PHYS1210 Advanced Physics I: Magnetic Resonance Imaging

Question 1:

a) Is an electromagnetic radiation of 1.1 keV considered ionizing for the human body? Justify your  answer.

b) An object 0.8 kg in weight has been irradiated with ionising radiation and has absorbed 20 J of that radiation. What is the absorbed dose by the object?

Question 2:

a) Are radiopharmaceuticals necessary in CT and micro-CT imaging? Explain.  If yes, please mention at least one and explain.

b) Are radiopharmaceuticals necessary in PET imaging? Explain.  If yes, please mention at least one and explain.

Question 3:

Computed tomography: 

a) What does the pixel in a reconstructed cross-section image represent? Explain.

b) Is a computer necessary in CT? Explain.

Question 4:

a) In an experiment with radioactive sources emitting radiations between 120 and 160 keV, you want to detect and measure these energies. In the lab you have a scintillator crystal (NaI(Tl)) and a multichannel analyzer. Can you detect the radiation with just these two devices? Explain

b) Would you need another device coupled to the scintillator crystal? If yes, what is it, and why do you need it? 

Question 5:

Testing the energy resolution of two detection systems “A” and “B”: The energy of a gamma ray of 140 keV is being measured. In the energy histogram of two systems A and B, the photopeak is observed.

a)System A has a full width at half maximum (FWHM)= 12 keV, “system B” has a FWHM of 7 keV. What is the energy resolution of each of the two systems?

b) Between the two systems (A and B in question a), which system has the higher energy resolution? Explain, by drawing a histogram.

Question 6: 

MRI, ultrasound, PET, SPECT, CT scanner.

a) Which systems do not need physical collimation?

b) Which of the above systems needs an X-ray tube for generating the corresponding medical image?

c) Which systems do not require radiopharmaceuticals?

Question 7:

Medical Imaging: Radiography, PET, CT, MRI, Ultrasound, SPECT.

a) For the above 6 imaging modalities, build two groups by grouping ionizing and non-ionizing imaging modalities

b) In the above listed systems, which system is the most expensive financially? (Do not consider the cost of a cyclotron in this instance)

c) For the anatomical description of the musculoskeletal system of a patient, you want to have accurate tomographic images of the skeleton, as well tomographic images of the muscles and tendons. Which two imaging modalities of the above would you combine, and use for what?