NMT Production of Ra Word Scramble

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Question	Answer
Production of Radionuclides	Cyclotron-Produced Reactor-Produced Radionuclide Generator
Cyclotron-Produced 1	Charged particles accelerated and irradiate a target of stable elements Protons, deuterons, alpha, 3He
Cyclotron-Produced 2	Incident particle may leave all or part of it’s energy in the target
Cyclotron-Produced 3	Target nucleus becomes excited and emits nucleons in addition to a gamma ray leading to the formation of a different nuclide
cyclotron	particle accelerator used for the production of radioisotopes
Cyclotron Operation	entire process is controlled by a personal computer.
cyclotron consists of	a pair of hollow, semicircular metal electrodes (called "dees" because of their shape), positioned between the poles of a large electromagnet
radioisotope can be formed	by protons and neutrons from cyclotrons and nuclear reactors; nuclear reactions
man-made isotopes	are cyclotron isotopes and reactor isotopes
cyclotron isotopes	are formed by nuclear reactions with protons (from a cyclotron, a ring-shaped particle accelerator).
Reactor isotopes	are produced by nuclear reactions with neutrons which can only be generated in sufficient quantities during fission of uranium in a nuclear reactor.
Cyclotron-Produced - 111In produced	with 12 MeV protons 111Cd(p,n)111In 111Cd -- target p (proton) -- irradiating particle n (neutron) -- emitted particle 111In -- product
carrier-free	Radionuclides produced with atomic numbers different form those of the target do not contain any stable (“cold” or “carrier”) isotopes
Target	should be mono-isotopic
Isotopes	are then separated by chemical means solvent extraction, precipitation, ion exchange, and distillation
Cyclotron-Produced are	Usually neutron deficient Decays by positron emission or electron capture.
Cyclotron-Product	123-Iodine Likely to be contaminated with 124I and 125I Indirect method -- 123Xe produced then decays to 123I 67-Gallium 111-Indium 201-Thallium
Short-Lived Cyclotron-Produced	Used mostly in PET (positron emission tomography), Cyclotron must be located on site. 11-Carbon 13-Nitrogen 15-Oxygen 18-Fluorine (FDG)
Reactor - Produced Radionuclides 1	Fissile material fuel rods undergo spontaneous fission 235U and 239Pu
Reactor - Produced Radionuclides 2	Neutrons emitted cause further fission Reaction controlled by cadmium rods in the core
Reactor - Produced Radionuclides 3	Target elements are inserted in the core and interact with thermal neutrons to produce another nuclide
Reactor - Produced Radionuclides - Two types of interactions	Fission of heavy elements Neutron capture [ (n, g)]
Fission	breakup of a heavy nucleus into two fragments of approximately equal mass, accompanied by the emission of two to three neutrons with mean energies of about 1.5 MeV
Fission [(n,f)] Reaction - Heavy elements	atomic number greater than 92 235U, 239Pu, 237Np, 233U, 232Th
Nuclides	produced range in atomic number from 28 to nearly 65
Fission [(n,f)] Reaction - Products	Products separated by chemical procedures Normally carrier-free with high specific activity Products usually neutron rich and decay by b- emission Products of 235U fission 131I, 99Mo, 133Xe, 137Cs
Neutron Capture [(n,g)] Reaction	Target captures a neutron and emits a gamma ray producing an isotope of the same element Not carrier-free, low specific activity Target and product same element, chemical separation unnecessary unless impurities develop
Neutron Capture [(n,g)] Reaction - Radionuclides produced	Radionuclides produced 131Te-131I 98Mo(n,g)99Mo 50Cr(n,g)51Cr Molybdenum-99 so produced is called “irradiated molybdenum”
Targets	1000oC, water cooled, Designed in foil for heat dissipation-Copper, aluminum, uranium vanadium. Other forms - oxides, carbonates, nitrates and chlorides contained in aluminum tubing. Pneumatic tubes are often used to carry target to reactor or cyclotron.
