DE102020214568A1 - Computer-implemented method for imaging support in brachytherapy treatment, imaging device, computer program and electronically readable data carrier - Google Patents

Abstract

Computer-implemented method for imaging support in a brachytherapy treatment with at least one radiation source (18) guided according to a treatment plan by means of a medical guidance instrument (3) to a treatment site (19) in a treatment area (1) for a treatment time, wherein at least at a first point in time an anatomy image data set of the Treatment area (1) is recorded with a magnetic resonance device (8) of an imaging device (6) which, in addition to the magnetic resonance device (8), also has an X-ray device (9) registered with it, the treatment area (1) being in the field of view of both the magnetic resonance device (8 ) and the x-ray device (9) is placed, at the first and/or at least one further point in time, an x-ray image data set registered with the anatomy image data set for locating the at least one guide instrument (3) and/or one through the guide instrument (3). guided additional instrument (17), and in a control device (13) of the imaging device (6) the anatomy image data set and the x-ray image data set are evaluated together to determine the treatment plan and/or checking information that allows checking compliance with the treatment plan.

Description

The invention relates to a computer-implemented method for imaging support in a brachytherapy treatment with at least one radiation source guided according to a treatment plan by means of a medical guide instrument, in particular a catheter and/or a needle and/or a tube, to a treatment site in a treatment area for a treatment time. In addition, the invention relates to an imaging device, a computer program and an electronically readable data carrier.

Brachytherapy refers to internal radiotherapy measures in which at least one radioactive radiation source is placed inside or in the immediate vicinity of the tissue/anatomical section to be irradiated within the patient's body. Common uses of brachytherapy include cancers of the cervix, prostate, breast, and/or skin.

In a brachytherapy treatment, guide instruments are usually first introduced into the patient's body in such a way that the tips, ie end areas, of the guide instruments are located adjacent to or within the anatomy section to be treated in the treatment area. These guiding instruments and/or at least their tips or distal end areas are also referred to as applicators. For example, they can be inserted under ultrasound monitoring and positioned in the treatment area. After the positioning of the guide instruments, it is known to first carry out a treatment plan, for which images can be used, for example. As part of the treatment planning, a treatment plan is created, in particular at least partially automatically, which indicates from which treatment locations within the guidance instruments the radiation source should irradiate the anatomy, i.e. in particular the anatomy section to be treated, for how long (treatment time). The guidance instruments can be connected to a so-called reloading device, also referred to as an afterloader, which in particular can have a stepper motor in order to introduce the radiation source into the guidance instrument and to advance it within the guidance instrument to the treatment site. Here, the reloading device is supplied with the appropriate treatment plan and can then control the stepping motor accordingly. When the treatment time has elapsed, the radiation source is removed from the treatment site and, if there are other treatment sites, moved to the next treatment site and held there for the treatment time assigned to it. After completion of the irradiation that takes place in this way, the guide instruments can also be removed again.

In this context, it is known in particular to use a plurality of guidance instruments into which at least one radiation source can be inserted one after the other or simultaneously via various so-called “channels” of the reloading device. In this way, for example, guide instruments can be placed at different positions relative to the tissue section to be treated, for example a tumor, in order to achieve the best possible radiation treatment.

Different variants of brachytherapy are known, for example HDR brachytherapy (high dose rate brachytherapy) and PDR brachytherapy (pulsed dose rate brachytherapy). In the aforementioned variants of brachytherapy, extremely high doses with high gradients are used in a few treatment sections, in particular to treat solid tumors. The positioning of the radiation sources is extremely important with such high doses. For example, an uncertainty of one millimeter can already result in a 20% shift in dose at 10 mm from the radiation source for a typical ¹⁹² Ir source, as described in an article by MJ Rivard et al, “Update of AAPM Task group no. 43 Report: A revised AAPM protocol for brachytherapy dose calculations”, Med. Phys. 31:633-674, 2004. It follows that poor execution of a planned treatment has significant clinical implications, since high doses are administered in seconds and errors in a single treatment step cannot be easily corrected, as exemplified in an article by Ryan L Smith et al, "An integrated system for clinical treatment verification of HDR prostate brachytherapy combining source tracking with pretreatment imaging", Brachytherapy 17: 111-121, 2018. The ICRP (International Commission on Radiological Protection) published a study in 2005 showing that a large proportion of radiation incidents are caused by human error in manual procedures (ICRP, Prevention of High-dose-rate Brachytherapy Accidents, ICRP Publication 97, Ann ICRP 2005;35:1-51).

Since brachytherapy can be carried out with a variety of instruments, in particular guiding instruments, for example including interstitial needles, intracavity applicators and hoses, these different types of insertion aids for radiation sources in the In the following referred to as management tools. Other instruments used as part of brachytherapy, in particular those with which the radiation source is placed in the guide instrument, should be referred to as additional instruments.

• - ein oder mehrere Führungsinstrumente können sich in dem Zeitraum zwischen der Aufnahme eines Planungsbildes und dem eigentlichen Behandlungsvorgang verschieben, beispielsweise aufgrund von Patientenbewegung und/oder Wechseln des Behandlungsraumes.
• - Organe können sich im Zeitraum zwischen der Erstellung des Behandlungsplans und dem eigentlichen Behandlungsvorgang füllen, beispielsweise im Fall von einer Blase.
• - Es kann eine fehlerhafte Identifizierung der Spitze des Führungsinstruments, wo üblicherweise die radioaktive Strahlungsquelle ihren Weg als erster Behandlungsort beginnt, erfolgen. Dies tritt insbesondere dann auf, wenn Magnetresonanzbildgebung als die Grundlage für die Behandlungsplanung verwendet wird, da in Magnetresonanzdatensätzen die Spitze des Führungsinstruments schlecht identifiziert werden kann.
• - Ein fehlerhaft identifiziertes Führungsinstrument in einem Planungsbild, beispielsweise bei Kreuzung von Führungsinstrumenten, wenn Tiefeninformation fehlt, kann zu einem systematischen Fehler führen, der sich für den Rest des Behandlungsvorgangs fortsetzt, insbesondere von der Erstellung des Behandlungsplans bis hin zur Anwendung der Strahlung.
• - Wenn ein oder mehrere Kanäle der Nachladeeinrichtung („Afterloader Channels“) falsch verbunden sind, beispielsweise durch den Austausch zweier Verbinder aufgrund eines menschlichen Fehlverhaltens, wird der Behandlungsplan falsch durchgeführt.

