《英汉医学词典》source collimator distance 焦点-平行光距离 source-collimator distance: 焦点-平行光距离collimator distance: 准直距离source distance: 震源矩focus source distance: 焦源距source skin distance: 源与皮肤间距下载手机词典可随时随地查词查翻译