Nuclear Medicine Physics: Production of Radionuclides
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Questions and Answers

What is the total number of known radionuclides?

  • 2000
  • 3000
  • 4000
  • 2700 (correct)

    • How are radionuclides used in medical imaging produced?

  • Through chemical reactions
  • Naturally
  • Artificially (correct)
  • Both naturally and artificially

    • What occurs when an additional neutron is forced into a stable nucleus?

  • A proton deficit
  • An atomic number change
  • A neutron excess (correct)
  • A neutron deficit

    • What is the result of adding a neutron to the nucleus of Molybdenum-98?

    <p>Molybdenum-99</p> Signup and view all the answers

    What type of particle is accelerated in a cyclotron?

    <p>Positively charged ions</p> Signup and view all the answers

    What is the result of adding a proton to the nucleus of Oxygen-18?

    <p>Fluorine-18</p> Signup and view all the answers

    What is the typical half-life range of radionuclides produced in a cyclotron?

    <p>Less than a minute to a couple of hours</p> Signup and view all the answers

    What is the purpose of medical minicyclotrons?

    <p>To produce short-lived radionuclides at or near the hospital site</p> Signup and view all the answers

    What is the half-life of 99mTc?

    <p>6 hours</p> Signup and view all the answers

    What is the result of the decay of 99mTc?

    <p>It decays to Ru-99</p> Signup and view all the answers

    Which type of decay is characterized by a neutron deficit?

    <p>β+ decay</p> Signup and view all the answers

    What is a positron?

    <p>A positive electron</p> Signup and view all the answers

    What is the result of β+ decay in Fluorine-18?

    <p>It transforms into Oxygen-18</p> Signup and view all the answers

    What is the process by which a nucleus captures an extranuclear electron?

    <p>K-electron capture</p> Signup and view all the answers

    What is emitted when an electron from an outer shell fills a vacancy in the K-shell?

    <p>X-rays</p> Signup and view all the answers

    What is the result of K-electron capture?

    <p>A decrease in atomic number</p> Signup and view all the answers

    What is the half-life of the parent in a technetium generator?

    <p>67 hours</p> Signup and view all the answers

    What is the purpose of elution in a technetium generator?

    <p>To wash off the technetium-99m from the column</p> Signup and view all the answers

    How often can elution be made from a technetium generator?

    <p>Daily</p> Signup and view all the answers

    What happens to the molybdenum after elution?

    <p>It remains attached to the column</p> Signup and view all the answers

    What is the half-life of technetium-99m?

    <p>6 hours</p> Signup and view all the answers

    What is the purpose of using sodium pertechnetate-99mTc?

    <p>To image the thyroid, gastric mucosa, and salivary glands</p> Signup and view all the answers

    What is the purpose of administering potassium perchlorate in thyroid imaging?

    <p>To block technetium-99m</p> Signup and view all the answers

    How often is a technetium generator usually replaced?

    <p>After 1 week</p> Signup and view all the answers

    What happens to the activity of technetium-99m after 24 hours?

    <p>It grows again to a new maximum value</p> Signup and view all the answers

    What is the use of methylene diphosphonate (MDP) labelled with technetium-99m?

    <p>Bone imaging</p> Signup and view all the answers

    What is the use of hexamethyl propylene amine oxime (HMPAO) labelled with technetium-99m?

    <p>Cerebral blood flow imaging</p> Signup and view all the answers

    What is the use of diethylene triamine pentacetic acid (DTPA) aerosol labelled with technetium-99m?

    <p>Lung ventilation studies</p> Signup and view all the answers

    What is the use of autologous red cells labelled with technetium-99m?

    <p>Cardiac function imaging</p> Signup and view all the answers

    What is the use of heat-damaged autologous red cells labelled with technetium-99m?

    <p>Spleen imaging</p> Signup and view all the answers

    What is the characteristic of 131I that makes it an excellent label?

    <p>High reactivity</p> Signup and view all the answers

    What is the primary radiation emitted by 131I?

    <p>Beta particles</p> Signup and view all the answers

    Which radionuclide is used for thyroid ablation?