If there is no monitoring or verification during brachytherapy treatment, the following problems can occur, for example:

• - One or more guide instruments can shift in the period between the recording of a planning image and the actual treatment process, for example due to patient movement and/or changing the treatment room.
• - Organs can fill up in the period between the creation of the treatment plan and the actual treatment procedure, for example in the case of a blister.
• - There may be an erroneous identification of the tip of the guidance instrument, where the radioactive radiation source usually begins its path as the first treatment site. This occurs particularly when magnetic resonance imaging is used as the basis for treatment planning, since the tip of the guide instrument can be poorly identified in magnetic resonance data sets.
• - An incorrectly identified guidance tool in a planning image, e.g. at the crossing of guidance tools, when depth information is missing, can lead to a systematic error that continues for the rest of the treatment process, especially from the creation of the treatment plan to the application of the radiation.
• - If one or more Afterloader Channels are incorrectly connected, for example by exchanging two connectors due to human error, the treatment plan will be performed incorrectly.

In today's clinical routine, brachytherapy treatments are often carried out without monitoring/checking, so to speak "blindly" by connecting the different guide devices to different channels of the afterloading device and starting the treatment according to the treatment plan generated on the basis of a previous image recording. It also follows from this that there is no documentation to complete the patient file, only a log file of the reloading device, for example. However, the problems just outlined cannot be solved in this way.

In order to solve this problem, it has already been proposed in the prior art to carry out in vivo dosimetry with point detectors which are positioned close to the path of the radioactive radiation source. However, it is disadvantageous that further invasive steps are required and the point detectors can only be positioned in naturally occurring cavities or on the patient's skin, so that the radiation dose can only be measured at points.

It has also been proposed to use electro magnetic tracking (EMT) since such tracking systems have excellent spatial resolution. The problem here, however, is the intrinsically different coordinate system compared to the imaging system used to create the treatment plan, with which the contouring of the anatomy section to be treated and the dose calculations were carried out. However, the ultimate goal of treatment verification and treatment monitoring is to track the radiation source in relation to the human anatomy, which is not achieved via the EMT approach because the anatomy cannot be imaged here.

A similar problem arises with the use of flat panel detectors for X-rays, which have been proposed by research groups. Here, too, the problem arises that the coordinate system of the flat panel detector cannot be correlated with the coordinates of the imaging system that shows the anatomy, so that no in-vivo dosimetry is possible. It was also suggested in this context to recalculate the dose after treatment using the treatment times and treatment locations as measured with the flat panel detector. In this way, the user still has no possibility to intervene or interrupt the treatment after the determination takes place after the end of the treatment process. In addition, it also applies here that there is uncertainty in the position of the flat panel detector relative to the anatomy of the patient.

The invention is therefore based on the object of specifying an improved monitoring and checking option in brachytherapy, in which an assessment with regard to the patient's anatomy is made possible during the treatment.

To solve this problem, a method, an imaging device, a computer program and an electronically readable data carrier according to the independent patents are provided according to the invention envisaged. Advantageous developments result from the dependent claims.

• - zu wenigstens einem ersten Zeitpunkt, insbesondere wenigstens vor Beginn des Behandlungsvorgangs mit der wenigstens einen Strahlungsquelle bei positioniertem Führungsinstrument, ein Anatomiebilddatensatz des Behandlungsbereichs mit einer Magnetresonanzeinrichtung einer Bildgebungseinrichtung, die neben der Magnetresonanzeinrichtung auch eine mit dieser registrierte Röntgeneinrichtung aufweist, aufgenommen wird, wobei der Behandlungsbereich im Blickfeld sowohl der Magnetresonanzeinrichtung als auch der Röntgeneinrichtung platziert ist,
• - zu dem ersten und/oder wenigstens einem weiteren Zeitpunkt ein mit dem Anatomiebilddatensatz registrierter Röntgenbilddatensatz zur Lokalisierung des wenigstens einen Führungsinstruments und/oder eines durch das Führungsinstrument eingeführten, insbesondere die wenigstens eine Strahlungsquelle tragenden, Zusatzinstruments aufgenommen wird, und
• - in einer Steuereinrichtung der Bildgebungseinrichtung der Anatomiebilddatensatz und der Röntgenbilddatensatz zur Ermittlung des Behandlungsplans und/oder einer die Überprüfung der Einhaltung des Behandlungsplans erlaubenden Überprüfungsinformation gemeinsam ausgewertet werden.

In a computer-implemented method of the type mentioned, it is therefore provided according to the present invention that

• - at least at a first point in time, in particular at least before the start of the treatment process with the at least one radiation source with the guide instrument positioned, an anatomy image data set of the treatment area is recorded with a magnetic resonance device of an imaging device which, in addition to the magnetic resonance device, also has an x-ray device registered with it, with the treatment area placed in the field of view of both the magnetic resonance facility and the X-ray facility,
• - at the first and/or at least one further point in time, an X-ray image data set registered with the anatomy image data set is recorded for locating the at least one guiding instrument and/or an additional instrument inserted through the guiding instrument, in particular carrying the at least one radiation source, and
• - In a control device of the imaging device, the anatomy image data set and the x-ray image data set are evaluated together to determine the treatment plan and/or checking information that allows checking compliance with the treatment plan.

According to the invention, it is therefore proposed, in particular for checking the implementation of a treatment plan, to use a hybrid imaging device with a magnetic resonance device and an X-ray device during brachytherapy treatment, the X-ray device and the magnetic resonance device being registered with one another and having at least partially overlapping and/or corresponding fields of view. Hybrid imaging solutions of this type have already been proposed in principle in the prior art and are characterized, for example, by the fact that a cylindrical main magnet unit, into which the patient is moved into a patient receptacle, is divided into three areas, for example, with the middle area being made of metal components, in particular Coil components, is kept free and offers space for the components of the X-ray device. Of course, other configurations are fundamentally conceivable and can be used within the scope of the present invention. Purely as an example for an embodiment of such an imaging device WO 2018/095587 A1 referred.

