WO2018087049A1 - Réduction de dose en radiographie dynamique - Google Patents

Réduction de dose en radiographie dynamique Download PDF

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Publication number
WO2018087049A1
WO2018087049A1 PCT/EP2017/078373 EP2017078373W WO2018087049A1 WO 2018087049 A1 WO2018087049 A1 WO 2018087049A1 EP 2017078373 W EP2017078373 W EP 2017078373W WO 2018087049 A1 WO2018087049 A1 WO 2018087049A1
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Prior art keywords
bin
respiration
determining
radiation emission
bins
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PCT/EP2017/078373
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English (en)
Inventor
Sven Kabus
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Koninklijke Philips N.V.
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Publication of WO2018087049A1 publication Critical patent/WO2018087049A1/fr

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/54—Control of apparatus or devices for radiation diagnosis
    • A61B6/542—Control of apparatus or devices for radiation diagnosis involving control of exposure
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/02—Arrangements for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
    • A61B6/03—Computed tomography [CT]
    • A61B6/032—Transmission computed tomography [CT]
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/54—Control of apparatus or devices for radiation diagnosis
    • A61B6/541—Control of apparatus or devices for radiation diagnosis involving acquisition triggered by a physiological signal
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/54—Control of apparatus or devices for radiation diagnosis
    • A61B6/545—Control of apparatus or devices for radiation diagnosis involving automatic set-up of acquisition parameters
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/48—Diagnostic techniques
    • A61B6/486—Diagnostic techniques involving generating temporal series of image data
    • A61B6/487—Diagnostic techniques involving generating temporal series of image data involving fluoroscopy

Definitions

  • the present invention relates to the field of dynamic radiographic imaging, e.g. dynamic imaging using ionizing radiation, such as dynamic computed tomography (CT) imaging. More specifically it relates to a radiation emission controller, a system comprising such controller and a method for controlling radiation emission in dynamic radiographic imaging.
  • dynamic radiographic imaging e.g. dynamic imaging using ionizing radiation, such as dynamic computed tomography (CT) imaging.
  • CT computed tomography
  • a temporal series of radiographic images of a subject can be acquired in dynamic imaging, such as in dynamic CT acquisitions, e.g. in respiratory- gated CT imaging.
  • dynamic CT acquisitions may be used in imaging settings where periodic motion, such as breathing, or contrast flow, such as in perfusion scans, occur.
  • a patient may be scanned, followed by a retrospective sorting of the acquired image data, e.g. of the acquired projection images, into respiratory states.
  • These respiratory states may be defined as a function of breathing amplitude, for example by binning the breathing amplitude.
  • amplitude binning the two respiratory signal extremes, i.e. the end-inhale and the end-exhale state, may be detected, and the breathing amplitude range defined by these extremes may be partitioned into bins.
  • the data may thus be divided into, for example, ten bins according to breathing amplitude signal thresholds such that these bins are representative of ten corresponding respiratory states, e.g. ranging from an end-exhale over an end-inhale to an end-exhale position.
  • the total number of acquisitions and therefore the dose exposed to the patient may be significantly higher compared to a static CT acquisition.
  • Dynamic CT imaging results in a larger number of projections and thus in a larger dose exposed to the patient compared to static CT imaging, since for each respiratory state a sufficient number of projections needs to be acquired. Furthermore, such dose increase of a dynamic imaging technique as compared to its static counterpart is not specific to CT imaging, e.g. similar dose increases can be observed in other dynamic radiographic imaging techniques, such as fluoroscopic imaging.
  • a dose reduction can be achieved in dynamic imaging during the extreme phases of the respiratory cycle, e.g. in extreme exhalation phases.
  • a low total radiation dose can be achieved in dynamic imaging due to a reduced dose exposure of the imaged subject at the extremal breathing positions, relative to a dose exposure in a comparable imaging technique known in the art that does not apply respiration dependent dose modulation.
  • a substantial dose reduction can be achieved in dynamic imaging, e.g. in dynamic respiratory-gated CT imaging, for example a dose reduction in the range of 35% to 70%, e.g. in the range of 45% to 65%), e.g. in the range of 55% to 62%, such as 59%, relative to a corresponding conventional dynamic imaging protocol that does not take the respiratory cycle into account for modulating the radiation dose received by the imaged subject.
