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NM 4103 Radiopharmaceuticals & Quality Control. What is a Radiopharmaceutical? Radionuclide –Allows imaging Pharmaceutical –Chosen based on localization.

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Presentation on theme: "NM 4103 Radiopharmaceuticals & Quality Control. What is a Radiopharmaceutical? Radionuclide –Allows imaging Pharmaceutical –Chosen based on localization."— Presentation transcript:

1 NM 4103 Radiopharmaceuticals & Quality Control

2 What is a Radiopharmaceutical? Radionuclide –Allows imaging Pharmaceutical –Chosen based on localization

3 Ideal Radiopharmaceutical Easily produced Inexpensive Readily available Short half-life Gamma rays

4 Half-Life Physical –Time for radionuclide to reduce activity by one-half Biologic –Excretion, perspiration Effective –Physical and biologic half-lives

5 Common Radionuclides 99m Tc - Technetium6 hours 123 I – Iodine13.2 hours 131 I - Iodine8 days 133 Xe - Xenon5.3 days 67 Ga - Gallium78.3 hours 111 In - Indium67 hours 201 Tl – Thallium73.1 hours

6 How do they do that? 99mTc eluted from generator  Mix Kits  Images Physiology  Methods of localization

7 Methods of Localization Passive Diffusion Compound diffuses across a biologic membrane from a compartment of higher concentration to one of lower concentration. 99m Tc-DTPA (brain imaging) 99m Tc DTPA aerosol 133 Xe ventilation 111 In DTPA cisternography Myocardial perfusion with 99m Tc Sestamibi Filtration of 99m Tc DTPA by kidney

8 Methods of localization Ion Exchange (Chemisorption) The diophosphates are absorbed onto and form a complex with the Calcium Hydroxyapatite crystals. They bind exclusively to the mineral phase of the bone and not to organic matrix. Phosphate bone-scanning (MDP, HDP) Where bone modeling is most active is where the highest amount of Tc-MDP accumulates.

9 Methods of localization Capillary blockage Pulmonary capillaries and small arterioles trap larger particles 99m Tc MAA particles trapped in the lung capillaries

10 Methods of localization Phagocytosis Engulfment and ingestion by specialized cells –Colloid scanning for Liver (middle range particles) –Colloid scanning for the Spleen (largest particles) –Colloid scanning for bone marrow (smallest particles) –Colloid scanning for lymph nodes Removal of 99m Tc sulfur colloid particles by the reticuloendothelial cells in the liver, spleen and bone marrow

11 Methods of localization Active Transport Movement of a compound across a biologic membrane against a concentration gradient, uphill, from a lower to a higher concentration. –Iodine or Tc for thyroid –Pertechnetate for Meckel’s diverticulum –Pertechnetate for stomach –Pertechnetate for choroid plexus –Pertechnetate for hepatobiliary imaging –Pertechnetate for salivary gland –Thallium in myocardium

12 Methods of localization Cell Sequestration To separate certain cells apart from the whole Leukocytes for abscess scanning (WBC) Labeled platelets Sequestration of heat-damaged 99m Tc labeled rbc’s by the spleen

13 Methods of localization Metabolism 18 F-FDG uptake in myocardial, brain tissues and tumors PET imaging ~ glucose metabolism

14 Methods of localization Receptor binding 11 C-dopamine binding to the dopamine receptors in the brain ~ Neuroreceptor imaging

15 Methods of localization Compartmental localization Partitioning and Retention of the radiopharmaceutical into a biologic compartment. –Cardiac scanning with labeled RBC’s (gated blood pool) –Cisternogram with In111 DTPA (injected intrathecally and confined to CSF Compartmental Leakage : Labeled RBC’s for GI bleeding detection

16 Methods of localization Antigen-antibody Specific for a tumor associated antigen imaging Localizes via an antibody-antigen reaction Monoclonal antibodies 131 I, 111 In and 99m Tc labeled antibody to localize tumors

17 Methods of localization Chemotaxis 111 In labeled leukocytes to localize infections

18 Biodistribution Consists of absorption, distribution, metabolism, plasma clearance and excretion. Organ systems involved in 99m Tc pertechnetate biodistribution: *Stomach * Salivary glands * Thyroid * Bowel * Choroid plexus * Brain * Sweat glands * Kidney

19 Reducing agent Chemically, 99m TcO - 4 is nonreactive and won’t label by direct addition of a pharmaceutical compound. The oxidation state needs to first be reduced to allow reaction (tagging) Reducing agents: –Stannous chloride (most common) –Stannous citrate, stannous tartrate, ferrous sulfate, sodium borohydride

20 Oxygen in the vial Oxygen can cause oxidation of the stannous ion –Especially before the addition of 99m Tc Free 99m Tc Some kits (MDP,HDP) have an antioxidant to prevent oxidation –Ascorbic acid, gentisic acid

21 Kits Facilitated nuclear pharmacy Long shelf-life Some are as simple as just adding 99m TcO - 4 Sterile environment, laminar flow hood,

22 Colloids Size falls between a solution and a suspension Particles range between 10 nm and 1µm Gelatin : stabilizing agent used to prevent aggregation Examples : 99m Tc Sulfur colloid & 99m Tc MAA

23 Physicochemical Tests Determine purity and integrity of a radiopharmaceutical –Check for particulate matter, color, clarity –Particle size /number of colloids checked under microscope pH : 2-9 (ideal is 7.4 ~ same as blood) Radionuclide Purity : Moly breakthrough Radiochemical Purity : free 99mTcO-4 Chemical Purity: Aluminum

24 Biologic Tests Sterilization: membrane filtration is most common –Radionuclides can be sensitive to heat sterilization –Sterility testing takes longer than the half- life of radionuclides.

25 Nuclear Pharmacy Lab coat Gloves Tongs Lead barrier shield Laminar flow hood Aseptic technique

26 Dispensing Prescription Name ID number Technologist Type of radiopharmaceutical Dose given

27 Pediatric doses Biodistribution is different in children Dose must be adjusted Usually calculated based on weight or body surface area

28 Disposal Decay in storage ~ most common Sewer Incineration Burial in landfill

29 Decay in Storage Radionuclides with half-lives of 120days or less. Can be released to waste when: –10 half-lives –Radioactivity cannot be detected above background –Radioactive signs are removed

30 Sewerage system Radioactive material must be soluble Biologic matter Quantity of monthy allowances

31 Transfer to an Authorized Recipient Long-lived radionuclides Usually buried or incinerated

32 Good Practice Radiation signs Wear Lab coat and gloves Absorbent paper Lead containers Film badge Identify radionuclide containers Survey work area Do not eat or drink in radiation lab Monitor hands and feet

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