condition of the simulated lesion.
- the simulation image display device 230 is a device that displays a simulation image generated by the simulation image generation device 200, and specifically, a CRT (Cathode Ray Tube) or a liquid crystal display. Note that the display device 125 may be used as the simulation image display device 230.
- FIG. 3 is a diagram showing a processing flow until a simulation image is generated according to the present embodiment.
- the general flow is to set a reference image in steps S301 to S303, generate noise data in steps S304 to S308, generate simulated lesion data in step S309, and generate a simulation image in steps S310 to S312. .
- FIG. 4 shows an example of a simulated lesion condition setting screen.
- the simulated lesion condition setting screen 400 includes a reference image display area 410 and a simulated lesion condition setting area 420, and is displayed on the image display device 230.
- the selected reference image 411 is displayed in the reference image display area 410, and various boxes 421 to 425 used for setting various conditions of the simulated lesion are displayed in the simulated lesion condition setting area 420.
- Various boxes include x-coordinate setting box 421 and y-coordinate setting box 422 for setting the coordinate of the simulated lesion, 423 for setting the size of the simulated lesion, and for setting the CT value difference between the simulated lesion and surrounding tissue
- a box 424 and a simulated lesion shape setting box 425 are displayed. Boxes 421 to 424 are boxes for numerical editing, and box 425 is a box for menu selection. The operator can set the conditions of the desired simulated lesion by operating these boxes. Alternatively, the coordinates of the simulated lesion may be set by a method such as clicking the desired position in the reference image 411 with the mouse and setting the simulated lesion coordinate setting cursor 412.
- Step S301 The X-ray CT scan simulator 2 searches the image storage device 210 for a past image of the subject to be simulated, and determines whether there is a history of imaging the same part in the past. If it is determined that there is a past image, the process proceeds to step S302; otherwise, the process proceeds to step S303.
- Step S302 The X-ray CT scan simulator 2 sets the past image as the reference image.
- X-ray CT scan simulator 2 sets the human phantom image as the reference image.
- Step S304 The subject approximate model calculating unit 201 calculates the subject approximate model based on the reference image set in S302 or S303 as follows.
- Figure 5 outlines the approximate model calculation method.
- the CT values of the reference image are integrated in the y direction as shown in Equation 1 to obtain profile1.
- vch Virtual detector channel number
- vch 0,1, ..., XMTX-1
- XMTX Number of pixels in the x direction
- ypt Pixel pitch in the y direction
- YMTX Number of pixels in the y direction
- CT of the reference image Accumulate the values in the x direction as shown in Equation 2 to obtain profile2.
- the transmission length ypd in the y direction and the transmission length xpd in the x direction are calculated, and these are used as the diameters in the y direction and the x direction of the elliptic approximation model.
- the approximate model is assumed to be composed of water, but is not necessarily limited to water.
- nmaxave (prf, n) a function for calculating a simple addition average of n pieces of data from the larger value of the data string prf (step S305)
- the image noise calculation means 202 calculates the image noise amount of the subject approximate model calculated in S304 as follows. In order to calculate the amount of noise to be added to the reference image in order to realize the target image SD, first, it is necessary to calculate the image noise variance in the reference image, that is, the square value of the image SD in the reference image.
- the added noise amount calculating means 203 calculates the amount of noise to be added to the reference image based on the image noise amount of the reference image calculated in S305 and a preset target noise value. Also, a virtual scan condition for creating noise projection data corresponding to the amount of noise to be added is calculated. The calculation method will be described below.
- the target image SD is SDtgt
- the target image noise variance Vtgt is as shown in Equation 4.
- a noise image having the image noise variance Vn_img represented by Equation 5 may be created.
- the tube current / time product of the reference image is xmAs0
- the tube current / time product xmAs_ni of the noise image to be added to the reference image is as shown in Formula 6.
- the reference projection data creation means 204 creates reference projection data as shown in FIG. 6 by reprojecting the reference image.
- the reprojection processing integration similar to Equation 1 or Equation 2 is performed.
- the X-ray tube is set to 0 °, and the angle of the position of the X-ray tube increases clockwise. For convenience of explanation, only the reprojection result in two directions is shown. Yes. In actual processing, it is desirable to perform re-projection at the X-ray tube position based on the same view as the assumed scan, or at the X-ray tube position based on the half-round view.
