Radiobiology Flashcards
When an individual takes any x-ray, what method should always be practiced, and what does that method stand for?
- ALARA
- As Low As Reasonably Achievable
T/F: For the patients protection, the doctors should minimize time, maximize distance, shield the patient, filter the x-ray tube, and establish the patients ability to understand and cooperate during imaging,
TRUE
In order to limit x-ray exposure the tube has to be ____ to the smallest field size of the desired anatomy.
collimated
T/F: Only order and perform radiographic study as determined by medical necessity.
True
Understand the importance of _____ examination and differential diagnosis before ordering the study.
physical examination
T/F: Radiography could be used in place of physical examination
FALSE!
Who are the most vulnerable patients to radiographic study?
Pregnant women and children
When is full body shielding used?
Extremity imaging
When is partial shielding used?
Cervical and thoracic spine radiography
When is gonadal shielding used?
Patients that are either…
- Patients of reproductive age
- Children
What view is better for radiation exposure in the thoracic area PA or AP?
PA
What does the 1906 Law of Bergonie and Tribondeau state?
Radiosensitivity of cells is dependent on their rate of maturation or differentiation and metabolism
What cells in your body are the most sensitive to radiographic imaging…
- Stem cells
- young cells
- Cells with higher rate of mitosis (ex. enterocytes, skin cells)
In imaging young children, where should the partial shielding, specifically on the gonads, be placed on the children.
Male - lower on the testicles (as they hang lower)
Female - higher to cover the ovaries
How is radiation measured?
Physical factors influencing radiosensitivity. It is estimated by the amount of energy absorbed per unit mass or (Rad)
T/F: The same radiation amount irradiating (exposure to radiation) the same mass unit may produce different tissue damage
TRUE
What is the Linear Energy Transfer (LET)? What does this measure?
- This measures the rate with which energy is transferred from ionizing radiation to soft tissues.
- The LET is another method of expressing radiation quality and determining the value of radiation weighting factor, this reflects the different amount of potential biological effect for each type of radiation source (ex. x-rays, gamma rays, b-particles or a-particles)
T/F: The ability of ionizing radiation to produce biologic response increases as the linear Energy Transfer of radiation decreases.
FALSE: The ability of ionizing radiation to to produce biologic response increases as the LET of radiation increases
What are the 3 biologic factors affecting radiosensitivity?
- Age
- Oxygen effect
- Recovery
How is the oxygen effect a biological factor affecting radiosensitivity?
- Tissues are more radiosensitive when irradiated under oxygenated state
- Hypoxic or anoxic tissues are less radiosensitive
How is Age a biological factor that affects radiosensitivity?
- Humans are more radiosensitive before birth (3-7 weeks of fetal life)
- After birth radiosensitivity decreases and reaches its lowest point after maturity (tissues are better at repairing themselves)
- In old age radiosensitivity is increasing slightly (cells are old, and not as good at repair)
How is Recovery a biological factor affecting radiosensitivity?
- If the radiation is not sufficient to kill the cell, biochemically the cell will be able to recover
- Some cells may die which will cause organ atrophy. The surviving cells will eventually repopulate the damaged tissue
T/F: Tissues are less radiosensitive when irradiated under oxygenated state. Hypoxic or anoxic tissues are more radiosensitive
- FALSE:
- Tissues are more radiosensitive when irradiated under oxygenated state
- Hypoxic or anoxic tissues are less radiosensitive
T/F: If the radiation is not sufficient to kill the cell, the cells biochemical machinery may recover. Some cells may die causing organ atrophy. The surviving cells will eventually repopulate the damaged tissue.
TRUE
A chemical agent is considered what?
- Radiosensitizers
- Radioprotectors