    <p>131I</p> Signup and view all the answers

    What is the half-life of 123I?

    <p>13 h</p> Signup and view all the answers

    Which radionuclide is used for brachytherapy seeds?

    <p>125I</p> Signup and view all the answers

    What type of radiation does 133Xe emit?

    <p>Beta particles and low energy gamma rays</p> Signup and view all the answers

    How is 81mKr produced?

    <p>From a generator</p> Signup and view all the answers

    What is the half-life of 81mKr?

    <p>7.13 s</p> Signup and view all the answers

    What is the parent radionuclide of 81mKr?

    <p>Rubidium-81</p> Signup and view all the answers

    What is the energy of the gamma rays emitted by 133Xe?

    <p>81 keV</p> Signup and view all the answers

    How is the patient administered 81mKr for pulmonary ventilation studies?

    <p>Through inhalation</p> Signup and view all the answers

    What is the advantage of 123I over 125I?

    <p>Superior for imaging</p> Signup and view all the answers

    Study Notes

    Production of Radionuclides

    • There are over 2700 known radionuclides, but only some are used in medical imaging.
    • Radionuclides are produced artificially in two ways:
      • Neutron excess: adding a neutron to a stable nucleus, resulting in a neutron excess (e.g., 98Mo + n → 99Mo).
      • Neutron deficit: adding a proton to a stable nucleus, resulting in a neutron deficit (e.g., 18O + p → 18F + n).

    Radionuclides with a Neutron Excess

    • Radionuclides with a neutron excess undergo β- decay.
    • Example: 99mTc (half-life = 6 hours) decays to 99Tc (unstable, half-life = 211,000 years), which decays to ruthenium-99 (stable).

    Radionuclides with a Neutron Deficit

    • Radionuclides with a neutron deficit undergo β+ decay or K-electron capture.
    • Example: 18F (fluorine-18) with atomic number 9 transforms into 18O (oxygen-18) with atomic number 8, resulting in a decrease in atomic number but no change in mass number.

    Technetium Generator

    • A technetium generator is used to produce technetium-99m (99mTc).
    • 99mTc is washed off the column (eluted) with sterile saline solution, leaving behind the molybdenum (99Mo).
    • Elution takes a few minutes and can be repeated daily.

    Uses of Technetium-99m

    • Sodium pertechnetate-99mTc is used for imaging tissues, such as:
      • Thyroid, gastric mucosa, and salivary glands
      • Cerebral blood flow and testicular imaging (with potassium perchlorate)
      • Gastric emptying studies (with bran porridge)
    • 99mTc can be labeled to various compounds for:
      • Bone imaging (methylene diphosphonate, MDP)
      • Cerebral imaging (hexamethyl propylene amine oxime, HMPAO)
      • Renal studies (dimercaptosuccinic acid, DMSA, and mercaptoacetyltriglycine, MAG3)
      • Biliary studies (iminodiacetic acid, HIDA)
      • Liver, spleen, and red bone marrow imaging (human serum albumin, HSA)
      • Lung ventilation studies (diethylene triamine pentacetic acid, DTPA, aerosol)
      • Cardiac function and perfusion imaging (autologous red cells, sestamibi, or tetrofosmin)

    Other Radionuclides and Their Uses

    • Iodine-131 (131I): used for thyroid imaging and therapy, but largely replaced by 123I due to its long half-life and beta emissions.
    • Iodine-123 (123I): used for thyroid imaging, more expensive than 131I, but with a shorter half-life and fewer beta emissions.
    • Iodine-125 (125I): used for therapy, particularly brachytherapy seeds.
    • Xenon-133 (133Xe): used for lung ventilation imaging, produced in a nuclear reactor, and has a half-life of 5.2 days.
    • Krypton-81m (81mKr): used for pulmonary ventilation studies, produced in a generator, and has a half-life of 13 seconds.

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    Nuclear Medicine Physics Module PDF

    Description

    Learn about the production of radionuclides in medical imaging, including artificial production methods and nuclear reactions. This quiz covers the basics of radionuclide production, including neutron excess and nuclear reactors.

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