  • the present invention relates to a radiation emission controller for generating an output signal to control radiation emission in a radiographic imaging device configured to perform a plurality of image acquisitions.
  • the radiographic imaging device may be configured to rotate a radiation source, e.g. x-ray tube, around a subject at a substantially constant rotational velocity while acquiring the plurality of images, e.g.
  • the radiation emission controller comprises an input port for receiving an input signal from a respiration phase tracking device, an output port for transmitting the output signal to a radiographic imaging device, and a processor.
  • the processor is adapted for (in operation of the radiation emission controller):
  • determining e.g. in real-time or substantially in real-time, a present respiration bin of the plurality of bins, in which the determined bin corresponds to a present input signal value received from the respiration phase tracking device, and
  • the output signal in response to the determined present respiration bin such that the output signal indicates either a normal dose condition or a reduced dose condition in accordance with the sparse sampling value determined for the respiration bin.
  • the processor may be adapted for determining the value representative of the dwell time in each bin as a percentage of the total time of a respiration cycle that is spent in that bin.
  • the processor may be adapted for determining the value representative of the dwell time in each bin as a number of image acquisitions in an imaging sequence that correspond to that bin, in which a respiratory model and an imaging sequence with a constant number of image acquisitions per unit of time may be taken into account.
  • the processor may be adapted for determining the number of image acquisitions by applying a predetermined respiratory model to determine a dwell time in each bin over a respiration cycle.
  • the predetermined respiratory model may be a lung volume model based on a continuous periodic function, such as a periodic, continuous and differentiable function, e.g. a periodic continuously differentiable function.
  • the predetermined respiratory model may be a lung volume model based on a cos 2n function, where n is a strictly positive integer, or a similar function.
  • the processor may be adapted for determining the number of image acquisitions by determining a subject-individualized respiration model.
  • the processor may be adapted for determining a threshold value
  • the sparse sampling value as a quotient of the number of image acquisitions per bin divided by the threshold value.
  • the processor may be adapted for amplitude binning the input signal by determining two extremal values of the input signal that are representative of respectively an end-inhale and an end-exhale phase in the respiration cycle and dividing the range of the input signal in between these two extreme values in the plurality of bins.
  • the range of the input signal in between the two extremal values may be divided in a first set of bins for the inhalation part of the respiration cycle and the range of the input signal in between the two extremal values may be divided in a second set of bins for the exhalation part of the respiration cycle.
  • the processor may be adapted for sampling the reduced dose condition stochastically, wherein the sparse sampling value indicates the sampling probability of this reduced dose condition in the generated output signal per bin.
  • the processor may be adapted for sampling the reduced dose condition deterministically, wherein the processor may be adapted for determining for each sparse sampling value, corresponding to a bin of the plurality of bins, a sampling pattern, e.g. a deterministic sampling pattern, for emitting the reduced dose condition and the normal dose condition via the output port.
  • the present invention relates to a system comprising a radiation emission controller in accordance with embodiments of the first aspect of the present invention and a respiration phase tracking device for providing the input signal to the input port of the radiation emission controller.
  • the present invention relates to a system comprising a radiation emission controller in accordance with embodiments of the first aspect of the present invention and a radiographic imaging device connected to the output port of the radiation emission controller.
  • the radiographic imaging device comprises an x-ray tube.
  • the radiographic imaging device is furthermore adapted to enable an emission of ionizing radiation from the x-ray tube when the normal dose condition is received as output signal via the output port and disabling or reducing this emission of ionizing radiation when the reduced dose condition is received as output signal via the output port.
  • the radiographic imaging device may be configured to rotate the x-ray tube around a subject at a substantially constant rotational velocity while acquiring the plurality of images, e.g. projection images, and while receiving the output signal and controlling the radiation emission in response to the output signal.
  • the radiographic imaging device may be a computed tomography scanner.
  • the present invention also relates to a method for controlling radiation emission in dynamic radiographic imaging using a radiographic imaging device configured to perform a plurality of image acquisitions.
  • the radiographic imaging device may be configured to rotate a radiation source, e.g. x-ray tube, around a subject at a substantially constant rotational velocity while acquiring the plurality of images, e.g.
