final exam Flashcards
define collective dose
the risk for the population as a whole
who discovered mutagenesis
Herman mueller
what is mutagenesis
that ionizing radiation produces mutations
what animal was used in the discovery of mutagenesis
fruit flies
what is the measure of the ionization of air
air kerma
what is the energy that is absorbed in matter
gray
what is the unit for occupational exposure / dose equivalent
sievert
what is the most commonly used unit for occupational workers
mSv
Radiographers: whole body dose
50mSv / 5 rem yearly
radiographers: lens of eye dose
150mSv / yr
radiographers: whole body skin dose
500 mSv / 50 rem / year
radiographers: extremities dose
500 mSv/ 50 rem / yr / each extremity
dose for embryo / fetus / pregnancy
.5 mSv / .05 rem / month
annual dose for radiographers
50 mSv
what is the main source of radiation to the US population
radon
what does the NCRP do
collects, analyze, develop and disseminate radiation protection measurements, quantities and units
where does the NCRP get their information from
BEIR and NSC
when is occupational radiation monitoring required
when the person has a chance to receive more than 1/10th of the recommended dose limit
what are the two main groups for radiation protection
- radiation workers (occupationally exposed & occasionally exposed)
- general public
what is the dose limit doe general public
1/10th of rad workers (5mSv / .5 rem)
six ways to ensure the patient is protected as much as possible
- avoid errors by verifying requisition and verify pt ID
- avoid repeats
- maintain minimum 40 sid
- shield
- collimate
- use highest kvp and lowest mas possible
what does a geiger mueller do
detects the presence of alpha and beta radiation
what does a cutie pie do
measures the exposure rate for xray gamma alpha and beta
what do occupational radiation monitors detect
quantity of radiation
what are the three types of occupational radiation monitors
OSL: optically stimulated luminescence dosimeters
TLD: thermoluminescent dosimeters
film badge
what 5 things does a dosimetry report have
- participant ID
- type of dosimeter
- radiation quality
- exposure in mrem
- location on the body of exposure
what is a dosimetry report
documents the personnel’s radiation dose equivalent for a specific month
what is an individual assigned to develop and implement the radiation safety program
RSO
what is primary radiation
the useful beam, it is image forming
what is secondary radiation
leakage and scatter
leakage: from tube housing
scatter: spreads isotropically from the beam after interaction with matter
every xray tube housing must have protective housing enclosed by ____ Pb
1/16th inch
leakage radiation must be less than ____ mGy/hr at a distance of ___ from the housing
100 mGy
1 m / 3ft
how long is the exposure switch
6ft
what is the controlled or control area
the area occupied by radiology personnel. occupancy of 1
what is an uncontrolled area
area occupied by the public
thickness for glass window
1.5mm pb equiv.
where is the primary barrier wall
perpendicular to beam travel
what is the height and lead thickness for primary wall
7ft tall, 1/16th in pb
what is the secondary barrier wall
wall parallel to beam travel and control booth
what is the pb thickness for secondary wall
1/32pb
how many times do xrays scatter before reaching control booth
2x
The secondary wall is exposed to what types of radiation
scatter and leakage
what are the three factors that determine barrier thickness
time of occupancy
workload
use
what does an aluminum filter do
absorb low energy photons
improve beam quality
decreases pt absorbed dose
what is the determining factor for the total filtration required
kvp
what is the minimum filtration for operating above 70 kvp
2.5 mm al eq
what is HVL
the thickness of material that will reduce the xray intensity to half its original value
HVL measures beam _____
quality
what are some beam limiting devices
aperture diaphragm
cones
collimators
what utilizes a direct capture system, with a solid state detector plate
digital radiography
what is placed between the patient and IR to absorb scatter
grids
lowest grid radio = (lower/higher) pt dose
lower
the principal factors that affect the amount of scatter produced are
kilovoltage and the irradiated material
as volume of the irradiated tissue increases, scatter …
increases
volume ___ as field size increases
increases
volume increases as patient size ____
increases
larger field size means more or less chance of scatter
more
large body parts mean more or less scatter
more
long scale contrast is more (b&w/gray)
gray
long scale high or low kvp
high