- Step S308 The noise projection data creation unit 205 creates noise projection data as follows based on the virtual scan condition calculated in S306 and the reference projection data created in S307.
- the tube current / time product xmAs_ni of the noise image is shown in the above equation (6).
- the projection data value Vr_ref (prf) when the projection data value is prf and scanning is performed with a certain reference tube current / time product xmAs_ref can be obtained in advance by an experiment, for example, expressed by Equation 7 it can.
- bsprf (vch) The value of the reference projection data for the virtual detector channel number vch, that is, the projection data indicated by Vr_ni (vch) in which the average value is 0 and the variance is several 8 in each channel of the virtual detector is the noise projection data
- the simulated lesion projection data creating means 206 creates simulated lesion projection data based on preset simulated lesion conditions (coordinates, size, and CT value difference with surrounding tissue) as follows.
- ⁇ w Water X-ray attenuation coefficient
- the distribution of the simulated lesion in the image slice thickness direction is considered. That is, as shown in Fig. 7 (a), the X-ray path in the cross-sectional image viewed from the body axis direction is a line segment, but it is necessary to consider that it is actually a plane having a depth corresponding to the slice thickness. is there.
- the diameter ⁇ of the intersection Cfs between the simulated lesion and the X-ray path p shown in FIGS. 7 (b) and 7 (c) is expressed by equation (10).
- Step S310 The projection data adding means 207 adds the noise projection data created in S308 and the simulated lesion projection data created in S309, and creates projection data of the image for addition.
- Step S311 The image reconstruction unit 208 reconstructs an image by applying a filtered back projection method or the like to the projection data of the image for addition created in S310, and creates an image for addition.
- Step S312 The simulation image creation means 209 adds the addition image created in S311 to the reference image set in S302 or S303 to create a simulation image. If the simulation image created in S312 is satisfactory for the operator in terms of visual effects of image noise and discriminability of the simulated lesion, the actual scan conditions for achieving the preset target image noise value are captured.
- the scanning conditions may be used.
- the tube current / time product xmAs_app to be applied as the scanning condition for the main imaging is as shown in Equation 12.
- the operator may input the result of Formula 12 displayed on the simulation image display device by the simulation image generation apparatus 200 using the input device 121.