According to the present invention, it has now been recognized that with regard to brachytherapy treatment processes, in particular HDR or PDR brachytherapy treatment processes, these two modalities complement each other excellently, since the anatomy of the patient to be treated can be excellently represented by means of magnetic resonance imaging, while X-ray imaging with particular Accuracy and reliability of the instruments used, specifically the guidance instruments and/or additional instruments, in particular also the radioactive radiation source forming part of an additional instrument, can be detected. After the magnetic resonance device and the X-ray device have been registered with one another, this also applies to magnetic resonance data sets, here anatomy image data sets, and X-ray image data sets, so that positions of instruments determined using X-ray imaging, for example, are also known in relation to the anatomy image data set determined using magnetic resonance imaging. This means that, if necessary, it can be checked during the entire treatment process whether the position of the radiation source relative to the anatomy corresponds to the specifications of the treatment plan. According to the invention, this is represented by the verification information, which can be particularly advantageously output to a person performing the brachytherapy treatment via an output device of the imaging device, for example a monitor and/or an acoustic output device.

However, it has also been shown that such a hybrid imaging device with an X-ray device and a magnetic resonance device is excellently suited to creating the treatment plan itself, so that the information that leads to the creation of the treatment plan and the treatment locations are also included in the treatment plan later recorded image data, in particular the anatomy image data set and the X-ray image data set, are registered, which allows immediate monitoring and verification. The creation of a treatment plan can include, for example, the contouring of the anatomy section to be treated, for example a solid tumor, which can also be achieved at least partially automatically, for example, by means of fundamentally known segmentation methods. This can be followed, for example, by the dose calculation, from which suitable treatment locations and treatment times can be derived. In this regard, too, work can be carried out automatically at least partially, preferably completely, in particular in the control device.

A main focus of the present invention, however, lies in the monitoring and checking of the subsequent treatment process, ie the use of the radiation source in accordance with the treatment plan that has already been determined. It was recognized that, in particular when using afterloaders, which have already been explained in the introduction, the patient can easily remain within the patient admission of the imaging device, since the guide instruments have already been introduced and through them the radiation source is automatically detected by means of a corresponding additional instrument that Radiation source carries, can be brought to the treatment sites through the particular hollow guide means. The reloading device usually receives the treatment plan and, once the length of the guide instruments that are connected to the corresponding channels of the reloading device is known, can use actuators provided to move the at least one additional instrument with the at least one radiation source into the at least one guide instrument to reach the treatment sites and leave the radiation source there for the duration of the treatment. Since the reloading device has no knowledge whatsoever of the anatomy/current position relative to it, the method according to the invention can therefore make it possible to collect verification information that describes the correctness of the treatment site that has been approached. However, other application options for checking are also conceivable, as will be explained in more detail below.

The guiding instrument can be, for example, an interstitial needle, a catheter and/or a tube. Other management tools are also conceivable in principle. Additional instruments can have, for example, a wire which can be guided through the hollow guide instrument and on which the radiation source is arranged. An anatomy section to be treated can be, for example, a tumor in an organ and/or the organ itself, wherein the organ can be a prostate and/or a cervix, for example. It is also not important within the scope of the present invention how the guiding instruments were introduced into the patient, for which purpose, for example, ultrasound and the like can be used. It is also conceivable that the at least one guide instrument is inserted in a manner monitored by the imaging device by means of imaging.

This is because the present invention is not aimed at the actual brachytherapy treatment, which merely represents the context for the use of an operating method for the imaging device that is not linked to the actual brachytherapy treatment. In other words, the method according to the invention can also be understood as a method for operating an imaging device for imaging support in a brachytherapy treatment, wherein all steps can be carried out within the control device of the imaging device, so that the method is self-contained and in particular can be separated from the actual brachytherapy treatment .

By using a hybrid modality, namely an imaging device with a magnetic resonance device and an X-ray device, information about the anatomy and medical instruments that is directly correlated in terms of time and space is obtained, which is therefore in a direct context with one another and is used particularly advantageously for monitoring and checking a brachytherapy treatment process be able. Due to the common field of view of the X-ray device and the magnetic resonance device, a movement in the sense of a transfer of the patient is not necessary; Access to the patient during the treatment process is also not necessary, particularly when using a reloading device.

Depending on the extent to which it can be ensured that no or only insignificant movements occur within the treatment area of the patient, it can be determined how frequently anatomy image datasets are recorded. If a movement in the treatment area or the treatment area during the treatment process with the at least one radiation source is unthinkable or extremely improbable, an anatomy image data set recorded at the beginning of the treatment process can also be sufficient. However, ultimately permanent magnetic resonance monitoring is also conceivable, which means that new magnetic resonance image datasets are recorded at least cyclically as anatomy image datasets, in which case X-ray image datasets with a significantly shorter recording time can then be assigned to corresponding anatomy image datasets, which in particular were recorded at least essentially synchronously with them. For example, if the treatment process has a total duration in which physiological processes such as the filling of a bladder or rectal emptying play a role, the anatomy image data set can document the changes in the anatomy in order to check whether the originally determined treatment plan is still valid and/or or whether a new/adjusted treatment plan is necessary to avoid radiation doses in unplanned healthy anatomy areas.

If the imaging device, which is preferred, is also used to create the treatment plan itself, the positions of the guide instruments (applicators) known from the X-ray dataset and the anatomy known from the anatomy image dataset can be merged, whereby the relative position of the applicators, i.e. in particular the Tips of the guide instruments for which the anatomy is known and can be determined, preferably automatically, according to treatment locations of the radiation source in the applicator and treatment times. In the case of guiding instruments made of a material that is less visible in x-ray imaging, for example plastic, the guiding instrument can have markers at least at its tip in order to achieve improved localization in the x-ray image data set.

Preferably, in a treatment plan determined based on and/or additionally dependent on a preoperative image of the treatment area not recorded with the imaging device and/or preoperative image recording, the preoperative image recording can be registered by recording with the imaging device and/or by a registration process with regard to the anatomy image data set. In this way, anatomical positions from an external or preoperative image recording that is used to create the treatment plan are also known in the coordinate system of the imaging device and can be set in relation to corresponding anatomical features in the anatomy image data set and/or the position of the instruments.

