Dose estimation of scattered radiation

Abstract

Method for dose estimation of scattered radiation, wherein a scattered radiation model is provided which specifies a spatial distribution of the scattered radiation expected in a predefined use of a radiation source (4) in an environment of the radiation source (4), characterized in that: - a position of the mobile electronic device (6) relative to the radiation source (4) is determined by means of a mobile electronic device (6) of a user (12); - at least one dose parameter of the scattered radiation expected according to the use of the radiation source (4) is determined by means of the mobile electronic device (6) depending on the scattered radiation model and depending on the determined position.

Description

The present invention relates to a method for estimating the dose of scattered radiation, wherein a scattered radiation model is provided which specifies a spatial distribution of the scattered radiation to be expected in the environment of the radiation source when a radiation source is used in a predefined manner. The invention further relates to a corresponding system for dose estimation of scattered radiation and to a computer program product.Radiation sources, such as x-ray sources or other modalities for imaging or radiation therapy, which use alpha, beta, gamma rays, ion beams, proton beams or neutron beams, generally emit not only radiation in the region which is to be examined or treated, but also in the other environment of the radiation source, inter alia as scattered radiation. This may pose a health hazard to persons located in the vicinity of the radiation source, such as medical personnel. It is therefore desirable to provide persons in the environment of the radiation source with information about their scattered radiation exposure. The persons could then, for example, avoid areas of high radiation exposure or the dose awareness of medical personnel could be increased.It is known to provide so-called person dosimeters which can carry persons in the vicinity of the radiation source and which can measure the dose actually arriving at the site of the person dosimeter. Since these are based on the direct measurement of the scattered radiation, properties of the radiation source or operating parameters of the radiation source, such as the type of radiation used, an energy spectrum of the radiation and so forth, cannot be easily taken into account. This makes it difficult to provide corresponding information directly to the user. In addition, the measured values do not offer the possibility of estimating dose characteristics to be expected in the future or, if appropriate, an overall dose to be expected overall during the entire use.From EP 2 117 649 B1 a system is known which supplies a perceptible signal which indicates a predicted or measured spatial distribution of scattered radiation. A method for predicting a scatter distribution takes into account at least one object-related parameter and at least one radiation-related parameter and predicts a scatter distribution in response thereto.WO 2015 / 044 016 A1 discloses a system for estimating the radiation load of a person by radiation generated by a radiation source outside the person. The system comprises an intensity distribution calculation unit for estimating a spatial radiation intensity distribution of the radiation generated by the radiation source using a model of the radiation source. The system further comprises a person tracking unit for determining a current position and posture of at least one person. The system further comprises a beam exposure estimation unit for estimating a beam exposure of the at least one person based on the estimated spatial radiation intensity distribution and the detected current position and posture and a model of the body of the person.EP 3 177 364 B1 discloses a method for estimating a spatial distribution of the hazardousness of radiation doses for persons. The radiation doses are generated in a medical operating room which represents a three-dimensional environment surrounding at least one radiation source. First, a three-dimensional model of the environment is created. A simulation of the radiation doses which are attributable to the ionizing radiation emitted by the radiation source and scattered by the environment is then calculated in the model. An image is then generated and displayed indicating the spatial distribution of the dangerousness of the radiation doses for a person.It is also known to create scattered radiation models, also referred to as dose models, which create a spatial and / or temporal distribution of the scattered radiation to be expected in the environment of a radiation source when the radiation source is used in a defined manner, in particular the corresponding dose rate of the scattered radiation. Approaches are proposed in the publications N. L. Rodas et al: "3D global estimation and augmented reality visualization of intraoperative X-ray dose.", Medical image computing and computer-assisted intervention, 17(Pt 1):415-22 (2014) and N. L. Rodas et al: "Seeking is supporting: increasing intraoperative awareness to scattered radiation in interventional procedures by combining augmented reality, Monte Carlo simulation and wireless dosimeters.", International Journal of Computer Assisted Radiology and Surgery volume 10, 1181-1191 (2015), where wireless dosimeter data is combined with the radiation spread simulation to provide a global map of the radiation risk near an x-ray device. For this purpose, a multi-camera system is used to obtain a 3D point cloud reconstruction of the space. The positions of the patient table, the X-ray device and the attending physician are then used to simulate the propagation of the radiation in the real environment and to place the resulting 3D risk map over the scenario in a type of augmented reality. The simulation is calibrated or its accuracy is validated by the wireless dosimeters.A disadvantage here is that although the risk distribution can be visualized to a person, no estimation of the radiation exposure actually to be expected at present or in the future is provided.It is an object of the present invention to specify a possibility for estimating the dose of scattered radiation from a radiation source which does not rely on the specific measurement of physical parameters of the scattered radiation and which makes it possible to provide a user with a dose characteristic to be expected depending on the position.This object is achieved by the respective subject matter of the independent claims. Advantageous refinements and preferred embodiments are the subject matter of the dependent claims.The invention is based on the idea of using a mobile electronic device of the user, which locates himself, and based on the position of the mobile electronic device determined thereby and a predefined scattered radiation model, to determine at least one expected dose characteristic variable of the scattered radiation by means of the mobile electronic device.According to one aspect of the invention, a method for estimating the dose of scattered radiation is provided. In this case, a scattered radiation model is provided which specifies or, in other words, describes a spatial distribution of the scattered radiation to be expected in the environment of the radiation source when a radiation source is used in a predefined manner. By means of a mobile electronic device of a user of the mobile electronic device, in particular exclusively by means of the mobile electronic device, a position of the mobile electronic device relative to the radiation source is determined. By means of the mobile electronic device, in particular exclusively by means of the mobile electronic device, at least one dose characteristic variable of the scattered radiation to be expected, in particular to be expected currently and / or in the future, according to the use of the radiation source is determined depending on the scattered radiation