Radiation Protection Ch 13 Part 1 and 2 Flashcards
designed to limit exposure to reasonable levels of risk comparable with risk from other common sources
dose limit
expresses the relationship between distance and intensity (quantity) of radiation and governs the dose received
inverse square law
prevents direct or unscattered radiation from reaching from reaching personnel or members of the general public on the other side of the barrier
primary protective barrier
typical installation of primary protective barrier
consist if 1/16” (1.6mm)lead that extends 7ft (2.1m) upward from the floor of the x-ray room when the x-ray tube is 5-7ft from wall in question
where are primary protective barrier located
undeflected line of travel of the x-ray beam
consist of radiation that has been deflected from the primary. Leakage from the tube housing and scatter make it up.
secondary radiation
protects against secondary radiation (leakage and scatter))
secondary protective border
classification of the secondary protective barrier
any wall or barrier that is never struck by the primary beam is classified as a secondary protective border
typical installation of the secondary protective barrier
should overlap the primary protective barrier by 1/2” and consist of 1/32” lead
secondary protective barrier: must extend 7ft upward from the floor and permanently secured to it. X-ray should scatter a minimum of 2 times before reaching any area behind it.
control booth barrier
what is the annual occupational dose?
EfD=50mSv or 5 rem whole body
what the lifetime effective dose recommendations is
should not exceed 10xs the occupationally exposed persons age in years
what is the annual effective dose limit allowed for nonoccupationally exposed individuals frequent exposure?
1 mSv (0.1 rem)
what is the annual effective dose limit allowed for nonoccupationally exposed individuals for infrequent exposure?
5 mSV (0.5 rem)
know the 9 dose-reduction methods and techniques
- Avoiding repeat examinations
- the pt is a source of scattered radiation
- scattered radiation occupational hazard
- filtration of the x-ray beam
- protective apparel
- technical exposure factors
- use of high speed image receptor systems
- retakes in digital imaging
- correct processing of radiographic images
know the process that make the patient become a source of scatter radiation
Compton interaction process
at what angle and distance should a technologist stand, because the intensity of the scatter is approximately 1/1000 of the primary beam?
90 degree angle at a distance of 1m (3.3 ft)
what poses the greatest occupational hazard in radiology
scatter radiation
what s the first step in a pregnancy policy that makes the facility recognize the pregnancy
voluntary declaration of pregnancy
know what the pregnant worker does after receiving radiation safety counseling
must read and sign a form acknowledging they received the counseling and understands the ways to implement appropriate measure to ensure the safety
know what maternity protective apparel must consist of
maternity aprons consist of 0.5 mm lead over their entire length and width and have an extra 1mm lead equivalent protective panel that runs transversely across the width of the apron for added protection
if regular wraparounds are worn by a pregnant worker how much lead equivalency must be in them
0.5 mm lead equivalent
know the 3 basic principles of radiation protection
time, shielding, distance
know what the amount of radiation received is directly proportional to
length of time for which the individual is exposed to radiation
under the cardinal principle of time, when is the only time a radiographer should be present in a fluoroscopic exam
only when needed to perform relevant patient care and to fulfill respective duties associated with the procedure
what is the most effective means of protection from ionizing radiation
distance
be able to state the inverse square law
“the intensity of radiation is inversely proportional to the square of the distance from the source.”
know when the principle of shielding should be used
when it is NOT possible to use the cardinal principles of time and/or distance to minimize occupational radiation exposure
what are the most common materials used for structural protective barriers
lead and concrete
know what accessory protective devices are made of
lead impregnated vinyl
know what makes up secondary radiation
leakage from the tube housing and scatter
know how many times a typical x-ray will scatter before reaching any area behind a control booth barrier
minimum of 2 times
know the lead equivalent that a lead glass window must have
1.5 mm lead equivalent
know how the exposure cord plays a role in protecting the radiographer
it must be short enough so that the exposure switch can be operated from only behind the control booth barrier
know how modular x-ray barriers are made
must be shatter resistant, can extend 7ft (2.1 m) upward from the floor and is available in lead equivalency from 0.3 to 2mm
know what clear lead plastic protective barriers lead equivalent is typically
0.5 mm
radiation that emerges directly from x-ray tube collimator and moves without deflection
primary radiation
whenever a diagnostic x-ray beam passes through matter
scattered radiation
radiation generated in x-ray tube that does not exit from the collimator opening but rather penetrates through the protective tube housing and sides of collimator
leakage radiation
the quantity that best describes the weekly radiation use of a diagnostic x-ray unit
-radiation output weighted time that the unit is actually delivering radiation during the week
workload
used to modify the shielding requirement for a particular barrier by taking into account the fraction of the work week during which the space beyond the barrier is occupied
occupancy factor
a region adjacent to a wall of any x-ray room and is used only be occupationally exposed personnel
control area
a nearby hall or corridor that is frequented by the general public
uncontrolled area
in protective shielding devices what material other than aluminum and lead can be used
tin
when should protective lead aprons and leaded gloves be used
when radiographer cannot remain behind a protective lead barrier during an exposure and lead gloves when the radiographers hands will be ear the x-ray beam
what is the minimum lead equivalent that can be used in a protective apron
0.25 mm
know what the most commonly used equivalency throughout the department is?
0.5mm
lead equivalency of lead aprons
0.5 mm - 1 mm
lead equivalency of thyroid shields
0.5 mm
lead equivalency of protective eye wear
0.35 mm
lead equivalency of lead aprons during fluoro
0.5 mm
lead equivalency of protective spot film curtain
0.25 mm minimum
lead equivalency of bucky slot shielding device
0.25 mm at least
know where you should stand during fluoro procedure to protect yourself from scatter
stand as far away as practical from the patient, only move closer when assistance is required. Stand behind the radiologist and or behind the control booth until needed.
if you are in a fluoro room but not required to assist with the patient where should you stand
as far away as possible behind control booth
know the methods and devices included in dose-reduction techniques
- adequate beam collimation
- filtration
- gonad shielding
- control of technical exposures
- high speed IR systems
- correct imaging processing
- adequate structural shielding
- appropriate source to skin distance
- using a cumulative timing device
- correct tube housing
know what the bucky slot shielding device does
automatically cover the bucky slot opening on the side of the x-ray table during standard fluoro exams when the bucky tray is positioned at the foot end of the table
how long does the exposure cord have to be
long enough to permit the radiographer to stand 6ft (2M( from the tube, patient, and beam
where does a radiographer need to stand during mobile radiography
6 ft (2m) from tube, patient, beam
what happens to dose when magnification is used
adds additional radiation
when restraining a patient know where a radiographer should never stand
never stand in the primary beam
when you cannot use mechanical restraint device know what should be done (or used) to restrain patient?
nonoccupationally exposed person should hold the patient
what is workload essentially
the radiation output weighted time that the unit is actually delivering radiation during the week
know what must be posted in any area where radiation and radioactive material is present as part if a radiation safety program
caution signs
