Radiation Protection Flashcards
every living organism is exposed to constant low dose radiation. what is this radiation?
background radiation
natural radiation exposure arises from external (_______) and internal (_____) sources
external = cosmic, natural terrestrial radionuclides
internal = ingested or inhaled radionuclides
amount of radiation per year
background =
medical =
consumer =
background = 3.0 mSv medical = 3.1 mSv consumer = 0.1 mSv
quantity of radiation or energy absorbed
Gray (Gy) and rad (radiation absorbed dose)
dose equivalent to Gy
Sievert (Sv) and rem (rad equivalent mammal)
1 Sv = ___ rem
100 rem
most US cities experience ____ mSv
3.0-4.0 mSv
mSv for CT scan
1.5 mSv
mSv for dental diagnosis
0.1 mSv
mSv for consumer products
0.10 mSv
background radiation sources radon = terrestrial = internal = space =
radon = 73% terrestrial = 7% internal = 9% space = 11%
man-made radiation exposure
- CT =
- nuclear medicine =
- interventional radiography =
- conventional radiography =
- consumer product =
- dental =
- CT = 46%
- nuclear medicine = 25%
- interventional radiography = 14%
- conventional radiography = 10%
- consumer product = 4%
- dental = 1%
3 guiding principles
- justification (benefits > risks)
- optimization (reduce exposure)
- dose limitation (limit dose so no one is exposed to high radiation dose
Radiation protection in Dentistry
year? Issue No.?
2003, No. 145,
need for new NCRP guideline after the 2003 edition
- No formal guidelines on safe/effective use
- CBCT, digital radiographs, hand-held x-ray units in wide use
- CBCT often viewed as an “improved” PAN
new Radiation Protection in Dentistry & OM year
2019
primary focus of 2019 guideline
- CBCT
- digital radiography
- hand-held x-ray machine
BWX rectangular collimation effective dose (mSv)
5
FMX round collimation, D speed effective dose
388 mSv
FMX rectangular collimation F speed effective dose (mSv)
35
PAN effective dose (mSv)
9-24
FMX rectangular collimation CCD (digital) effective dose (mSv)
17
chest CT effective dose (mSv)
5800
means of reducing dental exposure
- fastest film, digital sensor
- 60 to 70 kVp
- lone cone
- rectangular collimation
- stand at least 6 feet away form x-ray machine
when you are taking radiographs, stand at least _____ away from source
6 feet
people who are exposed to radiation (3 main groups)
- occupationally exposed
- non-occupationally exposed
- patients
occupational exposure can be reasonably regard as being the _____
responsibility of management
occupationally exposure excludes ____
medically/dental exposure
in occupational exposure, individual monitoring (is/is not) needed to classify occupationally exposed individuals
is not needed
individual monitoring dose per year for occupational exposure
1 mSv/year
annual average dose to US dental workers radiation exposure
0.2 mSv
__-% of dental workers receive measurable dose (____mSv)
32%, 0.7mSv
non-occupationally exposed members are/are not receiving radiation as a patient
are not receiving radiation
example of non-occupationally exposed
dental receptionist, members of adjacent office, families in waiting room
is there a dose limit for non-occupationally exposed? for patients?
yes for non-occupationally exposed; no for patients
ALARA
as low as reasonably achievable
if we reduce dose to patient, we reduce dose to ____________ individuals
non-occupationally and occupationally exposed
collimation requirements
circular =
rectangular =
circular = 2.76" rectangular = 2.0"
rectangular collimation of x-ray beam ___ be used for PA and BWX radiographs and ____ be used for occlusal
shall, should
receptor-holding devices ____ be used whenever possible
shall
______ should be used to minimize any unnecessary radiation
leaded aprons and collars
MN regulation of lead aprons: use of lead apron if radiation exposure is within __ inches of ____
two, gonads
thyroid shielding ___ be provided for patients when it will not interfere with examination
shall
protective aprons and thyroid shields ____ be evaluated for damage quarterly
should
patient should not _____
hold films by fingers
film holding device considerations (no law requirements)
ease of use, stability, cost/maintenance
increasing kVp from 70 to 90 reduces dose by ___
23%
operating potentials of intraoral dental x-ray units _____ be less than 60kVp and _____ be >80kVp
shall not, should not
a barrier of radiation-absorbing material used to reduce radiation exposure to _____ or ____ beam of radiation
primary, usable
in the absence of a barrier, the operator ___ remain at least ___ but preferably ____. If distance cannot be maintained, then a barrier ___ be provided
shall, 2m, 3m, shall
occupancy factor for administrative office/lab/pharmacy/waiting area/children’s play area
T = 1
occupancy factor for patient exam room, treatment room
T = 1/2
occupancy factor for inside corridors/employee lounges/staff toilets
T = 1/5
occupancy factor for public toilets, unattended vending areas, storage rooms, patient holding area
T = 1/20
occupancy factor for unattended parking lots, attics, stairways, unattended elevators, janitor closet
T = 1/40
lower kVp _____ radiographic contrast
increases
there is a ____ diagnostic benefit from high contrast film
limited
3 sources of radiation
primary, scattered, leakage
if operator is within the room (and has no barrier) then he/she should stand _____ to central ray and _________
90-135 degrees; 45 degrees from the exit beam
if you are taking Mx PA, exit beam will be…
out of the back of the patient’s head
did you look at position slide on Radiation Protection handout?
I hope! We are most likely going to be tested on this!
conventional building materials _____ be sufficient for dental installations
may be (could not be)
workload equation
mA x minutes/week
areas where employees have significant potential for exposure to radiation in the course of their assignments OR where employees are directly responsible for radiation
controlled area
degree of occupancy of the area in question while the source is in the “ON” condition and emits radiation
occupancy factor