Principles of a Generator	Decay-growth relationship Long-lived parent radionuclide and short-lived daughter radionuclide Chemical property of daughter is distinctly different from parent Easily transportable
Generator	Glass or plastic column fitted at bottom with fritted disk
Generator - column	is filled with adsorbent material cation-, or anion- exchange resin, alumina or zirconia on which the parent is absorbed
Generator - daughter	activity is eluted in a carrier-free state with an solvent
Generator - After elution	the daughter activity starts to grow again in the column until an equilibrium is reached.
Generator - Bacteriostatic agents	may be added to the column and a membrane filter attached to keep a sterile and pyrogen-free condition
Generator - “Milking the Cow”	Eluant is inverted onto needle A Evacuated vial is inverted onto needle B Vacuum in vial on needle B draws eluant through column and elutes the daughter nuclide, leaving the parent on the column
First commercial radionuclide generator was	132Te -- 132I
Most important radionuclide generator in nuclear medicine is	the 99Mo -- 99mTc generator
99Mo - decays	87% decays to metastable 99mTc 13% decays to ground state 99Tc
99mTc decays	by isomeric transition or gamma transition of 140 keV (10% are via internal conversion
99Tc decays	by b- with a half-life of 2.1 X 105 years to 99Ru
99Mo -- 99mTc Generator Construction	Liquid Column generator is rarely used in nuclear medicine and will not be discussed Solid Column Generator is used in modern day nuclear medicine
Solid Column Generator	“Moly” Generator, Alumina (Al2O3) loaded in a plastic or glass column, 99Mo is absorbed on alumina (MoO4-2, molybdate), Column is washed with isotonic saline, 99Mo is fission-produced
Solid Column Generator 99mTC	99mTc will grow until maximum activity is reached after approximately four half-lives After maximum activity is reached 99mTc activity follows that of 99Mo (Fig. 5.2) 99mTc is eluted as sodium pertechnetate (Na99mTcO4) with 0.9% NaCl solution
Solid Column Generator - dry column	Isotonic saline is provided in vials of different sizes Evacuated vials are used to draw the saline through the column not leaving saline in the column
Solid Column Generator - wet column	Isotonic saline is provided in a bottle inside the generator Evacuated vials are used to draw the saline through the column leaving some of the saline in the column
Wet - Solid Column Generator	Radiation cause radiolysis of water in generator column result in formation of hydrogen peroxide (H2O2) & perhydroxyl free radical (HO2.), Radiolysis is more likely in high activity generators, Saline in tube may freeze extremely cold weather during ship
ATc =	= 0.956 (AMo)O(e-0.01034t - e-0.11550t) + (ATc)Oe-0.11550t
After transient equilibrium is reached	ATc = 0.956(AMo)t
99Tc in the eluate	increases from 13% over time, this may cause reduction in labeling efficiency in radiopharmaceutical kits with small amounts of stannous ion
99mTcHMPAO	the eluate must not be more than 2 hours old and the generator must have been eluted at least once in the past 24 hr.
Quality Control of 99mTc-Eluate	99Mo Breakthrough Other Radionuclide Contamination Aluminum Breakthrough pH Radiochemical Purity
99Mo Breakthrough	Small quantity of 99Mo may be eluted with the 99mTc NRC limit 0.15 mCi 99Mo/mCi 99mTc per administered dose at time of administration The eluate is shielded in lead to measure only the 740 and 780 keV 99Mo photons
Other Radionuclide Contamination	Other contaminants can be checked by a multichannel pulse height analyzer Usually performed by the manufacturer
Aluminum contamination	may come from the alumina bed of the generator
Aluminum interferes	with preparation of 99mTcSC and RBC tagging
Aluminum Breakthrough - Limits	10 mg Al/ml of 99mTc
Detected by colorimetric method	Standard Al+ solution spotted on test strip 99mTc spotted on test strip Colors are compared, If 99mTc spot is denser than the standard there is excessive aluminum
pH	should be between 4.5 and 7.5
Radiochemical Purity	Radiochemical impurities of the 99mTc eluate are all chemical forms of radioactivity other than 99mTcO4-. Described in Chapter 8.
Other Generators	113Sn -- 113mIn 68Ge -- 68Ga 82Sr -- 82Rb 81Rb -- 81mKr

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