Data transmission device, medical imaging device and method for transmitting data packets

Abstract

Data transmission device for transmitting data packets (24, 26), comprising at least one receive interface (3-5) for receiving data packets (24, 25) from a respective data source (2-5), a respective receive buffer (12-14) for temporarily storing the data packets (24, 25) received via the respective receive interface (2-5), a transfer device (15) for transferring the data packets (24, 25) from the respective receive buffer (12-14) to a transmit buffer (16-18) selected for the respective data packet (24, 25) from among several available transmit buffers (16-18), and a respective transmit interface (19-21) for sending the data packets (24, 25) stored in the respective transmit buffer (16-18) to a receive device (6, 55), wherein the transfer device (15) is configured for this purpose is the transmission of the respective data packet (24,25) from the respective receive buffer (12 - 14) to the selected transmit buffer (16 - 18) only when a release condition (22) is fulfilled, the fulfillment of which depends on a fill level (39, 39') of another of the transmit buffers (16 - 18) that differs from the selected transmit buffer (16 - 18), characterized in that the fulfillment of the release condition (22) additionally depends on the length (38) of the data packet (24, 26) to be transmitted to the selected transmit buffer (16 - 18).

Description

[0001] The invention relates to a data transmission device for transmitting data packets, in particular measurement data from a medical imaging device, comprising at least one receiving interface for receiving data packets from a respective data source, in particular via a wired connection, a respective receiving buffer for temporarily storing the data packets received via the respective receiving interface, a transfer device for transferring the data packets from the respective receiving buffer to a transmitting buffer selected from several available transmitting buffers for the respective data packet, and a respective transmitting interface for sending the data packets stored in the respective transmitting buffer to a receiving device, in particular via a wireless connection. The invention also relates to a medical imaging device and a method for transmitting data packets.

[0002] Data transmission devices are described, for example, in US patent application US 2019 / 0334837A1 and European patent application EP 2797269A1, the latter corresponding to the preamble of claims 1 and 13.

[0003] In medical imaging, for example in computed tomography (CT) scanners, and in other applications, it may be necessary to transfer data between components that are moving relative to each other. For instance, the imaging X-ray sensors in CT scanners are typically mounted on a gantry that can rotate with respect to a base, while data processing and visualization are performed by components that are fixed relative to the base, such as workstations or stationary image processors. Modern CT scanners, for example, can utilize very high data rates of 35 Gbit / s, which places high demands on such a communication link.

[0004] In principle, such data transmission can be achieved, for example, via sliding contacts. However, to achieve high data rates with low maintenance and low susceptibility to interference, it can be advantageous to use wireless data transmission over short distances. This data transmission can be carried out, for example, via radio waves or, more generally, via high-frequency technology or capacitive coupling.

[0005] It is advantageous for several reasons to provide multiple simultaneously usable radio channels. Firstly, this can increase the data transmission rate. Secondly, due to factors such as the rotation of a gantry, transmitting antennas may pass by receiving antennas, meaning that individual transmitting antennas could temporarily be located in areas where their signals cannot be reliably received by receiving antennas. Therefore, it is beneficial to use multiple transmitting and receiving antennas so that, regardless of the gantry's rotation angle, communication is always possible via at least one or a certain number of channels.

[0006] Since hybrid transmission systems, where part of the transmission path is wired and part is wireless, typically achieve different transmission rates in the various parts of the path, "store and forward" approaches, specifically FIFO (First In, First Out) buffering of data packets, are typically used at the transition points between wired and wireless transmission and vice versa. This will be discussed later with reference to... Fig. As will be explained in an example in point 2, the combination of using multiple transmission channels and buffering can, in some cases, lead to a change in the order of transmitted data packets.

[0007] While this could theoretically be accepted, for example, by having a processing unit handling the data packets—such as a workstation used in computed tomography to generate three-dimensional image data—first store the received packets and arrange them in the correct order before further processing. However, since computed tomography uses very high data rates, such a subsequent reordering of received data packets would lead to significant additional demands regarding the required computing time and the speed and amount of available storage, especially if near-real-time visualization of measurement data is desired. Therefore, near-real-time data visualization would only be feasible with considerable limitations, at least in lower-priced devices.

