radbio midterm.docx

Radiation in general is harmful for the body. It destroys cells slowly depending on the amount and type of radiation that will be received by the patient. Today, radiation is one of the most useful ways to determine many pathologic conditions that cannot be seen by our naked eye. Health effects ca...

Radiation in general is harmful for the body. It destroys cells slowly depending on the amount and type of radiation that will be received by the patient. Today, radiation is one of the most useful ways to determine many pathologic conditions that cannot be seen by our naked eye. Health effects can occur due to either long-term low-level exposure or short-term high-level exposure. **RADIATION BIOLOGY** - It is the job of the radiologic technologist, the radiologist, and the medical physicist to produce high-quality X-ray images with minimal radiation exposure. The effect of X-rays on humans is the result of interactions at the atomic level. The deposited energy can result in a molecular change, the consequences of which can be measurable if the molecule involved is critical. If the atom is a constituent of a large molecule, the ionization may result in breakage of the molecule or relocation of the atom within the molecule. The abnormal molecule may in time function improperly or cease to function, which can result in serious impairment or death of the cell. Molecules can be mended by repair-enzymes. Cells and tissues can regenerate and recover from the radiation injury. If the radiation response occurs within minutes or days after the radiation exposure, it is classified as EARLY EFFECT of RADIATION. If the human injury is not observed for months or years, it is called a LATE EFFECT of RADIATION. The ultimate goal of radiobiological research is the accurate description of the effects of radiation on humans so that radiation can be used more safely in diagnosis and more effectively in therapy. **CELL THEORY** Radiation interaction at the atomic level results in molecular changes, and this in turn can produce a cell deficient in normal growth and metabolism. - - - - **MOLECULAR COMPOSITION** There are five principal types of molecules in the body. Four of these molecules -- proteins (15%), lipids (2%), carbohydrates (1%) and nucleic acids (1%) are macromolecules. And the fifth one is water. **MACROMOLECULES** - - - - - - - - - **HUMAN CELL** - the nucleus also contains some RNA, protein, and water. most of the RNA is contained in a rounded structure, the nucleolus. The nucleolus is often attached to the nuclear membrane that at some location is connected to the endoplasmic reticulum.- a number of intracellular structures are found in the cytoplasm: - - - - **BIOLOGICAL EFFECTS** The occurrence of particular health effects from exposure to ionizing radiation is a complicated function of numerous factors including: - - - - - - **1. Type of Radiation Involved** - **2. Size of Dose Received** - **3. Rate of the Dose Received** - **4. Part of the Body Exposed** - **5. The Age of the Individual** - **6. Biological Differences** - ------------- **TOPIC 2** ------------- **CELL PROLIFERATION** Cell Proliferation is the act of a single cell or group of cells to reproduce and multiply a number. The human body consists of two general types of cells: **somatic cells and genetic cells.\ ** - - - **MITOSIS** - - - - **MEIOSIS** - - - **LAW OF BERGONIE AND TRIBONDEAU** - - - - - - - **PHYSICAL FACTORS AFFECTING RADIOSENSITIVITY** When one irradiates tissue, the response of the tissue is determined principally by the amount of energy deposited per unit mass -- the dose in rad (Gy). **LINEAR ENERGY TRANSFER (LET)** - - **RELATIVE BIOLOGIC EFFECTIVENESS** - - **PROTRACTION AND FRACTIONATION** - - - **BIOLOGIC FACTORS AFFECTING RADIOSENSITIVITY** A number of biologic conditions alter the radiation response of the tissue. Some of these factors have to do with the inherent state of tissue, such as age and metabolic rate. 1. - - 2. - - - - 3. - 4. - - - - 5. - - - - **RADIATION HORMESIS** - - - **RADIATION EFFECT ON DNA** - - - **IRRADIATION OF MACROMOLECULES** When macromolecules are irradiated in solution in vitro, **three major effects occur,** **main-chain scission, cross-linking, and point lesions.** 1. 2. 3.