Projection data acquisition apparatus
First Claim
1. A projection data acquisition apparatus for acquiring projection data, the projection data acquisition apparatus comprising:
- a radiation device with a radiation source for generating a pulsed radiation beam for traversing an object,a detection device for generating projection data being indicative of the pulsed radiation beam after having traversed the object,a moving unit for moving the radiation device and the object relative to each other, in order to generate the projection data at different acquisition positions of the radiation device relative to the object,wherein the radiation device is adapted to generate the pulsed radiation beam such that at different acquisition positions the pulsed radiation beam has different shapes, andwherein the radiation device comprises a grid switching x-ray source for generating a pulsed radiation beam and a collimator for partially blocking and/or attenuating the pulsed radiation beam,wherein the collimator comprises a rotatable cylinder with several openings, and is adapted to rotate the cylinder such that the openings are arranged at different rotational positions relative to the radiation source at the different acquisition positions such that at the different acquisition positions the pulsed radiation beam has different shapes,wherein the openings of the cylinder include first openings arranged at a first position along a longitudinal axis of the cylinder and second openings arranged at a second position along the longitudinal axis of the cylinder, wherein the first openings and the second openings have a circumferential offset relative to each other,wherein the first and second openings are rectangular,wherein the collimator is adapted to partially block the pulsed radiation beam such that a shadowed region and a non-shadowed region are generated on the detection device,wherein the detection device is adapted to generate the projection data based on the pulsed radiation beam directed onto the non-shadowed region and to generate scatter data based on radiation, which has been scattered onto the shadowed region,wherein the projection data acquisition apparatus further comprises a correction unit for correcting the generated projection data based on the scatter data.
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Abstract
The invention relates to a projection data acquisition apparatus (31) for acquiring projection data. The projection data acquisition apparatus comprises a radiation device (32) for generating a pulsed radiation beam (4) for traversing an object and a detection device (6) for generating projection data being indicative of the pulsed radiation beam (4) at different acquisition positions, wherein the radiation device (32) is adapted to generate the pulsed radiation beam (4) such that at different acquisition positions the pulsed radiation beam (4) has different shapes, i.e. is differently blocked and/or attenuated. Thus, not the complete radiation providable by the radiation device is used at each acquisition position, but at least at some acquisition positions only a smaller pulsed radiation beam is used. This can lead to less scattered radiation and hence to improved projection data and an improved computed tomography image, which may be reconstructed based on the acquired projection data.
16 Citations
17 Claims
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1. A projection data acquisition apparatus for acquiring projection data, the projection data acquisition apparatus comprising:
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a radiation device with a radiation source for generating a pulsed radiation beam for traversing an object, a detection device for generating projection data being indicative of the pulsed radiation beam after having traversed the object, a moving unit for moving the radiation device and the object relative to each other, in order to generate the projection data at different acquisition positions of the radiation device relative to the object, wherein the radiation device is adapted to generate the pulsed radiation beam such that at different acquisition positions the pulsed radiation beam has different shapes, and wherein the radiation device comprises a grid switching x-ray source for generating a pulsed radiation beam and a collimator for partially blocking and/or attenuating the pulsed radiation beam, wherein the collimator comprises a rotatable cylinder with several openings, and is adapted to rotate the cylinder such that the openings are arranged at different rotational positions relative to the radiation source at the different acquisition positions such that at the different acquisition positions the pulsed radiation beam has different shapes, wherein the openings of the cylinder include first openings arranged at a first position along a longitudinal axis of the cylinder and second openings arranged at a second position along the longitudinal axis of the cylinder, wherein the first openings and the second openings have a circumferential offset relative to each other, wherein the first and second openings are rectangular, wherein the collimator is adapted to partially block the pulsed radiation beam such that a shadowed region and a non-shadowed region are generated on the detection device, wherein the detection device is adapted to generate the projection data based on the pulsed radiation beam directed onto the non-shadowed region and to generate scatter data based on radiation, which has been scattered onto the shadowed region, wherein the projection data acquisition apparatus further comprises a correction unit for correcting the generated projection data based on the scatter data. - View Dependent Claims (2, 3, 4, 5, 10, 11, 12, 13, 14, 15)
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6. A projection data acquisition method for acquiring projection data, the projection data acquisition method comprising:
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generating a pulsed radiation beam with a radiation source for traversing an object by a radiation device with a grid switching x-ray source, generating projection data being indicative of the pulsed radiation beam after having traversed the object by a detection device, moving the radiation device and the object relative to each other by a moving unit, in order to generate the projection data at different acquisition positions of the radiation device relative to the object, wherein the radiation device generates the pulsed radiation beam such that at different acquisition positions the pulsed radiation beam has different shapes, wherein the collimator comprises a rotatable cylinder with several openings, and is adapted to rotate the cylinder such that the openings are arranged at different rotational positions relative to the radiation source at the different acquisition positions such that at the different acquisition positions the pulsed radiation beam has different shapes, wherein the openings of the cylinder include first openings arranged at a first position along a longitudinal axis of the cylinder and second openings arranged at a second position along the longitudinal axis of the cylinder, wherein the first openings and the second openings have a circumferential offset relative to each other, wherein the first and second openings are rectangular, wherein the collimator partially blocks the radiation beam such that a shadowed region and a non-shadowed region are generated on the detection device, wherein the detection device generates the projection data based on the pulsed radiation beam directed onto the non-shadowed region and to generate scatter data based on radiation, which has been scattered onto the shadowed region, wherein the generated projection data are corrected based on the scatter data by using a correction unit. - View Dependent Claims (7, 8, 9)
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16. A non-transitory computer storage medium encoded with computer readable instructions, which, when executed by a processor of a computing system, causes the processor to perform acts of:
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generating a pulsed radiation beam with a radiation source for traversing an object by a radiation device with a grid switching x-ray source; generating projection data being indicative of the pulsed radiation beam after having traversed the object by a detection device; and moving the radiation device and the object relative to each other by a moving unit, in order to generate the projection data at different acquisition positions of the radiation device relative to the object, wherein a collimator partially blocks the radiation beam such that a shadowed region and a non-shadowed region are generated on the detection device, wherein the collimator comprises a rotatable cylinder with several openings, and is adapted to rotate the cylinder such that the openings are arranged at different rotational positions relative to the radiation source at the different acquisition positions such that at the different acquisition positions the pulsed radiation beam has different shapes, wherein the openings of the cylinder include first openings arranged at a first position along a longitudinal axis of the cylinder and second openings arranged at a second position along the longitudinal axis of the cylinder, wherein the first openings and the second openings have a circumferential offset relative to each other, wherein the first and second openings are rectangular, wherein the radiation device generates the pulsed radiation beam directed onto the non-shadowed region. - View Dependent Claims (17)
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Specification