  • the method comprises:
  • respiration phase tracking device tracking a respiration phase of a subject using a respiration phase tracking device
  • amplitude binning the respiration phase into a plurality of bins, determining, for each bin of the plurality of bins, a value representative of the dwell time in the bin over at least one respiration cycle of the subject,
  • a source of ionizing radiation e.g. in a medical imaging system, in response to the determined present respiration bin such that either a normal radiation dose or a lower radiation dose, such as no radiation dose, is generated by the source of ionizing radiation in accordance with the sparse sampling value determined for the present respiration bin.
  • the present invention also relates to a computer program product, having computer readable program code embodied therein, for instructing a processor to control radiation emission in a radiographic imaging device according to a method in accordance with embodiments of the present invention.
  • FIG 1 shows a respiration model of lung volume over time as a periodic function, for illustrating principles related to embodiments of the present invention.
  • FIG 2 shows a histogram representative of time spent in every respiratory bin, for illustrating principles related to embodiments of the present invention..
  • FIG 3 shows an exemplary sparse sampling function related to embodiments of the present invention.
  • FIG 4 schematically shows a radiation emission controller in accordance with embodiments of the present invention.
  • FIG 5 shows a system in accordance with embodiments of the present invention.
  • FIG 6 illustrates a method in accordance with embodiments of the present invention.
  • radiographic imaging reference is made to imaging modalities in which ionizing radiation is applied to discern an internal structure of a subject being imaged, such as conventional X-ray projection imaging or computed tomography (CT) imaging.
  • CT computed tomography
  • dynamic radiographic imaging reference is made to radiographic imaging to obtain a sequence of images, e.g. projection images, or a sequence of reconstructed image volumes representative of different moments in time.
  • the 'dynamic radiographic imaging' may refer to the imaging of changes that occur in the imaged subject on a time scale that is generally less than 30 minutes, e.g. less than 10 minutes, e.g. has a substantial frequency component in the 0.1 Hz to 10 Hz range.
  • the 'dynamic radiographic imaging' may refer to the imaging of changes in the imaged subject that correlate, e.g. strongly correlate, to the respiratory motion of the subject.
  • a normal radiation dose or a normal dose condition reference is made to a condition comparable to the use of ionizing radiation in a conventional imaging protocol.
  • 'normal' should only be interpreted as being representative of a higher radiation dose than the associated reduced dose condition or lower radiation dose.
  • this may also refer to a substantially zero radiation emission condition.
  • a subject may be imaged while undergoing a breathing cycle.
  • CT computed tomography
  • a breathing cycle may be approximated by a respiration model that is based on a continuous periodic function, such as a periodic, continuous and differentiable function, e.g. a periodic continuously differentiable function.
  • the predetermined respiratory model may be a lung volume model based on a cos 2n function.
  • Amplitude-based binning may divide the function interval into respiratory bins of equal lung volume interval.
  • the respiration time spent in the individual bins may be largest for the end-exhale state 101, second-largest for the end- inhale state 102 and smallest for those respiratory states where the lung volume changes the fastest.
  • a radiation dose that is at least 5 times, e.g. in the range of 8 to 14 times, for example 10 times, higher at the extremal positions as opposed to an intermediate position, e.g. intermediate bin.
  • the time spent at the extremal positions may be substantially larger, e.g. by about a factor ten, compared to the intermediate respiratory positions.
  • the radiation dose received by the imaged subject may be a corresponding factor, e.g. about 10 times, higher at the extremal positions.
  • FIG 2 shows a histogram representing a count of CT projections per respiratory bin for a conventional dynamic CT imaging sequence.
  • a predetermined minimum number of image acquisitions e.g. CT projections
  • the threshold 201 e.g. to achieve a target image quality
  • image acquisitions at regular, uniform intervals would result in a high number of image acquisitions, e.g. CT projections, being performed in the extremal inhalation and exhalation bins (represented by bins 6 and 1).
  • Embodiments of the present invention may advantageously allow the application of a similar, e.g. about the same, e.g. the same, amount of dose for each respiratory state, e.g. each respiratory state as characterized by a breathing amplitude bin, such that a total dose exposure of the imaged subject can be reduced at the extremal breathing positions where a conventional technique would result in the higher dose referred to hereinabove, e.g. a factor of about 10 higher dose relative to the intermediate respiratory states.
