Radiation Protection Flashcards
QA
human factor
repeat analysis
patient satisfaction
QC
equipment operation
genetically significant dose
EqD of population of childbearing age
Annual effective dose for whole body as a radiation worker
50 mSv or 5 rem (5000 mrem)
cumulative effective does of lifetime for radiation worker
Age x 10 mSv or 1 rem (1000 mrem)
primary protective barrier
1.6mm (1/16 in) lead
is lead shielding/glasses/etc considered primary or secondary protection?
secondary
How do you protect yourself during fluoro, portables, OR?
distance from patient (6 feet)
wear lead
stand at right angle from pt
Inadvertent radiation during early pregnancy - what dose is unlikely to affect embryo?
20 rad/0.2 Gy
studies say less than 1 rad/0.01 Gy
What is the leakage radiation limit
100 mR/hr at 1 meter (3.3 ft) from the tube when tube is operated at highest kvp and mas
how is tube housing benefit radiation protection
protects from off focus and leakage radiation
lead lined
What is the air kerma rate?
0.88 mGy/hr
How is the control panel helpful in radiation protection?
indicates when tube is energized by visual and audible tone
kvp and mas is visible on panel
located behind protection radiation absorbent barrier
How is the exam table helpful in rad protection?
radiolucent material that absorbs minimal amount of radiation - reduces patient exposure
thickness is uniform - image quality
How accurate does the SID indicator need to be?
Within 2% of SID in RAD room
What is skin sparing?
keeping a safe distance between pt skin and the source of the primary beam
What is the purpose of the spacer bars on the xray tube?
keeps tube from getting too close to the patient
What is the minimum safe distance skin should be from the collimator box?
6 inches or 15cm
What is PBL?
automatic collimation
collimation does not exceed the size of the IR
What is the purpose of filtration?
hardens the beam
increases quality
Inherent/intrinsic filtration is…
approx 1.5mm of AL filtration equivalent before leaving the collimator
Added filtration is…
outside the glass housing above the first set of collimators
Total Filtration = ___ + ____
inherent filtration
added filtration
Total filtration is how thick?
2.5mm of AL equivalent for rooms using 70+ kvp
3-4 mm of AI or AL for fluoro rooms (higher kvp)
What is HVL?
Half Value Layer
thickness of absorber that decreases primary beam intensity by 50%
A higher the HVL, the ____ (higher/lower) the average kev of the beam
higher
Define exposure reproducibility.
ability for xray unit to duplicate radiographic exposures for any given combo of kvp, ma, and time
How do you test exposure reproducibility?
use the same techniques to make multiple exposures
variance of 5% or less
Define exposure linearity.
measures how the radiation output in mR/mSv changes when mA and time combos change (but mAs stays the same)
What is the range that radiation output can vary while keeping true exposure linearity?
+/- 10%
What is the source to skin (SSD) distance for mobile radiography?
need at least 12 inches/30 cm from source (anode)
