Key Terms
Principle
Competitive binding. A radioactive isotope of the target substance is prepared; known antibodies are introduced; unbound
Applications
Cancer screening, hepatitis diagnosis, narcotics investigation.
Two reasons
1. Radiation penetrates tissue — useful probe for internal conditions.
Tagged compound
A compound with a radioactive nuclide attached.
Radiopharmaceutical
A tagged compound used for medical purposes.
Iodine
Concentrated in thyroid; most active (including cancerous) thyroid cells concentrate the most iodine and emit the most r
Thallium scan
Used for cardiovascular system, especially coronary artery blockages. TlCl acts like NaCl and follows blood flow.
Production process
Neutron activation of molybdenum → Mo-99, which decays into Tc-99m.
Components
Lead collimator (with bored holes) + radiation detectors + computer. Function: collimator allows gamma rays from specifi
Resolution
0.5 cm — better than SPECT. Common PET isotopes: C-11, N-13, O-15, F-18.
Rad
Ionizing energy deposited per kilogram of tissue. 1 rad = 0.01 J/kg
Formula
Dose (rad) = energy deposited (J) / mass of affected tissue (kg) x 100
Gray (Gy)
SI unit for absorbed dose. 1 Gy = 1 J/kg Conversion: 1 Gy = 100 rad
Rem (roentgen equivalent man)
Rem = rad x RBE
Sievert (Sv)
SI equivalent of rem. 1 Sv = 1 J/kg x RBE Conversion: 1 Sv = 100 rem