Radiopharmaceuticals and PET Tracers

Radiation Exposure and Automated Synthesis

• Automated synthesis devices for PET tracers minimize radiation exposure to staff during the preparation of radiopharmaceuticals.

Quality Control of Radiopharmaceuticals

• Quality control assesses several parameters essential to ensure patient safety and effective imaging:
  • Radionuclide Purity: Tested for contamination, such as 99Mo, by measuring gamma radiation after blocking 99mTc emissions.
  • Radiochemical Purity: Assessed by chromatography to identify free pertechnetate in labeled 99mTc compounds.
  • Chemical Purity: Evaluated using the spot color test for alumina, which may interfere with labeling processes.
  • Calibration Response: Verified by testing against a standard radioactive source with an extended half-life.

Planar Imaging Procedures

• Involves administrating a radiopharmaceutical to concentrate in specified organs/tissues, typically via intravenous injection.
• 82Rb sourced from a strontium-82 generator, lasting about one month, is utilized for myocardial perfusion imaging.

Positron Emitters

• Technetium-94m (94mTc), produced in cyclotrons with a 50-minute half-life, is applicable for labeling existing pharmaceuticals for 99mTc imaging.
• 94mTc sestamibi serves in tumor imaging studies using PET technology.

Preparation of Radiopharmaceuticals

• Involves simple mixing or shaking of radionuclide (e.g., 99mTc as sodium pertechnetate) with labeling compounds and necessary chemicals.
• Implementation of shielded syringes for sterile transfers, alongside adherence to sterile conditions within workstations like glove boxes or laminar down-flow cabinets.

Sterile Environments

• Surfaces are designed to be impervious, including continuous floors and gloss-painted walls, ensuring proper sterile practices.
• Access to preparation areas through air locks and changing rooms is crucial in maintaining sterility during preparation.

Automation in Pharmaceutical Preparation

• Due to the brief preparation time required for PET radiopharmaceuticals, automated microprocessor-controlled synthesis devices are extensively employed.
• Enhancement of gamma camera technology can significantly improve the detection of primary gamma photons, leading to superior imaging results.

Gamma Ray Collimation Principles

• The selection of appropriate collimators for gamma ray detection is influenced by various factors, including field of view (FOV) size, targeted areas, and required sensitivity.
• Only gamma photons that pass through collimator openings contribute to imaging, with others absorbed, thus affecting camera sensitivity.

Common Collimators in Nuclear Medicine

• Parallel hole collimators are prevalent for gamma image formation and are made from high-density materials like lead.
• These collimators contain a hexagonally structured arrangement of holes to optimize the area exposed to the gamma camera detector, facilitating effective imaging.

Learn about the preparation and quality control of radiopharmaceuticals, including automated synthesis and testing for radionuclide purity. Understand the importance of minimizing radiation exposure and ensuring the quality of PET tracers.