DE102006048606A1 - X-ray image producing method for use in medical field, involves superimposing X-ray image on another X-ray image, and representing X-ray images periodically time-synchronously with body function according to type of film - Google Patents

Abstract

The method involves dividing a periodic duration of a periodic body function (16) of a patient (6) into several periodically recurring time intervals. A time interval of a X-ray image of the patient is recorded and assigned to the respective time interval. Another X-ray image of the patient is recorded in each time interval, where the latter X-ray image is superimposed on the former X-ray image. The two X-ray images are represented periodically time-synchronously with the body function according to type of a film, where the time interval contains a recording time of the latter X-ray image.

Description

The The invention relates to a method for generating an X-ray image a patient.

in the Medical environment today are radiographs of patients for a variety of Purposes created. An x-ray picture This always represents a snapshot of the patient dar. To be displayed in the X-ray body structures in the patient, however, are forced (involuntarily) movements, e.g. by heartbeat or breathing (breathing excursion). These movements are usually cyclic, e.g. with the appropriate pulse or Respiratory rate. Because the x-ray represents only a snapshot of the patient, the actual Location of the structures moving cyclically in the patient from the X-ray differ. This represents e.g. in medical subtraction procedures, such as digital subtraction angiography (DSA), an accuracy problem. Even with roadmap procedures, which is a pre-recorded DSA image as a medical map and a live image of the patient, by e.g. a catheter in the vascular tree of a Navigating patients results in accuracy issues.

at In fact, moving structures can make a difference between the location of a vessel during the Capture the images for the vessel representation (Blank image and contrast agent image) and the following measurement (catheter image, Live picture) e.g. for intervention (determination of catheter position) consist. This raises the problem of the best possible, i. exact location Capture of the vessel during the Movement and a timely synchronization the detected movement with the at the time of the following measurement (e.g., X-ray image while the intervention) given (local) conditions.

in the The state of the art is relevant known, from a periodic body function of the patient to generate a trigger signal which is e.g. with the R wave of one ECG of the patient is synchronized, and X-ray images always the same phase of the recurring body function. hereby However, the recording time of an X-ray image is always the same phase time limited. So far, especially in the field of X-ray C-arm applications no triggered investigations.

task The present invention is an improved method for Generating an X-ray image of a patient.

• eine Periodendauer (T) einer periodischen Körperfunktion (16) des Patienten (6) wird in mehrere periodisch wieder kehrende Zeitintervalle (I) unterteilt,
• – in jedem Zeitintervall (I) wird mindestens ein erstes Röntgenbild (A, B) vom Patienten (3) aufgenommen und dem jeweiligen Zeitintervall (I) zugeordnet,
• – ein zweites Röntgenbild (D, E) des Patienten (6) wird aufgenommen,
• – das zweite Röntgenbild (D, E) wird demjenigen ersten Röntgenbild (A, B) überlagert, dessen zugehöriges Zeitintervall (I) den Zeitpunkt (τ) der Aufnahme des zweiten Röntgenbildes (D, E) enthält.

The object is achieved by a method for generating an x-ray image of a patient with the following steps:

• a period (T) of a periodic body function ( 16 ) of the patient ( 6 ) is subdivided into several periodically recurring time intervals (I),
• In each time interval (I) at least a first X-ray image (A, B) is taken from the patient ( 3 ) and assigned to the respective time interval (I),
• A second x-ray image (D, E) of the patient ( 6 ) is recorded,
• - The second X-ray image (D, E) is superimposed on that first X-ray image (A, B) whose associated time interval (I) the time (τ) of the recording of the second X-ray image (D, E).

Of the Zero point for the determination of the period in the periodic body function is hereby freely selectable. In general, a characteristic point, e.g. the R-wave in an ECG of the patient, chosen. The period is then the distance between two consecutive following R-waves. The number of intervals into which the period resp. Period is decomposed, is freely selectable. The length of the individual time intervals does not necessarily have to be the same.

in the Course of time, e.g. while a medical treatment on the patient, are now the once fixed time intervals in synchronism with the periodic body function of the patient always one after the other and over and over again, thus recurring run through. Each of the time intervals is therefore always repeated again at the interval of the period.

In every time interval now becomes at least a first x-ray image taken by the patient and assigned to the respective time interval. Single x-rays different time intervals must thus not necessarily within the same period, but only within the respective time interval, but in one any period, be included. After completion of this process step exists for each time interval of the entire period a first x-ray image.

Now becomes at any arbitrary time a second x-ray image taken by the patient. The second radiograph is different from the first x-ray pictures usually by having in the patient either e.g. an actual change has taken place, e.g. by inserting a catheter or other medical instruments or by engaging in the patient e.g. while an operation, or that a potential change in the patient should be checked, e.g. whether a kidney stone has shrunk.

