Physics

Question 1

What does the radiation unit of absorbed dose measure?

Answer 1

Amount of energy absorbed per unit mass from ionizing radiation (NOT related to photoelectric or compton)

Question 2

Seven days post-treatment, this scan was obtained. Which collimator was used for this exam? Pinhole, low energy, medium energy or high energy?

Answer 2

High energy; this is a whole body I-131 NaI examination showing residual/recurrent disease in the neck and diffuse lung mets. I-131 has a photopeak of 134 keV, which requires a high energy collimator.

Question 3

In doppler frequency shift, as blood in a vessel flows towards the transducer, is the reflected frequency of the US pulse GREATER or LESS than the incident frequency? Will the doppler shift DECREASE or INCREASE as the doppler angle increases from 10 to 30 degrees?

Answer 3

reflected frequency is GREATER as movement is towards the transducer

the closer the doppler angle is to 90degrees, there is DECREASE in frequency shift