model and depending on the determined position of the mobile electronic device.The fact that the mobile electronic device is an electronic device of the user can be understood in such a way that the position of the mobile electronic device allows at least approximately conclusions to be drawn about a position of the user. The mobile electronic device is thus carried along in particular by the user. This can be understood in such a way that, in the event of a change in the position of the user, the position of the mobile electronic device generally also changes. The relationship between the position of the mobile electronic device and the position of the user can be derived, for example, from suitable model assumptions. In particular, it is also possible to equate the position of the mobile electronic device to the position of the user or to assume a constant, permanently predefined displacement between the position of the mobile electronic device and the position of the user.The mobile electronic device can be, in particular, an electronic terminal for wireless data communication, such as a mobile telephone, a smartphone, a tablet computer, a so-called smart watch or another so-called wearable.The scattered radiation model specifies the distribution of the scattered radiation in the environment of the radiation source in particular in such a way that a physical variable of the scattered radiation, in particular a dose rate or a radiation energy or a dose energy of the scattered radiation, specifies location-dependent and optionally also time-dependent according to the predefined use of the radiation source.The term dose is used here and hereinafter equivalently with the term radiation dose. The same applies accordingly to terms derived therefrom, such as dose rate and so forth. Depending on the embodiment or depending on the specific implementation of the scattered radiation model, the dose can correspond to an energy dose in Gray or an equivalent dose in Sievert.The term scattered radiation can be understood to refer to radiation components generated by the radiation source which are not emitted, or not only emitted, into a region of an object, for example a patient, that is to be examined or treated.The scattered radiation model can be created in a known manner, compare in this connection the publications mentioned at the beginning, in such a way that it takes into account the type of radiation of the radiation source, an energy spectrum of the generated radiation of the radiation source, a change in position of the radiation source in space as a function of time and so forth. The position and / or orientation of the object to be examined or treated with respect to the radiation source, its spatial extent and / or material properties of the object can also be taken into account when creating the scattered radiation model.The scattered radiation model thus indicates, for each location in a predefined region around the radiation source, which is referred to here and below as the environment of the radiation source, wherein the location can be discretized or continuously indicated or defined, a physical property of the scattered radiation to be expected according to the use of the radiation source, optionally as a function of time.The fact that the scattered radiation model specifies the distribution of the scattered radiation according to the use of the radiation source can be understood in particular in such a way that one or more parameters of the use of the radiation source, such as an energy spectrum of the radiation used, a movement trajectory of the radiation source, the duration of the use or individual sections thereof, other details of an examination protocol, an X-ray acceleration voltage, a recording geometry, a target patient dose and so forth, are also taken into account by the radiation model.The radiation source can be designed differently. Preferably, the radiation source is an X-ray radiation source. However, it is also possible for the radiation source to be configured to emit other types of ionizing radiation, for example alpha radiation, beta radiation, gamma radiation, ion irradiation, proton radiation or neutron radiation.The radiation source is in particular part of an imaging modality for radiation-based imaging, for example medical imaging, in particular X-ray-based imaging, and / or for radiation therapy, in particular X-ray therapy.The scattered radiation model is provided in particular in computer-readable form on a storage medium. The storage medium may be part of the mobile electronic device. Alternatively, the storage medium is provided independently of the mobile electronic device, for example on a server computing unit or another backend device. In the latter case, the mobile electronic terminal is capable of fully or partially loading or reading the scattered radiation model from the storage medium, in particular by wireless data communication.The fact that the at least one dose characteristic variable is a dose characteristic variable to be expected according to the use of the radiation source can be understood in particular in such a way that, under the assumption that the scattered radiation model would exactly reflect the distribution of the scattered radiation in the environment, the at least one dose characteristic variable would result from the use of the radiation source. This is therefore in particular an estimate of the at least one dose characteristic variable. The at least one dose characteristic variable to be expected can be determined for a current time instant, i.e. for a time instant at which the position of the mobile electronic device is determined, and / or at one or more future time instants, taking into account the position of the mobile electronic device.The at least one dose characteristic variable can, for example, contain at least one dose output and / or dose energy. Optionally, in some embodiments, further information relating to the user, in particular in the form of a user model, can also be taken into account for determining the at least one dose characteristic, such as body dimensions of the user or a typical wearing position of the mobile electronic device and the like. The user model may be advantageously stored exclusively on the mobile electronic device. In particular, personal information can be stored exclusively on the mobile electronic device, such as body dimensions, sex, age, etc. This avoids central storage of personal user data. In this way, protection of personal data of the user can be achieved.The at least one dose characteristic variable, in particular dose power and / or dose, can be determined for a single position, namely the determined position of the mobile electronic device or a position derived therefrom, or for a plurality of positions which are likewise derived depending on the determined position of the mobile electronic device, for example in order to take account of a plurality of positions in or on the body of the user.The position of the mobile electronic device is determined by means of the mobile electronic device itself, in particular exclusively with the latter. For this purpose, methods known per se for self-localization, in particular for self-localization in interior areas or interior spaces, can be used, which are based, for example, using visual markers or radio transmitters attached in the environment. In other words, although the mobile electronic device can take into account information for determining the position which lies outside the mobile electronic device itself, the determination of the position, i.e. in particular the execution of all the computing steps required for this, is carried out exclusively by the mobile electronic device.As a result, it is possible in particular for the determined position of the mobile electronic device and, in corresponding embodiments, all further positions derived therefrom, for example relating to the user, to be held or stored exclusively on the mobile electronic device