Card Set Information
Radiologic Equipment Imaging
Fluoroscopy, Mammography, Dexa, QC/QA
Bone density scanning also called:
Dual Energy X-ray Absorptiometery (DEXA)
Dexa is today's standard for measuring:
Bone minderal density (BMD); or bone loss
Dexa is most often performed on
Lumbar Spine and hips
Dexa is most often used to diagnose:
Dexa can also assess an individuals risk for:
Risk of fracture affected by:
Age, weight, history or prior fracture, family history of osteoporotic disease, and lifestyle
Bone mineral denisity is calculated by finding the difference between:
peak energy absorbed by soft tissue and by bone
Dexa score that shows the amount of bone you have as compared to a young adult of the same gender with peak bone mass.
Normal T Score
A score above -1
T score classifying osteopenia (low bone mass)
A score between -1 and -2.5
T Score identifying osteoporosis
Score below -2.5
T Score is used to estimate risk of
developing a fracture
The Dexa number that reflects the amount of bone you have compared with other people in your age group of the same size and gender.
A DXA test cannot predict who will experience a fracture but can provide indications of
Osteoporosis involves a gradual loss of:
X-ray imaging of a selected plan of the obdy by a method that elimiates the outline of structures in other planes.
Principal advantage of tomography:
Improved contrast resolution
Principal disadvantage of tomography:
Increased patient dose
X-ray tube attached mechanically to the image receptor; the tube moves in one direction while the bucky moves in the opposite direction.
Imaginary point about which the x-ray tube and image receptor moves
What determines the object plane in Tomography?
Anatomical structures lying within what plane are imaged clearly in tomography?
The object plane
The farther from the object plane an anatomical structure is, the more
blurred the image will be
Section thickness in tomography is determined by:
A large angle in tomography results in
A thin section
Long flexible fine spring used to introduce and position an intravascular angiographic catheter:
Hollow flexible tube for insertion into a body cavity, duct, or vessel to allow passage of fluids or distend a passageway.
Common uses of catheter angiography:
To examine blood vessels in the brain, kidneys, pelvis, legs, lungs, heart, neck and abdomen
X-ray tube and IR move around the head
Images of structures above and below the object plane become more blurred as tomographic angle
The thickness of tissue to be imaged is called the ____ ____ and is controlled by ____ ____.
tomographic section/tomographic angle
If the tomographic angle is less than 10 degrees, the section thickness will be ____. This is called _____.
Primary function of fluoroscope:
To provide real-time dynamic images of anatomic structures; to view motion and function
What is used for the examination of moving internal structures and fluids?
Who invented the fluoroscope? When?
Thomas Edison; 1896
Zinc Cadmium Sulfide backed by leaded glass
Permanent fixed image taken during fluoroscopy; a small static image on a small format image receptor:
Fluoroscopic visualization of vessels:
What is Automatic Brightness Control (ABC)?
The image brightness selected by the radiologist is maintained automatically by varying the kVp, mAs, or both.
Radiographs are visualized under illumination levels of:
Lumen per square meter
How many rods and cones are there in the eye per cubic mm of retina?
More than 100,000
Cones are concentrated at the ___ ____ and are used for ____ vision.
Rods are concentrated at the ____ of the retina and are used for ____ vision.
Threshold for rod vision:
Threshold for cone vision:
Ability to perceive fine detail:
Detecting differences in brightness:
Developed to replace conventional fluorescent screen:
An image intensifier raises illumination into the:
Cone vision region
Complex electronic device that receives the image forming x-ray beam and converts it into a visible light image of high intensity:
Image intensifier tube
X-rays that exit the patient and are incident on the image intensifier tube interact first with the:
The input phosphor is composed of:
When x-rays interact with the input phosphor, their energy is converted to:
What is bonded directly to the input phosphor with a thin transparent adhesive?
The photocathode responds to light from the input phosphor by emission of:
The emission of electrons by the photocathode is called:
The number of electrons emitted by the photoemission of the photocathode is _____ to the intensity of the incident image forming x-ray beam.
Circular plate with a hole through which electrons pass to theh output phosphor.
What is the potential difference maintained across the tube between the photocathode and anode?
Site where electrons interact and produce light:
The output phosphor is composed of:
Zinc Cadmium Sulfide
What are located along the length of the image intensifier tube to ensure that the electrons are reduced to the small output phosphor?
Electrostatic focusing lenses
What is the flux gain?
