P2 Flashcards
(81 cards)
ideal for gamma cameras
Gamma emissions of suitable energy (100-200 keV)
for external detection of radioactive decay
Positron emission tomography (511 keV) and sufficient abundance (percent likelihood of emissions per decay)
most closely matches these desirable features for the gamma camera and fluorine-18 for PET.
Technetium-99m
Neutron bombardment of enriched uranium-235 results in
fission products
Bombardment of medium-atomic-weight nuclides with low-energy neutrons (neutron activation) in a nuclear reactor results in
neutron-rich radionuclides
Neutron-rich radionuclides (e.g., iodine-131, xenon-133, chromium-51, and molybdenum-99) generated through fission or neutron activation undergo
beta-minus decay
They have no clinical role in diagnostic nuclear medicine.
Naturally occurring radionuclides
commonly used clinically are artificially produced by nuclear fission or through the bombardment of stable materials by neutrons or charged particles.
Radionuclides
Charged particle bombardment (with protons, deuterons, alpha particles) to a wide variety of target materials in cyclotrons or other special accelerators produces proton-rich radionuclides that will undergo:
Positron decay
Electron capture
is produced by the fission of U-235.
Mo-99
Mo99 is produced by the fission of
U-235
• Mo-99 is produced by the fission of U-235. The product is often referred to as _____.
fission moly
is readily available from a generator used in ~80% of all nuclear medicine examinations
Technetium (99mTc)
• 99mTc has a gamma ray energy of _____ that is ideal for imaging and a half-life of 6 hours that is convenient.
140 keV
is produced directly from 99Mo using a saline eluant.
Pertechnetate
(99mTc04)
Pertechnetate (99mTc04) is produced
directly from ____ using a ___.
99Mo, saline eluant
99mTc decays by _____ where 88% of nuclear transformations result in emission of a 140 keV gamma ray
isomeric transition
The half-life of 99Mo is _____, which allows the generator to remain useful for approximately 1 week (*2.5 half-lives).
66 hours
A ____ generator is normally eluted daily over the course of a week and then replaced.
99mTc
The technetium generator is shielded with _____ and consists of an alumina column loaded with ___
lead, 99Mo
99Mo decays to 99mTc, and ____ is added to the generator when 99Tc is needed.
saline
Saline passes through the column to elute (wash off) the 99mTC in the form of ____
sodium pertechnetate
_____is not soluble in saline and remains in the column.
99Mo
The process of removing Tc-99m from the Mo- 99/Tc-99m generator is known as ____.
elution