- the simulation image generation apparatus 200 may set the result of Formula 12 in the X-ray control apparatus 110.
- the simulation image generation apparatus 200 sets the result of Formula 12 in the X-ray control apparatus 110, the operation of the operator can be simplified.
- the above-described functions may be realized by configuring a scan simulator program that causes a computer to execute the functions described in the above-described embodiment, and installing the program in a personal computer or a workstation.
- the simulator image does not necessarily have to be displayed on the monitor of the personal computer or workstation on which the scan simulator program is installed, and the simulator image is transmitted to a terminal device connected via a network such as a LAN.
- a simulator image may be displayed.
Abstract
Description
図1は本発明を適用したX線CT装置1の全体構成図である。X線CT装置1はスキャンガントリ部100と操作卓120とを備える。
X線CT装置1での撮影に先立ち、撮影により得られる画像をシミュレートするX線CTスキャンシミュレータ2の構成図を図2に示す。X線CTスキャンシミュレータ2は、画像格納装置210と、条件設定装置220と、シミュレーション画像生成装置200と、シミュレーション画像表示装置230を備える。
図3は、本実施形態によりシミュレーション画像を生成するまでの処理の流れを示す図である。大まかな流れは、ステップS301~S303での基準画像の設定、ステップS304~S308でのノイズデータの生成、ステップS309での模擬病巣データの生成、ステップS310~S312でのシミュレーション画像の生成、である。
X線CTスキャンシミュレータ2は、シミュレーション対象となる被検体の過去画像を画像格納装置210の中で検索し、過去に同一部位を撮影した履歴があるか否かを判断する。判断の結果、過去画像があればステップS302に、なければステップS303に進む。
X線CTスキャンシミュレータ2は、過去画像を基準画像に設定する。
被検体近似モデル算出手段201は、S302若しくはS303で設定された基準画像に基づき、以下のように被検体近似モデルを算出する。
vch:仮想的な検出器チャネル番号で、vch=0,1,...,XMTX-1
XMTX:x方向の画素数
ypt:y方向の画素ピッチ
YMTX:y方向の画素数
org_img(vch,iy):x座標=vch、y座標=iyにおける基準画像のCT値
次に、基準画像のCT値を数2式のようにx方向に積算し、profile2を得る。
vch:仮想的な検出器チャネル番号で、vch=0,1,...,YMTX-1
YMTX:y方向の画素数
xpt:x方向の画素ピッチ
XMTX:x方向の画素数
org_img(ix,vch):x座標=ix、y座標=vchにおける基準画像のCT値
次に、数3式によりy方向の透過長ypdとx方向の透過長xpdを算出し、これらを楕円近似モデルのy方向とx方向の径とする。なお、本実施形態では近似モデルが水で構成されるものとしているが、必ずしも水でなくてもよい。
nmaxave(prf,n):データ列prfの値の大きい方からn個のデータによる単純加算平均を算出する関数
(ステップS305)
画像ノイズ算出手段202は、S304で算出された被検体近似モデルの画像ノイズ量を以下のように算出する。目標とする画像SDを実現するために基準画像に加算するノイズ量を算出するためには、まず基準画像における画像ノイズ分散、すなわち基準画像における画像SDの二乗値を算出する必要がある。そこで前記の楕円近似モデルに基づき、画像再構成に使用する各ビューの透過長や、X線管電圧、X線管電流、再構成時のビュー重み付け等を考慮して、たとえば特許文献2に開示された方法により、基準画像における画像ノイズ分散Vorg_imgを算出する。
加算ノイズ量算出手段203は、S305で算出した基準画像の画像ノイズ量と予め設定された目標ノイズ値に基づき、基準画像に加算すべきノイズ量を算出する。また、加算すべきノイズ量に対応するノイズ投影データ作成用の仮想的なスキャン条件も算出する。算出方法について以下で述べる。
基準投影データ作成手段204は、基準画像を再投影処理することにより図6に示すような基準投影データを作成する。再投影処理には数1式や数2式と同様な積算を行う。なお、図6ではX線管が真上の状態を0°とし、X線管の位置をしめす角度は右回りに増大するものとしてあり、説明の便宜上、2方向の再投影結果のみを示している。実際の処理では想定するスキャンと同じビューによるX線管位置、または半周分のビューによるX線管位置において再投影を行うことが望ましい。
ノイズ投影データ作成手段205は、S306で算出された仮想的なスキャン条件とS307で作成した基準投影データに基づき、ノイズ投影データを以下のように作成する。
ノイズ画像の管電流・時間積xmAs_niは前記の数6式に示されている。また、投影データの値がprfであり、ある基準管電流・時間積xmAs_refでスキャンした場合の投影データノイズVr_ref(prf)は実験により予め求めておくことができ、たとえば数7式で表すことができる。
cおよびa:予め実験によって求めておく定数
exp(x):引数xに対し、自然対数の底eのx乗を算出する指数関数
prf:投影データの値