A verification image data record showing at least part of the anatomy of the treatment area together with the at least one guidance instrument and/or additional instrument can be determined as verification information. Such a verification image data record can be used by a person performing the treatment for visual monitoring and verification of the implementation of the treatment plan, for example to be able to better recognize displacements of the guide instruments and/or the anatomy. It is particularly advantageous in this connection if at least one of the at least one treatment site, in particular assignable to the guide instrument and/or additional instrument assigned to the treatment site, is inserted and displayed in the verification image data set. In addition to the treatment location, which can be displayed for a direct comparison, other information can of course also be determined by evaluating the image datasets and/or the treatment plan and displayed in the verification image dataset, in particular the treatment times and/or a shift that has already been determined by image data evaluation as verification information.

With particular advantage, at least one of the at least one X-ray image dataset can be recorded as a three-dimensional image dataset and/or as at least two projection images, in particular using at least two X-ray sources with a respective assigned X-ray detector, recorded at least partially simultaneously, projection images of different projection geometry, in particular projection directions perpendicular to one another at least in pairs, be recorded, the control device determining a three-dimensional position of the guide instrument and/or the additional instrument when determining the verification information. To record a three-dimensional image data set as an X-ray image data set, at least the X-ray source can be moved around the patient, for example along a circular path, with projection images recorded from different projection directions being able to be reconstructed into the three-dimensional image data set, as is already known from computed tomography imaging. However, the imaging device can particularly advantageously have two recording arrangements, each of which can have an x-ray source and an associated x-ray detector, for example a flat-panel detector, so that x-ray images can be recorded simultaneously with projection directions at an angle to one another. The projection directions are particularly advantageous when recording the projection images, perpendicular to one another. This takes into account the fact that the recording of the X-ray image data set essentially serves to determine a current position of the guide instrument and/or the additional instrument, in particular the radiation source, as precisely as possible, which can easily be derived by back-projection from two projection images recorded simultaneously in projection directions that are perpendicular to one another can, as is known in the prior art, for example an article by M. Wagner et al., "4D interventional device reconstruction from biplane fluoroscopy", Med. Phys. 43 (2016), pages 1324-34. In this way, it is possible to determine the positions of instruments in the treatment area in a particularly precise and simple manner.

In particular when using a reloading device, as already described, it is known that the reloading device initially has a placeholder (dummy) for the radiation source in order to check an unhindered movement through the guide instruments Inserts the additional instrument into each guide instrument up to the tip and withdraws it again. This is done sequentially for all channels/leadership tools. This automatic verification process is usually not monitored, but can play an important role in the verification of the treatment plan according to the invention, so that it is proposed that during the introduction of an additional instrument comprising a placeholder for the radiation source, in order to check that the introduction path is free of obstacles, the X-ray device is operated as a fluoroscopy monitor for recording the X-ray image data sets. This particularly advantageously allows the checking information for checking a correct assignment of treatment sites to guide instruments to be determined in the case of a plurality of guide instruments assigned to different treatment locations. Whenever the "dummy source", i.e. the placeholder for the radiation source, is moved through each guiding instrument in the distal direction and then again proximally, in particular to the reloading device, in order to check that the path formed in the guiding instrument is free of obstacles, can Fluoroscopy can be performed, in particular using the orthogonal recording arrangements mentioned, in order to be able to determine the position of the placeholder three-dimensionally, from which, after the channels are checked one after the other, it can be concluded whether the guide instruments are connected to the correct channels of the afterloading device, such as this is provided for by the treatment plan. Only then will the correct treatment locations be approached via the respective channel, which means only then will the treatment locations in the treatment plan be correctly assigned to the management instruments. If the verification information indicates an error, the channels can be swapped accordingly and the verification process can be repeated. If, for example, the connections of two guide instruments to corresponding channels of the reloading device have been swapped, for example the first and second channel, one will be able to determine by comparing the channel order according to the treatment plan and the order in which the placeholder visits the corresponding treatment sites/guide instruments that there must be an incorrect assignment, so that the verification information can, for example, directly display the error and the replacement instruction when this error is automatically detected, or, for example, by observing correspondingly output verification information, optionally comprising at least one verification image data set, a person carrying out the treatment can determine this himself. An automatic check, in particular in addition to a visual check by the treatment person, is preferred and can also be carried out, since the treatment plan and thus its treatment locations and the assignment to the treatment channels are all expediently known in the coordinate system of the imaging device. It should be noted that a communication link between the reloading device and the imaging device is also particularly advantageous in this context, since the reloading device can then send a trigger signal indicating the start of the check for freedom from obstacles to the imaging device, which is then associated with the fluoroscopic monitoring and the determination of the verification information can begin.

In addition to this check, which is already carried out before the radiation source is used, there can, generally speaking, be continuous monitoring of the correct implementation of the treatment plan, which can also be adjusted and/or redetermined if the deviations are too great. In other words, it can be provided that when a deviation criterion evaluating the verification information is met, the treatment plan is adjusted and/or redetermined based on the verification information and/or the anatomy image data set and/or X-ray image data set used to determine it. In this way it is therefore possible to react in real time during the treatment and thus in particular to avoid and/or at least reduce undesired doses for specific anatomical regions and/or inadequate irradiation of the anatomical section.

A specific embodiment of the present invention provides that the imaging device is connected via a communication link to a reloading device for controlling the at least one additional instrument on the basis of the treatment plan. Such a reloading device can have, for example, a radioactivity-shielding container for the at least one radiation source and/or the at least one additional instrument carrying it, in which case an actuator, in particular at least one stepping motor, can be provided in order to rotate the at least one additional instrument carrying the radiation source by a corresponding To insert a channel associated channel connection into a guide instrument and to advance through this to a treatment site. Such reloading devices are also referred to as afterloaders. They usually receive the treatment plan, which then specifies for each of the channels connected to the guiding instruments which treatment sites (in particular with regard to the tip of the guiding instrument) are approached should and how long (treatment time) the radiation source should remain at these treatment locations. The actuator system, in particular the stepper motor, is then operated accordingly. As already mentioned, however, the reloading device knows nothing about the anatomy, its position in relation to the radiation source and/or the guiding instrument. Internal inaccuracies due to the stepping motor can occur as well as changes to the anatomy and/or the guide instrument that are not noticeable due to the reloading device. Consequently, treatment errors cannot be completely ruled out despite the processing of the treatment plan received.

