fig1 shows the front docking region of a patient transportation device 2 and a docking module 20 fastened to a medical instrument ( not shown ). the components shown in fig1 define a mechanical interface designed for locking the patient transportation device 2 on the medical instrument . the docking procedure has an associated outlay and is to be learned by the operating staff . for successful docking , the patient transportation device 2 is led to the docking module 20 at the correct position and at angle . fig2 shows a patient transportation device 2 , configured in accordance with the present teachings . the control is implemented by a wheel 11 that is fastened to the central lower region of the patient transportation device 2 . a motor unit 6 that contains first motor 61 and second motor 62 is situated over the wheel 11 . the first motor 61 controls the position of the wheel 11 and the second motor 62 drives the wheel . fastening the motor centrally in the lower region of the patient transportation device may facilitate docking onto a magnetic resonance imaging scanner since the positioning minimizes magnetic interference . the patient transportation device 2 contains a control device 5 ( e . g . a microprocessor ). the control commands for the motor unit 6 are generated by the control device 5 . additional wheels , such as first wheel 12 , second wheel 13 , third wheel 14 , and fourth wheel 15 , may be coupled to the central wheel 11 . the coupling is shown in fig3 . the central wheel 11 is coupled to the first wheel 12 and the second wheel 13 by a coupling mechanism 7 . the positions of the first wheel 12 and the second wheel 13 adapt based on the position of the central wheel 11 . the motor component 6 changes the wheel position of the central wheel 11 . different motors for controlling and driving the wheels and for adjusting the height of the patient transportation device may be used . in some embodiments , one motor is used . in other embodiments , a plurality of motors is used . fig4 shows an embodiment of the patient transportation device that includes a double wheel 11 in place of a single wheel . fig4 also shows a component 8 for docking ( e . g ., a docking interface ) and an operator 9 . the patient transportation device may include movement sensors that assist the movement ( e . g ., direction or braking ) produced by the operator 9 . fig5 shows a further embodiment of a patient transportation system in accordance with the present teachings . the patient transportation device 2 shown in fig5 is configured to assist the approach to the medical modality 1 along a path 5 . the patient device may be formed with a central wheel or a central pair of wheels 11 . the central wheel or the central pair of wheels 11 may be coupled to other wheels , such as first wheel 12 , second wheel 13 , third wheel 14 , and fifth wheel 15 . the registration apparatus contains two subsystems . a first subsystem is fastened to the patient transportation device 2 . the second subsystem is fastened external to the patient transportation device . the registration subsystem on the patient transportation device 2 includes a sensor 21 that determines a distance 4 from the medical modality 1 ( e . g ., using ultrasound ). a camera 22 fastened close to the ceiling may be provided as an external registration subsystem . the camera 22 records an image of the patient transportation device 2 and the modality 1 . the image is transmitted to an evaluation device 221 that is shielded from magnetic fields by a shield 222 . the evaluation device 221 determines or calculates control information ( e . g ., a current approach vector of the patient transportation system 2 and the deviation thereof from an ideal approach vector ). the evaluation system 221 establishes control information ( e . g . wheel position ) and passes the control information to a transmitter 223 that transmits the control information wirelessly to the receiver 224 of the patient transportation device 2 . the wheel position may be adapted on the basis of the control information . fig6 shows a further embodiment of a patient transportation device 2 in accordance with the present teachings . the patient transportation device 2 includes a central wheel 11 , first wheel 12 , second wheel 13 , third wheel 14 , and fourth wheel 15 . the transportation device 2 includes a handle 25 for manual movement . as shown in fig6 , the patient transportation device 2 includes first motor 61 and second motor 62 . the first motor 61 sets the position of the central wheel 11 . the second motor 62 controls height adjustment of the patient bearing . no motor is provided for the drive in the embodiment shown in fig6 since the transportation device 2 is configured to be driven by operating staff . as shown in fig6 , the patient transportation device 2 contains an optical sensor 231 fastened on the underside at the front of the device and configured to detect floor markings . the use of floor markings is shown in more detail in fig7 and 8 . in addition to the front optical sensor 231 , the patient transportation device 2 shown in fig7 optionally includes an additional optical sensor 234 that is