Chapter 11, 12, 15 Flashcards
Every diagnostic imaging system MUST have:
Protective tube housing
A correctly functioning control panel
In equipment design, leakage:
Leakage cannot exceed 100 mR/hr at a distance of 1 meter
Control panel (console):
Must indicate condition of exposure and have light or audible c-ray indicator
a Table is:
Radiolucent- absorbs only minimal amount of radiation
Commonly carbon filter
SID
Must have a means of measurement from anode focal spot to IR
Beam Limiting devices
Devices that limit the x-ray beam before it enters the patient
In scatter radiation, tight collimation:
Decreases patient dose
To minimize skin exposure in Skin Sparing:
the patients skin surface should be at least 15 cm below collimator for fixed equipment
Positive Beam Limitation:
Automatic collimation
Purpose is to restrict the size and shape, so it does not exceed the size and shape of the IR
Effects of filtration:
Increases quality of the beam
Decreases quantity of x-rays by absorbing some low energy beams- fewer overall beams are left
2 types of filtration?
Inherent- original filtration
Added- any filtration occurring outside the tube housing and before the IR
Half Value Layer (HVL)
Decreases the intensity of the primary beam by 1/2 (50%) of its original value
Types of compensating filters:
Wedge: bone and joint- T spine, feet (thicker part towards toes)
Trough (bilateral wedge): CXR- PA (thin center)
Reproducibility
Consistent output in radiation intensity for identical generator setting from one exposure to the next
Automatic Exposure Control (AEC)
Back up timer is set at 150%
For Mobile Radiographic Units:
Minimum SSD of at least 30 cm (12 inches)
Exposure factors for children:
Decrease kVp by 25% of adult
Filtration
Minimum 2.5 mm total Al
Permanently installed
Lead shielding
minimum .25 mm lead
Cumulative timing device requirement:
sounds at 5 minutes
Fluoroscopic exposure control switch must:
Be of the dead-man type
C-arm operator, if standing close to the patient, could also receive:
A significant increase in occupational exposure from patient scatter
Holistic Approach to Patient Care means to:
Care for the whole person rather than just the area of interest
Advantages of Effective Communication:
-Reduces patient anxiety
-Creates better tech/patient relationship- trust and caring
-Increases chance of completing exams and reduces repeats
2 types of motion:
Voluntary - patient controlled
Involuntary- body systems
Voluntary motion examples
Age
Breathing
Fear
Mental instability
Involuntary motion examples:
Muscle spasms
Chills
Tremors
15% rule effect on Exposure Factor
Increase kVp by 15% and reducing mAs 1/2 will reduce radiation exposure
Fluoroscopically Guided Positioning (FGP)
Must not be used on patients positioning
Unacceptable and unethical practice
Pregnant Patient
Ask LMP
Annual occupational EfD limit is:
50 mSv (5 rem)
Annual limit for general population is:
1 mSv (100 mrem) for continuous or frequent exposure from artificial sources
Occupational dose for eyes
150 mSv
The most effective means of protection from ionizing radiation:
Distance
Lowest scatter area:
90 degrees to the patient
Primary Protective Barrier
Prevents DIRECT or un-scattered radiation from reaching personnel or public
1/16 inch lead
Secondary Protective Barrier:
1/32 inch lead
Included ceiling and control booth
Control Booth Barrier also considered
Secondary Barrier
Gloves have
.25 mm lead
Protective Eyeglasses
0.35 mm lead
Protection during fluoro:
Protective apron: .5 mm
Protective gloves: .25 mm
Thyroid shield: .5 mm
Where should radiographer stand during mobile procedure?
At a right angle (90 degrees) to the c-ray beam-scattering object (the patient) line
What is collectively known as Secondary Radiation?
Scatter radiation and leakage radiation
Workload (W) is used to:
Used to determine barrier shield requirements
Use Factor (U):
The factor that represents the portion of beam-on time that the x-ray beam is directed at a primary barrier during the week
Order of person holding:
Male relative
Female relative
Non-radiology personnel
Radiology personnel
