Voltage modulation in dual energy computed tomography
AssigneesKabushiki Kaisha Toshiba, Toshiba Medical Systems Corporation
InventorYu ZOU
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Abstract
To prevent patients from being overexposed or underexposed, it has been attempted to modulate either voltage or current in conventional single energy CT systems. The voltage modulation causes incompatibility in projection data among the views while the current modulation reduces only noise. To solve these and other problems, dual energy CT is combined with voltage modulation techniques to improve the dosage efficiency. Furthermore, dual energy CT has been combined with both voltage modulation and current modulation to optimize the dosage efficiency in order to minimize radiation to a patient without sacrificing the reconstructed image quality.
Claims27
A method of voltage modulation in dual energy computed tomography (CT), comprising the steps of:
- a) generating X ray at a predetermined high energy level and a predetermined low energy level at one or more X-ray tube based upon at least one voltage level applied to the X ray tube;
- b) projecting the X ray towards a subject portion;
- c) modulating at least one of the high energy level voltage level and low energy level applied to the X-ray tube according to attenuation in the subject portion to improve dose efficiency, the dose efficiency being defined by squared signal to noise ratio divided by radiation dose;
- and
- d) acquiring dual energy data sets at a predetermined total number of projections per rotation (TPPR) as said steps a) through c) are repeated to scan the subject portion.
A method of voltage modulation in dual energy computed tomography (CT), comprising:
- generating X ray at two or more energy spectra of X ray including a predetermined high energy level and a predetermined low energy level at one or more X-ray tube based upon at least one voltage level applied to the X ray tube at one or more current levels through the X-ray tube;
- projecting the X ray towards a subject portion;
- acquiring dual energy data sets;
- modulating the voltage level of at least one of the high energy level and the low energy level applied to the X-ray tube according to attenuation in the subject portion and modulating the current level to reduce noise in order to optimize dose efficiency, the dose efficiency being defined by squared signal to noise ratio divided by radiation dose;
- and
- acquiring other dual energy data sets at a predetermined total number of projections per rotation (TPPR) as the voltage level and the current level are modulated.
A dual energy computed tomography (CT) system configured to perform voltage modulation during dual energy data acquisition, comprising:
- one or more X-ray tube configured to generate at least two energy spectra of X ray at a predetermined high level and a predetermined low level based upon at least one voltage level applied to said X-ray tube, said X-ray tube emitting the X ray towards a subject portion;
- a system controller connected to said X-ray tube for modulating the voltage level of at least one of the high energy level and the low energy level applied to the X-ray tube according to attenuation in the subject portion to improve dose efficiency;
- and
- a X-ray detector located opposite from said X-ray tube across the subject portion and configured to detect dual energy data sets at a predetermined total number of projections per rotation (TPPR).
A dual energy computed tomography (CT) system configured to perform voltage modulation during dual energy data acquisition, comprising:
- one or more X ray tube configured to generate at two or more energy spectra of X ray including a predetermined high level and a predetermined low level based upon at least one current level applied to said X-ray tube, said X-ray tube projecting the X ray towards a subject portion;
- a system controller connected to said X ray tube for modulating the voltage level of at least one of the high energy level and the low energy level applied to the X-ray tube according to attenuation in the subject portion and for modulating the current level to reduce noise in order to optimize dose efficiency, the dose efficiency being defined by squared signal to noise ratio divided by radiation dose;
- and
- a X-ray detector located opposite from said X-ray tube across the subject portion and configured to detect dual energy data sets at a predetermined total number of projections per rotation (TPPR) as the voltage level and the current level are modulated.
Dependencies are inferred from the claim text.