[0008] The invention is therefore based on the objective of providing an improved possibility of achieving a correct packet order even when combining data buffering with multiple transmission channels.

[0009] This problem is solved according to the invention by a data transmission device of the type mentioned at the outset, wherein the transfer device is configured to carry out the transmission of the respective data packet from the respective receive buffer to the selected transmit buffer only when a release condition is met, the fulfillment of which depends on a fill level of a further transmit buffer that differs from the selected transmit buffer.

[0010] The inventive delay of the data packet transmission to the selected send buffer until the release condition is met makes it possible to prevent changes in the packet order caused by parallel data transmission via the transmit interfaces assigned to the various send buffers by means of a suitable delay. This ensures that the packets are received by the receiving device in the correct order and thus no subsequent correction of the packet order is necessary. This allows for further processing of the received data packets with significantly less technical effort. At the same time, it was recognized that the delay of individual data packets when the release condition is not met only marginally reduces the achievable data rate in real-world applications and hardly increases the latencies resulting from the data transmission.This allows, for example, the advantages of parallel wireless data transmission to be used without the need for complex post-processing of the data to correct the packet order.

[0011] The transfer device can, in particular, transfer the oldest data packet, for example, the oldest message, from the receive buffer to the currently selected transmit buffer. The receive buffer can thus implement a FIFO (First In, First Out) buffer. The transmit buffer can also serve as a FIFO buffer for the transmit interface, meaning that the transmit interface can first read the data from the transmit buffer that was written to it earliest.

[0012] The selected transmit buffer can be chosen depending on the operating state of the data transmission device or a larger system that includes it, such as a medical imaging system. As previously explained, certain transmit interfaces may be temporarily unable to transmit data packets to the receiving device, for example, due to the current position of their transmitting antennas. It may therefore be advantageous to select the transmit interface used, and thus the transmit buffer, based on, for example, the rotational position of a gantry. Furthermore, to achieve optimal utilization of the available transmission channels and thus the available bandwidth, an empty or nearly empty transmit buffer can be selected.

[0013] The transfer device may be configured to consider, as part of the evaluation of the release condition, the transmit buffer into which another data packet was transferred that was received immediately before the data packet to be transferred into the selected transmit buffer.

[0014] In particular, the transfer device may be configured to consider, as part of the evaluation of the release condition, that of the transmit buffers into which another data packet was transferred, which was received via the same receive interface immediately before the data packet to be transferred into the selected transmit buffer.

[0015] In most applications, especially when the data transmission rate for receiving via the receiving interface and sending via the transmitting interface does not differ significantly, it is inherent to the system, regardless of the release condition check, that the transmission of the penultimate data packet is completed before the transmission of the current data packet. Therefore, it is generally sufficient to ensure, within the framework of the release condition, that the transmission of the immediately preceding data packet to the receiving device or to subsequent devices, such as a processing device, is completed before the transmission of the current data packet to those devices.

[0016] According to the invention, the fulfillment of the release condition additionally depends on the length of the data packet to be transmitted to the selected send buffer. The length of the data packet can be specified, for example, in bytes or more generally in characters. It is possible for the length of the data packet to be determined when receiving or writing to the receive buffer. In many common communication protocols, the data packets themselves contain information about their length, for example, in a header. The length of the data packet can also be determined based on specific start and end markers.

[0017] As will be explained in more detail below, a delay to ensure the correct packet order can be particularly relevant for relatively short data packets, which is why taking length into account is advantageous.

[0018] The fill level can describe the length of a remaining partial data packet of a previously transmitted data packet that has not yet been sent via the transmit interface assigned to the further transmit buffer, provided that the release condition is met or can only be met if the length of the data packet to be transmitted to the selected transmit buffer reaches or exceeds the length of the partial data packet or the sum of the length of the partial data packet and a predefined offset value.

[0019] An undesirable change in packet order would occur if the transmission of a later-sent data packet to the receiving device or a downstream device were fully completed before the transmission of an earlier-sent data packet to that location was complete, since data packets are generally only forwarded or processed after they have been fully received. Typically, especially when data packets are transmitted wirelessly from the sending interface to the receiving device, transmission speeds from the send buffer to the receiving device or downstream device are lower than those achieved when transmitting from the receive buffer to the send buffer.If the length of the remaining partial data packet is greater than the length of the partial data packet to be transferred to the transmit buffer, the time required to completely transfer the partial data packet to the receiving device or a downstream device can exceed the sum of the relatively short time required to transfer the data packet into the transmit buffer and the time required to transfer this data packet from the transmit buffer to the receiving device or downstream device. This would lead to a change in the order of the data packets. The described procedure prevents this.