  • embodiments of the present invention may result in a reduction of an overall dose exposure of a subject, e.g. a patient, in a dynamic radiographic imaging examination.
  • the present invention relates to a radiation emission controller.
  • This radiation emission controller may be adapted for generating a signal to control radiation emission in a radiographic imaging device, e.g. to directly and/or indirectly control an X-ray tube in a radiographic imaging device such as a computed tomography system.
  • FIG 4 shows an exemplary radiation emission controller 10 in accordance with embodiments of the present invention.
  • the radiation emission controller 10 comprises an input port 3 for receiving an input signal from a respiration phase tracking device.
  • the input port may comprise an input means such as a data communication network connection or a dedicated device link, such as a data bus connection, for connecting the radiation emission controller to the respiration phase tracking device.
  • the radiation emission controller 10 further comprises an output port 4 for transmitting an output signal to a radiographic imaging device, e.g. directly or indirectly controlling an X-ray tube in a radiographic imaging device such as a CT system.
  • the radiation emission controller 10 also comprises a processor 2.
  • the radiation emission controller may comprise a computer.
  • the radiation emission controller may be integrated in an operator console or workstation associated with a medical imaging system.
  • the radiation emission controller may comprise a human readable output device such as a monitor or display and a human interface input device such as a keyboard and mouse. An operator may interact with the radiation emission controller in a non-interactive or interactive manner, e.g. using a graphical user interface or otherwise.
  • the radiation emission controller may be adapted for controlling an x-ray tube of a medical imaging system, e.g. for controlling a CT scanning unit.
  • the processor 2 is adapted for amplitude binning the input signal into a plurality of bins, for example, by determining two extreme values of the input signal representative of an end- inhale and an end-exhale phase in the respiration cycle and dividing the range of the input signal in between these two extreme values in a plurality of bins.
  • the range of the input signal in between the two extreme values may be divided in a first set of bins for the inhalation part of the respiration cycle and the range of the input signal in between the two extreme values may be divided in a second set of bins for the exhalation part of the respiration cycle.
  • Each bin may be determined such as to have similar, e.g. substantially the same, e.g. the same, size in terms of the corresponding input signal value range, e.g. in terms of the corresponding lung volume interval.
  • the number of bins in the plurality of bins may lie in the range of 4 to 20, e.g. in the range of 6 to 15, e.g. in the range of 8 to 12.
  • the number of bins may equal 10
  • the plurality of bins may consist of two bins that respectively correspond to the extremal inhalation and exhalation positions, four bins that correspond to the non-extremal exhalation phase and another four bins that correspond to the non-extremal inhalation phase, such as illustrated in FIG 1.
  • the processor is also adapted for determining, for each bin of the plurality of bins, a value representative of the dwell time in each bin over at least one respiration cycle.
  • this value representative of the dwell time may comprise a percentage of the total time of a respiration cycle that is spent in each bin, e.g. as delimited by the vertical lines 104 shown in FIG 1.
  • this value representative of the dwell time may comprise a number of image acquisitions in an imaging sequence that correspond to this bin, taking a respiratory model and an imaging sequence with a constant number of image acquisitions per unit of time into account.
  • the processor may be adapted for determining, for each bin of the plurality of bins, a number of image acquisitions of an imaging sequence that correspond to this bin, taking a respiratory model and an imaging sequence with a constant number of image acquisitions per unit of time into account.
  • This determining of the number of image acquisitions may comprise applying a predetermined respiratory model, e.g. a lung volume model based on a continuous periodic function, such as a periodic, continuous and differentiable function, e.g. a periodic continuously differentiable function, to determine a dwell time in each bin over a respiration cycle.
  • a predetermined respiratory model e.g. a lung volume model based on a continuous periodic function, such as a periodic, continuous and differentiable function, e.g. a periodic continuously differentiable function, to determine a dwell time in each bin over a respiration cycle.
  • the predetermined respiratory model may be a lung volume model based on a cos 2n function.
  • a breathing rate may be measured, via the input signal received from the input port, or received via a further input, e.g.
