Radiation Biology

  1. Know the difference between Fractionation and Protraction,and the benefits of them.
    • Fractionation-A dose delivered in smaller equal doses
    • Protractionation-A dose delivered continuously over a specific period of time.
  2. What is the difference between Linear and Nonlinear and what both look like on a chart?
    • Linear-Direct relationship beteween response and dose(Straight Line)
    • Non-Linear-Curved Line
  3. What is the difference between Threshold and Non-threshold and what both look like on a chart?
    • Threshold-Refers to the point at which a response to radiation first occurs
    • Non-Threshold-dose response will begin to occur at any dose regardless of size
  4. Why fractionation and protraction benefit the patient during radiation therapy?
    Causes less effect b/c time is allowed for intracellular repair and tissue recovery.
  5. When humans are most radiosensitive during their
    Before birth and when older
  6. What is the curve that has a radiation response at any given dose?
  7. What is LET and it's characteristics?
    • Linear Energy Transfer-Measure of the rate at which energy is transferred from ionizing radiation to soft tissue/
    • AKA-Radiation Quality
    • Expressed in units of kiloelectron volt
  8. What is RBE and it's characteristics?
    • Relative Biologic Effectiveness
    • Average 250 kVp
  9. What are the DX values for LET and REB
    • LET-3
    • RBE-1
  10. What is the law of Bergonie and Tribondeau?
    • The radiosensitivity of living tissue varies with maturation and metabolism.
    • PG 513, 33-1
  11. What is hormesis?
    An idea tgat a little bit of radiation is good for you. By stimulating hormonal and immune responses to other toxic environemntal agents(ALARA)
  12. What conditions are tissue more radiosensitve?
    • When irradiated in an oxygenated (aerobic) states
    • Recovery-
    • Chemical Agents-
    • Hormesis PG 515-516
  13. What is the relationship between LET and RBE?
    As LET increases the ability to produce biologic damage increases.
  14. What are the characterisitics of x-radiation?
  15. What method expresses radiation quality?
    It is expressed by LET
Card Set
Radiation Biology
Jennifer Hodges