[0020] In many applications, transmission rates or propagation times for the transmission path from the transmit buffer to the receiving device or downstream equipment can vary to a certain extent. For example, the required transmission time for a wireless transmission can depend on the relative position of the transmitter and receiver, which can change, for instance, when transmitting from a moving gantry to a stationary base, depending on the gantry's rotational position. Furthermore, transmission interference can lead to deviations in this time. Even with wired transmissions, slight variations in transmission time can occur, for example, due to multiple possible transmission paths and / or temporary buffering during transmission.

[0021] Variable transmission time can lead to a situation where, even in cases where the data packet to be transferred to the send buffer is slightly longer than the remaining partial data packet, this data packet is fully received by the receiving device or a downstream device before the remaining partial data packet is fully received, thus changing the order of the data packets. This problem can be compensated for by using a predefined offset. A suitable offset can, for example, be estimated during the system design phase or determined through test measurements and then fixed.

[0022] The length of the remaining sub-data packet is usually known anyway, since both the length of the data packet and the amount of data already transferred from it are known. Alternatively, the length of the sub-data packet, or even of a data packet placed in a buffer, could be determined, for example, by calculating the distance between a read pointer and a write pointer on the corresponding buffer, or more complex data structures could be used where entries into a data structure are counted, for example, within the framework of object-oriented programming.

[0023] The receiving interface can be wired to, or connectable to, the respective data source. Additionally or alternatively, the transmitting interface can be configured for wireless transmission of the data packet to the receiving device. This allows for the use of a hybrid transmission path, where data packets are transmitted wirelessly in some sections and wirelessly in others. Nevertheless, as explained above, it can be ensured that the data packets arrive at the receiver in the correct order.

[0024] As already explained, the data transmission device can be used in particular for transmitting measurement data from a medical imaging device as data packets.

[0025] In addition to the data transmission device according to the invention, the invention relates to a medical imaging device, in particular a computed tomography scanner, wherein the imaging device comprises a data transmission device according to the invention. As detailed above, the data transmission device according to the invention can be particularly advantageous when data at relatively high data rates is to be transmitted between components that are moving relative to each other, as is the case, for example, in computed tomography scanners and other medical imaging devices.

[0026] The imaging device may include a sensor device, which in particular is or comprises an X-ray sensor, wherein the sensor device is configured to provide data packets to the data transmission device either as the data source or via a processing device serving as a data source. In particular, the sensor device may provide image data, for example, X-ray images.

[0027] The medical imaging device can comprise a frame, in particular a rotatably mounted gantry, which is movable relative to a base and includes the data source and the data transmission device, with the receiving device being fixed relative to the base. The data transmission device can, in particular, serve to transmit data from a moving coordinate system, for example, a rotating gantry, to a stationary coordinate system. If short-range wireless transmission is used, depending on the frame's position or rotation angle relative to the base, only parts of the transmitting interfaces or their associated transmitting antennas may be arranged such that their signal can be reliably received by a respective receiving antenna of the receiving device.This can be taken into account when selecting the transmit buffer into which a data packet is transferred, and thus the transmit interface to be used.

[0028] As already mentioned, the imaging device may be or include a computed tomography scanner, and / or the sensor device may be or include an X-ray sensor, and / or the movable frame may be a rotatable gantry.

[0029] The invention also relates to a method for transmitting data packets, wherein - Data packets are received from a respective data source and temporarily stored in a receive buffer, - the data packets are transferred from the receive buffer to a transmit buffer selected from several available transmit buffers for the respective data packet, whereby the transfer of the respective data packet from the respective receive buffer to the selected transmit buffer only takes place when a release condition is met, the fulfillment of which depends on a fill level of another of the transmit buffers that differs from the selected transmit buffer, and - the data packets stored in the respective transmit buffer are sent to a receiving device via a respective transmit interface assigned to the transmit buffer.

