Topic 39

Question 1

Describe the radioactive tracer method

Answer 1

Isotopes placed in the body, the accumulation and fate of which can be traced.

Single atoms can be replaced by isotopes to observe organ function (Labelled molecules)

Question 2

What are the preferences of radioisotopes?

Answer 2

Isotopes with a short half-life and short biological half-life (Hours/minutes)

Gamma photons used as they are less absorbed.

Question 3

What are In vitro uses of isotopes?

Answer 3

Determines the amount of certain hormones

Question 4

What is an vivo radio radioisotope application?

Answer 4

Diagnosis of the thyroid gland (Iodine uptake measured)

Measurement of blood volume

Question 5

Equation to calculate the Volume by dilution method in the thyroid gland.

Answer 5

• V₀ = Known volume*
• c₀ = Specific activity*

Question 6

Describe Radioimmunoassay (RIA)

Answer 6

In Vitro method

Combines high specifity of immunoreactions with the sensitivity of the isotope technique