导师出的题目请大家帮忙

andyyang

1. 1.pulse sequences optimized for imaging the cns are usually not appropriate for body imaging because for cns compared with body tissues,（脑组织和身体组织用不同的脉冲，为什么）

a. t1 and t2 are long(短t1和t2）
b. t1 and t2 are short长t1和t2)
c. t1 is long and t2 is short(长t1和短t2)
d. t1 is short and t2 is long(短t1和长t2)

2.
2.2.if a quench occurs and helium escapes, the principal effect on the mri technologist will be(

a. donald duck’s voice
b. lowered body temperature
c. skin rash
d. sticky hair

3.
3.3..proper quality control for an mri system requires that test object imaging be performed at least(正确的mri质量控制）

a. daily（每天）
b. weekly（每周）
c. biweekly（隔一周）
d. monthly（每月）

4. 4.the principal hazard to patients and personnel in an mri facility is the biological effect of(mri设备对病人的主要生物危害）

a. ferromagnetic projectiles（磁的发射体）
b. the main magnetic field（主磁场）
c. the rf field（rf射频磁场）
d. the sound level（声音）

5. 5.the raw data of an mr signal contains what components of spatial frequency?（什么组成mri的空间频率）

a. angle ad frequency（频率角）
b. intensity and frequency（频率强度）
c. magnitude and phase（相位矢量）
d. phase and angle（相位角）

6. 6.t2* is shorter than t2, principally because of(t2*短于t2为什么）

a. differences in t1（不同的t1)
b. differences in t2不同t2
c. proton density variations质子密度不同
d. 7.the influence of reversible magnetic field inhomogeneities(什么影响磁场的可逆均匀性）

7. long repetition time (trs) result in 长trs

a. accelerated t1 relaxation加速的t1驰豫
b. accelerated t2 relaxation 加速的t2驰豫
c. longitudinal magnetization that is close to equilibrium纵向磁场趋于平衡
d. transverse magnetization that is close to equilibrium横向磁场趋于平衡


8. 8.the gyromagnetic ratio for hydrogen is equal to (氢质子回转磁的频率等于）

a. 21 megahertz per tesla
b. 21 tesla per megahertz
c. 42 megahertz per tesla
d. 42 tesla per megahertz