[0030] In particular, measurement data from a medical imaging device can be transmitted as data packets using this method. Additionally or alternatively, the data packets can be received from the respective data source via a wired connection. Additionally or alternatively, the data packets stored in the respective transmit buffer can be sent to the receiving device via a wireless connection using the transmit interface assigned to the transmit buffer.

[0031] The method according to the invention can be implemented, in particular, by the data transmission device according to the invention or used for data transmission in the medical imaging device according to the invention. In particular, the data transmission device according to the invention can be configured to carry out the method according to the invention. Regardless of this, the features and advantages described for the data transmission device according to the invention and for the medical imaging device according to the invention can be transferred to the method according to the invention, and vice versa.

[0032] In particular, when evaluating the release condition, the transmit buffer into which another data packet was transferred, received immediately before the data packet to be transferred into the selected transmit buffer, can be considered as an additional transmit buffer. Furthermore, according to the invention, the fulfillment of the release condition also depends on the length of the data packet to be transferred into the selected transmit buffer. For further details, reference is made to the above explanations of the data transmission device according to the invention.

[0033] The invention further relates to a computer program comprising instructions for the execution of which a transfer device transfers data packets from a receive buffer to a transmit buffer selected from several available transmit buffers for the respective data packet. The transfer of the respective data packet from the respective receive buffer to the selected transmit buffer only occurs upon fulfillment of a release condition, the fulfillment of which depends on the fill level of another transmit buffer, different from the selected transmit buffer. Any programmable processing device capable of at least reading a receive buffer or a memory area constituting it, and at least writing to several transmit buffers or the respective memory areas constituting the transmit buffers, can serve as the transfer device. For example, a CPU, a microcontroller, or an FPGA can serve as such a processing device or transfer device.

[0034] The instructions of the computer program can, in particular, implement that part of the method according to the invention in which the data packets are transferred from the receive buffer to the selected transmit buffer and in which the release condition is checked. The features described above for the method according to the invention can thus be transferred accordingly to the computer program according to the invention.

[0035] The transfer device programmed by the computer program according to the invention can be used as a transfer device in the data transmission device or the imaging device according to the invention. Features disclosed relating to these items can therefore be transferred to the computer program according to the invention with the aforementioned advantages.

[0036] The invention also relates to a computer-readable data carrier comprising a computer program according to the invention.

[0037] The described functionality or the transfer device used in the data transmission device according to the invention can be implemented not only by a computer program but also by hardwiring a corresponding functionality, e.g. by an ASIC.

[0038] Further advantages and details of the invention will become apparent from the following exemplary embodiments and the accompanying drawings. These schematically illustrate: Fig. 1 an embodiment of a medical imaging device according to the invention, comprising an embodiment of the data transmission device according to the invention, wherein an embodiment of the method according to the invention is used for the transmission of the data packets, Fig. 2. The impact of the evaluation in the release condition on the timing of the transmission of data packets in the Fig. 1 medical imaging device shown, Fig. 3. An illustration to clarify the evaluation of the release condition, and Fig. 4 another embodiment of a medical imaging device according to the invention.

[0039] Fig. Figure 1 schematically shows components of a medical imaging system relevant to the provision, transmission, and processing of measurement data. A specific design of such a medical imaging system as a computed tomography scanner will be described later with reference to… Fig. 4 will be explained in more detail.

[0040] The imaging device 1 comprises several data sources 3, 4, 5, which are primarily formed by sensor devices, for example, an X-ray sensor of a computed tomography scanner. Alternatively, the data sources 3, 4, 5 can also be formed, at least partially, by processing devices that already perform preprocessing of measurement data provided by sensors. The provided measurement data, or these comprehensive data packages, are to be made available to a processing device 7 via a receiving device 6.

[0041] For example, in computed tomography scanners, it is common for the data sources to move relative to a base and thus typically also relative to the processing unit 7 during the measurement, for instance, because they are arranged on a rotating gantry. The transition from the moving reference frame of the rotating gantry to the stationary reference frame of the base is enabled in this example by using a data transmission unit 8, to which the data packets from data sources 3, 4, and 5 are transmitted via wired connections and which may also be mounted on the gantry. The transmission from the data transmission unit 8 to the receiving unit 6, however, is wireless, so that the use of sliding contacts or similar devices for data transmission can be dispensed with.

