Topic 3 (midterm) Flashcards
2 general components of radiopharmaceutical
Radionuclide
Pharmaceutical
Are medicinal products designed for the use in the investigation or treatment of human diseases. Contain “radionuclide” as an integral part of the main ingredient. Are administered to a human subjects usually by intravenous injection.
Radiopharmaceuticals
The atoms involved and the only nuclei that undergo radioactive decay. Emits gamma ray as it decays. This is tagged to a radiopharmaceutical
Radionuclide
Any chemical substances intended for use in medical diagnosis, cure treatment or prevention of disease. Carries the radionuclide to the organ being examined. This is chosen in the basis of its preferential localization or participation in the physiological function of a given organ. Produces gamma-ray emission from within the organ is being studied.
Pharmaceuticals/tracer
The radionuclide decay should result in __ (100-300 keV is ideal for gamma cameras) and sufficient
abundance of emission of external detection.
gamma emissions of suitable energy
It should not contain particulate radiation (__), which increases patient’s radiation dose without adding diagnostic information.
beta emissions
are suitable for therapeutic radiopharmaceuticals.
Beta emissions
The __ should only be longer enough for the intended application, usually a few hours.
effective half-life
The specific activity should be __. (Tc-99m).
high
The pharmaceutical component should be free of any _ or _
toxicity or secondary effects.
Should be __ or easily compounded and should have a reasonable cost
readily available
The agent should __ localize according to the intended application.
rapidly and specifically
the radiopharmaceutical must achieve a satisfactory distribution in the body or trace a particular metabolic absorptive, excretory or other pathway.
Biological behaviour
A “__” or “__” produced with an area increased radioactivity.
Hot lesion or hot spot
__ is detected with decreased radioactivity
Cold lesion
Used to denote the organ or the volume which is desired to concentrate the radiopharmaceutical
Target
Areas of increased flow & metabolism e.g metastases and inflammatory lesion
Hot spot images
Areas of diminished flow or metabolism e.g cardia perfusion infarct
Cold spot images
The radionuclide must have suitable properties as regard radiation emitted energy and abundance of gamma rays and half-life
Radionuclide characteristics
This will depend on the mode of the production of the radionuclide, the nature of radiopharmaceutical and the cost
Availability
Most agents are injected intravenously and must therefore be of high __ quality
Pharmaceutical
Modes of administration of radiopharmaceutical
Injection-
Swallowing/ingesting
Inhalation
Instilling
Are products of microbacterial metabolism which produce fever when injected to human subjects. They are heat-stable and are not destroyed by normal methods of sterilisation.
Pyrogen
Involves cellular metabolic process that results in organ or tissue concentration above plasma levels.
Active Transport
Involves movement of substance from regions of higher concentration to a lower concentration.
Simple Diffusion
Particles larger than RBC’s are lodged at the first capillary bed it encounters.
Capillary blockade
Involves the recognition and removal of small foreign particles in the blood.
Phagocytosis
Process by the which the spleen recognition and removes the damaged RBC’s and cells nearing the end of heir life expectancy.
Cell Sequestration
Antibody complexion, It is a tumor localization
Antigen
most famous naturally occurring nuclide, was first used in treatment in 1903 (half-life of 1620 years)
Ra-226
other significant naturally occurring radionuclides
-0.012% of natural potassium is K-40, as the human body contains about 190g of potassium, this represents an activity of approximately 0.2uCi
K- 40 and C-14
is produced in the upper atmosphere due to the effect of cosmic radiation and becomes incorporated into plants and animals man.
C-14
Produce radioactive substances
Nuclear reactor
This is the most important method of producing artificial radionuclides
Neutron bombardment
Radionuclide are normally obtained by neutron bombardment of a uranium target (U-235) in reactor splitting the uranium atom into two radionuclides. Process which uranium is bombardment with neutron.
Fission products
Important in pet facility, expensive to run usually only a single target can be irradiated at one time, products decay either by positron emission or electron capture
Cyclotron
Consist of a longer-lived parent and a shorter wavelength daughter. The daughter product will still have a useful half-life for clinical applications.
Radionuclide generator
Molybdenum/Tc-99m Generator System
most important generator system
Which is a radioactive parent decays a radioactive daughter
Radioisotope “cow”
Mechanism organ radiopharmaceutical
Metabolic activity, thyroid I-131, sodium iodide
Phagocytosis, liver, tc99m, sulfur colloid
Diffusion brain, tc99m sodium pertechnetate
Capillary blockage lung tc-99m serum albumin
Cell Sequestration Spleen Tc-99m, damaged red
cells
Compartmental Localization Vascular space Labelled protein
Kidney, I-131 hippuran
Bone Tc-99m Diphosphonate/
Pyrophosphonate
Mo-99 (half life of 66 hours) produced by a nuclear reactor generator and fission products comes a radioactive daughter – Tc-99m(half life 6 hrs)
Radioactive parent
Accomplished by placing a special sterile vacuum vial on the exit or collection port
Volume: 5-20 mL
Elution
The parent of Tc-99m
• Half-life: 66 hours
• Mode of Decay: Beta minus
• Principal Photon energies: 740 and 780 KeV
• the most common radionuclide contaminant in the generator eluate.
