Sources of Radiation exposure from medical activities

Question 1

State specific sources of radiation exposure from medical activities

Two major users of radioactive material in MTF

Answer 1

Diagnostic- X-ray, CT

Therapeutic- Radiation Oncology

Question 2

List ideal Characteristics needed for a radiopharmaceutical. 6 Total

Answer 2

Localizes in a specific organ yielding a high target to non-target ratio

low toxicity

chemically stable both in-vivo and in-vitro

emit a high abundance of clinically useful photons close to 140 keV, ideal for detector absorption

Gamma emitters with high energy to penetrate tissue but low enough energy to attenuated by detector and not penetrate collimator

Minimal effective half-life

Question 3

Rationale used for selecting radioisotopes used in clinical imaging

Answer 3

Minimizing radiation dose to patient

detection characteristic of modern-day instrumentation

Question 4

Radioisotopes used in clinical imaging

Answer 4

Technetium99

Thalium201

Gallium67

Xenon-133

Indium-111

Iodine-131 and 123- thyroid gland imaging
T-131 T1/2 - 8.02 days
Gamma energy- 364.5 kev

Chromium51

Question 5

Most common Radioisotope used in nuclear medicine imaging

Answer 5

Tc-99 Technetium