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1. (WO2018087049) RÉDUCTION DE DOSE EN RADIOGRAPHIE DYNAMIQUE
Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

CLAIMS:

1. A radiation emission controller (10) for generating an output signal to control radiation emission in a radiographic imaging device configured to perform a plurality of ima acquisitions, said radiation emission controller comprising:


representative of the dwell time in each bin over at least one respiration cycle,

determining, for each bin of the plurality of bins, a sparse sampling value based on the value representative of the dwell time,

determining 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

generating said 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.

2. The radiation emission controller of claim 1, wherein said processor (2) is adapted for determining said value representative of said dwell time in each bin as a percentage of the total time of a respiration cycle that is spent in said bin.

3. The radiation emission controller of claim 1 , wherein said processor (2) is adapted for determining said value representative of said dwell time in each bin as a number of image acquisitions in an imaging sequence that correspond to said bin, in which a

respiratory model and an imaging sequence with a constant number of image acquisitions per unit of time are taken into account.

4. The radiation emission controller of claim 3, wherein said processor (2) is adapted for determining said number of image acquisitions by applying a predetermined respiratory model to determine a dwell time in each bin over a respiration cycle.

5. The radiation emission controller of claim 4, wherein said predetermined respiratory model is a lung volume model based on a cos2n function, where n is a strictly positive integer.

6. The radiation emission controller of claim 3, wherein said processor (2) is adapted for determining said number of image acquisitions by determining a subject-individualized respiration model.

7. The radiation emission controller of any of claims 3 to 6, wherein said processor (2) is adapted for determining a threshold value representative of a minimum number of images to be acquired per bin of said plurality of bins, and determining, for each bin of the plurality of bins, said sparse sampling value as a quotient of said number of image acquisitions per bin divided by said threshold value.

8. The radiation emission controller of any of the previous claims, wherein said processor (2) is adapted for amplitude binning said 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 said plurality of bins.

9. The radiation emission controller of claim 8, wherein said range of the input signal in between said two extremal values is divided in a first set of bins for the inhalation part of said respiration cycle and the range of the input signal in between the two extremal values is divided in a second set of bins for the exhalation part of the respiration cycle.

10. The radiation emission controller of any of the previous claims, wherein said processor (2) is adapted for sampling said 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.

11. he radiation emission controller of any of the previous claims, wherein said processor (2) is adapted for sampling said reduced dose condition deterministically, wherein the processor is adapted for determining for each sparse sampling value, corresponding to a bin of said plurality of bins, a sampling pattern for emitting the reduced dose condition and the normal dose condition via the output port.

12. A system comprising a radiation emission controller in accordance with any of the previous claims and a respiration phase tracking device for providing said input signal to said input port (3).

13. A system comprising a radiation emission controller in accordance with any of claims 1 to 11 and a radiographic imaging device connected to said output port (4), the radiographic imaging device comprising an x-ray tube, wherein the radiographic imaging device is furthermore adapted to enable an emission of ionizing radiation from said x-ray tube when said normal dose condition is received as output signal via the output port and disabling or reducing said emission of ionizing radiation when said reduced dose condition is received as output signal via the output port.

14. The system of claim 13, wherein said radiographic imaging device is a computed tomography scanner.

15. A method (60) for controlling radiation emission in dynamic radiographic imaging using a radiographic imaging device configured to perform a plurality of image acquisitions, the method comprising:

tracking (61) a respiration phase of a subject using a respiration phase tracking device,

amplitude binning (62) said respiration phase into a plurality of bins, 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,

determining (64), for each bin of the plurality of bins, a sparse sampling value based on the value representative of the dwell time,

determining (65) a present respiration bin (70) while tracking said respiration phase of said subject, and

controlling (66) a source of ionizing radiation in response to said 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.