Final 1st spring Flashcards
The test used to determine proper operation/malfunctioning of the system— should be done regularly by
TG 18-QC
Technologist but responsibility of medical physicists
The German standards;document for acceptance testing is called ____the and published by ______
DIN 2001
By deutsches institut fur normunng
The standard that allows medical images to be transferred through DICOM
GSDF
Gray scale display function
The flat panel display measurement is a set of instructions that can be used to evaluate performance
VESA
The ACR recommended these patterns for QC purposes: qualitative and quantitative
AAPM TG 18
2 types of photometers
Near range -close to display device
Telescopic -test at 1 m distance
The luminance response can be tested with what
TG 18-CT
A maximum of 171 cd
Multiple fields on a single IP:
A discrete plot or graph :
Partitioning
Histogram
A softwAre correction to equalize response of each pixel to a uniform X-ray beam
Flatshielding
The process of assigning a value to a dead pixel on recorded values
Interpolation
2 laws of photometry
Inverse
Cosine
Luminous flux is measured by :
Measure of brightness; units of candela:
Candela
Nit
Digital viewing is best done\_\_\_\_\_\_ # a gray scale that can be produced on an imaging system :
Straight on
Dynamic range
X-rays that get converted to light and then to electrical signal
Indirect DR
CSI/CCD
X-rays that are converted straight to electric signal
Direct DR
A-Se
The lens or fiber optic that transfers X-rays to collection
Coupling element
A photostimuable phosphor for DR is the
Capture element
1024 bytes =
Group of 8 bits and
1024x1024
KB
Byte
MB
The electronic circuitry that does computations and memory supports together is the
Processor
To give the best details; we need
More SID, no OID, and small focal spot
Visibility of image detail is determined by
Contrast resolution
Optical Density has 2 controlling factors which are:
MAs and SID
High frequency generators are used for which modalities
CT, mammo, portables
The high voltage generator
3 phase 6 pulse has what percentage ripple???
And 3 phase 12 pulse?,
14%
4%
Full ancestry half wave are 100%
These are 3 steps to what?
Acceptance testing
Routine performance
Maintenance
A QC Program
Image interpretation, scheduling, pt preparation are all part of what program??
Quality assurance QA
Filtered ion chambers can be used to test what?
Kvp calliboration
The purpose of the autotransformer?
Rectifier is on the high voltage side and it’s purpose is to
Kvp selector
Convert AC to DC
Any mAS change is only affecting
mAS!!!!
Increasing or decreasing KvP affects
Contrast and density only!!!!
Focal spot size: increasing focal spot size will make the image
Worse!!
It only affects detail!!!
The more scatter will do what to contrast
Decrease
The higher the grid ratio, causes density to _______ and contrast to ________
Decrease and contrast increase
Grids only affect
Density and contrast!!!
Increasing or decreasing SID has what affect on contrast??
No affect!!!!
The source of X-rays come from
The focal spot
Outer shell electrons of the filament atoms are “boiled off”
Thermionic emission
The protective housing around X-ray tubes contain oil to serve as an
Insulator and a cushion to dissipate heat !
The cathode is the negative side of the time and it contains 2 primary parts which are:,
Focusing cup
The filament
Most exposure timers are controlled by a
Microprocessor
Electric current is
Electric potential is
Electric power
Ampere
Volts and measured in joule !!!
Watts
Transfer of heat from one place to another
Transfer of energy
Convection
Conduction
What is the best method is specifying X-ray quality ?,
HVL
Th purpose of filtration is to remove
Low energy X-rays
Lossless
Lossy
Reconstructible
Fine detail not required, video
of shades of gray that an imaging system can produce
Dynamic range
X-rays that are converted to electric signal and uses a-Se are
Direct DR
X-rays that are converted to light and then to electric signal and uses CSI/CCD is
Indirect DR
The lens/fiber optic; piece that transfers X-ray to collection
Coupling element
The image plate has a lead backing to
Reduce scatter and improve contrast
These consist of devices that translate computer info into a form that humans can understand
Output hardware
Kvp varies with thickness of a part which is
2kvp/cm of part
Air gap acts as what grid?
Disadvantage of OID
8:1
Magnification and Fs blur
Most grid interspace material is made of what ?
Aluminum or plastic fiber
Aluminum has less visible lines but it take more primary X-rays so Plast fiber is preferred
A measure of the penetrating primary and scatter X-rays through the grid (used to compare grid to non grid)
Bucky factor
THe advantages to compression devices
Improves spatial and contrast resolutions and decreases pt dose
To have quantum mottle means to have
Not enough mAs
The bigger the object; the _______ distortion
More
2 things affect magnificAtion
OID
sID
X-rays that exit the pt and interact with the Image receptor
Image forming X-rays
As scatter increases , the image loses
Contrast
The 3 scatter factors
Part thickness, kvp, and fold size
The atomic # for bone
The atomic # tissue
The atomic # iodine m barium
13
7.4
53 & 56
Differential absorption occurs when X-rays
Are transmitted thru the pt
Photoelectrically absorbed
X-rays that are transmitted thru the patient are
Radiopaque OR radiolucent
Radiolucent
Compton scattering is only partially
Absorbed
No energy transfer or ionization but causes noise on image
Coherent
Lowers contrast on image (more shades of gray
Incident X-rays interact with the outer shell electron and ejects it; ionizing the atom
Compton
Inner shell electrons & is total absorption
Photoelectric
After photoelectric interaction: ejection of K shell gives a vacancy when the outer shell L takes its place is called
Characteristic X-rays
Which only occurs at 69-70kvp!
