Image Noise Suppression of High-Voltage Power Supplies for Surgical C-Arms

The surgical C-arm is a core imaging device for orthopedic, cardiovascular and other surgeries. Its image quality directly affects the doctor's judgment on the location of the lesion and the accuracy of surgical operations, and image noise is one of the main factors restricting image quality. During the X-ray imaging process of the C-arm, the ripple and electromagnetic interference output by the high-voltage power supply (HVPS) will affect the stability of the X-ray intensity through the X-ray tube, and then produce snowflake-like noise on the image, interfering with the display of lesion details. Therefore, the image noise suppression of the HVPS for surgical C-arms needs to make breakthroughs in three aspects: ripple control, electromagnetic compatibility design, and dynamic load response.
In terms of ripple suppression, a combined scheme of "pre-voltage stabilization + multi-stage filtering" is adopted: the front stage uses a Buck-Boost converter to achieve coarse voltage stabilization, controlling the input voltage fluctuation within ±2%; the rear stage designs a series structure of LC filtering and active filtering. Among them, the active filtering module adopts a control algorithm based on the instantaneous reactive power theory to compensate the harmonic current in real time, reducing the output ripple coefficient of HVPS to less than 0.02%, which significantly reduces the image noise caused by ripple.
In the electromagnetic compatibility design, triple protection of shielding, grounding and filtering is adopted: the HVPS shell adopts a composite structure of galvanized steel plate and electromagnetic shielding film, with a shielding effectiveness of more than 40dB; the internal adopts a grounding method combining single-point grounding and floating grounding to avoid electromagnetic interference caused by ground circulation; EMC filters are set at the input and output ends to suppress common-mode and differential-mode interference, meeting the requirements of GB 9254-2008 electromagnetic compatibility standard.
Aiming at the problem of load mutation caused by the movement of the C-arm during surgery, a fast dynamic response module is designed: a DC/DC converter controlled by peak current mode is used, and the response speed is increased to 50μs. When the load change rate reaches 50%/ms, the output voltage fluctuation is less than ±1%, avoiding the X-ray intensity fluctuation caused by load mutation and reducing the instantaneous increase of image noise.
This design was applied in orthopedic surgery in a top three hospital. The signal-to-noise ratio of the C-arm image was increased by 40%, the clarity of the lesion edge was increased by 35%, and the accuracy of doctors' judgment on surgical operations was increased by 20%, providing clear image support for precise surgery.