Production of Radionuclides

Vocabulary flashcards covering the production methods, nuclear reactions, physical properties, and mathematical principles of medical radionuclides from lecture notes.

Natural Radioactivity

The spontaneous radioactivity discovered in $1896$ by Becquerel in potassium uranyl sulfate, present in all natural elements with an atomic number greater than $83$ (bismuth).

Artificial Radioactivity

Induced radioactivity first reported by I. Curie and F. Joliot in $1934$ by irradiating boron and aluminum targets with $\text{α}$-particles from polonium.

Cyclotron

An accelerator in which charged particles move along circular trajectories under an electromagnetic field inside evacuated dees A and B to gain kinetic energy.

No Carrier Added (NCA)

A radionuclide preparation produced without intentionally adding any stable ('cold' or 'carrier') isotope of the same element to the target or final product.

Medical Cyclotron

A compact cyclotron located in healthcare institutions designed to accelerate low-energy, high-intensity charged particles primarily for clinical radionuclide production.

Gallium-67 ($^{67}\text{Ga}$)

A cyclotron-produced radionuclide ($t_{1/2} = 78.2\,h$) decaying $100\%$ by electron capture to $^{67}\text{Zn}$, with principal \u03b3-photons at $93\,keV$, $184\,keV$, $300\,keV$, and $393\,keV$.

Iodine-123 ($^{123}\text{I}$)

A radionuclide ($t_{1/2} = 13.2\,h$) decaying by electron capture with a $159\,keV$ \u03b3-ray emission, produced directly or indirectly via $^{123}\text{Xe}$ decay ($t_{1/2} = 2.1\,h$).

Iodine-124 ($^{124}\text{I}$)

A PET radionuclide ($t_{1/2} = 4.2\,d$) produced by proton irradiation of enriched $^{124}\text{Te}$ oxide and separated by dry distillation at $750\,^\circ\text{C}$.

Germanium-68 ($^{68}\text{Ge}$)

A parent radionuclide ($t_{1/2} = 270.8\,d$) decaying $100\%$ by electron capture to $^{68}\text{Ga}$ ($t_{1/2} = 68\,min$), used in generator systems and as a PET transmission source.

Strontium-82 ($^{82}\text{Sr}$)

A radionuclide ($t_{1/2} = 25.5\,d$) produced by proton bombardment of rubidium, decaying by $100\%$ electron capture to $^{82}\text{Rb}$ ($t_{1/2} = 75\,s$).

Indium-111 ($^{111}\text{In}$)

A radionuclide ($t_{1/2} = 2.8\,d$) decaying $100\%$ by electron capture to $^{111}\text{Cd}$, emitting useful \u03b3-photons at $171\,keV$ ($90\%$) and $245\,keV$ ($94\%$).

Copper-64 ($^{64}\text{Cu}$)

A radionuclide ($t_{1/2} = 12.1\,h$) produced via the $^{64}\text{Ni}(p, n)^{64}\text{Cu}$ reaction, decaying by $17.9\%$ $\beta^+$, $39.0\%$ $\beta^-$, and $43\%$ electron capture.

Thallium-201 ($^{201}\text{Tl}$)

A myocardial perfusion agent ($t_{1/2} = 73\,h$) decaying $100\%$ by EC to $^{201}\text{Hg}$, produced indirectly via decay of $^{201}\text{Pb}$ ($t_{1/2} = 9.4\,h$).

Fluorine-18 ($^{18}\text{F}$)

A positron emitter ($t_{1/2} = 110\,min$) produced via the $^{18}\text{O}(p, n)^{18}\text{F}$ reaction on an $^{18}\text{O}$-water target, commonly used to prepare $^{18}\text{F}\text{-FDG}$.

Nuclear Fission

The splitting of a heavy nucleus (such as $^{235}\text{U}$) into two medium-mass fragments upon absorbing a thermal neutron, yielding carrier-free neutron-rich radionuclides.

Molybdenum-99 ($^{99}\text{Mo}$)

A major reactor fission product ($t_{1/2} = 66\,h$) that serves as the parent radionuclide in $^{99}\text{Mo}\text{-}^{99\text{m}}\text{Tc}$ generators.

Iodine-131 ($^{131}\text{I}$)

A reactor-produced fission radionuclide ($t_{1/2} = 8.0\,d$) decaying $100\%$ by $\beta^-$ with a principal $364\,keV$ \u03b3-emission ($81\%$), used in thyroid diagnosis and therapy.

Xenon-133 ($^{133}\text{Xe}$)

A fission product noble gas ($t_{1/2} = 5.3\,d$) decaying by $\beta^-$ with an $81\,keV$ \u03b3-emission ($37\%$), dispensed for lung ventilation and blood flow evaluation.

Neutron Capture Reaction $(n, \gamma)$

A reactor nuclear reaction where a target nucleus absorbs a thermal neutron and emits excitation energy as a \u03b3-ray, generating an isotope of the same element.

Phosphorus-32 ($^{32}\text{P}$)

A pure $\beta^-$-emitting radionuclide ($t_{1/2} = 14.3\,d$) decaying to $^{32}\text{S}$, commonly produced via the $^{32}\text{S}(n, p)^{32}\text{P}$ reaction for leukemia and polycythemia vera therapy.

Strontium-89 ($^{89}\text{Sr}$)

A bone-seeking $\beta^-$-emitting radionuclide ($t_{1/2} = 50.6\,d$) produced by neutron capture on $^{88}\text{Sr}$, utilized for palliating cancer bone pain.

Gadolinium-153 ($^{153}\text{Gd}$)

A radionuclide ($t_{1/2} = 241.6\,d$) decaying $100\%$ by electron capture to $^{153}\text{Eu}$, produced by $^{152}\text{Gd}(n, \gamma)^{153}\text{Gd}$ for bone absorptiometry and SPECT attenuation correction.

Samarium-153 ($^{153}\text{Sm}$)

A therapeutic radionuclide ($t_{1/2} = 1.9\,d$) emitting $\beta^-$ particles and a $103\,keV$ \u03b3-photon, complexed as $^{153}\text{Sm}\text{-EDTMP}$ for palliative treatment of bone metastases.

Lutetium-177 ($^{177}\text{Lu}$)

A lanthanide radionuclide ($t_{1/2} = 6.65\,d$) decaying by $\beta^-$ to $^{177}\text{Hf}$, produced directly via $^{176}\text{Lu}(n, \gamma)^{177}\text{Lu}$ for targeted radionuclide therapy.

Radium-223 ($^{223}\text{Ra}$)

An $\alpha$-emitting radioisotope ($t_{1/2} = 11.4\,d$) obtained from the $^{227}\text{Ac} \rightarrow ^{227}\text{Th} \rightarrow ^{223}\text{Ra}$ decay chain, used to treat castration-resistant prostate cancer.

Saturation Factor

The term $(1 - e^{-\lambda t})$ in the radionuclide production equation, which approaches unity ($1$) as irradiation duration $t$ reaches $5$ to $6$ half-lives.

Production Activity Equation

The mathematical equation $A = I N \sigma (1 - e^{-\lambda t})$ describing the activity $A$ produced in a target based on particle flux $I$, target atom number $N$, cross-section $\sigma$, and irradiation time $t$.

Specific Activity

The radioactivity per unit mass of a radionuclide or labeled compound, expressed for carrier-free isotopes as $\text{Specific Activity} (mCi/mg) = \frac{3.13 \times 10^9}{A \times t_{1/2}}$.