Chapter 13 Management of Imaging Personnel Radiation Dose during Diagnostic X-ray Procedures
Terms in this set (82)
Federal government standards permit diagnostic imaging personnel to receive an " annual occupational EfD of ____" for whole-body exposure during routine operations.
This effective dose does not include:
Personal medical exposure
Natural background exposure
Imaging procedures that increase the radiographer's risk of exposure:
intervention procedures that employ HLCF
general radiographic procedures
lifetime effective dose in millisieverts should not exceed __ times the person's age in years
____ for continuous or frequent exposures from artificial sources other than medical irradiation and natural background radiation
____ for infrequent annual exposure
____ annual effective dose limit set for members of the general public is designed to limit that exposure " to reasonable levels of risk comaparable with risks form other common sources."
The ___ maximal annual effective dose limit recommendation " is made because annual exposures in excess of the __ mSv recommendations, usually to a small group of people, need not be regarded as especially hazardous, provided it does not occur often to the same groups and that the average exposure to individuals in these groups does not exceed an average annual Effective dose of about 1 mSv."
Both these limits " will keep the annual equivalent dose to those organs and tissues that are considered in the effective dose system ____."
below levels of concern for deterministic effects
genetically significant dose GSD
the average annual gonadal EqD to members of the population who are of childbearing age
that nevertheless always resides in the background is the slight possibility of developing a future radiogenic cancer or the induction of a genetic defect as a consequence of whatever cumulative radiation exposure is received
90 degree angle to the primary xray beam at a distance of 1 m the scattered x-ray intensity is generally approximately ___ of the intensity of the primary xray beam
______ poses the greatest occupational hazard in diagnostic radiology
The use of any device or appropriate technique that lessens the amount of scattered radiation significantly reduces___.
occupational exposure of diagnostic imaging personnel
This reducation in beam size decreases the number of x-ray photons available to undergo _____.
These devices protect from personnel from _____ radiation.
Protective apparel garments are available in various thickness such as _____ and ___ of lead equivalent.
.25, .5, 1mm
Conversely, higher kVp techniques:
Increase the mean energy of the photons comprising the radiographic beam
Require lower photon beam intensity
As the average energy of the beam ____, the percentage of radiation that is forward scattered ____.
The purpose of this additional monitor is to ensure that the monthly EqD to the embryo fetus does not exceed ___.
This EqD limit excludes both:
Natural background radiation
Specially designed maternity protective aprons consist of ___ lead equivalent over their entire length and width and also have extra ___ lead equivalent protective panel that runs transversely across the width of the apron to provide added safety for the embryo fetus.
.5 mm, 1 mm
Wraparound protective aprons of ____ lead equivalent can also be used during pregnancy.
The EqD to the embryo fetus from occupational exposure of the mother not exceed the NCRP recommended monthly EqD limit of __ mSv or a limit of ___ mSv during the entire pregnancy.
the amount of radiation a worker receives is directly proportional to the length
During fluoroscopy, reduced exposure time will decrease both:
is the most effective means of protection form ionizing radiation and imaging personnel receive significantly less radiation exposure by standing farther away form a source of radiation
Inverse square law ISL
expresses the relationship between distance and intensity of radiation and governs the dose received and it states " the intensity of radiation is inversely proportional to the square of the distance form the source."
The most common materials used for structural protective barriers are:
Structural barriers such as walls and doors in an x-ray room have been designed to provide radiation shielding for both:
Imaging department personnel
The general public
A qualified medical physicist determines the exact ______.
protection requirements for a particular imaging facility
Primary protective barrier
is to prevent direct, or unscattered, radiation form reaching personnel or members of the general public on the other side of the barrier
If the peak energy of the beam is 130 kVp, the primary protective barrier in a typical installation:
-Consists of 1.6 mm lead
-Extends 2.1 m upward form the floor of the x-ray room, when the xray tube is 1.5 to 2.1 m from the wall in question
Secondary protective barrier
protects against leakage and scatter radiation and typical installation consists of 0.8 mm lead
Control Booth barrier
must extend 2.1 m upward form the floor and be permanently secured to the floor
Diagnostic x-rays should scatter a minimum of _ times before reaching any area behind this control booth.
The window typically consists of ___ mm lead equivalent.
Clear Lead acrylic material
impregnated with approx. 30% lead by weight may be fashioned into an effective secondary protective barrier, such as for the control booth.
Modular x-ray barriers:
Are shatter resistant
can extend 2.1 m upward form the floor
are available in lead equivalency form 0.3 to 2 mm
Clear lead acrylic overhead protective barrier offers __ lead equivalency protection.
These protective garments are available in a variety of:
If the peak energy of the x-ray beam was 100 kVp, then a protective apron must be equivalent to at least a ___ thickness of lead.
The need for ___ lead equivalent for fluoroscopy and interventional purposes and the recommendations from various authorities that ___ lead aprons are desirable for all purposes have induced most facilities to stock personal shielding devices of this nature only
The neck and thyroid shield should be a minimum of ___ lead equivalent.
