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Description : Check out this medical presentation titled "Radiation Sources in Nuclear Medicine - Introduction, Sources and Equipment", to know about the uses of radiopharmaceuticals and equipment used in nuclear medicine.

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Published on : Jul 20, 2021 | Views : 2727 | Downloads : 13

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Slide 1-

Introduction, Sources and Equipment Radiation Sources in Nuclear Medicine Day 7 – Lecture 7
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2 Objective To understand the uses of radiopharmaceuticals and equipment used in nuclear medicine.
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3 Contents Introduction to Nuclear Medicine, Objectives of Nuclear Medicine, Most commonly used radionuclides Equipment used.
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“Introduction to Nuclear Medicine”
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5 is a medical specialty that uses radioactive materials to both diagnose the body and treat disease; What is nuclear medicine? Nuclear medicine: documents organ function and structure; uses relatively small amounts of radioactive materials (radiopharmaceuticals) to diagnose and treat which are substances that are localized in specific organs, bones, or tissues;
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6 Most radiopharmaceuticals used in nuclear medicine procedures can be detected externally using special detectors e.g. gamma cameras, PET scanners. What is nuclear medicine? (cont) Cameras work in conjunction with computers to form images that provide data and information about the organ or area of body being imaged. The radiation dose received from a diagnostic nuclear medicine procedure is comparable to that received from some diagnostic x-ray examinations.
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7 There are nearly 100 different nuclear medicine imaging procedures in use today, including: What is nuclear medicine? (cont) diagnosis and treatment of hyperthyroidism; cardiac stress tests to analyze heart function; bone scans for metastatic growths; lung scans for blood clots; kidney, liver and gall bladder procedures to diagnose abnormal function or blockages.
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Define clinical problem Select Instrumentation Diagnosis and Therapy with Unsealed Sources Choose radiopharmaceutical
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9 For diagnostic procedures, the objective is to : Objectives of Nuclear Medicine obtain clinical data regarding the distribution of radiopharmaceuticals that reflect a combination of blood flow, capillary permeability and tissue extraction, and record images of the activity distribution to determine organ function (e.g. determine cerebral blood flow, ventricular function, thyroid uptake). For therapeutic procedures, the objective is to administer a prescribed radiation dose to the target tissue to obtain the desired effect (e.g. reduce tumor size).
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Commonly Used Radionuclides
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11 The primary radionuclide used for diagnostic nuclear medicine procedures is Technetium-99m (99mTc). The primary radionuclide used for therapeutic nuclear medicine procedures is Iodine-131 (131I). Commonly used Radiopharmaceuticals
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12 are constructed on the principle of the decay-growth relationship between a long-lived parent and its short-lived daughter radionuclide. i.e. a long-lived parent nuclide is allowed to decay to its short-lived daughter nuclide and the latter is then chemically separated. e.g. 99Mo (T½ = 66.6 hours)  99mTc (T½ = 6 hours) Radiopharmaceutical Generators Radiopharmaceutical generators:
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13 are easily transportable; and can serve as sources of short-lived radionuclides in institutions located in remote areas where contracting the services of a radiopharmacy is impracticable. Radiopharmaceutical Generators (cont) The importance of generators lies in the fact that they:
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a 6 hour physical half-life; the absence of β radiation permits the administration of GBq activities for diagnostic purposes without significant radiation dose to the patient; emits 140 keV photons which can be readily collimated to give images of superior spatial resolution; Is readily available in a sterile, pyrogen free and carrier free state from 99Mo - 99mTc generators. Technetium 99m 99mTc has the very favorable physical and radiation characteristics of:-
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15 Technetium 99m 99mTc labeled radiopharmaceuticals are easily produced by simply adding 99mTcO4 to many choices of “cold kits”.
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16 In short, 99mTcO4 is added to a vial containing a chemical compound that binds to the radionuclide. The result is a radiopharmaceutical which will be taken up in the designated organ for imaging (or analysis) with a gamma camera. Technetium 99m (cont)
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17 is produced in a reactor; Iodine 131 131Iodine: is used in diagnostic procedures involving the thyroid and also for the treatment of thyroid disorders; can be administered in capsule or liquid solution form; requires special precautions to be implemented during administration.
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18 Industrial cyclotron Medical Cyclotron The production of other radionuclides for nuclear medicine (e.g. PET) involves the use of a cyclotron. Other Radionuclides
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19 has two components; a radionuclide and a pharmaceutical. Principles of Uptake (localization) A radiopharmaceutical: In designing a radiopharmaceutical, a pharmaceutical is first chosen on the basis of its preferential uptake (localization) by a given organ or its participation in the physiological function of the organ i.e. the morphology and / or the physiology of the organ can be assessed.
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The prescribed activity of a radiopharmaceutical is that activity documented in a written directive or in the diagnostic clinical procedures manual, in accordance with the direction of the authorized user. Calculating the Required Activity Prescribed dose
