Saia Unit 3 Flashcards
the 3 cardinal rules for xray:
time, distance, shielding
inverse square law:
I1/I2=D2^2/D1^2
primary protective barrier:
direct impact, 1/16” lead or equivelent; 7 feet high
secondary protective barrier:
scatter/leakage, 1/32” lead equivelent
xray must scatterat least:
2 times before hitting the control booth
protective tube housing enclosed by lead lined metal covering:
1/16 lead, reduces leakage
leakage from the tube housing should exceed:
100mR/hr at 1 meter
time of occupancy factor:
amount of time an area is ossupied and by whom
workload:
radiation activity level (max kvp and max mas)
Use:
the amount of time xray is “on” during the day
Lead underwear keep radiation and are used for:
brachytherapy of the prostate
mobile unit switch
should allow tech to obtain at least a distance of 6’ from patient
fluoroscopy drapes and bucky slot cover should have a minimum:
.25mm pb/eq
fluoroscopy deadman switch:
only emits radiation when constant pressure is applied
c-arm source to tabletop must not be less than:
12”
source to tabletop for fixed fluoro unit must not be less than:
15”
Total filtration of fluoroscopy equipment must be at least:
2.5mm al/eq
cumulitive timing device in fluoro creates an audible sound after:
5 minutes
lead used in fluoroscopy must be at least:
.5mm pb/eq
Fluoroscopy xray intensity at tabletop must not exceed:
10R/min
Fluoroscopy uses a high KV and low MA to
minimize dose
Fluoroscopy MA must not exceed:
5MA
Air exposure is measured in:
Traditional - Roentgen (R) ; SI - Air Kerma - grays in air (gyA)
Absorbed dose is measured in:
Traditional - RAD; SI - grays in tissue (gyT)
1 Gray is equal to:
100 Rads
Dose equivelent (tissue damage due to dose) is measured in:
Traditional - REM; SI - Seivert
RAD X QF =
REM
Activity is measured in:
Traditional - Curie; SI - Bacquerel
Roentgen (T) =
Air Kerma (SI)
RAD (T) =
Gray (SI)
REM (T) =
Sievert (SI)
Curie (T) =
Bacquerel (SI)
Quality Factor for Xray. Gamma, Beta =
1
Quality Factot for Alpha:
20
An Optically Stimulated Luminescence (OSL) Badge:
Uses Aluminum Oxide and is accurate to 1 mREM (like our badge)
A film badge uses:
Real film (old school)
A Thermoluminescent Dosimeter (TLD) badge uses:
lithium fluoroide - used in nuclear medicine
A pocket dosimeter uses:
ionization chamber, has an immediate readout, but not highly accurate
EMR - Elecrtromagnetic Energy:
Bundles of pure energy, no mass, no charge, moves at speed of light, waveform movement
Photon:
smallest quantity of any type of EMR;
AKA quanta or ray
ionizing radiation:
energy with the ability to disrupt atomic structure thereby creating ions
Energy Based:
low LET; XRAY/Gamma; bundles of pure energy; no mass/charge; travel at speed of light; waveform movement
Matter Based:
high LET; Alpha, Beta, Photon, Neutron; have matter/mass/charge; travel slower than the speed of light; straight line movement
Primary radiation:
radiation produced in xray tube, AKA useful beam
secondary radiation:
a brand new xray produced in the patient
Scatter:
re-directed primary radiation due to interraction with matter
remnant radiation:
portion of the primary beam that survives the trip through the patient
leakage radiation:
X-ray that escapes the tube housing at a point other than the tube window
off focus radiation:
X-ray produced at points of the anode other than the true/actual focal spot
Annual dose limit (Occupational) for whole body:
5 rem (50 mSv)
Annual dose limit (Occupational) for lens of eye:
15 rem (150 mSv)
Annual dose limit (Occupational) for skin/extremities:
50 rem (500 mSv)
Annual dose limit (Occupational) for whole body cumulitive:
Age x 1 rem (age x 10 mSv)
Annual dose limit (Occupational) for fetus (9 month):
0.5 rem (5 mSv)
Annual dose limit (Occupational) for fetus (1 month):
.05 rem (0.5 mSv)
Annual dose limit (Occupational) for Student less than 18 years old:
0.1 rem (1 mSv)
Annual dose limit (PUBLIC Exposure) for Infrequent Exposure:
0.5 rem (5 mSv)