Method and device for balancing CT gantry
View Patent ↗A method and a device for balancing a CT gantry device are provided. The method includes: obtaining a fluctuation chain of pulses generated in one revolution of the CT gantry and obtained when the CT gantry collects data; obtaining an eccentric angle of a center of mass according to the fluctuation chain, and calculating a magnitude of imbalance; and adjusting weight at a weight counterbalancing position according to the eccentric angle and the magnitude of imbalance, to locate the center of mass at the rotation center. The device includes a data collection unit for collecting a fluctuation chain, and a processor for obtaining an eccentric angle of a center of mass, and calculating a magnitude of imbalance; and the processor adjusts weight at the weight counterbalancing position according to the eccentric angle and the magnitude of imbalance, to locate the center of mass at the rotation center.
1. A method for balancing a Computed Tomography (CT) gantry comprising the following steps:
1) obtaining a fluctuation chain of pulses generated in one revolution of the CT gantry and obtained when the CT gantry collects data;
2) obtaining an eccentric angle of a center of mass deviating from a rotation center according to the fluctuation chain, and calculating a magnitude of imbalance; and
3) adjusting weight at a weight counterbalancing position according to the eccentric angle and the magnitude of imbalance, to locate the center of mass at the rotation center; and
wherein step 1) comprises: performing sampling once each time the gantry rotates by a constant angle, obtaining a curve of a pulse generated in each sampling, and connecting successively curves corresponding to respective angles in a rotational direction of the gantry to form the fluctuation chain.
2. The method for balancing the CT gantry according to claim 1 , wherein the data collected during the sampling of the CT gantry is data collected without X-ray exposure.
3. The method for balancing the CT gantry according to claim 2 , wherein the step 2) comprises the following steps:
21) performing a Fourier transform on the fluctuation chain, and obtaining a cosine function of the fluctuation chain by remaining a fundamental frequency component and assuming other harmonic components to be zero, and a phase angle of the cosine function being the eccentric angle; and
22) calculating the magnitude of imbalance according to the cosine function and the eccentric angle.
4. The method for balancing the CT gantry according to claim 3 , wherein in the step 22), the magnitude of imbalance is represented by the product of a mass (m) of the gantry and an eccentric distance (r), and is obtained through the following equation:
P
→
=
2
π
J
(
t
i
-
t
i
+
1
)
gNt
i
+
1
t
i
2
sin
α
Wherein, {right arrow over (P)} is an imbalance vector, J is a rotational inertia, N is a number of constant angles by which the gantry rotates in one revolution, t i is a duration required for the gantry rotating by the ith constant angle, t i+1 is a duration required for the gantry rotating by the (i+1)th constant angle, g is the acceleration of gravity, and α is the eccentric angle.
5. The method for balancing the CT gantry according to claim 1 , further comprising the following step 0) before the step 1):
adjusting a torque voltage of a motor configured to drive the gantry to rotate, to enable the rotation of the gantry to reach a steady state.
6. The method for balancing the CT gantry according to claim 5 , wherein the step 2) comprises the following steps:
21) performing a Fourier transform on the fluctuation chain, and obtaining a cosine function of the fluctuation chain by remaining a fundamental frequency component and assuming other harmonic components to be zero, and a phase angle of the cosine function being the eccentric angle; and
22) calculating the magnitude of imbalance according to the cosine function and the eccentric angle.
7. The method for balancing the CT gantry according to claim 6 , wherein in the step 22), the magnitude of imbalance is represented by the product of a mass (m) of the gantry and an eccentric distance (r), and is obtained through the following equation:
P
→
=
2
π
J
(
t
i
-
t
i
+
1
)
gNt
i
+
1
t
i
2
sin
α
Wherein, {right arrow over (P)} is an imbalance vector, J is a rotational inertia, N is a number of constant angles by which the gantry rotates in one revolution, t i is a duration required for the gantry rotating by the ith constant angle, t i+1 is a duration required for the gantry rotating by the (i+1)th constant angle, g is the acceleration of gravity, and α is the eccentric angle.
8. The method for balancing the CT gantry according to claim 1 , wherein the step 2) comprises the following steps:
21) performing a Fourier transform on the fluctuation chain, and obtaining a cosine function of the fluctuation chain by remaining a fundamental frequency component and assuming other harmonic components to be zero, and a phase angle of the cosine function being the eccentric angle; and
22) calculating the magnitude of imbalance according to the cosine function and the eccentric angle.
9. The method for balancing the CT gantry according to claim 8 , wherein in the step 22), the magnitude of imbalance is represented by the product of a mass (m) of the gantry and an eccentric distance (r), and is obtained through the following equation:
P
→
=
2
π
J
(
t
i
-
t
i
+
1
)
gNt
i
+
1
t
i
2
sin
α
Wherein, {right arrow over (P)} is an imbalance vector, J is a rotational inertia, N is a number of constant angles by which the gantry rotates in one revolution, t i is a duration required for the gantry rotating by the ith constant angle, t i+1 is a duration required for the gantry rotating by the (i+1)th constant angle, g is the acceleration of gravity, and α is the eccentric angle.
10. A device for balancing a Computed Tomography (CT) gantry, the CT gantry having a data collection unit for collecting data and a weight counterbalancing position for balancing the CT gantry, wherein the device comprises a processor in signal connection with the data collection unit; the data collection unit is configured to collect a fluctuation chain of pulses generated in one revolution of the gantry; the processor is configured to obtain an eccentric angle of a center of mass deviating from a rotation center according to the fluctuation chain, and calculate a magnitude of imbalance; and the processor is configured to adjust weight at the weight counterbalancing position according to the eccentric angle and the magnitude of imbalance, to locate the center of mass at the rotation center; and
wherein a sampling is performed once each time the gantry rotates by a constant angle, a curve of a pulse generated in each sampling is obtained, and curves corresponding to respective angles in a rotational direction of the gantry are successively connected to form the fluctuation chain.
11. The device for balancing the CT gantry according to claim 10 , further comprising a detector for detecting a rotation velocity of the gantry in real time, wherein the detector is in signal connection with the processor, and the processor is configured to adjust a torque voltage of a motor according to the rotation velocity of the gantry, to enable the rotation of the gantry to reach a steady state.