To remedy this problem, a particularly advantageous embodiment of the present invention provides that upon receipt of a trigger signal indicating completed positioning of at least one of the at least one radiation source according to the treatment plan, at least one X-ray data set is recorded and the verification information for verifying the correct positioning is determined. For example, whenever the reloading device has completed a positioning command and the radiation source is now left at the supposed treatment site for the duration of the treatment, a trigger signal can be generated and an X-ray image data set can be recorded immediately, which shows the position of the additional instrument carrying the radiation source, in particular the radiation source as Part of the additional instrument itself, which makes it ascertainable. The already mentioned recording arrangements using two mutually perpendicular projection directions can be used with particular advantage in order to simultaneously generate an X-ray image data set in an extremely short time, from which the three-dimensional position of the additional instrument, specifically the radiation source, can be derived and with the provided according to the treatment plan Treatment site, in particular due to the anatomy image data set with respect to the anatomy, can be compared. If deviations occur here, a warning can be issued. However, it can be provided with particular advantage that, in the event of a deviation in the position of the radiation source from the treatment site, which is determined by the control device on the basis of the checking information and can be corrected within the guidance instrument, correction information for controlling the reloading device for repositioning the Radiation source is sent to the reloading device. In this case, deviations in relation to the anatomy, described by the anatomy image data set, are monitored in particular. The determination of the correctable deviation in the position of the radiation source can be an embodiment of a deviation criterion since the correction information that is determined from this ultimately describes a modification/adaptation of the treatment plan in real time.

It should also be noted at this point that within the scope of the method according to the invention, such trigger signals can also be used for further checking of compliance with the treatment plan, namely with regard to the treatment times. A measurement of the time difference between such trigger signals results in the residence time of the radiation source if the corresponding shift time is also taken into account, which can be compared with the treatment time in the control device in order to also generate checking information in this regard.

In a further, particularly advantageous embodiment of the present invention, it can be provided that anatomy image datasets and/or X-ray image datasets are recorded at a plurality of points in time and, as verification information, by comparing anatomy image datasets and/or X-ray image datasets recorded at different points in time, change information with regard to the treatment area, in particular with regard to the relative Position of at least one of the at least one guide instrument in relation to an anatomy section to be treated and/or with regard to a change in shape of the anatomy section is determined, with the treatment plan being adapted and/or redetermined if the change exceeds a threshold value and/or the treatment process being aborted. For example, if the treatment process has a total duration in which physiological processes such as filling the bladder or rectal emptying play a role, the original assumptions when determining the treatment plan may turn out to be wrong, but the anatomy image data set in particular shows such changes in the anatomy of the treatment area. Such changes can also occur as a result of patient movements, with differences occurring, of course, when the position/location of guide instruments changes, which can be determined via the X-ray image data set. Whenever changes of this type are detected, they are checked against a threshold value in a deviation criterion. Several deviation criteria with different threshold values can also be provided, with one being assigned an adaptation of the treatment plan and another being assigned a new determination of the treatment plan. Deviation criteria are also conceivable, especially in the case of very strong changes, if the treatment is fulfilled process - at least for the time being - is completely aborted, which can be expedient, for example, in less preferred exemplary embodiments in which the treatment plan is not registered with the imaging device. In this way, it is possible to react promptly to physiological or other processes in the treatment area that change the situation there.

As already mentioned, it can be particularly expedient within the scope of the present invention for at least one anatomy image data set and at least one x-ray image data set to be recorded synchronously with the imaging device. Depending on the requested synchronicity of the magnetic resonance imaging and the x-ray imaging or the tolerable time delay between the acquisition of the anatomy image data set and the x-ray image data set, different operating modes of the imaging device can be considered.

In the case of sequential imaging, the X-ray imaging can take place after the acquisition of the anatomy image data set by magnetic resonance imaging or before this. Since typical three-dimensional magnetic resonance imaging of a treatment area can take a few seconds to a few minutes, there is a corresponding time delay between the magnetic resonance imaging and the X-ray imaging.

In an advantageous embodiment of the present invention, however, it can be provided that the synchronous recording is carried out at least partially by interlaced recording sections for the magnetic resonance imaging and the X-ray imaging and/or by carrying out the X-ray imaging in pulse-free sections of at least one magnetic resonance sequence used and/or by carrying out the X-ray imaging in parallel to a Readout section of the at least one used magnetic resonance sequence takes place. These other operating modes or operating variants were named in the order of increasing complexity, since problems can also arise, particularly in the case of actually simultaneous X-ray imaging and magnetic resonance imaging, which can be counteracted by appropriate correction and/or compensation measures, in particular interactions between the X-ray detector and/or the gradient system and /or the high-frequency system of the magnetic resonance facility. For example, it has been found that gradient pulses can trigger signals in X-ray detectors, while in turn the operation of detectors during the readout of magnetic resonance signals can lead to radio frequency interference. Appropriate approaches to a solution, as described in the prior art, can be used in order to still enable this in corresponding operating modes.

In the case of interleaved imaging, time segments of the magnetic resonance imaging process that can be separated in time, for example the recording of different slices or echoes, and the recording of X-ray images follow one another in alternation. In a first variant of parallel imaging, X-ray images can be used, for example, in a pulse-free section of the at least one magnetic resonance sequence used, for example when there are no gradient pulses and no radio-frequency pulses between a readout time window and an excitation time window. However, in a second variant of the parallel imaging, with the provision of appropriate correction and/or compensation measures, it is also conceivable to achieve perfect synchronicity, so to speak, by recording x-ray images during the readout time window in the magnetic resonance sequence.

Within the scope of the present invention, it has been shown that for the purposes of brachytherapy monitoring, the variant of interlaced imaging and parallel imaging provide comparable clinical information, with the variant of sequential imaging always being able to be used when relevant physiological processes are rather slow .

In summary and in general terms, for brachytherapy treatment, the present invention combines magnetic resonance imaging and X-ray imaging in a single hybrid imaging device with a single, defined coordinate system such that there is intrinsic registration of the images without the need to move the patient between different modalities and with high time correlation. so that relevant changes that call into question the validity or correct implementation of the treatment plan, both with regard to the anatomy and with regard to the instruments, can be determined in real time and a corresponding reaction can be made by adapting the treatment plan or otherwise.

In addition to the method, the invention also relates to an imaging device, comprising a magnetic resonance device, an x-ray device registered with the magnetic resonance device, and a control device that is designed to carry out the method according to the invention. All statements relating to the method according to the invention can be transferred analogously to the imaging device according to the invention gene, with which therefore also the advantages already mentioned can be obtained.