Molybdenum-99
• The most commonly used radionuclide in nuclear medicine.
• Most important radionuclide for visualization.
• The only desired radionuclide in Mo-Tc generator eluate.
• Advantage: provides adequate time for the imaging yet allows the
target organ to decay background radiation levels within 2 days.
• Modes of Decay: Isomeric Transition
• Principal Photon energy: 140 KeV
• Produced in a generator system.
• Can be bound to biologically active compounds or drugs to create
radiopharmaceutical. (e.g. Tc-99 MAA)
Technetium-99m
Two types of generator system with respect in elution
Wet and dry systems
Most commonly used in regional radiopharmacies come with reservoir of normal saline (0.9%)
Wet systems
Common in imaging clinics
• A volume calibrated saline charge is placed on the entry port.
• A vacuum vial is placed on a collection port.
• A vacuum draws the saline eluent out of the original vial across the column and into the elution vial.
Dry systems
Symbol: Cr-51
T ½: 27.8 days
Chromium
Chromium chemical form
A. __ for red blood cells
B. __ for gastrointestinal protein loss
A. Sodium chromate
B. Albumin
Symbol: Co-57
T ½: 270 days
Cobalt
Cobalt Chemical Form:
__ : for Vit. B12 absorption
a. Cynocobalamin (Vit. B12)
Symbol: Co-58
T ½: 72 days
Chemical Form:
__ for Vit. B12 absorption
a. Cynocobalamin (Vit. B12)
Symbol: Ga-67
T ½: 77 hours
Gallium
Gallium Chemical Form:
• __ for inflammatory process and tumor imaging
Gallium Citrate
Symbol: In-111
T ½: 67.4 hours
Indium
Indium Chemical form:
__ for CSF imaging
• __ for prostate CA
• __ for colorectal or ovarian CA
Diethylenetriamine penta-acetic acid (DTPA)
ProstaScint
OctreoScan
I. I-123
T ½: 13.3 hours
Iodine
Iodine-123 Chemical Form:
● __ for thyroid function imaging
Sodium Iodide (I-123):
T ½: 60 days
Iodine-125
I-125 Chemical form:
● __ – for thyroid hormone assay
● __ – for thyroid hormone assay
● __ – for plasma volume
Triiodothyronine
Thyroxine
Human serum albumin
Symbol- I-131
T ½: 8 hours
Iodine-131
I-131 Chemical Formula:
● __ – for thyroid function, imaging and therapy
● __ – for renal function
Sodium Iodide
Hippurate
Symbol: Tc-99m
T ½: 6 hours
Technetium
Tc-99m Chemical Form:
● __ for imaging of brain, thyroid, scrotum, salivary glands, renal perfusion and pericardial effusion; for evaluation of left to right cardiac shunts; for Meckel’s diverticulum detection.
● __: for imaging of liver, spleen and renal transplants; for lymphoscintigraphy and bone marrow scintigraphy.
Sodium Pertechnetate:
Sulfur Colloid
• for pulmonary perfusion and liver intraarterial scintigraphy
Macroaggregated Albumin (MAA)
for cardiovascular imaging and myocardial perfusion.
Sestamibi
for brain and renal scintigraphy; for lung ventilation (aerosol)
Diethylenetriamine penta-acetic acid (DTPA)
for renal cortical scintigraphy
Dimercaptusuccinic acid (DMSA)
for renal dynamic scintigraphy.
Mercaptoacetyl triglycine (MAG3) or Mertiatide
for skeletal scintigraphy
Diphosphonate
for bone and myocardial imaging
Pyrophosphonate
for brain function scintigraphy; for cerebral perfusion scintigraphy; for white blood cell labeling
Hexamethylpropyleneamineoxime (HMPAO)
for hepatobiliary scintigraphy
Iminodiacetic acid (IDA)
for cerebral perfusion scintigraphy
Neurolite (Bisicate)
for myocardial perfusion scintigraphy
Myoview (Tetrofosmin)
for radionuclide ventriculography, gastrointestinal bleeding and hepatic hemangioma
Red blood cells
Symbol: Tl -201
T ½: 75.5 hours
Thallium
Thallium Chemical Form:
● __ – for myocardial imaging
Thallous Chloride
Symbol: Xe-131
T ½: 5.3 days
Xenon
Xenon Chemical Form:
● __ – for lung ventilation imaging
Xenon-gas