Protective eyeglasses contain a minimal lead equivalent protection level of ___ mm
While manipulating the diagnostic type tube housing for a radiographic examination, the radiographer should avoid ________ the high tension cables that connect to the positive and negative terminals of the x-ray tube.
handling or severely bending
_____ should touch the tube housing or high tension cables while a radiographic exposure is in progress
To ensure protection form scattered radiation emanating form the patient during a fluoroscopic examination, the radiographer should:
Stand as far away form the patient as is pratical
Move closer to the print only when assistance is required
Protective lead gloves of at least ___ lead equivalent should be worn whenever the hands must be placed near the fluoroscopic field
These dose reduction techniques methods and devices include:
Adequate beam collimation
Adequate gonadal shielding
Control of technical exposure factors
Use of high speed image receptor systems
Appropriate source to skin distance
Use of a cumulative timing device
Diagnostic type protective x-ray tube housing
spot film device protective curtain, or sliding panel, with a minimum of ____ lead equivalent should normally be positioned between the fluoroscopist and the patient to intercept scattered radiation above the tabletop
Bucky slot shielding device
of at least 0.25 mm lead equivalent must automatically cover the Bucky slot opening in the side of the x-ray table during a standard fluoroscopic examination when the Bucky tray is positioned at the foot end of the table
Diagnostic imaging personnel receive the highest occupational exposure during:
_____ should be assigned to each mobile unit so that it is immediately available for the radiographer.
The mobile units the cord leading to the exposure switch must be long enough to permit the readiographer to stand at least ___ ( 6 ft) from the:
The radiographer should attempt to stand at a ____ to the x-ray beam scattering object line. This is the place which the _____ amount of scattered radiation is received.
90 degree angle
For C-arm devices with similar fields of view, the dose rate for personnel located within a ____ of the patient is comparable to that in routine fluoroscopy.
Lead apron should be ___ lead equivalent to ensure adequate protection.
A neck and thyroid shield of __mm lead equivalent should be worn.
At at the start of each produce, the ______ should set the unit's cumulative timer to ___ so that it will be possible to be a aware of the amount of beam on time actually used.
should be used only on the request of the physician performing the procedure
The NCRP currently recommends an annual EqD limit to localized areas of the skin and hands of ___.
Radiographers ____ stand in the primary beam to restrain a patient during a radiographic exposure.
If mechanical means of restraint are not ______,______,______, are to perform this function.
feasible, nonoccupationallly exposed persons, wearing appropriate protective apparel
Radiographic and fluoroscopic exposures should be made only when the doors are _____
Doors have attenuation for diagnostic energy xrays equivalent to that provided by ___ of lead.
0.8 mm (1/32 inch)
Radiation-Absorbent Barrier Design Consideratioins:
The mean energy of the xrays that will strike the barrier
Whether the barrier is of a primary or a secondary nature
The distance from the xray source to a position of occupancy 0.3 m from the barrier
The workload of the unit
The use factor of the unit
The occupancy factor behind the barrier
The intrinsic shielding of the xray unit
Whether the area beyond the barrier is controlled or uncontrolled
Three categories of radiation sources can be generated in an xray room are:
Primary, scatter, leakage
Scatter and leakage radiation are collectively known as _____
emerges directly form x-ray tube collimator and moves without deflection toward a wall, door, viewing window, and so on. Also is known as direct radiation.
is radiation generated in the x-ray tube that does not exit form the collimator opening but rather penetrates the protective tube housing and to some degree, the sides of the collimator
the radiation ouput weighted time that the unit is actually delivering radiation during the week
use factor U
is the quantity that was introduced to select this fractional contact time and also referred to as the beam direction factor
For the primary radiation, the use factor represents the portion of beam on time that the x-ray beam is ____.
directed at a primary barrier during week
Consider a typical radiographic suite with _____.
a wall Bucky unit
If 50% of the x-ray examinations involve this device, the wall behind the Bucky unit has a ____
U primary= 1/2
occupancy factor T
is 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
a region adjacent to a wall of an x-ray room is used only by occupationally exposed personnel and it is a much larger amount 1000 uSv or 1 mSv
a nearby hall or corridor that is frequented by the general public is classified as and the weekly max permitted equivalent dose MPED is = to 20 uSv
Regulatory standards mandate that the max permissible leakage exposure rate at ___ from the target of a diagnostic x-ray tube in all directions cannot exceed ___ when the tube is being operated continuously at its maximal permitted kVp and mA combination.
The signs that are posted are required to have the radiation______.
symbol colored magenta, purple, or black on a yellow background
Posting Sign Requirements:
1. A permanent sign bearing the words "Caution Radiation Area" - excess of 0.05 mSv in 1 hour at 30 cm from a radiation source
2. A permanent sign bearing the words "Caution High Radiation Area"- excess of 1 mSv in 1 hour at 30 cm from a radiation source
3. A permanent sign bearing the words "Grave Danger, Very High Radiation Area" - excess of 5 Gy in 1 hour at 1 m from a radiation source