The ratio of the number of light photons at the output phosphor to the number of x-ray photons at the input phosphor
Each photoelectron that arrives at the output phosphor produces how many times the light photons as were necessary to create it?
What is the minification gain?
The ratio of the square of the diameter of the input phosphor to the ratio of the square of the diameter of the output phosphor
What is the Brightness gain?
The minification gain x the flux gain; the ablility of the image intensifier to increase ilumination level of the image
Brightness gain of most image intensifiers:
The conversion factor of most image intensifiers is:
Output illumination/input exposure rate
What reduces the contrast of an image with internal scatter radiation?
What uses a smaller diameter to result in a magnified image in direct proportion to the ratio of diameters?
Multifield Image intensification
In magnified mode, the minification gain is____.
In magnified mode ____ photoelectrons incident on the output phosphor
In magnified mode, the image is _____.
Magnification mode results in ____ patient dose.
What effect does magnified mode in fluoroscopy have on spatial and contrast resolution.
Reduction in brightness at the periphery of the image:
In television fluoroscopy, the output phosphor is coupled:
directly to the camera tube
Television camera tube used most often in television fluoroscopy:
The input surface of the vidicion is the same size as:
the output phosphor
The vidicion converts light from the output phosphor into an:
Electromagnetic coils in the television camera are used to:
properly steer the electron beam within the tube
Two methods commonly used to couple the television camera tube to the image intensifier:
1. Bundle of Fiber Optics
2. Lens coupling
Power supply of 60Hz results in ___ television fields per second, and ____ frames per second. Each frame is ___
60, 30, 33ms
An active trace in field 2 lies between two active traces in field 1. This forms a frame.
When the electron beam blanks and turns off to return to the left side of the screen, this is called:
How many new cases of breast cancer are there yearly?
How many breast cancer patients are cured with early diagnosis?
Ratio of benefit to risk in mammography:
What tissue is most sensitive to cancer by radiation?
What percentage of breast tissue is ductal?
Incidence of breast cancer is highest in what part of the breast?
Upper outer quadrant
A baseline mammogram is usually obtained before age:
Optical densisty is highest with what kind of breast tissue?
Low kVp is used in mammography to minimize____, maximize ____, and enhance ____.
Compton scatter/ Photoelectric effect/ differential absorption
What kVp is effective in mammography?
What type of target/filter combination is best for thick, dense breasts?
What type of target/filter combination is best with thin, fatty breasts?
In mammography, effective focal spot is obtained with an anode angle of ____ and a tube tilt of ____.
23 degrees/ 6 degrees
The cathode is positioned toward the chest wall during mammography to make use of the:
anode heel effect
Focal spot blur in mammography results in reduced:
SID of most mammography imaging systems: 60-80 cm
Inherent filtration of mammography imaging systems:
.1 mm Al equivalent
Total beam filtration of mammography imaging system should never be less than:
.5 mm Al equivalent
The use of a filter of the same element as the target in mammography is done to allow ____ to expose the breast while limiting high and low ____.
Compression of breast reduces:
Motion blur, scatter, tissue superimposition, focal-spot blur, absorption blur, and patient dose.
Most mammography systems have a moving grid of:
4:1 or 5:1
HTC grid ratio:
Why are phototimers for mammography positioned after the IR?
to reduce OID and improve spatial resolution
Two types of AEC for mammography:
1. Ionization chamber 2. Solid State Detector
Magnification mammography requires a focal spot size no larger than:
When used with AEC, screen-film mammography must have a
low absorbing back cover
Quality assurance deals with:
Quality Control deals with:
Instrumentation and equipment
QA is principally the responsibility of:
QC is principally the responsibility of:
the medical physicist
The ten step monitoring and evaluation process resolves
identified patient care problems
Pertaining to whether the patient's ultimate disease or condition agree with the radiologist's diagnosis.
Three steps of an acceptable QC program:
Acceptance testing, monitoring and maintenance
In private officies, clinics and hospitals, the QC program is established and overseen by:
a medical physicist
The most important protection characteristic of a radiographic imaging system:
Collimation misalignment must not exceed
2% of the SID
Distance must be acurate within
2% of the SID
Centering must be accurate within
1% of the SID
Spatial resolution is determined principally by:
focal spot size
Focal spot size must be measured when:
new equipment or replacement tube are installed
Filtration should be evaluated annually or any time after
a change has occured in the tube or housing
3 tools used to measure focal spot size
slit camera, pinhole camera, star pattern
What is the standard tool for measuring focal spot size?