and not to have to be forwarded or transmitted by the latter to another location, in particular to another external computing unit such as a server or another central computing unit. The same applies analogously also to the determined at least one dose characteristic. Since this is determined by the mobile electronic device, in particular exclusively by the latter, it can be avoided or excluded that the corresponding information becomes available outside the mobile electronic device.This results in significant advantages with regard to data security and accordingly with regard to the protection of person-specific data of the user. An alternative conceivable per se to the approach according to the invention would be, for example, to use cameras distributed in space for determining the position of the user and to calculate the at least one dose characteristic variable on the basis thereof, for example by a central processing unit. However, this would have the decisive disadvantage that the position of the user could be monitored by external units and possibly stored over longer periods of time. Likewise, the at least one dose characteristic to be expected could be monitored or stored centrally. However, this increased the risk of data abuse of the user's person-specific data. Ultimately, this would also oppose the tendency for increased acceptance of the method of dose estimation by the user.According to the invention, however, a decentralized position determination and calculation of the dose characteristics is achieved in that the mobile electronic device is used for both mentioned purposes. In particular, the method according to the invention is based on not directly determining the position of the user, but instead, in a representative manner, to a certain extent, determining the position of the mobile electronic device and based on this, in turn, determining the at least one dose characteristic variable. As mentioned above, the position of the mobile electronic device may approximately reflect the position of the user or one or more characteristic positions of the user may be calculated or estimated based thereon.By using the scattered radiation model to calculate the at least one dose characteristic variable, this information and / or information derived therefrom can be provided directly to the user, so that the user can estimate his specific risk directly by exposure to the radiation. Furthermore, not only can dose characteristics characterizing the scattered radiation at the current time of the position determination be determined and optionally provided, but also those relating to a scattered radiation that is expected in the future.The mobile electronic device contains in particular at least one computing unit. All the computing steps required for determining the position of the mobile electronic device and for determining the at least one dose characteristic variable in each case by the mobile electronic device can be executed by the at least one computing unit.Depending on the embodiment and in particular depending on the type of self-localization that is used, various sensors of the mobile electronic device, such as one or more cameras, inclination and / or acceleration sensors or the like, can be used in order to provide corresponding sensor data to the at least one computing unit, so that the latter can determine the position of the mobile electronic device.According to at least one embodiment of the method for dose estimation, information relating to the at least one dose characteristic to be expected is displayed by means of a visual display unit of the mobile electronic device, for example by means of one or more LEDs or by means of a display. The displayed information can correspond, for example, to the at least one dose characteristic variable to be expected or be derived therefrom. The information may additionally or alternatively also include recommendations for the user that may result in a reduction in his personal spread exposure.According to at least one embodiment, the at least one dose characteristic variable comprises a dose power currently to be expected according to the use of the radiation source and / or a dose power to be expected at a predefined future point in time.The currently to be expected dose rate can be understood here as dose rate at a time of the determination of the position of the mobile electronic device, whereas the predefined future time is after the determination of the position of the mobile electronic device. The future point in time can be defined in absolute terms or relative to the determination of the position of the mobile electronic device. In other words, the at least one dose rate expected at the future time corresponds to at least one predicted dose rate.The at least one dose rate to be expected can also contain a correspondingly expected dose rate for a plurality of predefined future points in time.Based on the currently expected dose rate and the information generated and possibly output based thereon, the user can estimate how high his current risk due to the radiation exposure is and change his position as appropriate in order to reduce this risk. The same applies to the future or predicted dose rate. Based thereon, the user can proactively react to an increased radiation exposure to be expected later and, for example, change its position.According to at least one embodiment, the at least one dose characteristic variable is determined as a function of the expected dose power and / or the dose power to be expected at the predefined future point in time.According to at least one embodiment, the at least one dose characteristic variable comprises a previous dose to be expected according to the use of the radiation source and / or a future dose to be expected according to the use of the radiation source. Alternatively, the at least one dose characteristic is determined depending on the previous dose and / or the future dose.The dose corresponds in particular to a dose rate integrated or added over time.By determining the previous dose, the user can estimate not only whether his current or future position is associated with a particularly high radiation exposure, but also whether his previous positions in the environment of the radiation source have overall, i.e. viewed absolutely, led to a high radiation exposure. The future dose can correspond, for example, to a total dose predicted for the entire use of the radiation source, which can be estimated both on the basis of the profile of the position of the mobile device and on the basis of the prediction on the basis of the current position of the mobile electronic device, and optionally the imaging steps which are likely to be pending in the workflow of a running medical procedure.According to at least one embodiment, the position of the mobile electronic device relative to the radiation source is determined by means of the mobile electronic device at a plurality of times, that is to say in particular multiple times at different times. For each time of the plurality of times, a dose rate to be expected according to the use of the radiation source at the corresponding time is determined by means of the mobile electronic device as a function of the respectively determined position of the mobile electronic device and as a function of the scattered radiation model. The previous dose and / or the future dose is determined depending on the dose rates determined for the plurality of times.The plurality of times may include a current time, one or more past times, and / or one or more future times. For the current and past time points, respectively, the position of the mobile electronic device may be determined by self-localization as described above. For the future points in time, it can be assumed, for example, that the position of the mobile electronic device is maintained, or a trajectory of the mobile electronic device can be estimated from a previous course of the position of the mobile electronic device, for