Radiation Quantities and Units Flashcards
Radiation Quantities and Units
Exposure (X)
Kerma
Absorbed Dose (D)
Equivalent Dose (EqD)
Effective Dose (EfD)
Measurement Units in CT
- Computed Tomography Dose Index (CTDI)
- Multiple Scan Average Dose (MSAD)
- Dose Length Product (DLP)
Quantity of XRs or gamma rays required to produce a given amount of ionization (charge) in a unit mass of air
Exposure (X)
Exposure (X) is not applicable to photons of energy (1) or specifically, (2)
- above 3MeV
- particulate radn
Dry, non-humid at a standard temp and pressure
Air
Air temp, pressure, and device
750mmHg or 1atm @ sea level, 22deg Celsius, standard or free air ionization chamber
Kerma Meaning
Kinetic Energy released in matter
Energy absorbed per unit mass from the initial kinetic energy released ub natter if akk electrons liberated by XRs or gamma rays
Kerma
Incorporated in modern radiographic and fluoroscopy units
Dose Area Product (DAP)
Used to determine the entire amount of energy delivered to the pt by the XR beam
DAP
Measure of the amount of radiant energy that has been thrust into a portion of pt’s body surface
DAP
DAP Units
mgy-cm^2
Amounf of energy per unit mass absorbed by an irradiated object
Absorbed Dose (D)
Amounf od ionizing radn a pt receives during a diagnostic procedure
D
Total amount of radiant energy transferred by ionizing radn to the body during exposure
Surface Intergral Dose (SID)
Surface Intergral Dose (SID) other term
Exposure Area Product
Product of the average dose in a tissue or organ in the human body and its associated radn weighting factor chosen for the type and energy of the radn in question
Equivalent Dose (EqD)
Used for radn protection purposes when a person receives exposure from various types of ionizing radiation
Equivalent Dose (EqD)
Equivalent Dose (EqD)
Equal absorbed doses of diff types of radn produce diff amounts of — in body tissues
biological damage
Measure of the overall risk of exposure to humans from ionizing
Effective dose (EfD)
Incorporated both the effect o the type of Radiation used and the variability in radiosensitivity of the specific organ of body part irradiated
Effective dose (EfD)
1C = — e- charge
6.24x10^(18)
Radiation exposure of a population or group from low doses of diff sources of ionizing radiation
Collective Effective Dose (ColEfD)
Product of the average EfD for an individual belonging to the exposed population or group and the number of persons exposed
Collective Effective Dose (ColEfD)
TEDE vs CEDE
TEDE (Total Effective Dose Equivalent): Sum of effective dose equivalent from external radiation exposures
CEDE (Committed Effective Dose Equivalent): Sum of effective dose equivalent from internal radiation exposures
Whole-body TEDE limit
Ocupationnally exposed: 0.05sv
General public: 0.001sv
Who/ What is referred to by:
1. Ocupationnally exposed
2. General public
3. Internal radiation exposures
- Received by NucMed Techs and IV Technologists/ Radiologists
- Patient/s
- Intake of radioactive material
Dose in CXR
0.02msv
Radiation dose in a single slice over a 10cm length
Computed Tomigraphy Dose Index (CTDI)
Measures the radn dose in the primary beam that was delivered to the pt
Computed Tomigraphy Dose Index (CTDI)
To measure radiation dose to the pt as measured within primary beam of CT scanner
Computed Tomigraphy Dose Index (CTDI)
Average dose a pt receives during an exam, which would include numerous individual scans (or in the case of a helical scanner, a moving scan)
Multiple Scan Average Dose (MSAD)
Product of CTDI and slice thickness
Dose Length Product (DLP)
Depends only on selected CT parameters and does not reflect pt dose
Dose Length Product (DLP)
Rate of decay or disintegration of radioactive material
Radioactivity
1 Ci = — Bq
3.7x10^(10)