The star pattern is only useful for measuring focal spot sizes greater than
Specification of focal spot size depends on
geometry of the tube and focusing of the electron beam
An acceptable alternative to focal spot size measurement:
Line pair test tool
kVp calibration should be evaluated annually or when
high voltage generator components have changed
Measured kVp should be within
10% of the indicated kVp
For times above 10ms, exposure timer accuracy must be within
5% of indicated time
For times 10 ms or less, exposure timer accuracy should be within
AEC is evaluated by exposing an image receptor through:
varying thickness of aluminum or acryllic
The accuracy of the exposure timer should be assessed annually or more frequently if repairs have been made to:
the operating console or high voltage generator
Assessing the function of the backup timer can be done by inserting a
If the phototimer fails, the backup timer should terminate the exposure at
600 mAs or 6 seconds
The ability of a radiographic unit to produce a constant radiation output for various combinations of mA and time:
Exposure linearity must be within:
10% for adjacent mA stations
Exposure linearity is determined by a:
precision radiation dosimeter
Method of assessing exposure linearity:
Hold exposure time constant and vary the mA
Two methods to evaluate exposure reproducibility:
1. Make a series of at least 3 exposures with the same technical factors while changing between exposures. 2. Select technique factors and hold constant for 10 exposures
Sequential radiation exposures should be reproducible within:
Screen cleaning should not occur less often than
every other month
Screen-film contact is evaluated:
Protective apparel should be radiographed/fluoroscoped
Viewbox illumination is analyzed annually with a:
Filters used to determine adequacy of ABS:
aluminum, copper, lucite, and lead
As the active area of the input phosphor is increased, patient dose is:
Fluoroscopic ABC should be evaluated:
For conventional tomography, patient exposure should be measured for:
the most common procedures
Most frequent tomographic procedures:
TMJ, C-spine, T-spine, Chest, IVP, Nephrotomogram
In conventional tomography, section uniformity is evaluated by imaging:
a hole in a lead sheet
A 90 second film processor can handle
500 films per hour
90 second film processor requirements:
Water 87 degrees, developer temperature 95 degrees, high concentration chemistry, 22 second developer immersion
In most facilities, processor cleaning is done
Processor monitoring should be done at least
once per day
3 types of maintenance programs for QC
Scheduled maintenance, preventative maintenance, non-scheduled maintenance
Average ESE during fluoroscopy:
Skin dose during fluoro
Skin dose during interventional procedures
ESE for fluoroscopy should not exceed:
ESE for interventional studies should not exceed
Proper exposure of cassette spot film depends on:
kVp, mAs, and sensitivity characteristics of screen-film combination
ESE for cassette spot film:
Input exposure rate to the image intensifier tube should be in the range of:
In tomography, agreement between the indicated section level and the measure level should be within
Incrementing from one tomographic section to the next, section level should be within
QC team for mammo
Radiologist, Mammographer, and Medical Physicist
Daily QC the responsibility of:
How many specific tasks does the QC mammographer have and what is the total annual time required for mammographic QC?
12, 160 hours
Daily mammo. QC tasks:
Darkroom cleaning, processor monitoring
What kind of thermometer should never be used to check developer temperature in the processor?
Which end of the sensitometeric strip should be fed into the feed tray first?
Least exposed, emulsion side down
OD closest to 1.2 but not less than 1.2
Mid density/speed index
Difference between OD of 2.2 and OD closest to but not less than. 5
Density difference/contrast index
Average OD from unexposed area of the strips:
Base + Fog
MD and DD allowed to vary within:
Base plus fog allowed to vary within
Weekly mammography QC tasks:
Viewbox, screen cleaning, phantom images
Technique used for imaging mammographic phantom should be the same as used clinically for:
4.5cm compressed breast, 50% glandular, 50% adipose
Time or mAs values for mammographic phantom images should be within
For mammographic phantom images, background OD should be ___ with a range of ____
For mammographic phantom images, DD should be ___ with a range of ___
Monthly mammographic QC tasks:
Quarterly mammo QC tasks:
Repeat analysis, analysis of fixer retention, conferense w/radiologist
Quarterly repeat analysis valid if patient volume results in at least:
Analysis of fixer retention in film is used as an indicator of:
They hypo estimator should not result in more than
Semi-annual mammographic QC tasks:
Screen/film contact, compression, darkroom fog
Safelight or fluorescent light fog should not exceed
Background of the phantom image should be: