Chapter 15: MANAGEMENT OF IMAGING PERSONNEL DOSE DURING DIAGNOSTIC X-RAY PROCEDURES Flashcards
Exposure to the technologist is from what type(s) of radiation?
scatter and leakage radiation
The annual limit for occupationally exposed personnel set by the NCPR and enforced by the NRC is ______
50mSv
or
5 Rem
how is lifetime effective dose calculated?
lifetime effective dose =10mSv x age in years
nonoccupational effective dose limit
infrequent:
frequent:
frequent: 1mSv (0.1 rem = 100 millirem)
infrequent: 5mSv (0.5 rem = 500 millirem)
what is genetically significant dose?
the average gonadal EqD to members of the population of childbearing age
ALARA is also refered to as:
ORP optimization for radiation protection
what are some dose reduction methods and techniques?
limiting repeats
using appropriate technique
proper positioning
checking index numbers and making adjustments
knowing where to stand to limit scatter radiation dose
collimation
filtration (inherent/added/total)
protective apparel
restraint/ immobilization
What is used to limit the amount of photons available to scatter, and therefore reduces the technologist dose?
collimation / PBL
What is used to remove non useful, “soft rays” that are low energy and only contribute to patient dose?
filtration
What type of things are considered inherent filtration? how much inherent filtration is required?
tube housing, oil, 1st set of shutters
1.5mm Al Eq
how much added filtration is required for units capable of 70kvp + ?
1mm Al Eq
What are the 3 thicknesses of lead equivalent in lead aprons?
what are each used for?
.25mm, .5mm, 1mm
.25 is more for mammography and dx radiology
.5mm is the minimum to be used for fluoroscopy
1mm is heavy and more often used in interventional radiology/ cath lab
How is pregnancy handled within the radiology field?
should be able to continue working with proper radiation protection
if a VOLUNTARY declaration is made- it is recognized by the apartment- there is acknowledgement of counseling w RSO where a form is signed- additional radiation dosimeter is worn at waist inside of lead apron.
What is the monthly EqD for the pregnant radiation worker?
EqD for full gestation?
monthly: 0.5mSv (50 millirem)
gestation: 5 millisieverts (500millirem)
what type of protective maternity apparel is worn in radiology?
specially designed maternity lead apron (0.5mm) and a width with panel of 1mm lead equivalent for embryo-fetus/ wraparound .5mm lead can be worn
basic principles of radiation protection:
TIME
DISTANCE
SHIELDING
prevents direct (unscattered) radiation from hitting personnel//
barriers are perpendicular to undeflected line of photon travel
primary protective barrier
120 kVp units require ______ mm(inches) of lead extending ______ meters (inches) up when tube is ______ meters(feet) from the wall.
overlap with secondary barrier is _______ cm (inches).
1.6mm (1/16”)
2.1 meters (7 ft)
1.5-2.1 meters (5-7ft)
1.27cm (1/2”)
secondary protective barriers are used for _____ and ______ radiation and must be _____ mm (inches) of lead thickness
scatter and leakage
.8 mm (1/32 inches)
doors must be closed and contain _______ mm lead.
.8mm (1/32”)
The control booth barrier must extend ______ meters (ft) and be permanently secured to the floor
2.1 meters (7 feet)
The control booth is considered a _________ barrier.
secondary
thickness of lead equivalent within the window of the control booth must be _______ mm (inch)
1.5mm (1/6 inch)
exposure of the radiographer is not to exceed ______ mSv per week- and ideally should be _____ mSv per week.
1mSv
0.02mSv
clear lead-acrylic secondary protective barriers are used for ___________ and ___________ studies.
____% lead by weight
_____ to _____ mm lead equivalency and ______ meters fro the floor.
overhead barrier : _____ mm lead equivalency.
cardiac and interventional studies
30%
0.3- 2mm
2.1 meters
0.5mm
lead thickness for aprons and gloves
0.25 mm or 0.5mm
lead thickness for neck and thyroid shields
minimum of 0.5mm lead equivalent
lead thickness for protective eyeglasses
0.35 mm lead equivalent
during fluoroscopy, the safest place to be is
by the image intensifier – exit side)
routine fluoroscopy exposure rate maximum is ___________
0.88 cGy/ min (10R /min)
HLC can be _____ - _______ cGy/min.
20-40
extremity monitoring should be monitored for __________studies of physicians and assistants.
EqD limit to skin and hands is ______ mSv ( rem)
500mSv (50rem)
radiation shielding categories:
primary radiation & secondary radiation
emerges directly from x-ray tube and moves without deflection toward wall, door, or window
* require primary barriers
primary radiation
aka “direct radiation”
Compton interaction produces scatter in all directions
*require secondary barriers
Scatter radiation
penetrates from the housing, possibly sides of collimator/ is considered with secondary barriers
leakage radiation
calculation considerations for minimum thickness include:
workload(W)
inverse square law
use factor (U)
Occupancy factor(T)
controlled and uncontrolled areas
