LMW-400型MRI装置RF激励脉冲中尖刺噪声的消除

ＬＭＷ－４００型ＭＲＩ装置的射频激励信号中有尖刺噪声。此尖刺噪声在ＲＦ脉冲之后出现,具有约４０％的最大ＲＦ脉冲值。由于它存在于读出梯度期间。故必须消除此尖刺噪声以减少图像伪像。在调制板上进行的试验表明,由于两个控制信号的沿边突然升起,这种噪声是固有的。对此两种信号采用简单的积分电路,可成功地消除此种尖刺噪声。

TheSparkle Noise Abatement in RF Excitation Signal of LMW-400 MRI System

We found a sparkle noise in the Radio-Frequency excitation signal of LMW-400 MRI system manufactured by Guangdong Weida Medical Apparatus (Group)Corporation.This sparkle noise appeared just following the RF pulse and had a maximum level of about 40% of maximum RF pulse level.Furthermore,since this sparkle noise existed during the read-out gradient period,it must be eliminated in order to reduce image artifacts.Tests on the Modulation Board showed that this noise was inherent due to abrupt rising edges of two control signals.Simple integrating circuits had been applied to those two signals and the sparkle noise could be eliminated successfully by the modification.