example by extrapolation, and the position of the mobile electronic device for the future points in time can be determined as a function thereof.According to at least one embodiment, respective radio signals of a multiplicity of transmission units distributed in the environment are received by means of a reception unit of the mobile electronic device. The position of the mobile electronic device is determined, in particular by means of the at least one computing unit, as a function of the received radio signals.The receiving unit is thus in particular a radio receiving unit, i.e. contains, for example, one or more antennas for receiving the radio signals. The receiving unit can be, for example, a WLAN receiving unit, a Bluetooth receiving unit or a receiving unit designed for another radio network. The same applies analogously to the transmitting units.It is known to receive such radio signals from distributed transmitting units and to use them for self-locating the receiving device. For this purpose, various information transmitted by the radio signals and / or other parameters of the radio signals, such as a signal strength or the like, can be evaluated in order to be able to identify or locate the individual transmission units, for example. In this way, the at least one computing unit can determine the relative position of the mobile electronic device with respect to one or more of the transmitting units. The position of the radiation source relative to the transmitting units is likewise known and predefined, optionally also as a function of time. The at least one computing unit can therefore also determine the position of the mobile electronic device with respect to the radiation source on the basis of the relative position of the mobile electronic device with respect to the transmission units and the relative position of the radiation source with respect to the transmission units.In particular, at least one of the transmitting units can also be arranged on the radiation source, so that the position of the mobile electronic device with respect to that transmitting unit also corresponds to the relative position of the mobile electronic device with respect to the radiation source.It should be noted that various approaches for self-localization including the described approach may be combined with one another based on the radio signals in order to determine the position of the mobile electronic device with increased accuracy.According to at least one embodiment, image data is generated by means of the mobile electronic device, in particular by means of a camera of the mobile electronic device, said image data imaging one or more reference objects in the environment and / or the radiation source. The position of the mobile electronic device is determined, in particular by means of the at least one computing unit, as a function of the image data.The reference objects are in particular visually detectable objects or devices whose position in the environment of the radiation source is known. This can be, for example, the radiation source or other parts of the imaging modality, for example a patient table, a permanently mounted or mobile robot stand, for example a mobile X-ray device, or the like. They can also be components of a building infrastructure or visual markers which are arranged dedicated to this purpose in the environment of the radiation source.For example, the at least one computing unit may use image processing algorithms or machine vision algorithms or the like to identify the visual markers in the image data that include one or more camera images and determine their position and / or orientation with respect to the mobile electronic device. For example, certain two-dimensional patterns can be provided on the respective reference objects, in particular markers, which enable a determination of the position and / or orientation of the respective reference object, in particular markers. An example of visual markers are so-called ArUco markers. Alternatively or additionally, on the reference objects, in particular the visual markers, information relating to their position and / or orientation in space can also be shown visually detectable by the camera in text form or in some other way.Analogously to the transmission units for the radio signals, the at least one arithmetic unit can thus determine the respective relative position of the reference objects with respect to the mobile electronic device on the basis of the image data. In addition, the relative position of the radiation source with respect to the reference objects is also known and predefined, so that the computing unit can ultimately determine the position of the mobile electronic device with respect to the radiation source on the basis thereof.It can be provided that one or more of the visual markers are arranged on the radiation source. Alternatively or additionally, the radiation source can represent a reference object and can be directly recognized and localized from the image data.According to at least one embodiment, sensor data are generated by means of at least one inclination and / or acceleration sensor of the mobile electronic device. The position of the mobile electronic device is determined by means of the at least one computing unit as a function of the sensor data.On the basis of the sensor data, which relate to or contain the inclination and / or acceleration of the mobile electronic device, for example as a function of time, or which can be derived therefrom, the at least one computing unit can draw conclusions about a change in position of the mobile electronic device with respect to a starting position of the mobile electronic device or determine or estimate these relative movements. Various odometry methods are known, in particular in the area of robot navigation, which enable self-localization based on such sensor data. The starting position of the mobile electronic device can be provided by the user, for example, or can correspond to an initial position of the user or of the mobile electronic device, which can be estimated from other circumstances. For example, a position of an access to a space in which the radiation source is located may be known. It is also possible that the starting position is determined, for example, based on the image data and / or the radio signals, as described above.According to at least one embodiment, a position of the user, in particular relative to the radiation source, different from the position of the mobile electronic device is determined depending on the position of the mobile electronic device, in particular by means of the mobile electronic device, for example the at least one computing unit. The at least one dose characteristic to be expected is determined for the position of the user.In other words, a predefined relative position of the mobile electronic device with respect to the position of the user is therefore assumed in order to enable an estimation of the at least one dose characteristic variable that is as relevant as possible. The relative position of the mobile electronic device with respect to the user or with respect to the position of the user can be determined in different ways. For example, the user may provide corresponding information in advance, such as describing where the mobile electronic device is typically located, such as at a left side of the user's body or a right side, in a pants bag, or the like. Alternatively or additionally, camera images of the camera or of a further camera of the mobile electronic device, i.e. the image data or further image data of the further camera, can also be generated and used to determine the relative position of the mobile electronic device with respect to the position of the user.According to at least one embodiment, a three-dimensional spatial region is determined depending on the position of the mobile electronic device, in particular by means of the electronic device, for example by means of the at least one computing