Molecular and Cellular Radiation Biology

What is ionizing radiation and how does it affect living systems?

Ionizing radiation damages living systems by ionizing the atoms that make up the molecular structure, leading to biologic damage.

List types of ionizing radiation that cause biologic damage.

X-rays, Gamma rays, Alpha particles, Beta particles, Protons.

What does Linear Energy Transfer (LET) describe?

LET describes the average energy deposited per unit length of track by ionizing radiation as it passes through and interacts with a medium.

What is the significance of Linear Energy Transfer (LET) in radiation biology?

LET is an important factor in assessing potential tissue and organ damage from exposure to ionizing radiation.

Differentiate between low-LET and high-LET radiation.

Low-LET radiation (e.g., X-rays, gamma rays) deposits energy sparsely, while high-LET radiation (e.g., alpha particles) deposits energy densely.

What does the Relative Biologic Effectiveness (RBE) measure?

RBE measures the effectiveness of different types of radiation in producing a particular biological reaction.

What is the formula for calculating Relative Biologic Effectiveness (RBE)?

RBE = Dose in Gy from 250-kVp x-rays / Dose in Gy of test radiation.

What is the role of Oxygen Enhancement Ratio (OER) in radiation therapy?

OER measures how much more effective radiation is in causing a biologic response when oxygen is present.

What are the immediate effects of ionizing radiation on cells?

Instant death, reproductive death, apoptosis, mitotic death, and interference with function.

Explain the concept of Target Theory in radiation biology.

Target Theory posits that a master molecule is necessary for the survival of the cell, and exposure to radiation can lead to cell death or abnormalities.

What is the Law of Bergoiné and Tribondeau?

This law states that radiosensitivity is directly proportional to reproductive activity and inversely proportional to the degree of differentiation.

How does radiation affect blood cells?

Radiation can cause hematologic depression by depleting immature blood cells and affect the function of lymphocytes and neutrophils.

What are single-strand breaks and double-strand breaks in DNA?

Single-strand breaks occur when one of the DNA's sugar-phosphate chain side rails is damaged, while double-strand breaks involve both strands being severed, leading to potential mutations.

What does the response to radiation typically look like on a survival curve?

The survival curve illustrates the sensitivity of cell types to radiation, showing how different cells survive exposure.

How do mature and immature reproductive cells react to ionizing radiation?

Immature reproductive cells are more sensitive to radiation and can experience temporary or permanent sterility due to lower doses of radiation.