Radiobiology and Radiation Protection Quiz

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Questions and Answers

Concept of selecting minimum exposure factors during medical radiographic examinations:

Justification.
Risk analysis.
ALARA. (correct)
Dose limit.

The standard international (SI) unit used to identify dose equivalent is

Coulomb/kilogram (C/Kg).
Seivert (Sv). (correct)
Gray (Gy).
Bequerel (Bq).

Biologic material irradiated under hypoxic conditions is

less sensitive than when irradiated under oxygenated conditions. (correct)
less sensitive than when irradiated under anoxic conditions.
unaffected by presence or absence of oxygen.
more sensitive than irradiated under oxygenated conditions.

Which of the following is (are) composed of non-dividing, differentiated cells?

Nervous system. (C) Signup and view all the answers

Which of the following radiation-induced conditions is most likely to have the longest latency period?

Malignancy. (C) Signup and view all the answers

The unit of measurement identified by standard International system as the Gray, is equal to

100 rad. (A) Signup and view all the answers

Skin response to radiation exposure, appearing as reddening of the irradiated skin area, is known as

erythema. (A) Signup and view all the answers

Immature cells are referred to as

undifferentiated. (D) Signup and view all the answers

Which of the following have an effect on the type of radiation-induced tissue damage?

Quality of radiation. (D) Signup and view all the answers

Which of the following disorders is MOST likely to result from the irradiation of the fetus in utero during the first trimester?

CNS abnormalities. (C) Signup and view all the answers

A thermoluminescent dosimetry system would use which of the following crystals?

Lithium fluoride. (A) Signup and view all the answers

The X-ray interaction process with matter that is responsible for the majority of scattered radiation reaching the film is

Compton scatter. (B) Signup and view all the answers

Which of the following cells is most radiosensitive?

Myelocytes. (B) Signup and view all the answers

The minimum source-to-tabletop distance permissible in mobile fluoroscopic equipment is

18 inches. (A) Signup and view all the answers

What is the effect on relative biologic effectiveness (RBE) as linear energy transfer (LET) increases?

RBE increases. (C) Signup and view all the answers

Which of the following would MOST likely cause the highest skin dose?

Increased mA. (B) Signup and view all the answers

Irradiation of water molecules within the body, and their resulting breakdown, is termed

radiolysis. (A) Signup and view all the answers

The purpose of inherent and added filtration in the X-ray tube is to

soften the X-ray beam. (A), reduce patient skin dose. (C), reduce scattered radiation. (D) Signup and view all the answers

What minimum total amount of filtration (inherent plus added) is required in equipment operated above 70 Kvp?

3.5 mm Al equivalent. (C) Signup and view all the answers

Mice irradiated with 6.5 grays at 250 Kvp X-rays, result in death. However when mice are irradiated with fast neutrons, 2.2 grays results in death. What is the relative biological effectiveness of the neutron radiation?

2.96 Signup and view all the answers

Stochastic effects are

effects whereby the probability of an effect occurring is regarded as a function of dose. (B) Signup and view all the answers

Which is the major body (of 'recognised experts') whose publications are used as a basis to set legislative controls in radiation protection?

ICRP. (B) Signup and view all the answers

An unsealed source of alpha particle (only) emitting sunstance would be referred to as

an internal hazard. (C) Signup and view all the answers

Dose equivalent is given by

absorbed dose x quality factor x modifying factor. (C) Signup and view all the answers

The Dose Equivalent Limit is an intention to

minimise the risks for radiation workers. (A) Signup and view all the answers

Differentiate between the following biological effects of radiation: (i) stochastic and deterministic effects. (ii) genetic and somatic effects.

(i) Stochastic effects are those for which the probability of an effect occurring increases with the dose, however, the severity of the affected is independent of the dose. Deterministic effects are effects where there is a threshold dose that must be reached before the effect is observed. The effects severity is based on the dose received. (ii) Genetic effects are those that occur in the germ cells and affect the offspring. Somatic effects occur in the body cells and only impact the individual. Signup and view all the answers

List THREE methods of detecting radiation.

Some methods of detecting radiation are: (a) Ionization Chambers: Measure the amount of ionization produced by radiation. (b) Geiger-Muller detectors: Are commonly used to detect beta and gamma radiation (c) Thermoluminescent Dosimeters (TLDs): Are used to measure personal radiation exposure. They store energy when exposed to radiation and release it as light when heated. Signup and view all the answers

Describe the design of fluoroscopic equipment that help reduce dose to patients and staff.

Fluoroscopic equipment is designed to provide real-time imaging during medical procedures. The equipment incorporates features that minimize radiation exposure to both patients and staff. The design features include: (a) Pulse fluoroscopy - This technique reduces the amount of radiation produced during imaging by delivering it in short pulses only when needed. (b) Lead shielding - Lead shielding is used to reduce radiation scatter to the operator and other staff members. (c) Collimation - The X-ray beam is carefully collimated or restricted to reduce unnecessary exposure to the surrounding areas. Signup and view all the answers

Describe THREE factors that influence the thickness of primary radiation barrier.

Factors that determine the thickness of a radiation barrier in medical imaging include: (a) Energy of the radiation: The energy level of the radiation source, which is usually measured in kilovoltage peak (kVp), determines its penetrating power. Higher energy radiation requires thicker barriers. (b) Workload: The workload refers to the frequency of exposure to radiation for that specific area or equipment in the treatment area. Higher workload demands thicker barriers to provide adequate shielding. (c) Occupancy: The occupancy factor is based on the time people spend in a particular area. Areas with frequent human presence require thicker barriers to ensure safety. Signup and view all the answers

Explain how a radiographer can reduce radiation dose to the patient during plain radiography.

