Patent Document:

radiation dose involved with ct and conventional x - ray procedures has become a very import issue . field studies have shown that wrong patient positioning leads to unnecessarily repeated imaging procedures in numerous cases . this is mainly due to the complexity of imaging procedures and technology and increased workload for medical staff . in the state of the art , positioning of patients relative to a field - of - view is done manually with laser or light field assistance . current imaging devices can however not verify the correct positioning of the table and / or the patient . in view of this , it is proposed to use sensor units that are integrated into or attached to the top of a patient table and detect the patient pose / position . the sensor units may particularly be microwave coils . after specification of a target region ( as part of the data entry during imaging preparation ), signal processing routines may compare the specified target region and the patient position setup . in case of a misalignment , the operator may be warned . fig1 schematically shows an x - ray imaging system 100 that is designed according to the above principles . the imaging system 100 comprises the following components : a sensor system 110 comprising a regular two - dimensional array of ( identical ) sensor units , here microwave coils 111 . each sensor unit 111 is sensitive in an adjacent sensitive zone 112 ( indicated for one representative sensor unit only ). if a biological body like a patient p is within a sensitive zone 112 , the associated sensor unit produces a corresponding detection signal ( or , more generally , the continuously produced signal of this sensor unit changes in a definite way ). a patient table or support 150 that is movable by a motor 151 at least in axial direction ( z - direction ). typically , the patient table 150 is also movable in lateral direction ( x - direction ) and vertical direction ( y - direction ). furthermore , it can optionally be tilted about one or two axes . appropriate sensors , which may for example be integrated into the motor 151 , allow to determine the actual spatial position of the patient table 150 with respect to absolute x , y , z - coordinates . the array 110 of microwave coils 111 is integrated into the top of the patient table 150 over its full length . an imaging apparatus 140 with which images of a patient p or parts of his / her body can be generated if the latter is brought into the field - of - view 141 of said apparatus . the imaging apparatus may for example be a ct - scanner . an evaluation and control unit 120 which receives and processes the signals s from the microwave sensors 111 . this unit may for example be realized by dedicated electronic hardware , by digital data processing hardware with associated software , or a mixture of both . the subunits that are indicated in the figure shall represent different conceptual modules rather than separate hardware components . a user interface , for example a computer or console 130 , which can exchange information with the evaluation and control unit 120 . the evaluation and control unit 120 allows to detect patient position and pose from the received detection signals s in an associated processing module 121 . as part of the imaging setup on the console 130 , the operator may enter the imaging target region ( e . g . knee , chest ). the target region specification may also occur earlier in the clinical workflow ( e . g . by the referring physician ). this input is then compared with the patient &# 39 ; s position on the table in a comparison module 122 . if a mismatch between the specified target region and the patient / table position occurs , a warning signal is created and transmitted to the console 130 . optionally , the evaluation and control unit 120 may also propose the correct patient table position to an operator based on the specified target region . as indicated in the figure , it may even comprise a module 123 for controlling the motor 151 of the patient table 150 such that the target region is automatically moved into the field - of - view 141 of the imaging apparatus 140 . microwave technology is preferred to optical techniques ( e . g . cameras ) because it can be integrated into the table and is not disturbed by lighting conditions , patient clothing or blankets . moreover , the microwave coils 111 can be designed x - ray transparent and very thin . thus they can for instance be incorporated into a mat which can be attached to the table and registered with the device &# 39 ; s coordinate system as an upgrade to existing imaging systems . in summary , the invention allows to monitor patient position and to alert the operator in case of suspected misalignment . this is achieved via the integration of ( e . g . microwave ) detection technology into the patient table and subsequent signal - processing to determine the patient &# 39 ; s pose and position . thus accurate patient positioning can be achieved , particularly for ct and conventional x - ray imaging procedures , where it is essential for diagnostic outcome and dose minimization . the invention can also be applied for other imaging modalities ( e . g . spect , pet , mr ) to improve workflow and increase patient safety . while the invention has been illustrated and described in detail in the drawings and foregoing description , such illustration and description are to be considered illustrative or exemplary and not restrictive ; the invention is not limited to the disclosed embodiments . other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention , from a study of the drawings , the disclosure , and the appended claims . in the claims , the word “ comprising ” does not exclude other elements or steps , and the indefinite article “ a ” or “ an ” does not exclude a plurality . the mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage . any reference signs in the claims should not be construed as limiting the scope .

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