よって、ある仮想チャネルvchにおける基準投影データの値に対応するノイズのみの投影データの分散値Vr_ni(vch)は数8式によって算出することができる。
bsprf(vch):仮想検出器チャネル番号vchにおける基準投影データの値
すなわち、仮想検出器の各チャネルにおいて平均値が0で分散が数8式のVr_ni(vch)で示される投影データをノイズ投影データとする。
模擬病巣投影データ作成手段206は、予め設定された模擬病巣の条件(座標、大きさ、周囲組織とのCT値の差)に基づき、模擬病巣の投影データを以下のように作成する。
μw:水のX線減弱係数
また、模擬病巣の中心から距離dだけ隔たったX線経路における投影データを算出するため、模擬病巣の画像スライス厚方向の分布を考慮する。すなわち、図7(a)のように体軸方向からみた横断面画像でのX線経路は線分であるが、実際にはスライス厚さ分の奥行きを持つ面であることを考慮する必要がある。図7(b)及び(c)に示す模擬病巣とX線経路pとの交面Cfsの直径ξは数10式によって表される。
投影データ加算手段207は、S308で作成されたノイズ投影データとS309で作成された模擬病巣投影データを加算し、加算用画像の投影データを作成する。
画像再構成手段208は、S310で作成された加算用画像の投影データにFiltered Back Projection法等を適用して画像再構成し、加算用画像を作成する。
シミュレーション画像作成手段209は、S302若しくはS303で設定された基準画像に、S311で作成された加算用画像を加算し、シミュレーション画像を作成する。
S312で作成されたシミュレーション画像が画像ノイズの視覚的効果および模擬病巣の識別性の点で操作者にとって満足のいくものであれば、予め設定された目標画像ノイズ値を実現するスキャン条件を本撮影のスキャン条件として用いればよい。ここで、本撮影のスキャン条件として適用すべき管電流・時間積xmAs_appは数12式のとおりとなる。
Claims (7)
- 基準画像を格納する画像格納装置と、
所望画像のノイズ目標値を設定する目標ノイズ値設定装置と、
操作者が想定する模擬病巣の条件を設定する模擬病巣設定装置と、
前記設定された目標ノイズ値と模擬病巣の条件に基づき前記基準画像を用いて模擬病巣を含んだシミュレーション画像を生成するシミュレーション画像生成装置と、
前記模擬病巣を含んだシミュレーション画像を表示する画像表示装置と、
を備えることを特徴とするX線CTスキャンシミュレータ。 - 請求項1に記載のX線CTスキャンシミュレータにおいて、
前記模擬病巣設定装置で設定する病巣の条件として、病巣の位置、病巣の大きさ、病巣と周囲組織とのコントラストを含むことを特徴とするX線CTスキャンシミュレータ。 - 請求項2に記載のX線CTスキャンシミュレータにおいて、
前記模擬病巣設定装置は、前記基準画像上で指定された点を前記病巣の位置として取得することを特徴とするX線CTスキャンシミュレータ。 - 被検体にX線を照射するX線源と、前記X線源に対向配置され前記被検体を透過したX線を検出するX線検出器と、前記X線源と前記X線検出器を搭載し前記被検体の周囲を回転する回転装置と、前記X線検出器により検出された複数方向の透過X線量に基づき前記被検体の断層像を再構成する画像再構成装置と、前記X線の照射条件と画像再構成の条件を入力する操作に用いられる撮影条件入力装置と、前記断層像を表示する画像表示装置と、を有するX線CT装置において、
基準画像を格納する画像格納装置と、
所望画像のノイズ目標値を設定する目標ノイズ値設定装置と、
操作者が想定する模擬病巣の条件を設定する模擬病巣設定装置と、
前記設定された目標ノイズ値と模擬病巣の条件に基づき前記基準画像を用いて模擬病巣を含んだシミュレーション画像を生成するシミュレーション画像生成装置と、
をさらに備え、前記画像表示装置は前記模擬病巣を含んだシミュレーション画像を表示することを特徴とするX線CT装置。 - 請求項4に記載のX線CT装置において、
前記シミュレーション画像生成装置が前記シミュレーション画像を生成する際に算出したX線照射条件に基づいて前記X線源を制御するX線制御装置をさらに備えることを特徴とするX線CT装置。 - 請求項4に記載のX線CT装置において、
前記模擬病巣設定装置で設定する病巣の条件として、病巣の位置、病巣の大きさ、病巣と周囲組織とのコントラストを含むことを特徴とするX線CT装置。 - 請求項6に記載のX線CT装置において、
前記模擬病巣設定装置は、前記基準画像上で指定された点を前記病巣の位置として取得することを特徴とするX線CT装置。
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JP2020519863A (ja) * | 2017-05-01 | 2020-07-02 | コーニンクレッカ フィリップス エヌ ヴェKoninklijke Philips N.V. | 定量的分子撮像のための正確なハイブリッドデータセットの生成 |
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JP2017051395A (ja) * | 2015-09-09 | 2017-03-16 | 富士フイルム株式会社 | 放射線画像処理装置、方法およびプログラム |
AU2018225165B2 (en) * | 2017-02-24 | 2023-07-06 | Bayer Healthcare Llc | Systems and methods for generating simulated computed tomography (CT) images |
EP3384847B1 (de) * | 2017-04-05 | 2019-06-12 | Siemens Healthcare GmbH | Bestimmen eines referenzdosisparameters einer computertomographiebildgebung |
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JP7282487B2 (ja) * | 2018-06-07 | 2023-05-29 | キヤノンメディカルシステムズ株式会社 | 医用画像診断装置 |
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