unit. By means of the mobile electronic device, a local dose power and / or a local dose is determined for each of a plurality of points in the three-dimensional spatial region according to the use of the radiation source. By means of the mobile electronic device, in particular by means of the at least one arithmetic unit, the local dose powers and / or the local doses are summed up, in particular for all points of the plurality of points, in order to determine the at least one dose characteristic variable to be expected.The spatial region, which can be defined in particular relative to the radiation source, can be determined as a continuous spatial region and the plurality of points then correspond to a scanning of the spatial region. Alternatively, however, the respective position of the plurality of points can also be determined directly, wherein the spatial region is then defined by the plurality of points.The shape of the spatial region is predefined, for example, in particular on the basis of a user model. For this purpose, body dimensions of the user can be predefined in advance, for example. As described above, the user model may be advantageously stored exclusively on the mobile electronic device. In particular, personal information can be stored exclusively on the mobile electronic device, such as body dimensions, sex, age, etc. This avoids central storage of personal data of the user. In this way, the user's personal data can be protected. As described above for the position of the user, the position and / or orientation of the spatial region with respect to the position of the mobile electronic device can also be predefined and / or determined by means of the camera or further camera of the mobile electronic device. From the determined position of the mobile electronic device relative to the radiation source and the corresponding predetermined or determined relative position of the three-dimensional region with respect to the position of the mobile electronic device, the at least one computing unit can thus determine the relative position and / or orientation of the spatial region with respect to the radiation source and then, according to the scattered radiation model, the respective local dose powers or doses.The summing of the local dose powers and / or local doses can in particular include a weighting of the dose powers or doses determined for the individual points of the three-dimensional region. The weights are predefined, for example as part of the user model. As a result, for example, material properties or biological danger levels of the tissue regions of the user's body can be taken into account in order to generate more meaningful or more relevant dose characteristics.According to at least one embodiment, a further position or a region in the environment of the radiation source is determined by means of the mobile electronic device, in particular by means of the at least one arithmetic unit, depending on the at least one dose characteristic variable and depending on the scattered radiation model, for which a dose of the scattered radiation recorded by the user according to the use of the radiation source is reduced.The reduction of the recorded dose is in particular a difference between a predicted recorded dose on the assumption that the user moves from his current position to the further position or to the area. The fact that the recorded dose is reduced can be understood in particular in such a way that it is to be expected according to the scattered radiation model that the scattered radiation is likely to be reduced.The information that can be output by means of the visual display unit of the mobile electronic device in corresponding embodiments can also contain a recommendation that the user should move to the further position or the area in the environment in order to reduce the recorded dose of scattered radiation.According to at least one embodiment, further image data are generated by means of the mobile electronic device, in particular by means of the camera and / or a further camera of the mobile electronic device, said further image data imaging or partially imaging the user. By means of the mobile electronic device, in particular by means of the at least one computing unit, the user model is created or adapted on the basis of the further image data. The at least one dose characteristic to be expected is determined depending on the user model.Based on the further image data, for example, the relative position of the mobile electronic device with respect to the position of the user can be determined as described above or, additionally or alternatively, the spatial range for which the respective local dose rates and / or doses are determined as described above in corresponding embodiments. Alternatively or additionally, it is possible that protective clothing of the user is identified based on the further image data and the at least one dose characteristic to be expected is determined taking into account the detected protective clothing, for example by taking into account a reduction in the dose output and / or dose by the protective clothing.According to a further aspect of the invention, a system for estimating the dose of scattered radiation is specified, in particular according to a method according to the invention for estimating the dose of scattered radiation. The system comprises a mobile electronic device which is configured to determine its position relative to the radiation source, that is to say to determine the position of the mobile electronic device relative to the radiation source. The system, for example the mobile electronic device, has a storage medium which stores a scattered radiation model. The scattered radiation model specifies a spatial distribution of the scattered radiation to be expected in the environment of the radiation source when a radiation source is used in a predefined manner. The mobile electronic device is configured to determine at least one dose characteristic variable of the scattered radiation to be expected according to the use of the radiation source depending on the scattered radiation model and depending on the determined position of the mobile electronic device.In particular, the mobile electronic device has at least one arithmetic unit which is configured to determine its position relative to the radiation source and to determine the at least one dose characteristic variable to be expected.A computing unit can be understood in particular as a data processing device which contains a processing circuit. The computing unit can therefore process data in particular for carrying out computing operations. This also includes operations to perform indexed accesses to a data structure, for example a look-up table (LUT).The computing unit can in particular contain one or more computers, one or more microcontrollers and / or one or more integrated circuits, for example one or more application-specific integrated circuits, ASICs (application-specific integrated circuit), one or more field programmable gate arrays, FPGAs, and / or one or more single-chip systems, SoCs (system on a chip). The computing unit may also contain one or more processors, for example one or more microprocessors, one or more central processing units, CPUs (central processing units), one or more graphics processing units, GPUs (graphics processing units) and / or one or more signal processors, in particular one or more digital signal processors, DSPs. The computing unit may also include a physical or virtual group of computers or other of the aforementioned units.In various exemplary embodiments, the computing unit contains one or more hardware and / or software interfaces and / or one or more memory units.A memory unit can be used as volatile data memory, for example as dynamic random access memory, DRAM (dynamic random access memory) or static random access memory, SRAM (static random access memory), or as nonvolatile data memory, for example as read-only memory, ROM (read-only