Radiation Biology: Principles and Laws

The degree to which a tissue or cell is damaged by ionizing radiation.

Cells that multiply frequently, making them vulnerable to radiation damage.

A number assigned to different tissues/organs, reflecting the relative sensitivity to radiation damage..

A measure of how densely ionizing radiation deposits energy along its path.

A comparison of radiation types' effects on biological tissue.

Measures how oxygen affects radiation damage.

The time between radiation exposure and the appearance of biological effects.

Damage caused by radiation to an organism.

Expressed in kiloelectron volts per micrometer (keV/µm).

Penetrates deeply; interacts sparsely with atoms; causes mostly indirect damage.

Less penetrating, dense interactions; causes direct damage.

X-rays, gamma rays.

Alpha particles, heavy ions, low-energy neutrons.

Damage caused by free radicals produced from the interaction of radiation with matter.

Approximately 3 keV/µm

RBE compares the effectiveness of different types of radiation, relative to a reference radiation (like 250 kVp x-rays), at causing a specific biological effect.

A factor used to calculate the equivalent dose (EqD), which reflects the overall biological impact of different types of radiation.

The phenomenon where radiation damage is higher in oxygenated tissues than in oxygen-deprived tissues.

Free radicals can combine with oxygen to form organic peroxide compounds, which cause permanent damage to biological tissues.

A rupture in the structure of a chromosome, often caused by radiation. This disruption can lead to various anomalies.

A type of chromosome anomaly that occurs after DNA replication. It affects only one of the two chromatids in a chromosome pair.

A type of chromosome anomaly that occurs before DNA replication. It affects both chromatids in a chromosome pair.

Structural radiation damage to a single chromosome, often occurring at low doses. It can include deletions, acentric fragments, and isochromatids.

Severe damage to a chromosome, involving multiple breaks and rearrangements, often caused by higher doses of radiation. Examples include reciprocal translocation and ring formation.

A type of chromosome aberration where two chromosomes exchange segments. This can disrupt gene function. It is a multi-hit aberration.

A type of chromosome aberration where a chromosome breaks and the ends join together, forming a ring structure. This can also be a multi-hit aberration.

Chromatid aberration occurs after DNA replication, affecting only one chromatid, while chromosome aberration occurs before DNA replication, affecting both chromatids.

The total amount of radiation administered in a short period, preventing biological recovery.

Cell death that occurs immediately due to high-energy radiation, disrupting cell components.

Cell death caused by radiation, preventing further cell division but allowing essential functions.

Programmed cell death that occurs before the cell divides, a natural, controlled process.

Cell death occurring after one or more divisions following radiation exposure, impacting cell division.

Radiation-induced delay in cell division, preventing the cell from dividing on time, even at low doses.

Radiation can disrupt normal cell operations without causing death, affecting the cell's ability to work.

Epithelial tissue, found in areas like the lining of the intestines and blood vessels, rapidly regenerates through mitosis. This makes it highly susceptible to damage from radiation.

Muscle tissue, like the cells that make up your muscles, is highly specialized and doesn't divide often. This makes it relatively insensitive to radiation damage.

Mature nerve cells in the brain and spinal cord are highly specialized and don't divide. If the nucleus of a nerve cell is destroyed, the cell dies and cannot be replaced. It requires a very high dose of radiation to cause damage.

Developing nerve cells, especially during the 8th to 15th weeks of gestation, are particularly sensitive to radiation because they are actively dividing. Damage during this period can lead to microcephaly and mental retardation.

Immature spermatogonia in the testes are rapidly dividing, making them highly radiosensitive. Even a low dose of radiation can impact sperm cell production and potentially cause genetic mutations.

Immature ova, particularly during the ages of 12 to 50 years, are highly radiosensitive due to their rapid growth and development. Radiation can disrupt their maturation and fertility.

A radiation dose of 2 Gy can cause temporary sterility in males, while 5-6 Gy can lead to permanent sterility.

It is highly unlikely that patients receiving diagnostic imaging will receive a gonad dose high enough to cause significant damage. Radiographers working under normal conditions will never receive a gonad dose exceeding safety limits.