Which is false about the following statements on ultrasound

Which is false about the following statements on ultrasound and nuclear medicine imaging?

1) Snell’s Law applies to optics but not to acoustic signals.

2) Doppler imaging exploits frequency shift in ultrasound imaging to estimate tissue motion such as blood flow.

3) SPECT is characterized by the emission of positrons by a radioactive source that selectively binds to tissue, which entails the annihilation of each positron by a nearby electron, and which in turn results in a pair of photons being emitted in opposite directions.

4) Answers a and c are false.

5) Answers a, b and c are false.

Please explain answer

Solution

Ans:1)False:Snell\'s is applicable both in Optics & Acoustic.Acoustic waves can be totally reflected at firm boundaries and there reflectivity follows the snell\'s law.More over Rrefraction takes place at an interface due to the different velocities of the acoustic waves within the two materials The velocity of sound in each material is determined by the material properties (elastic modulus and density) for that material. Snell\'s Law describes the relationship between the angles and the velocities of the waves.

2)True:Doppler  imaging exploits frequency shift in ultrasound imaging, this technique mainly used to calculate blood flow.

3)True:Single-photon emission computed tomography (SPECT, or less commonly, SPET) is kind of of technique like PET where positron is released.But in SPECT the electron and positron reacts inside the atomic mediator to produce photon,

4)False;

5)False