memory), as programmable read-only memory, PROM (programmable read-only memory), as erasable programmable read-only memory, EPROM (erasable programmable read-only memory), as electrically erasable programmable read-only memory, EEPROM (electrically erasable programmable read-only memory), as flash memory or flash EEPROM, as ferroelectric random access memory, FRAM (ferroelectric random access memory), as magnetoresistive random access memory, MRAM (magnetoresistive random access memory) or as phase-change random access memory, PCRAM (phase-change random access memory).According to at least one embodiment of the system, the electronic device comprises a receiving unit for receiving respective radio signals of a plurality of transmitting units distributed in the environment. The mobile electronic device, in particular the at least one computing unit, is configured to determine the position of the mobile electronic device as a function of the received radio signals.The mobile electronic device, in particular the receiving unit, is therefore in particular configured to receive the radio signals.In various embodiments, the system includes the plurality of transmitting units.According to at least one embodiment, the mobile electronic device has a camera which is configured to generate image data which depict one or more reference objects, in particular visual markers, in the environment. The mobile electronic device, in particular the at least one computing unit, is configured to determine the position of the mobile electronic device as a function of the image data.In various embodiments, the reference objects, in particular the visual markers, are likewise part of the system.According to at least one embodiment, the mobile electronic device has at least one inclination and / or acceleration sensor which is configured to generate sensor data. The mobile electronic device, in particular the at least one computing unit, is configured to determine the position of the mobile electronic device as a function of the sensor data.Further embodiments of the system according to the invention follow directly from the various embodiments of the method according to the invention and vice versa. In particular, individual features and corresponding explanations and advantages with respect to the various embodiments can be transferred analogously to corresponding embodiments of the system according to the invention in relation to the method according to the invention. In particular, the system according to the invention is designed or programmed for carrying out a method according to the invention. In particular, the system according to the invention carries out the method according to the invention.According to a further aspect of the invention, a computer program with instructions is specified which, when the instructions are executed by a system according to the invention, in particular by the at least one arithmetic unit of the mobile electronic device, cause the system to execute a method according to the invention for dose estimation of scattered radiation.According to a further aspect of the invention, a computer-readable storage medium is specified which stores a computer program according to the invention.The computer program according to the invention or the computer-readable storage medium according to the invention can be referred to as respective computer program products with the instructions.The invention is explained in more detail below with reference to specific exemplary embodiments and associated schematic drawings. In the figures, identical or functionally identical elements can be provided with the same reference numerals. The description of identical or functionally identical elements may not necessarily be repeated with respect to different figures.The figures show: FIG. 1 shows a schematic representation of an exemplary embodiment of a system according to the invention for dose estimation of scattered radiation; FIG. 2 shows a flow diagram of an exemplary embodiment of a method according to the invention for dose estimation of scattered radiation; FIG. 3 shows a schematic representation of a further exemplary embodiment of a system according to the invention for dose estimation of scattered radiation; and FIG. 4 shows a schematic representation of a further exemplary embodiment of a system according to the invention for dose estimation of scattered radiation.FIG. 1 schematically shows an exemplary embodiment of a system 13 according to the invention for dose estimation of scattered radiation. The system 13 has a storage medium 8 and a mobile electronic device 6, for example a smartphone, wherein the storage medium 8 can be part of the mobile electronic device 6 in various embodiments. In other embodiments, the storage medium 8 may be provided externally to the mobile electronic device 6, and the mobile electronic device 6 may read the storage medium 8 based on, for example, wireless data communication.FIG. 1 furthermore shows a modality 1 for radiation-based imaging and / or radiation therapy. The modality 1 comprises a radiation source 4 configured to generate and emit ionizing radiation. For example, this is X-ray radiation, but other modalities are also possible. Purely by way of example, the modality 1 is shown in FIG. 1 as a C-arm X-ray system with a stand 3 and a patient couch 2, wherein the radiation source 4 and an X-ray detector 5 are arranged on opposite ends of the C-arm. However, this does not represent a limitation of the inventive idea, which is much more applicable to any ionizing radiations and corresponding radiation sources 4.The storage medium 8 stores a scattered radiation model which specifies a spatial distribution of the scattered radiation to be expected in the environment of the radiation source 4 when the radiation source 4 is used in a predefined manner. The mobile electronic device 6 is configured to determine its position relative to the radiation source 4.The mobile electronic device 6 is further configured to determine at least one dose characteristic variable of the scattered radiation to be expected according to the use of the radiation source 4 depending on the scattered radiation model and depending on the determined position of the mobile electronic device 6.The self-localization of the mobile electronic device 6 can be performed in various ways depending on the embodiment of the system 13. In particular, the mobile electronic device 6 contains position determination means 9, which in particular contain one or more sensors, for example inclination and / or acceleration sensors, one or more receiving units for receiving radio signals and / or one or more cameras. Furthermore, the electronic device 6 contains a computing unit 7, which in the present case can stand as representative of one or more computing units of the mobile electronic device 6. The computing unit 7 can determine the position of the mobile electronic device 6 relative to the radiation source 4 on the basis of the signals or measured sensor values or the like detected by the positioning means 9.The mobile electronic device 6 can be, for example, a device of a user 12 who carries the latter with it, and the position of the mobile electronic device 6 can therefore be directly or indirectly deduced from a position of the user 12 relative to the radiation source 4.FIG. 2 shows a schematic flow diagram of an exemplary embodiment of a method according to the invention for dose estimation of scattered radiation, as can be carried out, for example, by a system 13 described with reference to FIG. 1. In this case, the scattered radiation model is provided in step S 1 and the position of the mobile electronic device 6 relative to the radiation source 4 is determined in step S 2 by means of the mobile electronic device. In step S 3, the at least one dose characteristic to be expected is determined by means of the mobile electronic device 6 as a function of the scattered radiation model and as a function of the determined