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Calculating the Required Activity (cont) The technologist must: determine the volume of the radiopharmaceutical to draw into the syringe; because of the short half life of 99mTc, calculate the specific concentration of the radiopharmaceutical at the time of administration, e.g. a 10 ml solution containing 1.85 GBq will have a concentration of 0.185 GBq/ml. can then use the specific concentration and the decay constant for 99mTc, to calculate the exact volume to be drawn up for the prescribed activity to be administered. He also must measure the activity of each dose prior to use
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“Equipment Used in Nuclear Medicine”
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Categories of Equipment Important to Radionuclide Imaging: Activity Meters (also known as Dose Calibrators) Counting Equipment Monitoring Equipment Imaging Equipment
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24 A dose (or activity) calibrator measures the quantity of radioactive material in the prepared radiopharmaceutical prior to administration to the patient. Equipment Categories Dose (activity) calibrator
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25 Counting Equipment Several types of counting equipment are used in Nuclear Medicine including ionization chambers, proportional counters, GM- tubes and scintillation detectors. used for various tasks including ambient dose-rate survey monitoring, surveys for removeable contamination, sample counting and bioassay measurements.
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Monitoring (counting and survey) Equipment
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Mainly used for counting during thyroid uptake studies. Non-imaging Counting Devices
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mainly to count blood and urine samples. to count wipe test samples to identify if radioactive contamination exists in the area surveyed. Non-imaging Counting Devices (cont) Scintillation Well Counters are used:-
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29 Following administration of the radiopharmaceutical to the patient, a gamma camera is used to image the area of interest. Imaging Equipment
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30 Gamma Cameras Gamma cameras are used to show how the radiopharmaceutical distributes itself throughout the body or is taken up by specifically targeted organs.
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31 Gamma Cameras (cont)
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32 In most cases, gamma cameras are interfaced with a computer which controls data acquisition, processing and image display. Gamma Cameras (cont)
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33 Dynamic Static Tomographic Still and dynamic images can be acquired Gamma Cameras (cont)
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34 SPECT cameras looks at a patient from many different angles and is able to demonstrate very precise detail within the patient. Single Photon Emission Computed Tomography SPECT Imaging Information is presented as a series of planes that correspond to certain depths within the body. The planes presented may be a series of coronal, sagittal, transverse and / or oblique slices.
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35 SPECT Imaging (cont)
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36 Rollo 1977 Early scintillation imaging devices Rectilinear Scanners
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37 Processes studied include blood flow, oxygen, glucose and fatty acid metabolism, amino acid transport, pH and neuroreceptor densities. Positron Emission Tomography (PET) is used to study physiologic and biochemical processes within the body PET Scanners An on-site cyclotron is required to produce the very short half life PET radiopharmaceuticals.
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38 PET Scanners (cont)
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39 Mobile PET Scanner
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40 For any worker who usually works in a controlled area, and may receive a significant dose from occupational exposure, individual monitoring shall be undertaken where appropriate, adequate and feasible. Personal Monitoring [GSR Part 3 Requirement 25, 3.100]
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41 Thermoluminescent (TLD) or Optically Stimulated Luminescence (OSL) dosimeter Film dosimeter gamma, X and beta radiation Personal Monitoring (cont) Doses from External Radiation gamma, X and beta radiation
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42 Personal Monitoring (cont) Doses from External Radiation (cont) Electronic dosimeter, with or without alarm Film badge, electronic dosimeter, ring badge, TLD
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43 Urinalysis. Whole body monitor: gamma emitting radioisotopes. Thyroid monitoring: iodine radioisotopes. Personal Monitoring (cont) Assessing Doses from Internal Radiation
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44 Employers and licensees shall maintain exposure records for each monitored worker. Personal Monitoring (cont) Record Keeping Records are to be maintained as required by the Regulatory Body. Information is confidential and must be kept secure. Access to records shall be provided to: the relevant worker; relevant employer; Regulatory Body; health surveillance professionals
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45 (a) All sources giving rise to medical exposure are calibrated in terms of appropriate quantities using internationally accepted protocols; Calibration of Equipment and Sources [GSR Part 3 Requirement 38, 3.166] The medical physicist shall ensure that: (b) calibrations are carried out at the time of commissioning a unit prior to the clinical use, after any maintenance procedure that could affect the dosimetry and at intervals approved by the Regulatory Body.
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46 Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards. Generic Safety Requirements. GSR Part 3 (Interim) Vienna (2011) Regulatory Control of Radioactive Sources, Safety Standards Series No. GS-G-1.5, IAEA, Vienna (2004) Notification and Authorization for the Use of Radiation Sources. IAEA-TECDOC-1525. Vienna, 2007 References