  • This dwell time in each bin may be combined with an image acquisition frequency and/or a number of images to be acquired, e.g. a frequency at which projection images are to be acquired by a CT scanner in accordance with the imaging sequence that has the number of images to be acquired, to determine the number of image acquisitions in accordance with this sequence that would fall in each of the bins.
  • this determining of the number of image acquisitions may also comprise determining a subject-individualized respiration model.
  • at least one respiratory cycle of a subject when monitored by a respiratory phase tracking device connected to the input port, may be used to determine such subject-individualized respiration model.
  • the input signal representative of the at least one respiratory cycle may be captured and binned, as described hereinabove.
  • a plurality of such respiratory cycles may be averaged and the average signal trace may be binned, or a plurality of such respiratory cycles may be binned and then values characterizing corresponding bins may be averaged.
  • the subject-individualized respiration model may be combined with a characterization of the imaging sequence, e.g. received as user input, to determine the number of image acquisitions in accordance with this sequence that would fall in each of the bins.
  • determining the number of image acquisitions may also comprise combining a subject-individualized respiration model with a prior respiration model and/or with a general respiration model, e.g. a population-generalized respiration model.
  • FIG 2 illustrates a histogram representative of the number of image acquisitions in a dynamic CT sequence in each bin based on the exemplary respiration model shown in FIG 1, taking a projection image acquisition rate, a number of projection images to be acquired and a breathing rate into account.
  • the processor is furthermore adapted for determining for each respiratory bin a sparse sampling value for each bin based on the value representative of the dwell time.
  • this sparse sampling value may be proportional to this value, or, in an equivalent, alternative parametrization, the sparse sampling value may be inverse proportional to the value.
  • the sparse sampling value may be representative of a sampling probability, or, alternatively, of a sampling rate.
  • the processor may be adapted for determining a threshold value representative of a minimum number of images to be acquired per bin, e.g. a minimum of projections to be acquired per bin.
  • This threshold may be determined as function of a predetermined image quality criterion, e.g. a reconstructed image quality criterion, to be respected for each respiratory state when imaged.
  • the sparse sampling value per bin may thus be determined as a quotient of the number of image acquisitions per bin divided by the threshold value.
  • the sparse sampling function represented by the sparse sampling value as function of the bin identifier may thus describe for each respiratory bin how many projections are needed to meet a desired image quality, e.g. a desired image quality after tomographic reconstruction.
  • a desired image quality e.g. a desired image quality after tomographic reconstruction.
  • an x-ray source can be switched off for ten out of eleven time units in this example.
  • every possible projection image may be required.
  • the x-ray source may remain switched on during this respiratory phase.
  • respiratory bin 6 in this example corresponding to the end- inhale phase, only one out of every five possible projections may be required.
  • the x-ray source can be switched off for four out of five time units.
  • FIG 3 illustrates such sparse sampling function, e.g. such sparse sampling value per bin.
  • the sparse sampling function may thus determine for each respiratory bin how many image acquisitions, e.g. CT projections, can be skipped in order to achieve an acceptable image quality, e.g. an acceptable CT reconstruction quality per bin.
  • skipping 10 out of 11 projections for bin no. 1 may thus result in a similar or same total number of projections collected for bin no. 1 as for bin no. 4 or bin no. 8.
  • the percentage of skipped projections per respiratory bin may be estimated from a bar-plot such as shown in FIG 2.
  • a constant number of projections per respiratory bin may be achieved by skipping 59% of the projections, therefore reducing in turn a radiation dose exposure of the imaged subject, e.g. a patient, by 59%.
  • the processor is adapted for determining, e.g. in real-time or substantially in real-time during imaging, a present respiration bin of the plurality of bins, in which the determined bin corresponds to a present input signal value received from the respiration phase tracking device.
  • the processor is further adapted for generating the output signal via the output port in response to the determined respiration bin, such that the output signal indicates either a normal dose condition or a reduced dose condition in accordance with the sparse sampling value determined for the respiration bin.
  • the reduced dose condition may be sampled stochastically, wherein the sparse sampling value indicates the sampling probability of this reduced dose condition for each bin.
  • the reduced dose condition may also be sampled deterministically.