Radiographers can employ several strategies to minimize radiation dose to patients during radiography. Some best practices include: (a) Use the minimum necessary exposure: This involves carefully selecting the appropriate technical factors such as kVp, mAs, and filtration to achieve the desired image with the lowest possible radiation dose. (b) Collimation: Restricting the X-ray beam to the area of interest. (c) Shielding: The use of shields, such as lead aprons, gonadal shields, or thyroid collars can significantly reduce radiation exposure to sensitive tissues during the exam. Signup and view all the answers

Explain the advantages of using a film badge as a dosimeter for personnel monitoring.

Film badges are routinely used to monitor radiation exposure for medical professionals. The badges contain a piece of photographic film that darkens when exposed to radiation. Key advantages include: (a) Cost-effectiveness: Relatively inexpensive. (b) Simplicity: Easy to wear and use. (c) Permanent Record: Provides a visual record of exposure dose, which can be reviewed and analyzed for historical data. Signup and view all the answers

Define the following terms: (i) exposure (ii) absorbed dose (iii) dose equivalent (iv) effective dose

(i) Exposure is a measure of ionization produced in air by radiation, often expressed in Roentgens (R). (ii) Absorbed dose is the amount of radiation energy absorbed per unit mass of a material. The standard unit is the Gray (Gy). (iii) Dose equivalent is the adjusted absorbed dose to account for the biological effects of ionizing radiation of different types. The standard unit is Sievert (Sv). (iv) Effective dose is the sum of the weighted absorbed dose affecting different organs, providing a measure of the overall radiation risk to the body. Signup and view all the answers

State THREE general principles of radiation protection.

The fundamental principles of radiation protection aim to ensure the safety of individuals working or exposed to radiation. Main principles include: (a) Justification: The practice should be justified by the potential benefits, meaning the exposure should outweigh any potential risks. (b) Optimization: All practices should be optimized to minimize the exposure to radiation for the patient and staff. (c) Dose Limits: The occupational exposure to radiation should remain well below the established dose limits for individuals. Signup and view all the answers

Explain the following: (a) late effects of radiation. (b) fractionation of dose. (c) Law of Bergonie Tribondeau. (d) lethal dose. (e) genetically significant dose.

(a) Late effects of radiation are those that develop long after exposure to radiation and are often insidious. They are typically stochastic in nature and include cancer and genetic mutations. (b) Fractionation of dose refers to the process of dividing the total dose of radiation into smaller doses given over a prolonged duration, allowing for the repair of damaged cells and reduce the risk of side effects. (c) Law of Bergonie Tribondeau states that the sensitivity of cells to radiation is inversely proportional to their degree of differentiation and directly proportional to the rate of cell division. This means that rapidly dividing, undifferentiated cells, such as those in the bone marrow, are more sensitive to radiation than slowly dividing, well-differentiated cells. (d) Lethal dose is the minimum dose of radiation required to kill a living organism. (e) Genetically significant dose is the average dose to the reproductive organs of a population that could lead to genetically harmful effects, such as mutations in the offspring. Signup and view all the answers

List FOUR factors that can influence the effect of radiation on tissues.

Factors influencing the effects of radiation on tissues include: (a) Type of Radiation: Different types of radiation have varying biological effectiveness. Alpha particles are more damaging than beta or gamma rays. (b) Radiation Dose: The amount of energy absorbed by the tissue determines the severity of damage. Higher doses generally lead to more severe effects. (c) Tissue Sensitivity: Different tissues have varying levels of sensitivity to radiation. For example, rapidly dividing tissues like the bone marrow are more sensitive than slowly dividing tissues, such as nerve cells. (d) Age and health: The susceptibility to radiation effects can be influenced by factors such as the individual's age, overall health, and existing health conditions. Signup and view all the answers

Explain the response of organ systems to irradiation.

The response of various organ systems to radiation varies depending on the dose received and the individual's sensitivity to radiation. Some common responses include: (a) Hematopoietic System: Damage to bone marrow can lead to reduced blood cell production. This can result in anemia, decreased immunity, and increased risk of infections. (b) Gastrointestinal System: Damage to the lining of the gut can cause nausea, vomiting, diarrhea, and dehydration. (c) Nervous System: High doses of radiation can damage the nervous system, leading to seizures, coma, and even death. (d) Reproductive system: Radiation can damage the ovaries or testes, potentially leading to infertility. Signup and view all the answers

Following exposure to radiation dose in excess of 2 Gy, describe the haematological syndrome.

The hematopoietic syndrome is a complex set of symptoms that result from radiation exposure to the bone marrow. It occurs when the radiation dose exceeds 2 Gy. The syndrome can manifest in a range of severity depending on the dose received. Key features include: (a) Bone marrow suppression: Damage to bone marrow leads to reduced production of red blood cells, white blood cells, and platelets. (b) Anemia: Reduction in red blood cells leads to fatigue and weakness. (c) Infection: Reduction in white blood cells increases vulnerability to infections. (d) Bleeding: Reduced platelet count results in increased risk of bleeding. Signup and view all the answers

"The proportion of surviving cells diminishes as the radiation dose increases." With the aid of a suitable graph explain the above statement.

The statement is correct. As radiation dose increases, the proportion of surviving cells decreases due to radiation-induced cell death. Here is a simple illustration: [Graph illustrating exponential decay where the x-axis represents the radiation dose and the Y-axis representing the percentage of surviving cells. The graph shows a downward curve with the number of surviving cells dropping exponentially as the radiation increases.] This is due to the damage caused by radiation to DNA and cellular structures. With higher doses, cell death is more pronounced, leading to a steeper decline in the surviving cell population. Signup and view all the answers

Flashcards

ALARA

A principle meaning 'As Low As Reasonably Achievable' to minimize radiation exposure.

Dose Limit

The maximum level of radiation exposure allowed for workers or the public.