Chapter 4,5,6 Flashcards
When the imaging plate is irradiated, Stimulates electrons enters the ________ layers
Active
Scintillators are phosphor that
Produces LIGHT when absorbing X RAYS
During laser beam formation both ends of the laser reflect back and forth so that the atoms:
Bombard each other
Coherent lights is formed by the laser because the photons
Travel in the same direction
The layer of the imaging plate that traps the electrons during experiments is the ______layer
Active
Photoconductive are material that
Absorb X RAYS and produced ELECTRON S
In a flat panel detector, specialized silicon integrated circuit control
Lining scanning sequence
The type of flat panel detector that uses thin film of SILICON integrated with arrays of photodiode is known as
Amorphous silicon detector
The phosphor layer is made of phosphor from the ______ family
Barium fluorohalide
The imaging plate layer the absorb stimulating light and reflect emitted light is the _____
Color layer
Which of the following serves to protect against static build up, dust collection, and mechanical damage to the imaging plate
Felt material
Sends light in a forward direction, decreases resolution
The reflection layer
Detector performance is measured with all of the following except
Contrast
A device that acts like a SWITCH to send electrical charges to the image
processor in a direct conversion flat-panel detector is known as a ______
transistor.
Field effect
Each light photon is assigned a number during:
Digitization
Indirect conversion in flat-panel detectors is a ____-step process.
Two
CsI detectors use
Thin crystalline needles
The optical mirror in the reader
Directs the laser beam to the imaging plate surface
Contain photostimulable phosphor that traps electrons during exposure ( ionization occurs
Phosphor layer or active layer
Thin, tough, clear plastic protects the phosphor layer?
Protective layer
Absorbs and reduces static electricity?
Conductive layer
Semi- rigid material that produces strength?
Support
Soft polymer that protects the BACK of the cassette?
Backing layer
Interactions gives energy to electrons in the crystals, trapping them in an
area of the crystal known as?
The color or phosphor center
Imaging plates ?
Are never completely erased
Residual trapped electrons are?
Too small to interfere with subsequent exposures
. At any point in time, a SINGLE LASER point radiates the image plate?
Point scan
Are based on simultaneous stimulation of the imaging plate one LINE at a
time?
Line scan
The movement of the laser across the imaging plate also known as
“scan”
Fast scan directions
A device that includes a photosensitive array and small pixels that
convert light into electrical charges is known as a ______ transistor
thin-film
The movement of the imaging plate through the reader also known as
“translation or subscan direction”
Slow Scan Direction
A laser creates and amplifies a narrow intense beam of ? (
LIGHT
amplification by stimulated emission of radiation)
Coherent light
34). Most common laser?
Helium Neon Laser
The reader scans the plate with a
Red light in a zigzag pattern at 2ev
The extra energy allows trapped electrons toESCAPE the active layer
where they emit visible
Blue light at 3ev
The photodetector amplifies the light and sends it to an
Adc
The laser scans across the imaging plate multiple times, this process is
known as
Translation
The average fill factor of a DETECTOR is
50 to 80%
This system is highly efficient and takes up less fill space than CCDs
CMOS
CMOS stands for?
Complementary Metal Oxide Semi conductor
Output signal to signal - to - noise ratio
DQE ratio
The AMOUNT OF ELECTRONS produced relative to the incident light from the scintillator?
Quantum efficiency
Overfill of the dels will cause a
Blooming effect
The oldest indirect conversion digital radiography?
Charge Coupled Devices (CCD)
What is grain calibration used for
correct flaws in the detector
Detector performance measures
Numerical measurements of spatial resolution and DQE
(Highest DQE is 1)
Each pixel contains
sensing and switching component
The most popular type of Amorphous silicon detector uses a
Csl scintillator
Phosphors that produce light when absorbing x-rays
Scintillators(Indirect capture)
Absorb x-rays resulting and produce an electrical charge
Photoconductors (Direct capture
KVP values outside of the range of 45-120 may be
Inconsistent amount of phosphor
may produce little or too much excitation of phosphors
Insufficient phosphor stimulation
Too few photons no matter the kVp level will result in?
CR grid frequency 150 or higher is used to
ensure they don’t match up
Typical grid frequency is between
80 and 152 lines
A post exposure image manipulation that adds a black background to the
original collimation edges ( Does NOT replace proper collimation)
Shuttering
TFT flat panel was introduced In?
1995
ComPuted RadiograPhy useS
PSP (where capture happens) then plate reader
TFT and has *AMORPHOUS SELENIUM *
- (No light)
- Has one steps
Direct Capture uses
What uses Cesium Iodide (CCD) , TFT AMORPHOUS SILICON * ( Creates light), and Has two steps
Indirect Capture
mAs was selected according to the?
Number of photons required for the body part
The more angled the beam,
The more elliptical the shape of the beam
Differing spatial resolution and inconsistent output signals depending on
the position and ANGLE of the BEAM results in
elliptical shape of the beam
To correct the beam
It is shaped by special optics
Mirrors are used to ensure that the beam is
Positioned consistently
The typical THROUGHPUT is
50 cassettes per hour
Represents CHANGING VALUE as continuously variable physical quantities?
Analog
The thinner the phosphor layer,?
The higher the resolution
Systems erase the plate once a week by flooding it with bright ___ to REMOVE TRAPPED ELECTRONS left after the initial plate reading.
White Light
KVP was selected for?
Penetration and tissue type
mAs was selected according to the?
Number of photons required for the body part