[0042] The data transmission device 8 comprises several receive interfaces 9, 10, 11, through which data packets from one of the data sources 3, 4, 5 are received via cable. The received data packets are first stored in a respective receive buffer 12, 13, 14 and from there by a transfer device 15 in one of several selected transmit buffers 16, 17, 18. Various transmit interfaces 19, 20, 21 each transmit the data packets stored in one of the transmit buffers 16, 17, 18.

[0043] The use of multiple transmit interfaces 19, 20, 21 and associated transmit buffers 16, 17, 18 is advantageous when not every transmit interface 19, 20, 21 can be used to send data packets at every operating time, for example, not in every rotational position of a gantry. This might be the case, for instance, because a transmit antenna is not located within range of a receive antenna of the receiving device 6. Furthermore, distributing the received data packets across different transmit interfaces 19, 20, 21 allows for parallel data transmission and thus a higher data throughput.

[0044] In the example shown, received data packets are made available by receiving facility 6 to only one further facility, namely a processing facility 7. However, it would also be possible to make received data packets available to multiple facilities or to use address information in the data packets so that receiving facility 6 or a downstream facility can distribute the data packets to different further facilities depending on their content.

[0045] To achieve minimal delays in data transmission and maximum data throughput, it would ideally be possible for the transfer device 15 to write data present in one of the receive buffers 12, 13, 14 directly and without delay to the transmit buffer 16, 17, 18 of the transmit interface 19, 20, 21 through which this data is to be transmitted. However, due to the use of parallel transmission paths for wireless data transmission, different transmission rates achieved for wired and wireless data transmission, and the use of different data packet lengths, situations can arise in such a procedure where data packets are received by the receiving device 6 or the processing device 7 in a different order than they were sent by the respective data source 3, 4, 5.An example of such a situation will be given below with reference to . Fig. 2 will be explained.

[0046] In principle, it would be possible to correct an incorrect order of received data packets by subsequently reordering them. However, since very high data rates of, for example, 35 Gbit / s are used for transmitting measurement results in the field of computed tomography, subsequently reordering the received packets is technically quite complex.

[0047] In the medical imaging device 1 and the data transmission device 8, measures are taken during data transmission to prevent such misordering of the data packets at the receiving device 6 and the processing device 7, respectively. To achieve this, the transfer device 15 is configured to transmit a data packet from the respective receiving buffer 12, 13, 14 to the selected sending buffer 16, 17, 18 only when a release condition 22 is met. The fulfillment of this condition depends on the fill level of another of the sending buffers 16, 17, 18, which differs from the selected sending buffer 16, 17, 18. The effect and implementation of this release condition 22 are described below with reference to the Fig. 2 and Fig. 3 explained in more detail.

[0048] Fig. Figure 2 shows, in several lines 31-36, the temporal progression of different transmission processes in the medical imaging device 1. First, the transmission processes will be explained for the case where data stored in a receive buffer 12, 13, 14 is immediately transmitted to a respective selected transmit buffer 16, 17, 18. This corresponds to the case where the release condition 22 would not be evaluated or would always be met.

[0049] Line 31 shows the transmission of two data packets 24, 26 from data source 3 to receive buffer 12. The first data packet 24 is received at time 23 and the second data packet 26 at time 25.

[0050] At time 23, the transfer device 15 recognizes that the transmit interface 19 is available for transmission, for example, because a transmitting antenna is within the reception range of a receiving antenna of the receiving device 6, and that the transmit buffer 16 is empty. Therefore, the transmit buffer 16 is selected to copy the data of the first data packet 24 there. As soon as parts of the data packet 24 arrive in the transmit buffer 16, the transmit interface 19 begins transmitting this data.

[0051] In line 32 in Fig. Figure 2 visualizes the time sequence of the reception of the first data packet 24 by the receiving device 6. The start of the reception is delayed by time interval 27 from time 23, because copying the data into the receive buffer 16 and, in particular, the wireless transmission to the receiving device 6 requires a certain amount of time. Furthermore, a comparison of lines 31 and 32 clearly shows that a longer time interval 28 is required for the receiving device 6 to receive data packet 24 than the time interval between times 23 and 25, since a lower transmission rate is generally achieved during wireless transmission.