The control device can have at least one processor and at least one memory device. To implement the method according to the invention, the control device can first have a recording unit, via which the magnetic resonance device and the X-ray device can be controlled in order to record the anatomy image data set and the X-ray image data set. The control device can also include a determination unit for determining the verification information. Of course, other functional units are also conceivable in the control device, for example a communication unit for receiving trigger signals from a reloading device, a checking unit for evaluating deviation criteria, an adjustment unit for adapting the treatment plan, in which correction information for the reloading device can also be determined, and a planning unit to determine or re-determine a treatment plan. A user interface of the control device can be used to output verification information, in particular a verification image data set, and/or to receive inputs from a treatment person.

A computer program according to the invention can be loaded directly into a memory of a control device of an imaging device, for example, and has program means to carry out the steps of a method according to the invention when the computer program is executed in the control device of the imaging device. The computer program can be stored on an electronically readable data carrier according to the invention, which consequently includes electronically readable control information stored thereon, which includes at least one computer program according to the invention and is designed in such a way that when the data carrier is used in a control device of an imaging device, it carries out a method according to the invention. The data carrier can in particular be a non-transient data carrier, for example a CD-ROM.

• 1 einen Ablaufplan eines Ausführungsbeispiels des erfindungsgemäßen Verfahrens,
• 2 eine Ansicht eines Behandlungsbereichs,
• 3 eine Ansicht einer erfindungsgemäßen Bildgebungseinrichtung und weiterer Komponenten,
• 4 eine zweite Ansicht des Behandlungsbereichs, und
• 5 den funktionalen Aufbau der Steuereinrichtung der Bildgebungseinrichtung.

Further advantages and details of the present invention result from the exemplary embodiments described below and from the drawing. show:

• 1 a flowchart of an embodiment of the method according to the invention,
• 2 a view of a treatment area,
• 3 a view of an imaging device according to the invention and other components,
• 4 a second view of the treatment area, and
• 5 the functional structure of the control device of the imaging device.

1 shows a flowchart of an embodiment of a method according to the invention. This is used for image support, in particular monitoring and checking, for carrying out a brachytherapy treatment in a treatment area of a patient, in which case an anatomy section within the treatment area is to be subjected to an HDR or PDR brachytherapy treatment. For example, the anatomy section can be a prostate. In this context, guidance instruments, in the example of the prostate in particular interstitial needles, are used, which are hollow and define a movement path for an additional instrument that has a radioactive radiation source inside them. These guiding instruments are positioned with their tips adjacent to the anatomy section and/or within the anatomy section in a preceding step not belonging to the method according to the invention, for example under ultrasound monitoring. The tip area or the guide instruments as a whole can also be referred to as applicators.

2 shows an exemplary situation in a schematically indicated treatment area 1 with an anatomy section 2 to be treated, for example a prostate. In the present example, for the sake of simplicity, three guide instruments 3, which are designed as interstitial needles, are introduced into the treatment area and, in the present case, specifically into or adjacent to the anatomy section 2.

After the guiding instruments 3 have been positioned accordingly, the patient 4, as in 3 shown, positioned in a patient recording 5 of an imaging device 6 according to the invention by means of a patient couch 7 such that the treatment area 1 is within the field of view of both a magnetic resonance device 8 forming part of the imaging device 6 and an X-ray device 9 also forming part of the hybrid imaging device 6. The magnetic resonance device 8 and the X-ray device 9 are registered with one another, ie they use the same coordinate system. In the present exemplary embodiment, the X-ray device is in a section of a substantially cylindrical main magnet unit 10 of the imaging device 6 arranged in which no parts of the different coil arrangements for the magnetic resonance imaging are provided, in particular the preferably superconducting coil for the main magnet, the high-frequency coil arrangement and the gradient coil arrangement. The x-ray device 9 in the present case comprises two recording arrangements that are different, preferably mutually perpendicular, and use projection directions, at least for the implementation of the method according to the invention, each with an x-ray source 11 and an x-ray detector 12, with only the x-ray detector 12 of the second recording arrangement being indicated here due to the sectional view.

Each of the two recording arrangements can be mounted so that it can rotate, so that in particular projection images for a CT image data set can also be recorded; However, an embodiment with fixed recording arrangements is also conceivable, since this simplifies implementation in combination with magnetic resonance imaging.

The operation of the imaging device 6 is controlled by a control device 13, which is also designed to carry out the method according to the invention, as will be described further below, which is therefore an operating method for the imaging device 6.

Before the method according to the invention begins, however, the guidance instruments 3 are connected to corresponding channels 14 of an afterloading device 15 (afterloader). The reloading device 15 is designed in particular to introduce a radiation source stored in a radiation-tight vessel by means of an additional instrument that carries the radiation source through one of the channels 14 into the guide instrument 3 connected there and to position it in the area of the tip (applicator) inside the patient 4 . For this purpose, for example, an actuator, in particular comprising a stepping motor, can be used. The reloading device 15 communicates via a communication link 16 with the control device 13 and thus with the imaging device 6.

In steps S1 to S3 according to 1 a treatment plan should now first be created in optional steps of the method according to the invention, which treatment positions to which the reloading device 15 should move the radiation source, together with a treatment time for which the radiation source should remain at the respective treatment location. This treatment plan can also be determined in some other way, in particular externally to the imaging device 6, but is created with it in the present exemplary embodiment.

For this purpose, in a step S1, with the patient 4 positioned in the respective fields of view in the patient recording 5, an anatomy image data set is recorded by magnetic resonance imaging and an X-ray image data set by X-ray imaging using the magnetic resonance device 8 and the X-ray device 9, which are intrinsically registered with one another due to the use of the hybrid imaging device 6 and both showing treatment area 1. The anatomy of the treatment area 1, in particular the anatomy section 2, can be clearly seen in the anatomy image dataset recorded with the magnetic resonance device 8, while the guide instruments 3, in particular their tips, can be clearly seen in the X-ray image dataset, optionally with the additional use of X-ray markers. In the present case, a CT image data set can be recorded as the X-ray image data set, but if only a three-dimensional position determination of the guide instruments 3 is involved, two projection directions perpendicular to one another, as in FIG 3 shown, recorded projection images can be sufficient as an X-ray image data set. The positions of the guide instruments 3 that can be determined from this are then also known in the anatomy image data record due to the registration, so that, for example, a merged verification image data record can be created, which is shown schematically as shown in 2 works.

