Physics Midterm Essay Questions

The absorbed dose measures the energy deposited in matter, while dose equivalent measures the biological effect of that energy, factoring in the type of radiation and its impact on living tissue.

The main components of an atom are protons (positively charged, located in the nucleus), neutrons (no charge, also in the nucleus), and electrons (negatively charged, located in the electron cloud). Protons determine the element's identity, neutrons contribute to nuclear stability, and electrons influence chemical properties and bonding.

The Octet Rule states that atoms tend to react to achieve eight electrons in their outer shell, resembling the stable electron configuration of noble gases. This rule is significant as it helps predict how elements will bond and form molecules.

In alpha decay, an alpha particle (two protons and two neutrons) is emitted, resulting in a decrease in atomic mass. It is heavily ionizing but has low penetration ability (stopped by paper).

In beta decay, a neutron is transformed into a proton or vice versa, emitting a beta particle. Beta particles are less ionizing but can penetrate materials more effectively (stopped by wood or plastic).

Half-life is the time required for half of a radioactive substance to decay. Physical half-life refers to the decay of the isotope itself, biological half-life is the time for a substance to be cleared from biological systems, and effective half-life combines both physical and biological decay rates.

Equilibrium occurs when the production rate of a daughter isotope from its parent equals its decay rate. Transient equilibrium is when the daughter’s half-life is shorter than the parent’s, and equilibrium is reached relatively quickly. Secular equilibrium occurs when the daughter’s half-life is much shorter than the parent’s, leading to a stable ratio over a longer period.

Characteristics include excess neutrons, a range of decay modes (often beta decay), and low yields of the desired radionuclide compared to the total products.

A cyclotron accelerates charged particles to high energies using magnetic and electric fields, directing them at a target material to induce nuclear reactions, resulting in radionuclide production.

Reactor-produced radionuclides typically have higher yields and longer half-lives, making them suitable for a variety of applications. Cyclotron-produced radionuclides often have shorter half-lives and are used for specific diagnostic procedures due to their rapid decay.

Neutron activation occurs when neutrons are absorbed by a target nucleus, creating new isotopes. The two main types of reactions are the n, γ reaction (neutron capture with gamma emission) and the n, p reaction (neutron capture with proton ejection).

A "carrier" refers to a stable isotope present in a sample alongside the radioactive isotope, while "carrier-free" indicates a radionuclide without any stable isotope of the same element.

Ideal properties include sterility, the ability to produce a short-lived daughter nuclide, different chemical properties from the parent, and rapid elution. These properties are crucial for safe and effective medical applications, allowing for quick and clean usage.

The elution process involves removing the daughter radionuclide from the generator using a solvent. Elution efficiency refers to the actual amount of daughter radionuclide obtained compared to the theoretical yield, which is the maximum amount that could theoretically be produced.

Commonly used reactor-produced radionuclides include Iodine-131 (beta, gamma), Cesium-137 (beta, gamma), and Strontium-90 (beta).

Ligands are organic molecules that attach to a radioisotope, enhancing its ability to target specific biological tissues for imaging or treatment.