22. Principles of nuclear medicine

Question 1

What is the difference between gamma ray studies and x ray examinations?

Answer 1

Gamma ray studies- patient is source of radiation

X-ray- x ray is source of radiation in examination

Question 2

Discuss the basis of radioactivity?

Answer 2

If an atom does not have an equal amount of protons and electrons it will decay to try and make itself stable again.

Question 3

What is the most commonly used radioisotope?

Answer 3

Technetium-99m. Fulfils many of the criteria of an ideal radionuclide

Question 4

Explain how a V/Q scan works

Answer 4

Technimiun-99 is breathed into the lungs and a scanner shows how well it is uptaken

Then it is assessed how much has entered the blood stream

Question 5

What scans are commonly used in the kidneys?

Answer 5

Tc-99m MAG3- looks at renal excretion

Tc-99m DMSA- specialised scan, binds to the renal tubules. allows to show cortex and shows scarring

Question 6

Why do you do a gastric emptying scan

Answer 6

Look for gastroparesis, common in diabetics who have nerve damage.

Question 7

Why would you produce a bone scintigraphy

Answer 7

Picks up osteoscelrotic metasteses

Question 8

What does the region of lesions tell you about the disease present in a bone scintigraphy?

Answer 8

Single Sternal lesion- if someone has breast cancer 80% time metastasis

Focal uptake in the breast- breast cancer

Soft tissue and msucles- rhabdomyolysis, brittle bone

Question 9

How does a PET/CT scan work

Answer 9

Positron emission (fluorine combined with deoxyglucse)

Areas with higher uptake shows increased metabolism. May show up malignancy or infection

Question 10

Why would you do a PET/CT?

Answer 10

Lung cancer (staging)
Head and neck cancer (staging)
Lymphoma (staging)
Colon cancer (metastasis)
Oesophageal cancer (initial evaluation)
Breast cancer (staging)
Thyroid cancer