[0052] Since it is initially assumed that the release condition 22 is not checked, the data of the second data packet 26 are also transferred directly from their storage in the receive buffer 12 to a selected transmit buffer 17 and from there via the transmit interface 20 to the receiving device 6. The time course of the reception of the second data packet 26 by the receiving device 6 in this case is shown in line 33 of the Fig. Figure 2 visualizes this. As explained above for the first data packet 24, the reception of the second data packet 26 is also delayed by a short time interval 29, which is required for the transmission of the data from the receive buffer 12 to the transmit buffer 17 and from the transmit buffer 17 to the receiving device 6. Furthermore, the time interval 30 for receiving data packet 26 is longer than the duration shown in line 31, which is required for writing data packet 26 to the receive buffer 12, because lower transmission rates are achieved during wireless transmission than during the preceding wired transmission.

[0053] The transmission of data packets 24 and 26 from the receiving device 6 to the processing device 7 should only occur once the respective packet 24 or 26 has been completely received by the receiving device 6. Since wired transmission from the receiving device 6 to the processing device 7 typically achieves higher transmission rates than wireless transmission, this is the only way to ensure uninterrupted transmission of the data packet.

[0054] However, since the reception of the second data packet 26 is already completed at time 37, i.e., before time 46, at which the reception of the first data packet 28 is completed, the receiving device 6 transmits data packet 26 first, and only after this transmission is complete does it transmit data packet 24. The timing of the transmitted data packets 24 and 26 from the receiving device 6 to the processing device 7 is shown in line 34. Fig. Figure 2 shows that by comparing lines 31 and 34 it is obvious that the data packets 24, 26 are received by the processing unit 7 in reverse order of transmission, which would require a reordering of the packet order in the processing unit 7 before further processing.

[0055] As explained above, this unwanted change in packet order can be avoided by delaying the transmission of the second data packet 26 to the selected send buffer 17 until a release condition, which evaluates the fill level of another send buffer (in this example, send buffer 16), is met. An example of the evaluation of a release condition is described in more detail below with reference to... Fig. 3 explained.

[0056] Fig. Figure 3 schematically shows, on the one hand, the data packets 24 and 26 stored in the receive buffer 12, and on the other hand, the data packet 24 already transferred to the transmit buffer. Since the transfer of data packet 24 to the transmit buffer 16 is already complete, it should no longer be stored in the receive buffer 12 in the depicted state of the process. However, FIFO buffers are often designed as ring buffers, where data that has already been read has been passed over by a read pointer but remains in memory. The data is only overwritten when a write pointer reaches the data to be overwritten.

[0057] At time 25, when the second data packet is received, the first data packet has already been substantially transferred to the transmit buffer 16, so that a write pointer 41 of this buffer points to the end of data packet 24. Furthermore, as is shown in particular in line 32 in the Fig. As can be seen in Figure 2, approximately half of the data of data packet 24 has already been sent to the receiving device 6 and thus already read from the transmit buffer 16. Therefore, the read pointer 40 of the transmit buffer 16 points approximately to the middle of the second data packet 24. The distance between the read and write pointers 40, 41 corresponds to the length 43 of the remaining partial data packet 42 of data packet 24, which has not yet been sent to the receiving device 6 via the transmit interface 19 assigned to the transmit buffer 16. The length 43 can also be referred to as the fill level 39 of the transmit buffer 16.

[0058] As in Fig. As can be clearly seen in Figure 3, the length 43 is greater than the length 38 of data packet 26. However, this means that if data packet 26 were transferred directly to the transmit buffer 17, it would likely be completely transmitted to the receiving device 6 before data packet 24, leading to the packet order change explained above. Therefore, the release condition is not met at time 25.

[0059] Fig. Figure 3 also shows the reading pointer 40' at a position it reached at time 62, i.e., after the end of the time interval 45, in line 35 of the Fig. 2. Due to the continuous sending and thus the reading of data from data packet 24, the read pointer has shifted to the right towards the write pointer 41, meaning that the length 43' or the fill level 39' of the remaining partial data packet 42' is smaller than the length 38 of data packet 26.