likewise configured to detect floor markings . a marking 7 that specifies a transportation path to the medical instrument 1 is applied to the floor . the wheel positions of the central wheel 11 with the round configuration and of the coupled first wheel 12 , second wheel 13 , third wheel 14 , and fourth wheel 15 are corrected based on the detected line 7 , thereby providing automatic steering . thus , the trolley 2 may be pushed by operating staff without manual steering . for embodiments containing an additional motorized drive , the trolley 2 may be automatically driven to the docking position without human intervention . fig8 shows an alternative marking for the line shown in fig7 . a schematic top view of an examination room is shown in fig8 . a first area 1 is occupied by a medical modality . the patient transportation device 2 is positioned at the lower right - hand corner of fig8 . the floor is subdivided into a plurality of sections 8 . sections 8 of the floor that are relevant to the approach include markings 71 . the markings 71 are identified by sensors fastened to the underside of the patient transportation device 2 . alternatively , the sensors may be fastened externally to the ceiling and used to control the wheels of the patient transportation device 2 . the individual markings 71 encode information about the position of the respective section 8 in relation to the docking point of the medical instrument 1 . fig9 shows a patient transportation device 2 and a mobile medical instrument 1 ( e . g . a mobile computed tomography instrument ). the patient transportation device 2 and the mobile medical instrument 1 are configured for movement control using lines 7 on the floor that may be optically registered . the patient transportation device 2 and the mobile medical instrument 1 each include an optical sensor 231 configured to optically register the lines 7 . moreover , each of the patient transportation device 2 and the mobile medical instrument 1 includes a central wheel 11 with control functionality , and each of the patient transportation device 2 and the mobile medical instrument 1 may include additional wheels , such as first wheel 12 , second wheel 13 , and third wheel 14 . in addition , the patient transportation device 2 and the mobile medical instrument 1 each include an ultrasound sensor 16 . the ultrasound sensor 16 may be used for measuring the distance . the distance established may in turn be used to initiate and control a docking procedure . by way of example , based on the distance , the velocity may be reduced , the docking interfaces may be activated , and the angle of approach may be adapted . alternatively , or in addition , the distance information for controlling the docking procedure may also be encoded into the guide line 7 , as shown in more detail in fig1 . the guide line or marking line 7 may include detectable marking bars , such as a sequence of equidistant bars that contain a first bar 72 and a second bar 73 , as shown in fig1 . distance information that triggers the docking is encoded by the distance between bars . between the third bar 73 and the fourth bar 74 , bar spacing has increased in relation to the bar sequence . the increase in bar spacing is interpreted as a signal to initiate the docking procedure . for example , the velocity is reduced . the ultrasound sensors 16 are used to measure the distance , and the velocity is curbed as a function of the measured distance . the detection of the fourth bar 74 triggers the docking procedure . the next and final fifth bar 75 marks the end position for the docking procedure . while the present invention has been described above by reference to various embodiments , it should be understood that many changes and modifications may be made to the described embodiments . it is therefore intended that the foregoing description be regarded as illustrative rather than limiting , and that it be understood that all equivalents and / or combinations of embodiments are intended to be included in this description . it is to be understood that the elements and features recited in the appended claims may be combined in different ways to produce new claims that likewise fall within the scope of the present invention . thus , whereas the dependent claims appended below depend from only a single independent or dependent claim , it is to be understood that these dependent claims may , alternatively , be made to depend in the alternative from any preceding claim — whether independent or dependent — and that such new combinations are to be understood as forming a part of the present specification .
a patient transportation system includes : a patient transportation device configured to dock with a medical instrument , the patient transportation device having a plurality of wheels ; a registration apparatus configured to register information ; and a control unit configured to change at least one wheel position of at least one wheel of the plurality of wheels based on information registered by the registration apparatus . the system may be used to assist operating staff when the patient transportation device approaches the medical instrument .