CT机和普通X光片有何不同？
How does a CT scanner differ from a plain X-ray?
普通X光是单次投影的重叠影像，CT则让X射线管绕人体旋转采集多个角度，经计算机重建出横断面图像，避免结构互相遮挡。
A plain X-ray is one overlapping projection; CT rotates the tube around the body and reconstructs cross-sectional images from many angles, avoiding overlap.
难度 专业 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Kak & Slaney《CT 原理》；Haacke 等《MRI 原理》；超声成像（Hendee & Ritenour）
Kak & Slaney, Principles of Computerized Tomographic Imaging; Haacke et al., Magnetic Resonance Imaging; ultrasound (Hendee & Ritenour)
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL4974986W：Principles of computeri
#生物医学 #影像
MRI为什么没有辐射也能成像？
Why can MRI image without radiation?
MRI利用强磁场使体内氢原子自旋对齐，再用射频脉冲扰动，停止后氢原子释放电磁波信号，由接收线圈和算法重建出软组织图像，无电离辐射。
MRI aligns hydrogen atoms with a strong magnet, perturbs them with radiofrequency pulses, then detects the emitted signals to reconstruct soft-tissue images, with no ionizing radiation.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Kak & Slaney《CT 原理》；Haacke 等《MRI 原理》；超声成像（Hendee & Ritenour）
Kak & Slaney, Principles of Computerized Tomographic Imaging; Haacke et al., Magnetic Resonance Imaging; ultrasound (Hendee & Ritenour)
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL4974986W：Principles of computeri
#生物医学 #磁共振
超声成像靠什么得到图像？
How does ultrasound imaging form a picture?
探头发出超声波并接收组织界面的回声，不同组织声阻抗不同、反射强弱有别，由回波时间和强度重建出实时断层图像。
A probe emits ultrasound and receives echoes at tissue boundaries; differing acoustic impedance yields varying reflections, reconstructed by time and intensity into live images.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Kak & Slaney《CT 原理》；Haacke 等《MRI 原理》；超声成像（Hendee & Ritenour）
Kak & Slaney, Principles of Computerized Tomographic Imaging; Haacke et al., Magnetic Resonance Imaging; ultrasound (Hendee & Ritenour)
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL4974986W：Principles of computeri
#生物医学 #超声