[0060] If it were assumed that the transmission of data packets 24 and 26 always resulted in the same transmission rates and latencies, the release condition could always be met in this case, and thus the transmission of the second data record 26 into the transmit buffer 17 could begin. However, in order to robustly ensure a correct packet order even in cases where transmission times or rates vary, for example due to different possible transmission paths, possible interference with the wireless transmission path, etc., the release condition in the example shown is only met if the sum of the length 43, 43' of the remaining partial data packet 42, 42' and an offset value 44 is less than the length 38 of data packet 26.

[0061] By using this release condition, the transmission of the second data packet 26 is delayed by the time interval 45, as can be seen from a comparison of lines 33, 35 in Fig. 2 is recognizable. This results in the reception of data packet 26 by the receiving device 6 only being completed at a time that lies after time 46, at which the first data packet 24 is completely received. This results in the data packets 24, 26 being transmitted from the receiving device 6 to the processing device 7 in the correct order when the release condition 22 is used, as shown in line 36 in Fig. 2 is shown.

[0062] Fig. Figure 4 schematically shows a concrete example of a medical imaging device 2, namely a computed tomography scanner, in which the data transmission method described above is used. The imaging device 2 comprises a base 47 and a frame 46 rotatably mounted with respect to the base 47, namely a gantry, which supports an X-ray source 50 and, as sensor devices 48, 49, which are to provide data to a processing device 61 via the receiving device 55, an imaging X-ray detector and a voltage monitor for the X-ray tube 50. The transmission of the measurement data from the sensor devices 48, 49, which function as data sources 3, 4, is carried out via a data transmission device 63, shown only schematically, which, apart from a different number of channels, is essentially the same as the one described in Figure 4. Fig.This corresponds to the data transmission device 8 shown in Figure 1. The large-area transmitting antennas 51, 52, 53, 54 are each part of the transmitting interface of the data transmission device 63 and are thus, as already explained above, supplied by a respective transmitting buffer.

[0063] The base-side receiving unit 55 has five receiving channels, each assigned to one of the receiving antennas 56, 57, 58, 59, 60. Data streams received in parallel via these receiving antennas are subsequently serialized and transmitted to the processing unit 61. As explained above, the evaluation of a release condition by the data transmission unit 63 or its transfer unit ensures that the correct packet order is robustly maintained despite this segmented use of parallel transmission paths.

[0064] 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 by the person skilled in the art without leaving the scope of protection of the invention.

