Question 1

What is the difference between isotopes and radioisotopes?

Accepted Answer

Isotopes are atoms of the same element with identical proton counts but different neutron numbers, resulting in different mass numbers. Radioisotopes are unstable isotopes whose nuclei readily decay, emitting subatomic particles and electromagnetic energy. Heavy isotopes tend to be unstable and radioactive, making them useful for medical imaging and therapy when controlled.

Question 2

How do isotopes of hydrogen differ from each other?

Accepted Answer

Elemental hydrogen has three isotopes: hydrogen with zero neutrons, deuterium with one neutron, and tritium with two neutrons. All three share the same atomic number and chemical properties because they have identical proton counts. Tritium, the heaviest isotope, is radioactive and undergoes beta decay to form stable helium-three.

Question 3

What happens during radioactive decay of tritium?

Accepted Answer

During tritium's beta decay, one of its two neutrons transforms into a proton through emission of a low-energy beta particle. This transformation produces helium-three, a stable non-radioactive isotope. The decay process demonstrates how unstable heavy isotopes convert into more stable products through energy release.

Question 4

Why are radiotracers safe to use in medical imaging?

Accepted Answer

Radiotracers are weakly radioactive isotopes with short half-lives, the time required for half a sample to decay. They emit low-strength radiation and are eliminated from the body within hours or days through lungs, urine, or stool. These characteristics prevent radiation-induced illness while allowing detection and tracking by imaging technologies.

Question 5

How is positron emission tomography used to detect cancer?

Accepted Answer

Positron emission tomography uses fluorine-18 tagged fluorodeoxyglucose, a radioactive glucose variant, to identify cancer cells. Cancer cells consume glucose at high rates to fuel rapid reproduction, appearing as bright hot spots on PET images. The imaging technology detects radioactive glucose activity, revealing which tissues are most metabolically active.

Question 6

What medical applications use radioisotopes beyond cancer detection?

Accepted Answer

Thallium-201, a radioisotope, monitors blood flow to the heart and aids in diagnosing heart diseases. Radiation therapy uses high-energy radiation from radioisotopes to damage cancer cell DNA, killing cells or preventing division. When exposure is controlled, radioisotopes provide valuable diagnostic and therapeutic benefits despite their potential to cause cellular damage.

Question 7

Why do heavy isotopes tend to be radioactive?

Accepted Answer

Heavy isotopes contain more neutrons than typical atoms of an element, creating nuclear instability. Unstable nuclei release energy through radioactive decay, transforming into more stable configurations. This instability makes heavy isotopes useful as radiotracers and in radiation therapy, where their decay properties can be detected or used therapeutically.

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