  • the processor may be adapted for determining for each sparse sampling value, corresponding to a bin, a sampling pattern for emitting a reduced dose condition via the output port and emitting a normal dose condition via the output port, e.g. to switch an x-ray source respectively on and off.
  • this sampling pattern may comprise repeatedly emitting a signal to switch off the source for a first number x of units of time and to emit a signal to switch the source on for one time unit following an Off -signal for a number x of units of time.
  • the present invention also relates to a system comprising a radiation emission controller in accordance with embodiments of the first aspect of the present invention and a respiration phase tracking device for providing the input signal to the input port.
  • the respiration phase tracking device may comprise a real-time video analysis system for estimating a value indicative of a present lung volume in the respiration cycle of a subject being observed, such as, for example, a video-based respiratory gating system.
  • the respiration phase tracking device may also comprise an alternative system for estimating a value indicative of a present lung volume in the respiration cycle of a subject being observed, e.g. based on a spirometer measurement.
  • the respiration phase tracking device may be co-integrated with the radiation emission controller, e.g. such that processing for estimating a value indicative of a present lung volume in the respiration cycle of a subject being observed may be carried out on the processor of the radiation emission controller.
  • the input port of the radiation emission controller may merely refer to a virtual data exchange means, such as a variable stored in a memory, for making the value indicative of the present lung volume available to the radiation emission controller for processing.
  • the present invention relates to a system comprising a radiation emission controller in accordance with embodiments of the first aspect of the present invention and a radiographic imaging device connected to the output port 4 of the radiation emission controller.
  • the radiographic imaging device comprises an x-ray tube, and is adapted to enable an emission of ionizing radiation from the x-ray tube when the normal dose condition is received as output signal via the output port, and to disable or reduce this emission of ionizing radiation when the reduced dose condition is received as output signal via the output port.
  • a system in accordance with embodiments of the third aspect of the present invention may also comprise a respiration phase tracking device as described hereinabove for embodiments of the second aspect of the present invention.
  • the radiographic imaging device may comprise, e.g. may be, a fluoroscopy system.
  • the radiographic imaging device may comprise, e.g. may be, a computed tomography scanner or a cone beam computed tomography scanner.
  • FIG 5 such computed tomography scanner 200 is illustrated in FIG 5.
  • a CT scanning unit 200 may be adapted for performing multiple axial scans and/or a helical scan of a subject, e.g. of the thorax region of a patient.
  • the CT scanning unit e.g. the computed tomography scanner, may comprise a stationary gantry 202 and a rotating gantry 204, which may be rotatably supported by the stationary gantry 202.
  • the rotating gantry 204 may rotate, about a longitudinal axis, around an examination region 206 for containing the subject to be imaged when acquiring projection data.
  • the CT scanning unit may comprise a subject support 114, such as a couch, to support the subject in the examination region 206.
  • the CT scanning unit comprises an x-ray tube 208, which may be supported by and configured to rotate with the rotating gantry 204.
  • This radiation source may include an anode and a cathode.
  • a source voltage applied across the anode and the cathode may accelerate electrons from the cathode to the anode.
  • the electron flow may provide a current flow from the cathode to the anode, such as to produce radiation for traversing the examination region 206.
  • the CT scanning unit may comprise a detector array 210.
  • This detector array may subtend an angular arc opposite the examination region 206 relative to the radiation source 208.
  • the detector array may include a one or two dimensional array of pixels, such as direct conversion detector pixels, which include a direct conversion material such as cadmium telluride (CdTe), cadmium zinc telluride (CZT), and/or other direct conversion material.
  • the detector array may be adapted for detecting radiation traversing the
  • the radiographic imaging device is configured to perform a plurality of image acquisitions, e.g. to acquire a plurality of projection images, such as a plurality of CT projections.
  • This plurality of image acquisitions may be performed in accordance with a predetermined or configurable imaging sequence, e.g. defined in an acquisition schedule.
  • acquisition schedule may comprise a frequency setting for generating a plurality of uniformly distributed imaging pulses, in which an image is to be acquired for each imaging pulse.
  • the processor of the radiation emission controller may be configured to determine the present respiration bin of the plurality of bins corresponding to a present input signal value received from the respiration phase tracking device.
  • the input signal may be read out from a respiration phase tracking device, when connected to the input port, for each image acquisition, e.g. synchronized with the plurality of uniformly distributed imaging pulses.
