Shin M, Lillaney P, Hinshaw W, Fahrig R
Stanford University, Stanford, CA.
Med Phys. 2012 Jun;39(6Part3):3622. doi: 10.1118/1.4734706.
To evaluate a new rotating anode X-ray tube from the resonant frequency point of view for stable and safe operation, and to validate a finite element model for insight into X-ray tube rotor dynamics and vibration.
The 3-dimensional FEM model of the X-ray tube motor has been developed using ANSYS and COMSOL. The resultant resonant frequency from the FEM simulation is substantiated by experiments. During deceleration of the X-ray tube, an accelerometer and a corresponding amplifier send the time domain vibration response to a spectrum analyzer which generates the power spectrum. In the frequency domain analysis, a peak signifies large vibrations at that frequency. To corroborate the FEM model, the resonant frequency of the motor assembly without the anode attached was also measured. Lastly, a rough estimate of the resonant frequency can also be observed in angular speed curves which are obtained utilizing a quadrature position sensor.
The first mode resonance is expected at 20.3 Hz from the FEM simulation. This result matches closely with the peak at 22.2 Hz in the power spectrum and the location of the abrupt decreasing acceleration (slope) in the speed curve at 22 Hz. Without the anode, the FEM simulation result of 35.1 Hz is equal to the first peak at 35.1 Hz, and the angular acceleration is suddenly reduced at 34.4 Hz.
For image-guided interventional procedures using a hybrid system, the X-ray tube should create flux at various times requiring repeatedacceleration and deceleration of the motor. Hence it is ideal that the resonant frequency is higher than operational speed, although alternatively the motor could accelerate through the resonant frequency quickly. Design improvements to modify the location of resonance of our motor assemblyare underway using the verified FEM model. NIH R01 EB007626, Richard M. Lucas Foundation.
从共振频率的角度评估一种新型旋转阳极X射线管，以实现稳定和安全运行，并验证有限元模型，以便深入了解X射线管转子动力学和振动情况。
利用ANSYS和COMSOL开发了X射线管电机的三维有限元模型。有限元模拟得出的共振频率通过实验得到了证实。在X射线管减速过程中，加速度计和相应的放大器将时域振动响应发送到频谱分析仪，该分析仪生成功率谱。在频域分析中，峰值表示该频率下的大幅振动。为了验证有限元模型，还测量了未安装阳极的电机组件的共振频率。最后，在利用正交位置传感器获得的角速度曲线中也可以观察到共振频率的粗略估计值。
有限元模拟预计第一阶共振频率为20.3Hz。这一结果与功率谱中22.2Hz处的峰值以及速度曲线中22Hz处加速度突然下降（斜率）的位置密切匹配。没有阳极时，有限元模拟结果35.1Hz与35.1Hz处的第一个峰值相等，角加速度在34.4Hz处突然降低。
对于使用混合系统的图像引导介入程序，X射线管应在需要电机反复加速和减速的不同时间产生通量。因此，共振频率高于运行速度是理想的，尽管电机也可以快速加速通过共振频率。正在使用经过验证的有限元模型对我们的电机组件进行设计改进，以改变共振位置。美国国立卫生研究院R01 EB007626，理查德·M·卢卡斯基金会。