To create the treatment plan, which, as already mentioned, represents an optional part of the method, a joint evaluation of the anatomy image data set and the X-ray image data set is carried out in step S2, possibly together with a preoperative image recording that is or will be registered with the anatomy image data set and the X-ray image data set. In so-called contouring, for example by using automatic segmentation methods, the extent and shape of the anatomy section 2 is determined as precisely as possible in the control device 13 . After the position of the guide elements 3 and thus possible treatment locations provided are also known, a treatment plan containing treatment locations and treatment times for these treatment locations can be created automatically by the control device, for example as part of a dose optimization algorithm.

In step S3, this treatment plan is made available to the reloading device 15 via the communication link 16, in particular after it has been checked by a person carrying out the treatment. A local one, not closer The control unit shown can then control the actuators according to the treatment plan in order to gradually bring the radiation source to the appropriate treatment sites and hold it there for the appropriate time. The actual treatment process can now be started, for example based on an entry by the treatment person at the reloading device 15 or the imaging device 6, with the imaging device 6 being used to check the correct implementation and the continued applicability of the treatment plan 6, and therefore for treatment verification.

Before the radiation source itself is introduced into the patient 4, however, the introduction paths provided by the guide instruments 3 are checked to ensure they are free of obstacles 3 can retract. At the beginning of this test process, it transmits a trigger signal that this test process is now taking place via the communication link 16 to the control device 13. In step S4, the latter checks whether this trigger signal indicating the obstacle-freedom test to be carried out has been received. If this is the case, in a step S5 both recording arrangements of the x-ray device 9 are used in order to monitor this process fluoroscopically, since the additional instrument with the placeholder can also be excellently detected by the x-ray radiation. This additional instrument can now be seen one after the other in the various management instruments 3 , which is determined in the control device 13 . However, once the assignment of the guiding instruments 3 to the channels 14, on which the treatment plan is based, is also known there and the channels 14 are successively tested for freedom from obstacles, it can be determined fully automatically whether the guiding elements 3 are correctly connected to the various channels 14 of the reloading device 15 are connected. This check takes place according to step S6, with a failure of the check, ie a connection error, a corresponding message is output via a user interface of the imaging device 6 and a new test run, step S4, is awaited. However, if the test run is successful with regard to freedom from obstacles and the assignment is correct, as provided for the treatment locations in the treatment plan, the process continues with a step S7.

In step S7, it is monitored whether a trigger signal is received from the reloading device 15 via the communication link 16, which indicates that a new treatment location has been reached, at which the treatment plan should now remain for the scheduled treatment time. If such a trigger signal is received, the recording of two projection images in mutually perpendicular projection directions with the two recording arrangements of the x-ray device 9 as an x-ray image data set is automatically triggered in step S8. As already described, the position of the additional instrument, in this case the radiation source, can be determined from this X-ray image data set by back-projection, with a check image data set also being generated in addition in the control device 13 for display to the treatment person, which, for example, as in 4 displayed, can look like. The last recorded anatomy image data set, which shows the anatomy of the treatment area 1 together with the anatomy section 2 to be treated, as well as the current positions of the guide instruments 3 and the additional instrument 17, in particular the radiation source 18, deduced from the X-ray image data set, are displayed there. Furthermore, since the treatment plan is also registered with the anatomy image data record and the X-ray image data record, the planned treatment locations 19 can also be displayed. While it is fundamentally conceivable that the correct positioning can be checked by a treatment person using such a checking image data set, however, in the exemplary embodiment provided here, it is provided that in a step S9, based on at least one deviation criterion, the control device 13 automatically checks whether a too strong There is a deviation from the treatment plan. If this is the case, in a step S10, if the deviation can be corrected, for example by a short further displacement within the current guidance instrument 3, correction information for controlling the reloading device 15 is determined and transmitted to it via the communication link 16. In this way, an inaccuracy in the positioning can be corrected extremely quickly. If the deviation is too great to be corrected, it can be checked whether an adjustment or re-determination of the treatment plan can solve the problem and/or even be completely canceled in order to start anew with the planning, for example taking into account the radiation that has already been carried out to start.

Finally, in a step S11, a check is made as to whether further treatment locations 19 are to be visited, and if this is not the case, the method can be ended.

In parallel, in a step S12, constant monitoring can also be carried out as to whether the conditions under which the treatment plan was created continue to exist, take place. After changes in the anatomy or the position of the guidance instruments 3 relative to the anatomy in particular can be determined, current anatomy image datasets can be recorded, for example at periodic time intervals, but also continuously if necessary, in order to use them, but in particular in conjunction with current X-ray image datasets, to provide verification information to be determined, which describes whether changes in the anatomy, in particular with regard to the anatomy section to be treated, have occurred and/or changes in the position of the guide instruments 3 relative to the anatomy, in particular the anatomy section 2 to be treated, occur. Such can be given, for example, by unwanted movements of the patient 4 and / or the guide instruments 3; However, if the treatment process is planned over a total period in which physiological processes such as filling a bladder and/or rectal emptying may also be of interest, the shape or extent of the anatomy section 2 can also change, for example. If it is determined in the continuous monitoring and checking step 12, which is then used, that such change information regarding the treatment area 1 meets a change in a deviation criterion that exceeds a threshold value, the treatment plan is adjusted and/or redetermined in order to account for this change compensate and still continue to achieve the best possible irradiation success in the anatomy section 2 without excessive stress on the surrounding tissue.

Depending on the synchronicity requirements, in particular with regard to the physiological processes already mentioned, different synchronization measures of the anatomy image dataset and the X-ray image dataset can be used, for example by using corresponding operating modes of a recording unit of the control device. While it may be sufficient in the case of very slow, expected changes in the treatment area 1 to operate sequential imaging, i.e. to take the X-ray image data set after or before the acquisition of the anatomy image data set, better synchronicity and temporal assignment can be achieved if interlaced imaging is used , in which, for example, X-ray images are switched between individual sequence sections with at least one excitation and at least one read-out time window. In the case of high synchronicity requirements, parallel imaging approaches can be used, for example by the x-ray imaging taking place in a phase of the at least one magnetic resonance sequence for recording the anatomy image data set in which it does not include any radio-frequency pulses and gradient pulses to be output. However, if appropriate correction and/or compensation measures are provided, it is also conceivable to record the X-ray image data in the readout time window for the magnetic resonance image data (here anatomy image data) in order to achieve optimal synchronicity.

