Lecture 19

Question 1

What contrast is used in fluoroscopy?

Answer 1

Barium contrast is used in fluoroscopy

Question 2

What one advantage and one disadvantage of fluoroscopy?

Answer 2

Advantage: allows for analysis of physiological processes (swallowing, tracheal, collapse) Disadvantage: ionising radiation with a human needed to be present in the room.

Question 3

What is used for the source in nuclear medicine?

Answer 3

Use gamma ray emitting nucleotides. The exact type used depends on the study e.g. bone has a specific type

Question 4

Briefly explain how diagnostic nuclear medicine works:

Answer 4

1. Radioisotope is administered by various routes 2. Becomes concentrated in the area of interest 3. The isotope undergoes spontaneous decay and gamma photons are then emitted 4. More energy is emitted from areas of accumulation

Question 5

Briefly explain how therapeutic nuclear medicine works:

Answer 5

1. Involves treating a disease with the use of radio-nucleotides 2. Radioactive substance then binds to an organ of interest 3. Emits radiation causing local tissue destruction

Question 6

What is the unit to measure the amount of attenuation

Answer 6

The hounsfield unit (measures the degree of tissue attenuation compared to water)

Question 7

When is CT a good diagnostic tool to use?

Answer 7

CT is a good diagnostic test to use for bones, thorax, abdomen and foreign body tracks.

Question 8

When is MRI a good test to use?

Answer 8

MRI is good when assessing parts of the central nervous system. If the patient has foreign material though MRI should not be used.

Question 9

Name an advantage and a disadvantage of a CT scan:

Answer 9

Advantage: - fast - great bone detail - better spatial resolution than MRI - Images can be constructed in any plane Disadvantages: - specialist equipment is required - advanced skills for interpretation - large radiation doses - artefacts that causes motion (beam hardening, metal)

Question 10

Briefly explain how MRI works:

Answer 10

1. Hydrogen protons act like magnets when placed in a magnetic field 2. Radio-frequency pulses excite the electrons and the emitted radio frequencies are then recorded 3. Different patterns transmit and receive the radio radiofrequency pulses and they are then manipulated to form an image.

Question 11

When would MRI be the most appropriate imaging technique to use?

Answer 11

MRI is considered to be much better for the imaging of the central nervosu system and for soft tissues.

Question 12

State one advantage and one disadvantage of using MRI:

Answer 12

Advantages: no ionising radiation, possible to image in three planes - dorsal, sagittal and trasnverse plane

Diadvantages: Long time taken and it is not possible to reconstruct images. The plane you image in is the plane you get.

Question 13

Fill in the differences in the table below for T1 and T2 weighted CT scans:

Answer 13