  • the processor may then generate, e.g. synchronized with the plurality of uniformly distributed imaging pulses, the output signal in response to the determined present respiration bin.
  • the output signal may indicate either a normal dose condition or a reduced dose condition in accordance with the sparse sampling value determined for the present respiration bin.
  • the emission of ionizing radiation from the x-ray tube may then be either enabled or disabled as determined by the generated output value.
  • the x-ray tube may comprise an integrated signal transmission arrangement for grid switching the x-ray tube, such as described in WO 2013/001434, and the output signal may operate such grid switching of the x-ray tube. It is an advantage of such grid switching arrangement that fast switching of the ionizing radiation emission, e.g. between an on and an off state, can be achieved.
  • the emission of ionizing radiation from the x-ray tube may be either enabled at a high dose level or at a low dose level as determined by the generated output value.
  • the tube current supplied to the x-ray tube may be substantially lower at the low dose level than at the high dose level, e.g. the tube current at the low dose level may be in the range of 0% to 75%, preferably in the range of 0% to 50%, or in the range of 0%) to 25%, such as in the range 0%> to 10%> of the tube current at the high dose level.
  • the radiation emission controller may generate a deterministic pattern, e.g. a switch on/off pattern, associated with the detected respiration bin, to control the x-ray tube via the output signal.
  • a deterministic pattern e.g. a switch on/off pattern
  • Embodiments of the present invention may thus apply a similar or a same amount of dose for each respiratory state, by selectively controlling the x-ray tube in accordance with the detected respiration bin.
  • the dose exposure of a patient may be reduced at the extremal breathing positions and therefore the overall dose exposure of the patient may be reduced.
  • the x-ray tube may be switched repeatedly off and on when the lungs are in the extremal positions, such that, for each respiratory state, the dose exposure of the patient can be normalized, e.g. can be similar or about the same.
  • the number of projections per respiratory state in a CT sequence may be similar or about the same, such that reconstructed respiratory state images may be of a similar quality.
  • the present invention relates to a method for controlling radiation emission in dynamic radiographic imaging, e.g. in dynamic CT imaging.
  • FIG 6 illustrates an exemplary method 60 in accordance with embodiments of the present invention.
  • the method comprises tracking 61 a respiration phase of a subject using a respiration phase tracking device, amplitude binning 62 the respiration phase into a plurality of bins, and determining 63, for each bin of the plurality of bins, a value representative of the dwell time in each bin over at least one respiration cycle of the subject.
  • the method further comprises determining 64, for each bin of the plurality of bins, a sparse sampling value 69 that is based on the value representative of the dwell time. For example, this sparse sampling value may be proportional to this value, or, in an equivalent, alternative parametrization, the sparse sampling value may be inverse proportional to the value.
  • the sparse sampling value may be representative of a sampling probability, or alternatively, of a sampling rate.
  • the method further comprises determining 65 a present respiration bin 70 while tracking the respiration phase of the subject and controlling 66 a source of ionizing radiation in response to the determined present respiration bin such that either a normal radiation dose or a lower dose, e.g. no dose, is generated by the source of ionizing radiation in accordance with the sparse sampling value determined for the determined present respiration bin.
  • a processor of a radiation emission controller in accordance with embodiments of the present invention may implement steps of a method in accordance with embodiments of the present invention.
  • the present invention also relates to a computer program product, having computer readable program code embodied therein, for instructing a processor to control radiation emission in a radiographic imaging device according to a method in accordance with embodiments of the present invention.

