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38 Cards in this Set

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Name the types of Ionization Radiation
1. Particulate Radiation
Source: disintegration of the nucleous of radioactive atoms. Particles travel through space as alpha or beta particles

2. Electromagnetic Radiation
Source: gamma rays originates from disintegration of the nucleus of radioactive atom. X-rays originate from X-ray tube production. Gamma and X-ray travel through space at the speed of light and have no mass or charge.
The amount of exposure an individual receives depends on 4 factors:
1. type of radiation

2. amount of radiation received

3. length of time exposed

4. specific parts of the body
exposed.
Absorption
(absorbed dose)
the interaction between the x-ray photons and the living mtter resulting in energy transfer
Attenuation
>any process thatprevents X-ray photons from reaching the patient or the radiographic film.

> absorption & scatter (loss of intensity) of the x-ray beam as it passes through the patient.
Coherent (Classical/Thompsons)
(Type of Interactions)
1. Coherent(Classical/Thompsons)
-produced by low-energy
X-ray photons
-electrons not removed but
vibrate
-emit energy equal to the
incoming photon
-non-ionization
Photoelectric
(Type of Interactions)
-photon absorption interaction
-incoming X-ray photon strikes K-shell electron
-vacant hole in K-shell is filled by electrons from outer shells releasing energy w/c creates low-energy characteristic photons
-this type of interaction results in increased patient ration dose
Compton (Modified Scattering)
(Type of Interactions)
-scatter of X-ray photons in the atoms of the body

-incoming x-ray photon strikes a loosely bound, outer shell electron

X-ray photon transfers part of its energy to the electron

- electron is removed form orbit as a scattered electron

- ejected electrons may ionize other atoms or recombine with an ion needing an electron

- photon scatters in another direction w/less energy

-compton scatter radiation does not contribute to the diagnostic image rather it cases radiographic film fog & requires uf of lead shieling for protection o foperator and patient
Pair Production
Ionization does not occur but the photon has scattered

Does not occur in diagnostic radiography

Involves an interaction between the incoming photon and the nucleus of the atom
Cell
is the basic component of all living organisms.
Cell has 3 Basic Parts
1. membrane-permeable sustance to pass into and out of the cell

2. cytoplasm-watery substance inside the cell

3. nucleus-separated from the cytoplasm by a doubled wall membrane.
What is RNA and DNA
RNA=Ribonucleic Acid

DNA = Deoxyribonucleic
What are the 2 types of cell division
1. Mitosis - cell divides to form two cells.Occur in 5phase
interphase,prophase,metaphase,
anaphase & telophase

2. Meiosis-reduction division
Law of Bergonie & Tribondeau
1. Radiosensitivity varies inversely with the degree of cell differentiation - immature, nonspecialized cells are the most radiosensitive

2. Radiosensitivity varies direlty with the level of metabolic activity

3. Radiosensitivity varies directly with the rate of cell proliferation-rapidly growing or dividing cells are more radiosensitive.
Linear Energy Transfer (LET)
is the unit of measurement of the amount of the avearage energy deposited in tissue per unit of track or path length

This concept is important in determining potential biologic tissue damage from ionizing radiation.
Stochastic Effects
1. randomly occurring effects of radiation.

2. the probability of such effects is proportional to the dose (increased dose equals increased probability, not severity of effects.
Nonstochastic Effects
1. effects that become more server at high levels of radiation exposure

2. do not occur below a certain threshold dose
Linear-nonthreshold relationship
1. no level of radiation can be considered completely safe.

2. a response occurs at every dose

3. the degree of response to exposure is directly propotional to the amount of radiation received
Linear-threshold relationship
1. lower doses of radiation exposure (to the left of the line intersecting the x-axis), no response is expected

2. when threshold dose is exceeded the response is directly proportional to the dose recd.

3. Example, cataractogenesis does not occur at low levels of radiation exposure: therefore there is a threshold dose below w/c cataractogenesis will not occur
Nonlinear-threshold
1. indicates that at lower doses of radiation exposure (to the left of the curve intersecting the x-axis), no response is expected

2. when that threshold dose is exceeded the response is not directly proportional to the dose received and is increasingly effective per unit dose
Nonlinear-nonthreshold relationship
1. indicates that no level of radiation can be considered completely safe

2. a response occurs at every dose

3. the degree of the response is not directly proportional to the dose received

4. the effect is large even with a small increase in dose.
Direct Effect
photons hits DNA in the cellular nucleus
Indirect Effect
photons hits water molecules in the cytoplasm of a cell
Radiolysis
occurs when a water molecule is ionized resulting in free ions capable of recombining with other free radicals to form new molecules.
Biologic Effects
Short-term or long term effects
Short Term Effects
are found in the ARS (Acute Radiation Syndrome) w/c includes but is not limited to gonadal dysfunctions, epilation (hair loss), depression of the WBC and even death. (happens quickly)

Clinical signs/symptoms:
nausea, vomiting, diarrhea, anemia, leukopenia, hemorrhage, fever, infection, & shock
Long Term Effects or late effects
of radiation may result from small doses of radiation received over a number of years or latent period

Ex: local tissue effects, chromosomal changes, cataracts, life span shortening
Somatic Effects
refers to effects of radiation on the body being irradiated

appear w/in minuters, hrs, days or weeks after initial radiation exposure to the
ex. hematopoietic sysndrome, gastrointestinal sysndrome & CNS
Late somatic effects
those that appear after a period of months or years after initial exposure. May resuld from an intiail high dose of radiation taht caused early acute symptoms, and ultimately repair and recovery or chronic low level doses of radiation recd over long time period. ex: carcinogenesis
4 Major Areas to reduce radiation exposure for patient?
1. patient preparation
2. primary-beam limitation
3. gonadal shielding
4. technical factors
ALARA
As low as resoanably achievable
Occupational Personnel
1.Effective Absorbed dose equivalent limit
2. Lens of eye
3. all other organ, systems, tissue
Annual Dose Equivalent

1. 50 mSv (5 rem)
2. 150 mSv (15 rem)
3. 500 mSv (50 rem)
Non-Occupational(General public)

1. Continuous or frequent exposure
2. infrequent exposure
3. lens eye,skin,&extremities
Annul Dose Equivalent

1. 1 mSv (0.1 rem)
2. 5 mSv (0.5 rem)
3. 50 mSv (5 rem)
Education & training exposures

1. Effect absorbed dose equivalent limit

2. Lens eye, skin&extremities
Annual Dose Equivalent

1. 1 mSv (0.1 rem)
2. 50 mSv (5 rem)
Embryo-Fetus Exposures

1. Total dose equivalent limit to term

2. Dose equivalent limit in a month
Annual Dose Equivalent

1. 5 mSv (0.5 rem)
2. 0.5 mSv (.05 rem)
3 Cardinal Principle of Ratiation Protection
TDS

T=Time
D=Distance
S=Shielding
Protective Apparel
Lead apron - 0.5 mm lead
gloves .25 mm lead
Various cells - in order of diminishing sensitivity
1. Lymphocytes or WBC
2. Erythrocytes or RBC,granulocytes
3. Epithelial cells
4. Endothelial cells
5. Connective tissue cells
6. bone cells
7. muscle cells
8. nerve cells
9. brain cells
Most frequently occurring radiation-induces cancers include in descending order of susceptibility
1. female breast
2. thyroid gland (especially in women & young children)
3. hemopoetic tissue
4. lungs
5. gastrointestinal tract
6. bones