Radiopharmaceuticals

• Radiopharmaceuticals


  They can portray physiology, biochemistry, or pathology in the body without causing any significant physiological effect
• Radiotracers


  Radiopharmaceuticals given in subpharmacological doses that trace a particular physiological or pathological process in the body
• Radiopharmaceutical


  An FDA-approved radioactive/labeled agent for imaging or therapy
• Radionuclide


  An unstable isotope of an element that transitions to greater stability through radioactive decay
• Generator


  • Portable, allowing transport to locations far from the reactor or cyclotron, helping to overcome time limitations on production and delivery created by relatively short radiopharmaceutical half-life
  • Contains a glass or plastic column and an adsorbent material (Alumina, Anion or cation exchange resin, Zirconia)
• Elution


  Parent radionuclide is fixed to the column, and the loaded column is placed in a lead container with tubing attached at each endpoint to permit radionuclide removal from the column
• Elution in Wet System


  Commonly used in regional radiopharmacy, accomplished by placing a special sterile vacuum vial on the exit or collection port to draw the appropriate amount of saline across the column
• Elution in Dry System


  Common in imaging clinics, a volume-calibrated saline charge is placed on the entry port, and a vacuum vial is placed on the collection port to draw the saline eluent out of the original vial, across the column, and into the elution vial
• Elution in Dry System


  1. Elution volumes are in the range of 5-20 mL

  2. Elution can be performed for add-on emergency studies that are required in a day

  3. The amount of activity available from the generator decreases each day as a result of decay of the parent

  4. The maximal buildup of Tc-99m activity occurs at 23 hours after elution

  5. After a partial elution is performed, 50% of the maximum activity is reached in approximately 4.5 hours, and 75% of maximum is reached at 8.5 hour
• Radionuclide Production Quality Control


  • Radionuclide Purity - proportion of the desired radionuclide in its proper form
  • Chemical Purity - amount of unwanted chemicals in preparation
  • Radiochemical Purity - amount of the desired radiopharmaceutical in its proper from
• Dose Calibrator


  • An important instrument in radiopharmacy and is subject to quality control requirements
  • Measures the activity of the radioisotopes
• Accuracy

  1. Measured by using the reference standard sources (Co-57, Cs-137)

  2. If the measured activity in the dose calibrator varies from the standard or theoretical activity by more than 10%, the device must be recalibrated
• Linearity


  1. Designed to determine the response of the calibrator over a range of measured activities

  2. Performed quarterly, using a sample of Tc-99m pertechnetate and sequentially measuring it during radioactive decay
• Precision or Constancy


  1. Measures the dose calibrator's ability to measure the same specimen over time

  2. Performed daily, results should be within 10% of the reference standard value (Barium-133, Cesium-137, Cobalt-57)
• Geometry

  1. Measures the consistency of reading of the radioisotopes in a different container

  2. Measured once upon the installation
• Survey Limits for Radioactive Material Package Receipt

  • Surface survey: <200 mR/hr
  • Activity at 1m: <10 mR/hr
  • Wipe test: 6600 dpm/300 cm2
• PET-CT Radionuclides

  • Carbon-11
  • Nitrogen-13
  • Oxygen-15
  • Fluorine-18
  • Gallium-68
  • Rubidium-82
• NucMed Radionuclides

  • Gallium-67
  • Krypton-81m
  • Indium-111
  • Iodine-123
  • Iodine-131
  • Xenon-133
  • Thallium-201
  • Technetium-99m
• Pertechnetate

  • Thyroid
  • Salivary Glands
  • Meckel's Diverticulum
  • Testicular
• Sulfur Colloid

  • Liver/Spleen
  • Red bone marrow
  • Esophageal Transit
  • Gastric Emptying
• Sestamibi

  • Myocardial Perfusion
  • Parathyroid
  • Breast
• Macroaggregated Albumin (MAA)

  • Lung Perfusion
  • LeVeen shunt patency
  • Intraarterial liver
• Metaiodobenzylguanidine (MIBI)

  • Pheochromocytoma
  • Adrenal medullary
  • Neural crest
• Fluorodeoxyglucose (FDG)

  • Tumor
  • Cardiac viability
  • Brain metabolism
  • Infection
• Iodine-123

  • Sodium
  • Metaiodobenzylguanidine (MIBI)
• Indium-111

  • Diethylenetriamine Pectaacetic Acid (DTPA)
  • Oxygen Labeled White Cells
  • Pentetreotide