Radiation 2 Flashcards
define radiation dose
when ionizing radiation penetrates the human body or an object, it deposits energy
Define dose
the energy absorbed from exposure to radiation
what are the three ways radiation dose quantities are described?
Absorbed dose
Equivalent dose
Effective dose
What is the tradition and SI units of radiation quantity exposure?
traditional= R SI = Coulombs per kilogram (C/Kg)
What is the tradition and SI units of radiation quantity absorbed dose?
traditional = Rad SI = Gray (Gy)
What is the traditional and SI unit of the radiation quantity equivalent dose?
traditional = Rem SI = Sievert (Sv)
What is the traditional and SI units of the radiation quantity effective dose?
Traditional = Rem SI = Sievert (Sv)
define exposure
is a radiation quantity that expresses the concentration of radiation delivered to a specific area, such as the surface of the human body
define air kerma
a quantity used to express how energy is transferred from a beam of radiation to a material, such as the patients skin
Used to describe x-ray tube outputs and inputs to image receptors
What are the units for air kerma?
metric units if joule per kilogram (j/kg) or may be stated in Gy
define dose area product (DAP)?
is the sum total of air kerma over the exposed area of the patients surface
What are the units for Dose area product?
mGy-cm2
define absorbed dose and what is it measured in?
the amount of energy per unit mass absorbed by an irradiated object
measured in gray (Gy)
Define equivalent dose
the product of the average absorbed dose in a tissue or organ in the human body and its associated radiation weighting factor
what does equivalent dose take into account?
the potential variation in biological harm that is produced by different kinds of radiation
What are the units of equivalent dose?
Sieverts (Sv)
define effective dose
provides a measure of the overall risk of exposure to ionizing radiation
what does effective does take account in?
for the risk of the entire organism brought on by irradiation of individual tissues and organs
What are the units for effective dose?
Sieverts (sV)
What must be used when determining equivalent dose (EqD)?
Wr
What must be used in determining EfD (effective dose)?
tissue weighting factor (Wt)
what is the difference between equivalent dose and effective dose?
- equicalent uses Wr and effective uses Wt
- equivalent is absorbed dose and effective is equivalent dose
- equivalent is different capacities for producing biologic harm by various types of energies of ionizing radiation. Effective is both the type of radiation and the part of the body
Define collective effective dose (ColEfD) and what is it expressed in?
Represents an attempt to describe the radiation exposure of a population or group from low doses of different sources of ionizing radiation
expressed in person-sievert
What is the total effective dose equivalent (TEDE)?
is designed to take into account all possible sources of radiation exposure and is used for dose monitoring for occupationally exposed personnel who are likely to receive possibly significant radiation exposure during the course of the year
What are the three ways of specifying the amount of radiation received by a patient?
- Entrance skin exposure (ESE)
- Gonadal dose (GSD)
- Bone marrow dose
where is the maximum exposure received by in a patient?
NOT at the area of interest but at the skin surface
Why is Gonadal Dose of particular concern in DI?
because genetic effects may result from exposure to ionizing radiation
What is genetically significant dose (GSD)?
is used to assess the impact of gonadal dose. It represents an estimate of the genetic significance of gonad radiation doses
define bone marrow dose
the average radiation dose to the entire active bone marrow. It is measured as an estimate from ESE.
(Can also be referred to as mean marrow dose (MMD)
define personnel monitoring
is the monitoring of equivalent dose to any person occupationally exposed on a regular basis to ionizing radiation.
It ensures that occupational radiation exposure levels are kept well below annual effective dose (EfD) limits.
Where should the dosimeter be worn?
under the apron, more can be worn at extremities are needed
where should the dosimeter be placed for a pregnant women?
- primary dosimeter worn at collar level
- Second monitoring device is worn at abdominal level
what type of detector is in the optically stimulated luminescent (OSL)?
aluminum oxide
What is the most common dosimeter?
OSL
Which dosimeter is read out by a laser light at selected frequencies?
OSL
What does the chemiluminescent dosimeter (TLD) contain?
crystal form of lithium fluoride
What does thermoluminescent mean?
emitting light when heated
What does Thermoluminescent dosimeters contain?
crystal form of lithium fluroide
Which is the most sensitive dosimeter?
pocket ionization chamber
What are the two types of pocket ionization chamber?
self-reading, non-self reading
Which dosimeter resembles a flashdrive?
personnel digital ionization dosimeter
What are the three gas-filled radiation detectors?