According to the invention will now the second X-ray image superimposed on the first X-ray image whose associated Time interval the time of recording the second x-ray image contains. Since thus corresponding first and second X-ray image in the same time interval, although different periods have been recorded, these are almost in phase with respect to the periodic body function. These are the periodically moving imaged body structures in the least approximate same spatial position and first and second X-ray image thus congruent unchanged Structures in the patient. Subtraction or crossfading method by superposition of first and second X-ray image can thus error-free or without artifacts are performed.

Compared to the known method results in the advantage that still the recording time of the second X-ray image freely selectable is not so a trigger signal and thus the periodic body function at a given phase time, namely the same of the corresponding one corresponding first x-ray, is fixed. By the appropriate overlay technique can so On the one hand arbitrary subtraction scenes (second X-ray images) on the other hand, e.g. from the X-ray device a mode change between the recording of the first and second X-ray image possible. Thus, e.g. between a DSA recording and a potentially following roadmap recording an ordinary one Fluoroskopieaufnahme of the patient are made. The timely and correct representation of the image content in the first and second X-ray photograph (e.g., relative to a periodic vascular motion in the patient) still received. The inventive method is for all X-ray applications, e.g. also for 3D X-ray, applicable.

The Time interval for the time of recording the second X-ray image can be specified. Thus, in the process according to the invention a kind of triggering in the conventional Meaning of the second radiograph, namely in the specified time interval, ie phase time, the periodic bodily function will be realized.

In Each time interval, a second X-ray image can be recorded. Thus stand for all Time intervals of the entire period not only first but also second x-rays to disposal. For the entire period or any time are thus corresponding first and second x-rays to disposal, so that corresponding evaluation methods for the X-ray images, e.g. Difference, are possible at any phase time.

First and second x-rays can periodically time-synchronized according to their assigned time intervals with the body function be presented in the manner of a film. The time synchronicity can here Naturally Total scaled, so slow-motion or time-lapse images the corresponding resulting film are possible. The viewer of the movie gets so a realistic picture impression of the dynamic conditions in the patient, with respect to first and second x-rays.

The inventive method is particularly suitable for so-called Roadmapröntgenverfahren. As the first X-ray pictures then a track image and as a second x-ray image a live image of a medical Roadmap procedure recorded. The first X-ray images thus provide one Template or basic situation of the dynamic processes in the patient, where the live image is coupled into the track image in the correct phase.

There a roadmap method, in particular e.g. in vascular surgery used, the first x-ray pictures from a contrasted blood vessel of the patient and the second X-ray image of a medical instrument in the area of the blood vessel become. In this case, the first x-ray pictures strictly speaking make respective ones Blank images and contrast images, which correspond to each other Zeitin tervalle were recorded and processed to difference images which then give the track image.

For such Difference pictures is the gift of a contrast agent in the patient necessary. Again, the time interval for the administration of the contrast agent be determined. The contrast agent is thus in phase or to a desired Phase time introduced into the patient. Through the targeted, or with respect to the phase of the periodic body function triggered contrast agent administration is a reduction in the amount of contrast agent possible, nevertheless meaningful radiographs because the contrast agent administration e.g. with the corresponding Recording time of the first X-ray images synchronized specifically and thus only in one of the multiple time intervals and not permanently necessary is.

For the generation a first x-ray image can also several X-ray images assigned to the same time interval be recorded and averaged in different periods. This leaves e.g. reduce the noise in first X-ray images or the picture quality otherwise improve. The phase equality and thus equality of coverage however, the images to be averaged remain secure.

For another Description of the invention is directed to the embodiments of the drawings. They show, in each case in a schematic outline sketch:

1 a medical workstation for performing a vascular surgery on a patient,

2 an ECG of the patient 1 and generating a series of first x-ray images.

3 the ECG off 2 and the generation of second X-ray images.

1 shows a medical workplace 2 with whose help a doctor 4 on a patient 6 performs a vascular surgery. The workplace 2 includes a patient bed 8th on the patient 6 is stored, an X-ray machine 10 and a catheter instrument 12 , At the patient 6 is a patient monitor 14 connected to monitor its body functions.

The patient monitor 14 takes, inter alia, the ECG 16 of the patient 6 on which in 1 is shown symbolically. 2 shows the ECG 16 again in detail. At the ECG 16 it is a periodic body function of the patient. From this are in 2 two full periods P1 and P2 between the respective R-waves 8th shown. For the method according to the invention, first several periods of the ECG lying before the period P1 16 measured to determine their average period T. The period T is then subdivided into, in the example, equal intervals I. The interval number n is sixteen in the example. This results in 16 equal time intervals I ₁ to I ₁₆ .

In the period P ₁ are now from the patient 6 with the help of the X-ray machine 10 sixteen, first X-ray images A ₁ to A ₁₆ recorded. In order to improve this 16 X-ray images A ₁ to A _16, sixteen X-ray images A ₁ are added to A ₁₆ and averaged with the recorded during the period P ₁ during the period P ₂ again. Each X-ray image A ₁ to A ₁₆ is recorded again in the corresponding interval I ₁ to I ₁₆ . The X-ray images A ₁ to A ₁₆ are therefore with respect to the ECG 16 or the R-wave 18 phase synchronized.