position.Optionally, steps S 2 and S 3 can be repeated, for example, cyclically repeated, in order to thus repeatedly, in particular cyclically, determine the position of the mobile electronic device 6 or the at least one dose characteristic variable to be expected, in order in particular also to be able to take account of position changes of the mobile electronic device 6.In optional step S 4 of the method, the at least one dose characteristic variable to be expected, which has been determined once or several times in step S 3, can be further processed. If, for example, the current dose rate is determined in step S 3, a total dose accumulated up to now can be calculated in step S 4 or the like.In the likewise optional step S 5, which can follow directly after step S 3 or after the cyclical execution of S 2 and S 3 or after step S 4, if provided, user information can be displayed for the user on a display device, for example a display 14, of the mobile electronic device 6, depending on the results of steps S 3 and / or S 4.FIG. 3 schematically illustrates a further exemplary embodiment of the system 13 according to the invention. The embodiment of the system 13 from FIG. 3 is based on that of FIG. 1. here the mobile electronic device 6 contains, in particular, the position determination means 9 contain a camera 9 a, and a plurality of visual markers 10 a, 10 b, 10 c, for example ArUco markers, are arranged in the vicinity of the radiation source 4, the position and orientation of which with respect to the radiation source 4 is known, for example.By means of the camera 9 a, image data can be generated which image the markers 10 a, 10 b, 10 c, and the computing unit 7 can determine the position of the mobile electronic device 6 depending on the image data. For this purpose, the computing unit 7 can determine, in particular, the relative position and / or orientation of the mobile electronic device 6 with respect to one or more of the markers 10 a, 10 b, 10 cbased on the image data and calculate the relative position of the mobile electronic device 6 with respect to the radiation source 4 based on the predefined relative position of the radiation source 4 with respect to the markers 10 a, 10 b, 10 c.FIG. 4 schematically shows a further exemplary embodiment of the system 13 according to the invention, which is likewise based on the embodiment of FIG. 1. Instead of the visual markers 10 a, 10 b, 10 c, as provided in the embodiment of FIG. 3, in the embodiment of FIG. 4 a plurality of transmitting units 11 a, 11 b, 11 care provided, which are arranged at known positions of the radiation source 4 and can transmit radio signals. The mobile electronic device 6, in particular the position determination means 9, accordingly includes a receiving unit 9 bwhich can receive the radio signals emitted by the transmitting units 11 a, 11 b, 11 c. Based on the radio signals, the computing unit 7 can determine the position of the mobile electronic device 6 with respect to one or more of the transmitting units 11 a, 11 b, 11 cand ultimately with respect to the radiation source 4.In further embodiments not shown, both markers 10 a, 10 b, 10 cand transmitting units 11 a, 11 b, 11 cand consequently both the camera 9 aand the receiving unit 9 bmay be used to determine the position of the mobile electronic device 6 with respect to the radiation source 4. Alternatively or additionally, the inclination and / or acceleration sensors (not shown) of the mobile electronic device 6 mentioned further above can be used to track a movement of the mobile electronic device 6 in the vicinity of the radiation source 4 and to determine the position of the mobile electronic device 6 with respect to the radiation source 4 accordingly on the basis of the sensor data of the inclination and / or acceleration sensors.As described, in particular with reference to the figures, the invention provides a possibility for estimating the dose of scattered radiation from a radiation source which does not rely on the specific measurement of physical parameters of the scattered radiation and which makes it possible to provide a user with an expected dose characteristic variable as a function of position.Scattered radiation represents a potential health risk, for example for medical personnel or visitors in an examination room, for example for X-ray examination, angiography or computed tomography, or also in a hybrid operating room. Increasing the dose awareness of medical personnel would therefore be desirable. Accessible and simple information about the expected scattered radiation exposure at different locations in the environment of the corresponding radiation source, as can be provided by the invention, can make it easier to identify and avoid regions with high radiation exposure. Unsultured personnel and visitors can benefit therefrom in particular.According to corresponding embodiments of the invention, based on the at least one dose characteristic variable, information relating to the currently expected scattered radiation exposure can be displayed on the mobile electronic device of the user, for example, during an pending or ongoing radiation-based examination or therapy of a patient or of another examination object.The scattered radiation model used can be generated and provided by known methods. In this case, a model for the examination object, optionally also referred to as a patient model, can optionally also be taken into account. This can be created, for example, on the basis of an earlier image data record of the examination object or can be a statistical patient model.Optionally, known data relating to the user of the mobile device can be used, such as height, weight, sex and / or typical wearing position of the mobile device, for example whether the device is held in the right or left hand or is carried along on the body on the left or right and possibly also at what height in order to generate or adapt a user model. As a result, the intensity of the scattered radiation or the at least one dose characteristic variable can be calculated with respect to the complete body of the user. For this purpose, in particular a specific position of the user's body relative to the mobile electronic device can be assumed and / or it can be assumed, for example, that the user is standing upright on the ground and the like.Optionally, sensors of the mobile electronic device, such as a camera, for example a front camera, also referred to as a selfie camera, can also be used to create the user model. In this case, available radiation protection clothing can be detected, the body dimensions of the user can be estimated and / or the relative position of the mobile electronic device with respect to the user can be detected.Optionally, known parameters relating to a recording geometry and / or dose settings of a running or pending recording can be obtained from the mobile electronic device, for example via an interface to the modality which contains the radiation source. The scattered radiation model can be statically precomputed based, inter alia, on these parameters and / or parameterized or simulated on the basis of current data.In various embodiments, the mobile electronic device may display recommendations as to where the user should move to reduce the expected stray radiation.In various embodiments, the calculated scattered radiation, in particular dose power, can be summed or integrated over the period of use of the radiation source, and thus a future or previous total dose can be calculated and displayed to the user.In various embodiments, the position of radiation protection aprons, panes or walls of the modality or radiation source can also be detected and taken into account.Compared to camera-based approaches with a room overview camera that tracks the user's position, the invention can provide a data protection and acceptance advantage, since no tracking of the user's movement takes place outside the mobile electronic device or corresponding data is recorded or stored.