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Medical Informatics (AREA)
  • Radiology & Medical Imaging (AREA)
  • Molecular Biology (AREA)
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  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
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  • Apparatus For Radiation Diagnosis (AREA)

Abstract

La présente invention concerne des dispositifs et des procédés de commande d'émission de rayonnement dans une imagerie radiographique dynamique. L'invention concerne un dispositif de commande d'émission de rayonnement qui comprend un port d'entrée (3) pour recevoir un signal d'entrée provenant d'un dispositif de suivi de phase de respiration, un port de sortie (4) pour transmettre un signal de sortie à un dispositif d'imagerie radiographique, et un processeur (2). Le processeur est conçu pour segmenter l'amplitude du signal d'entrée en une pluralité de segment, déterminer pour chaque segment, une valeur représentative du temps d'arrêt dans chaque segment sur au moins un cycle de respiration, et à déterminer, pour chaque segment, une valeur d'échantillonnage clairsemée qui est basée sur la valeur représentative du temps d'arrêt. Le processeur est en outre conçu pour déterminer un présent segment de respiration correspondant à une valeur de signal d'entrée présente reçue en provenance du dispositif de suivi de phase de respiration, et à générer le signal de sortie en réponse au présent segment de telle sorte que le signal de sortie indique soit une dose normale soit une condition de dose réduite conformément à la valeur d'échantillonnage clairsemée pour cette segment.
PCT/EP2017/078373 2016-11-10 2017-11-07 Réduction de dose en radiographie dynamique WO2018087049A1 (fr)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021035511A1 (fr) * 2019-08-27 2021-03-04 Shanghai United Imaging Healthcare Co., Ltd. Systèmes et procédés pour tomodensitométrie 4d
US20210353244A1 (en) * 2019-12-04 2021-11-18 Data Integrity Advisors, Llc System and method for determining radiation parameters

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070027389A1 (en) * 2005-07-18 2007-02-01 Florian Wesse Method and X-ray diagnostic device for generation of an image of a moving body region of a living subject
JP2007195633A (ja) * 2006-01-24 2007-08-09 Toshiba Corp Ｘ線診断装置及び画像データ生成方法
WO2013001434A1 (fr) 2011-06-30 2013-01-03 Koninklijke Philips Electronics N.V. Transmission de signaux et d'alimentation électrique
US20140192952A1 (en) * 2011-07-28 2014-07-10 The University Of Sydney Modulating gantry rotation speed and image acquisition in respiratory correlated (4d) cone beam ct images
WO2015157799A1 (fr) * 2014-04-15 2015-10-22 4Dx Pty Ltd Procédé d'imagerie

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070027389A1 (en) * 2005-07-18 2007-02-01 Florian Wesse Method and X-ray diagnostic device for generation of an image of a moving body region of a living subject
JP2007195633A (ja) * 2006-01-24 2007-08-09 Toshiba Corp Ｘ線診断装置及び画像データ生成方法
WO2013001434A1 (fr) 2011-06-30 2013-01-03 Koninklijke Philips Electronics N.V. Transmission de signaux et d'alimentation électrique
US20140192952A1 (en) * 2011-07-28 2014-07-10 The University Of Sydney Modulating gantry rotation speed and image acquisition in respiratory correlated (4d) cone beam ct images
WO2015157799A1 (fr) * 2014-04-15 2015-10-22 4Dx Pty Ltd Procédé d'imagerie

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
COOPER BENJAMIN J ET AL: "Respiratory triggered 4D cone-beam computed tomography: A novel method to reduce imaging dose", MEDICAL PHYSICS, AIP, MELVILLE, NY, US, vol. 40, no. 4, 1 April 2013 (2013-04-01), pages 41901 - 41901, XP012171104, ISSN: 0094-2405, [retrieved on 20130311], DOI: 10.1118/1.4793724 *
RICKY T O BRIEN ET AL: "Paper;Optimizing 4D cone beam computed tomography acquisition by varying the gantry velocity and projection time interval;Optimizing 4D cone beam computed tomography acquisition by varying the gantry velocity and projection time interval", PHYSICS IN MEDICINE AND BIOLOGY, INSTITUTE OF PHYSICS PUBLISHING, BRISTOL GB, vol. 58, no. 6, 22 February 2013 (2013-02-22), pages 1705 - 1723, XP020242413, ISSN: 0031-9155, DOI: 10.1088/0031-9155/58/6/1705 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021035511A1 (fr) * 2019-08-27 2021-03-04 Shanghai United Imaging Healthcare Co., Ltd. Systèmes et procédés pour tomodensitométrie 4d
US20210353244A1 (en) * 2019-12-04 2021-11-18 Data Integrity Advisors, Llc System and method for determining radiation parameters
US11950940B2 (en) * 2019-12-04 2024-04-09 Data Integrity Advisors, Llc System and method for determining radiation parameters

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