- ionization chamber type meter
- proportional counter
- GM survey meter
What is a electrometer?
a device that measures electrical charge
What are the 6 things on personnel monitoring reports?
- personnal data
- Type of dosimeter
- Radiation quality
- Equivalent dose data
- Cumulative dose data
- Inception date
the damage that occurs varies based on a number of different factors including:
- type of cells
- Energy and type of radiation
- Metabolic rate/ prescense of oxygen
- Amount of radiation (dose/dose rate)
- Age and sex of patient
- Area/amount of tissue exposed
Define Linear Energy Transfer
the average energy deposited per unit length along its pathway or track
True or false: the higher the value of LET, the greater the chance of producing significant biological damage
True
Are x-rays low-LET or high-LET?
low-LET
What are the low-LET examples?
x-rays, gamma rays
What are the high-LET examples?
alpha articles, ions of heavy nuclei, neutrons
define relative biological effectiveness (RBE)
describes the relative capabilities of radiation with differing LETs to produce a particular biologic reaction
what tissue is more sensitive to low-LET?
oxygenated tissue
define cell survival curve
a method of displaying the sensitivity of a particular type of radiation
In the Law of Bergonie and Tribondeau, what is radiosensitivity
defined as the relative suscptibility of cells, tissues, organs, organisms or other substances to damage from radiation
What is the most radiosensitive cell?
blood cells
In biological effects of radaition, what are two basic types of cell structures?
genetic cells: found in reproductive tissue
Somatic cells: all non-reproductive cells in the body
Define gentic effects
- Biological effects on future generations
- Result of damage to the DNA molecule in sperm or ova
define somatic effects
when living organisms such as humans experience biologic damage from exposure to radiation, the results of this exposure
When are early somatic effects?
minutes, hours, days or weeks of the exposure
when are late somatic effects
appear months or years after exposure
define stochastic
(probabilistic) the probability that the effect happens increases as dose increases, but the severity does not.
- Non threshold
What are examples of stochastic?
- cancer
- embryologic effects (birth defects)
Define Non- Stochastic
(deterministic) - both the probability and the severity of the effect depend on dose.
- Threshold
What are the examples of non-stochastic?
cataracts
define advanced radiation syndrome (ARS)
-occurs in humans after whole-body reception of large doses of ionizing radiation delivered over a short period of time
What are the three separate dose-related syndromes occur as part of the total-body sydrome?
- Hematopoietic
- Gastrointestinal
- Cerebrovascular
What are the 4 major response stages in ARS?
- Prodromal
- Latent period
- Manifest illness
- Recovery or death
What is hematopoietic syndrome?
causes a decrease in the number of rbc, wbc, and platelets in the circulating blood.
What is the threshold and peak of gastrointestinal?
threshold- 6 Gy
Peak - 10 Gy
What is the most affected part of gastrointestinal syndrome?
small bowel
What are the 3 stages gastrointestinal syndrome?
- prodromal
- Latent
- Manifest illness
What is the threshold of cerebrovascular synrome?
50 Gy or more
When is death in cerebrovascular syndrome
few hours to 2-3 days
What are the 4 major response stages of ARS?
- prodromal or begining
- Latent period
- Manifest illness
- Recovery or Death
What does 50/30 mean?
50% of the exposed population within 30 days
What is the estimated lethal dose for humans?
30-40 Gy
What are the three major types of late effects? and what are they considered?
- carcinogenesis
- Embrylogic effects (birth defects)
- Cataractogenesis
stochastic effects
define epidemiology
a science that deals with the incidence, distribution and control of disease in a population
What is dose-response curves?
maps the effects of radiation exposure in relation to the dose of radiation recieved
define threshold and non threshold
Threshold: if below a certain radiation dose, no biological effects are observed
Non-threshold: if at any radiation dose a viologic effect will occur
What is the most important late stochastic effect caused by radiation exposure?
Cancer.
It is linear and non-threshold curve
What are examples of Linear non-threshold
Most types of cancer (exception of breast cancer and luekemia)
What are the examples of linear quadratic?
Breast cancer, leukemia
What are the examples for linear threshold?
skin erythema, hematological depression
What are the examples of non-linear thresholf?
cataracts
Are tissues threshold or non-threshold? Stochastic?
tissue-threshold
Stochastic-non-threshold
What are the stages of gestation in humans?
- Preimplantation
- Organogensis
- Fetal stage
What are the effects of radation in 2nd and 3rd trimester?
- congential abnormalities
- Functional disorders
- Leukemia