5 finally shows the functional structure of the control device 13 in a schematic diagram.

This initially has a recording unit 20 for controlling the recording mode of the magnetic resonance device 8 and the X-ray device 9, in particular also with regard to steps S1, S5, S8 and S12. A determination unit 21 for determining the verification information and/or the treatment plan and a planning unit 26 for determining or redetermining the treatment plan are available for evaluating anatomy image datasets and x-ray image datasets (cf. in particular steps S2, S5 and S8).

An interface 22 with a corresponding communication unit 23 is provided for transmitting data to the reloading device 15 or for receiving data, in particular trigger signals, via the communication connection 16, for example for steps S3, S4, S7 and S10, as far as the transmission of the correction information is concerned . Furthermore, the control device 13 can include a checking unit 24 for checking the fulfillment of deviation criteria, see for example steps S6, S9 and also partly S12. The general checking and monitoring step S12 naturally also uses the recording unit 20 and the determination unit 21. Step S12 can also use an adjustment unit 25 of the control device 13, in which the treatment plan can be adjusted.

Of course, other functional units are also conceivable, which can be implemented, for example, via a processor of the control device 13 and/or other hardware components. Generally speaking, the functional units can also use a storage means 27 of the control device 13 .

Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• WO 2018/095587 A1 [0015]

Claims (15)

Computer-implemented method for imaging support in a brachytherapy treatment with at least one radiation source (18) guided according to a treatment plan by means of a medical guidance instrument (3) to a treatment location (19) in a treatment area (1) for a treatment time, characterized in that - to at least a first point in time, an anatomy image data set of the treatment area (1) is recorded with a magnetic resonance device (8) of an imaging device (6) which, in addition to the magnetic resonance device (8), also has an X-ray device (9) registered with it, with the treatment area (1) in the field of view both the magnetic resonance device (8) as well as the x-ray device (9), - at the first and/or at least one further point in time, an x-ray image data record registered with the anatomy image data record for locating the at least one guide instrument (3) and/or one through the guiding instrument (3) inserted additional instrument (17), and - in a control device (13) of the imaging device (6) the anatomy image data set and the x-ray image data set are evaluated together to determine the treatment plan and/or checking information that allows checking compliance with the treatment plan. procedure after claim 1 , characterized in that in a treatment plan determined based on and/or additionally dependent on a pre-operative image recording of the treatment area (1), the pre-operative image recording is or will be registered by recording with the imaging device (6) and/or by a registration process with regard to the anatomy image data set. procedure after claim 1 or 2 , characterized in that a verification image data set showing at least part of the anatomy of the treatment area (1) together with the at least one guide instrument (3) and/or additional instrument (17) is determined as verification information. procedure after claim 3 , characterized in that at least one of the at least one treatment site (19), in particular assignable to the guide instrument (3) and/or additional instrument (17) assigned to the treatment site (19), is inserted and displayed in the verification image data set. Method according to one of the preceding claims, characterized in that at least one of the at least one X-ray image data set is recorded as a three-dimensional image data set and/or as at least two, in particular using at least two X-ray sources (11) each with an assigned X-ray detector (12) at least partially simultaneously recorded projection images of different projection geometry, in particular at least in pairs of projection directions that are at least essentially perpendicular to one another, are recorded, with the control device (13) determining a three-dimensional position of the guide instrument (3) and/or the additional instrument (17) when determining the checking information. Method according to one of the preceding claims, characterized in that during the introduction of an additional instrument (17) comprising a placeholder for the radiation source (18) in order to check that the introduction path is free of obstacles, the X-ray device (9) for recording the X-ray image data sets is operated as fluoroscopic monitoring In the case of a plurality of management instruments (3) assigned to different treatment locations (19), the verification information for checking a correct assignment of treatment locations (19) to management instruments (3) is determined. Method according to one of the preceding claims, characterized in that if a deviation criterion evaluating the verification information is met, the treatment plan is adapted and/or redetermined on the basis of the verification information and/or the anatomy image data set and/or X-ray image data set used to determine it. Method according to one of the preceding claims, characterized in that the imaging device (6) is connected via a communication link (16) to a reloading device (15) for controlling the at least one additional instrument (17) on the basis of the treatment plan, with the receipt of a completed positioning at least one of the at least one radiation source (18) according to the treatment plan indicating trigger signal at least one X-ray data set is recorded and the verification information for verifying the correct positioning is determined. procedure after claim 8 , characterized in that in the case of a discrepancy determined by the control device (13) on the basis of the checking information and correctable within the guide instrument (3). the position of the radiation source (18) from the treatment site (19) correction information for controlling the reloading device (15) for repositioning the radiation source (18) is sent to the reloading device (15). Method according to one of the preceding claims, characterized in that anatomy image data sets and/or X-ray image data sets are recorded at a plurality of points in time and, as verification information by comparing anatomy image data sets and/or X-ray image data sets recorded at different points in time, change information with regard to the treatment area (1), in particular with regard to the relative position at least one of the at least one guide instrument (3) is determined for an anatomy section (2) to be treated and/or with regard to a change in shape of the anatomy section (2), with the treatment plan being adapted and/or redetermined if the change exceeds a threshold value. Method according to one of the preceding claims, characterized in that synchronous recording for at least one anatomy image data set and at least one X-ray image data set is carried out with the imaging device (6). procedure after claim 11 , characterized in that the synchronous recording takes place at least partially by nested recording sections for the magnetic resonance imaging and the X-ray imaging and/or by performing the X-ray imaging in pulse-free sections of at least one magnetic resonance sequence used and/or by performing the X-ray imaging parallel to a readout section of the at least one used magnetic resonance sequence . Imaging device (6) comprising a magnetic resonance device (8), an X-ray device (9) registered with the magnetic resonance device (8) and a control device (13) which is designed to carry out a method according to one of the preceding claims. Computer program which comprises the steps of a method according to one of Claims 1 until 12 carries out when it is based on a control device (13) of an imaging device (6). Claim 13 is performed. Electronically readable data carrier on which a computer program Claim 14 is saved.

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