Rad Bio quantities & units

• Exposure


  It is a radiation quantity “that expresses the concentration of radiation delivered to a specific area, such as the surface of the human body.”
• coulomb (C)


  basic unit of electric charge
• ampere


  SI unit of electric current
• air kerma


  SI quantity used to express how energy is transferred from a beam of radiation to a material such as the patient’s skin
• J/kg & Gy


  Air Kerma may be expressed in what units?
• Dose Area Product (DAP)


  Is the sum total of air kerma over the exposed area of the patient’s surface, or a measure of the amount of radiant energy that has been thrust into a portion of the patients body surface
• mGy-cm2


  What is the unit for DAP
• absorbed dose (D)


  This quantity is the amount of energy per unit mass absorbed by an irradiated object
• Gy


  unit of measure for absorbed dose
• equivalent dose (EqD)


  Is the product of the average absorbed dose in a tissue or organ in the human body and its associated WR chosen for the type and energy of the radiation in question.
• Sv


  unit of measure for EqD
• Effective Dose (EfD)


  Provides a measure of the overall risk of exposure to humans from ionizing radiation. Incorporates both the effect of the type of radiation used and the variability in radiosensitivity of the organ or body part irradiated through the use of appropriate weighting factors
• Radiation Weighting Factor (WR)


  Is a dimensionless factor (a multiplier) used for radiation protection purposes to account for differences in biologic impact among various types of ionizing radiation
• What must be used when determining EqD?

  Radiation Weighting Factor (WR)
• Tissue weighting Factor (WT)


  Takes into account the relative detriment to each specific organ and tissue. Accounts for the risk to the entire organism brought on by irradiation of individual tissues and organs
• Collective EfD


  Used in radiation protection to describe internal and external dose measurements. Quantity used to describe radiation exposure of a population or group from low doses of different sources of ionizing radiation
• Collective EfD radiation unit

  person-sievert
• total effective dose equivalent (TEDE)


  “the sum of effective dose equivalent from external radiation exposure and a quantity called committed effective dose equivalent (CEDE) from internal radiation exposures.” Designed to take into account all possible sources of radiation exposure.
• effective dose

  a quantity that is a measure of general harm in humans
• millisievert mSv

  unit if measure for effective dose