Annihilation occurs above 1.02 meV (this interact room occurs on PET scans)
Pair production
The glass or metal enclosure of X-ray tube filters beam
Inherent filtration
A thin sheet of AL between protective tube housing and X-ray beam collimator
Added filtration
A way of increasing high energy X-rays and removing low energy X-rays is called
X-ray beam hardening
X-rays at any given energy are more penetrating in material with high or low atomic #s
Low atomic #
The process of the image intensifir:
X-rays photons
Light photons
Electrons
Back to light
Ration of The # of light photons at the output phosphor over the # of Xrays at the input phosphor
Flux gain
Ability of II to increase the illumination level of the image
Min gainXflux gain
Brightness gain
1 X-ray can create ______ light photons
3000
The photocathode in the image intensifier emits
Electrons!!
Parts of the eye : Iris Cornea Retina Fovea centralis
Diaphragm
Protective layer
Rods n cones
Center of eye
Dynamic process that are sometimes dim so it requires illumination (image intensifier)
Fluoroscopy
Who invented flouroscopy?
Thomas Edison
X-rays that exits the patient are incident on the II tube are transmitted thru the glass envelope & interact with the
Input phosphor
Which is CSI (cesium iodide)
When X-rays interact with the input phosphor of the II, it’s energy is converted to
Light
Electron emission that follows light stimulation
Photoemission
The photocathode emits electrons when illuminated by the input phosphor; this is called
Photoemission
This would occur from continuous synergies exposures & pt dose would be high!
Thermal overloading
Who endorsed Th “pause and pulse” and was adopted by image gently
Image wisely
2 image receptors used for digital flouro
CCD and flat panel
Method of temporal subtraction that results in successive subtraction images of contrast filled vessels
Mask mode
The devices used to test focal spot ?
The device used to test collimation?
Star, slit, pinhole
PBL (semi annually 2%)
The image forming X-rays hit the IR and creates the invisible
Latent image
Image contrast on the image formation in flouro is improved with
Subtraction techniques
The video system used in conventional flouro uses
525 line system
Background electronic noise
Is similar to image fog in digital- obscures electronic signal(reduces contrast)
Process by which very high energy X-rays can escape with electrons; the nuclear electric field and can be directly absorbed by nucleus
Photodisintegration
Interaction between the X-ray and the nuclear field that causes the X-ray to disappear and 2 electrons (one positive, one negative) to take its place
Pair Production
Geometric unsharpness; image blur that occurs from the size of the focal spot
Penumbra
Electron in the outermost shell
Valence electron
Electronic vacuum tube that amplified a flouro image to reduce pt dose
Image intensifier
Can be reconstructed like original
When fine details not required
100:1 compression factor
Lossless
Lossy (not used for mammo)
Emission of electrons from the photocathode
Photoemission
What conversion occurs in the image at the input phosphor of the II
X-rays converted to visible light
Which conversion occurs in the Image at the photocathode of the II
Light is converted to electrons
Which conversion occurs in the image at the output phosphor of an II
Electrons are converted to visible light
Which comes 1st in II fluoroscopy ?
Cesium iodide screen
Which component of the tv monitor transfers the video signal into a visible image ?
Fluorescent screen
What would not be found in the interspaces of a grid
Lead!
The image after processing is known as the
Manifest image
How far from The IR would we practice moving the patient for OID
10-15cm
Feature on a flouroscope That allows the radiologist to select image brightness that is maintained automatically
ABC
Automatic brightness control
X-ray that r suite from interaction of the projectile electron with a target nucleus, braking radiation
Brems X-ray
Electron beam tube that designed for a 2 dimensional display view
Cathode ray tube
Negative side of the X-ray tube
Contains filament and focusing cup
Cathode side
Solid state device that converts light to electrons
Charge couple device
Recording of flouro image on movie film
Cineflouragraphy
Percentage of X-rays absorbed by the IR
DQE
Standard that enables imaging systems to communicate
DICOM
Part of the cathode that emits electrons, resulting in tube current :
Metal shroud that surrounds the filament:
Filament
Focusing cup
Absence of optical density on a radiograph caused by unintended X-ray absorption in a grid
Grid cutoff
Deterioration of the radiograph image
Image noise
Electron cloud from the filament
Space charge
Television camera tube that is used most often in Tv flouro:
Reduction of brightness in the periphery
Vidicon
Vignetting
The___________ mode of reading the digital signal produces a sharper image with less flicker
Progressive
The output signal from The II digital image is transmitted to an analog-digital converter
ADC
When using s 1024x1024 matrix mode is being used than ___ images can be transferred per second
8
Two subtraction techniques; temporal and energy subtractions used in flouro together is called
Hybrid subtraction
subtracted images from a different mask and follow up frame
TID
Time interval difference
Energy subtraction -
Temporal subtraction -
Rapid kvp, complex image subtraction
Single kvp, simple subtraction
Conventional line system has _____ lines
Digital 1024x1024 has _____ line system
525
1000
Th federal law and most states under normal flouro the ESD should not exceed
10 R/min
Th entrance skin dose (ESD) for an adult during flour on average is
3-5 R/min
Th horizontal resolution in video monitoring is determined by the
Bandpass
The higher the better
The _____ is a heater filament that supplies constant electron current by thermionic emission
Electron gun
Use of a smaller dimension of a multifield II tube results in
A magnified image!
The ability to perceive fine detail is called
Visual acuity
This timer will terminate after 6 s
Guard timer
Reduction in contrast in the II
Veiling glare