Since the mean period T is known, ECG signals can be used 16 whose period is significantly smaller than T, eg extrasystoles, are hidden, ie x-rays taken during these periods are discarded.

In the example off 2 Thus, the X-ray images A ₁ to A _{16 are formed} by averaging in each case two images of the periods P ₁ and P ₂ . These X-ray images form the so-called empty images for the following subtraction angiography. The patient 6 becomes namely contrast agent afterwards 20 administered, and accordingly 2 in periods after the period P ₂ lying periods of the ECG 16 sixteen further X-ray images B ₁ to B ₁₆ corresponding to the X-ray images A ₁ to A ₁₆ generated. This happens during the periods P ₃ , P ₄ and is in 2 only symbolically represented. According to the invention, the contrast agent 20 but very specifically in a given time interval, in the example in the time interval I ₄ injected into the patient. As a result, the contrast agent spreads particularly favorably in the vein system of the patient, not shown 6 from X-ray images B ₁ to B ₁₆ with as little contrast agent as possible 20 and thus under the least possible burden on the patient 6 to produce in sufficient quality. The X-ray images B ₁ to B ₁₆ represent the contrast agent images with a correspondingly contrasted vascular tree of the patient 6 represents.

In a subtraction method not explained in detail, the X-ray images A ₁ to A ₁₆ and the X-ray images B ₁ to B ₁₆ are subtracted from each other. This results in sixteen difference images C ₁ to C ₁₆ , on which only the contrasted contrast medium vascular tree of the patient 6 is visible.

At a later time, during the period P ₅ will now be a catheter 22 with the help of the catheter instrument 12 into the vascular tree of the patient 6 advanced. This also happens under fluoroscopy. This is done with a significantly reduced dose, so that only the catheter 22 in the sixteen recorded during the period P ₅ X-ray images D ₁ to D _{16 is} visible.

In order to provide guidance to the physician, each of the X-ray images D ₁ to D _{16 is} therefore superimposed with the vessel image, that is, difference image C ₁ to C ₁₆ . In the period P ₆ new X-ray images E ₁ to E _{16 are} recorded and superimposed again corresponding to the images C ₁ to C ₁₆ . The images C ₁ to C ₁₆ show this, comparatively in an endless loop one behind the other on a monitor 24 played, the periodically with the period T moving vascular tree of the patient 6 ,

The X-ray images D ₁ to D ₁₆ , E ₁ to E ₁₆ and all X-ray images taken in the following periods are also superimposed on the repeated images C ₁ to C ₁₆ and thus in phase with the period T in addition to the arbitrary shift by the doctor 4 moving catheter 22 always in the right place with respect to the vascular tree.

In an alternative not shown off Guidance form in the periods P ₅ and P ₆ not sixteen, but only a single X-ray image, for example, generated in the interval I ₁₃ . The triggering time in the interval I ₁₃ thus represents a triggered X-ray release for the X-ray image. The difference images C ₁ to C ₁₆ are then not cinematic on the monitor 24 but, according to the interval I ₁₃ used as the triggering time, the differential image C ₁₃ generated in preceding intervals I _{13 of} the periods P ₁ to P ₄ is assigned and superimposed.

Claims (8)

Method for generating an X-ray image (X) of a patient ( 6 ), comprising the following steps: - a period duration (T) of a periodic body function ( 16 ) of the patient ( 6 ) is subdivided into several periodically recurring time intervals (I), in each time interval (I) at least one first X-ray image (A, B) is taken by the patient ( 3 ) and assigned to the respective time interval (I), - a second X-ray image (D, E) of the patient ( 6 ) is recorded, - the second X-ray image (D, E) is superimposed on that first X-ray image (A, B) whose associated time interval (I) contains the time (τ) of the acquisition of the second X-ray image (D, E). The method of claim 1, wherein the time interval (I) for the time (τ) the recording of the second X-ray image (D, E) is determined. The method of claim 1 or 2, wherein in each Time interval (I) a second X-ray image (D, E) is recorded. Method according to one of the preceding claims, in which the first (A, B) and second X-ray images (D, E) are periodically synchronized with the body function ( 16 ) are presented in the manner of a film. Method according to one of the preceding claims, in the first X-ray images (A, B) track images (C) and as a second X-ray image (D, E) a live image a medical roadmap procedure. Method according to Claim 5, in which the first X-ray images (A, B) are from a contrasted ( 20 ) Blood vessel of the patient ( 6 ), and the second X-ray image (D, E) of a medical instrument ( 22 ) in the area of the blood vessel. Method according to claim 5 or 6, wherein the patient ( 6 ) Contrast agent ( 20 ), in which the time interval (I) for the administration of the contrast agent ( 20 ). Method according to one of the preceding claims, in for generating a first x-ray image (A, B) several, the same time interval (I) associated X-ray images (X) recorded in different periods (P) and averaged become.