Claims

[1] Data transmission device for transmitting data packets (24, 26), comprising at least one receive interface (3-5) for receiving data packets (24, 25) from a respective data source (2-5), a respective receive buffer (12-14) for temporarily storing the data packets (24, 25) received via the respective receive interface (2-5), a transfer device (15) for transferring the data packets (24, 25) from the respective receive buffer (12-14) to a transmit buffer (16-18) selected for the respective data packet (24, 25) from among several available transmit buffers (16-18), and a respective transmit interface (19-21) for sending the data packets (24, 25) stored in the respective transmit buffer (16-18) to a receive device (6, 55), wherein the transfer device (15) is set up to transmit the respective data packet (24,25) from the respective receive buffer (12 - 14) to the selected transmit buffer (16 - 18) only when a release condition (22) is met, the fulfillment of which depends on a fill level (39, 39') of another of the transmit buffers (16 - 18) that is different from the selected transmit buffer (16 - 18), , characterized by , that the fulfillment of the release condition (22) additionally depends on the length (38) of the data packet (24, 26) to be transferred to the selected transmit buffer (16 - 18). [2] Data transmission device according to claim 1, characterized by , that the transfer device (15) is configured to take into account, as part of the evaluation of the release condition (22), that of the transmit buffers (16 - 18) into which another data packet (24, 26) was transferred, which was received immediately before the data packet (24, 26) to be transferred into the selected transmit buffer (16 - 18). [3] Data transmission device according to claim 1, characterized by , that the transfer device (15) is configured to take into account, as part of the evaluation of the release condition (22), that of the transmit buffers (16 - 18) as a further transmit buffer (16 - 18) into which another data packet (24, 26) was transmitted, which was received immediately before the data packet (24, 26) to be transmitted into the selected transmit buffer (16 - 18) via the same receive interface (9 - 11). [4] Data transmission device according to any of the preceding claims, characterized by, that the fill level (39, 39') describes a length (43, 43') of a remaining partial data packet (42, 42') of the data packet (24, 26) previously transmitted into the further transmit buffer (16 - 18) that has not yet been transmitted via the transmit interface (19 - 21) assigned to the further transmit buffer (16 - 18), wherein the release condition (22) is met or can only be met if the length (43, 43') of the data packet (24, 26) to be transmitted into the selected transmit buffer (16 - 18) reaches or exceeds the length of the partial data packet (42, 42') or the sum of the length (43, 43') of the partial data packet (42, 42') and a specified offset value (44). [5] Data transmission device according to any of the preceding claims, characterized by, that the receiving interface (9 - 11) is wired to or can be connected to the respective data source (3 - 5) and / or that the respective transmitting interface (19 - 21) is designed for wireless transmission of the respective data packet (24, 26) to the receiving device (6, 55). [6] Data transmission device according to any of the preceding claims, characterized by , that the data transmission device (8, 63) serves to transmit measurement data from a medical imaging device (1, 2) as data packets (24, 26). [7] Medical imaging facility, characterized by , that the imaging device (1, 2) comprises a data transmission device (8, 63) according to one of the preceding claims. [8] Medical imaging device according to claim 7, characterized by, that it comprises a sensor device (48, 49) wherein the sensor device (48, 49) is configured to provide data packets (24, 26) to the data transmission device (8, 63) either as the data source (3 - 5) or via a processing device serving as the data source (3 - 5). [9] Medical imaging device according to claim 7 or 8, characterized by , that it comprises a mounted frame (46) movable with respect to a base (47), comprising the data source (3, 4, 5) and the data transmission device (8, 63), wherein the receiving device (6, 55) is fixed in position with respect to the base (47). [10] Medical imaging device according to any one of claims 7 to 9, characterized by, that the imaging device (1, 2) is a computed tomography scanner or includes a computed tomography scanner, and / or that the sensor device (48, 49) is an X-ray sensor or includes an X-ray sensor, and / or that the movable frame (46) is a rotatably mounted gantry. [11] Method for transmitting data packets (24, 26) wherein - Data packets (24, 26) are received from a respective data source (3 - 5) and temporarily stored in a receive buffer (12 - 14), - the data packets (24, 26) are transferred from the receive buffer (12 - 14) to a transmit buffer (16 - 18) selected for the respective data packet (24, 26) from several available transmit buffers (16 - 18), wherein the transfer of the respective data packet (24, 26) from the respective receive buffer (12 - 15) to the selected transmit buffer (16 - 18) only takes place when a release condition (22) is met, the fulfillment of which depends on a fill level (39, 39') of another of the transmit buffers (16 - 18) that is different from the selected transmit buffer (16 - 18), and - the data packets (24, 26) stored in the respective transmit buffer (16 - 18) are sent to a receiving device (6, 55) via a respective transmit interface (19 - 21) assigned to the transmit buffer (16 - 18), characterized by , that the fulfillment of the release condition (22) additionally depends on the length (38) of the data packet (24, 26) to be transferred to the selected transmit buffer (16 - 18). [12] Method according to claim 11, characterized by , that measurement data from a medical imaging device (1, 2) are transmitted as data packets (24, 26) by the method, and / or that the data packets (24, 26) are received from the respective data source (3 - 5) via a wired connection, and / or that the data packets (24, 26) stored in the respective transmit buffer (16 - 18) are sent to the receiving device (6, 55) via a wireless connection through the respective transmit interface (19 - 21) assigned to the transmit buffer (16 - 18). [13] Computer program comprising instructions, the execution of which, by means of a transfer device (15), transfers data packets (24, 26) from a receive buffer (12-14) to a transmit buffer (16-18) selected for the respective data packet (24, 26) from among several available transmit buffers (16-18), wherein the transfer of the respective data packet (24, 26) from the respective receive buffer (12-15) to the selected transmit buffer (16-18) only takes place upon fulfillment of a release condition (22), the fulfillment of which depends on a fill level (39, 39') of another of the transmit buffers (16-18) that is different from the selected transmit buffer (16-18), characterized by , that the fulfillment of the release condition (22) additionally depends on the length (38) of the data packet (24, 26) to be transferred to the selected transmit buffer (16 - 18). [14] Computer-readable data carrier, characterized by that it comprises a computer program according to claim 13.

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