Claims

Method for estimating the dose of scattered radiation, wherein a scattered radiation model is provided which specifies a spatial distribution of the scattered radiation to be expected in a predefined use of a radiation source (4) in a surrounding area of the radiation source (4), characterized in that - a position of the mobile electronic device (6) relative to the radiation source (4) is determined by means of a mobile electronic device (6) of a user (12); - at least one dose characteristic variable of the scattered radiation to be expected according to the use of the radiation source (4) is determined by means of the mobile electronic device (6) depending on the scattered radiation model and depending on the determined position.Method according to claim 1, wherein information relating to the user, which is stored exclusively on the mobile electronic device, is also taken into account for determining the at least one dose characteristic.Method according to one of the preceding claims, wherein the at least one dose characteristic variable - comprises a dose rate currently to be expected according to the use of the radiation source (4) and / or a dose rate to be expected at a predefined future time; or - is determined depending on the currently to be expected dose rate and / or the dose rate to be expected at the predefined future time.Method according to claim 1 or 2, wherein the at least one dose characteristic variable - comprises a previous dose to be expected according to the use of the radiation source (4) and / or a future dose to be expected according to the use of the radiation source (4); or - is determined depending on the previous dose and / or the future dose.Method according to Claim 4, wherein - the position of the mobile electronic device (6) relative to the radiation source (4) is determined by means of the mobile electronic device (6) at a plurality of times; - for each of the plurality of times, a dose rate to be expected at the corresponding time is determined by means of the mobile electronic device (6) as a function of the respectively determined position and as a function of the scattered radiation model; and - the previous dose and / or the future dose is determined as a function of the dose rates determined for the plurality of times.Method according to one of the preceding claims, wherein - by means of a receiving unit (9b) of the mobile electronic device (6) respective radio signals of a plurality of transmitting units (11a, 11b, 11c) distributed in the environment are received; and - the position of the mobile electronic device (6) is determined as a function of the received radio signals.Method according to one of the preceding claims, wherein - image data are generated by means of the mobile electronic device (6), said image data imaging one or more reference objects (10a, 10b, 10c) in the environment and / or the radiation source (4); and - the position of the mobile electronic device (6) is determined as a function of the image data.Method according to one of the preceding claims, wherein - sensor data are generated by means of at least one inclination and / or acceleration sensor of the mobile electronic device (6); and - the position of the mobile electronic device (6) is determined as a function of the sensor data.Method according to one of the preceding claims, wherein - depending on the position of the mobile electronic device (6), a position of the user (12) different from the position of the mobile electronic device (6) is determined; and - the at least one dose characteristic to be expected is determined for the position of the user (12).Method according to one of Claims 1 to 8, wherein - a three-dimensional spatial region is determined as a function of the position of the mobile electronic device (6); - a local dose rate and / or local dose is determined for each of a multiplicity of points in the three-dimensional spatial region by means of the mobile electronic device (6); and - the local dose rates and / or the local doses are summed up by means of the mobile electronic device (6) in order to determine the at least one dose characteristic to be expected.Method according to one of Claims 1 to 8, wherein, by means of the mobile electronic device (6), depending on the at least one dose characteristic variable and depending on the scattered radiation model, a further position or a region in the environment of the radiation source (4) is determined, for which a dose of the scattered radiation recorded by the user (12) according to the use of the radiation source (4) is reduced.Method according to one of the preceding claims, wherein - further image data are generated by means of the mobile electronic device (6), said further image data mapping the user (12); - a user model is created or adapted by means of the mobile electronic device (6) on the basis of the further image data; and - the at least one dose characteristic variable to be expected is determined as a function of the user model.System for estimating the dose of scattered radiation, comprising a storage medium (8) which stores a scattered radiation model which specifies a spatial distribution of the scattered radiation to be expected in a predefined use of a radiation source (4) in a surrounding area of the radiation source (4), characterized in that - the system comprises a mobile electronic device (6) which is configured to determine its position relative to the radiation source (4); - the mobile electronic device (6) is configured to determine at least one dose characteristic variable of the scattered radiation to be expected according to the use of the radiation source (4) depending on the scattered radiation model and depending on the determined position of the mobile electronic device (6).The system according to claim 13, wherein the mobile electronic device (6) is configured to determine the at least one dose characteristic depending on information regarding the user exclusively stored on the mobile electronic device.The system according to claim 13 or 14, wherein the mobile electronic device (6) comprises - a receiving unit (9b) for receiving respective radio signals of a plurality of transmitting units (11a, 11b, 11c) distributed in the environment and is configured to determine the position of the mobile electronic device (6) depending on the received radio signals; and / or - a camera (9a) configured to generate image data which depict one or more reference objects (10a, 10b, 10c) in the environment and is configured to determine the position of the mobile electronic device (6) depending on the image data.The system according to any one of claims 13 to 15, wherein - the mobile electronic device (6) comprises at least one inclination and / or acceleration sensor configured to generate sensor data; and - the mobile electronic device (6) is configured to determine the position of the mobile electronic device (6) depending on the sensor data.A computer program product comprising instructions which, when executed by a system according to any one of claims 13 to 16, cause the system to perform a method according to any one of claims 1 to 12.

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