Podcast
Questions and Answers
The number of photons directly represent the intensity level in a ______ pixel.
The number of photons directly represent the intensity level in a ______ pixel.
single
Sectra Microdose Mammography (MDM) is based on ______ detectors.
Sectra Microdose Mammography (MDM) is based on ______ detectors.
Si
CCD systems use a ______ like gadolinium disulphide to convert x-rays to visible light.
CCD systems use a ______ like gadolinium disulphide to convert x-rays to visible light.
scintillator
A-Se is an example of ______ detection.
A-Se is an example of ______ detection.
Signup and view all the answers
Continuous fluoroscopy displays at ______ frames/sec.
Continuous fluoroscopy displays at ______ frames/sec.
Signup and view all the answers
Pulsed fluoro reduces blurring from patient motion by using a series of short x-ray ______.
Pulsed fluoro reduces blurring from patient motion by using a series of short x-ray ______.
Signup and view all the answers
The purpose of the automatic brightness control (ABC) is to keep the brightness of the image constant at the ______.
The purpose of the automatic brightness control (ABC) is to keep the brightness of the image constant at the ______.
Signup and view all the answers
The last-frame-hold feature is useful at ______ institutions.
The last-frame-hold feature is useful at ______ institutions.
Signup and view all the answers
Road mapping is a software-enhanced variant of the ______ feature.
Road mapping is a software-enhanced variant of the ______ feature.
Signup and view all the answers
Using 7.5 frames/sec instead of 30 frames/sec in pulsed fluoroscopy results in a dose savings of ______ %.
Using 7.5 frames/sec instead of 30 frames/sec in pulsed fluoroscopy results in a dose savings of ______ %.
Signup and view all the answers
In Indirect detection systems, the X-rays are absorbed in a ______ layer and produce light photons.
In Indirect detection systems, the X-rays are absorbed in a ______ layer and produce light photons.
Signup and view all the answers
The ______ detector converts X-ray photons directly into charges (electron-hole pairs).
The ______ detector converts X-ray photons directly into charges (electron-hole pairs).
Signup and view all the answers
In digital fluoroscopy, the image is captured using a ______ sensor.
In digital fluoroscopy, the image is captured using a ______ sensor.
Signup and view all the answers
The Fill Factor is calculated by dividing the sensitive area by ______ x ______.
The Fill Factor is calculated by dividing the sensitive area by ______ x ______.
Signup and view all the answers
The ______ detection systems use Imaging Plates based on photostimulable phosphors.
The ______ detection systems use Imaging Plates based on photostimulable phosphors.
Signup and view all the answers
In Direct photon counting systems, ______ photons are counted.
In Direct photon counting systems, ______ photons are counted.
Signup and view all the answers
Flat Panel Digital Fluoroscopy is a type of ______ radiography.
Flat Panel Digital Fluoroscopy is a type of ______ radiography.
Signup and view all the answers
The ______ screen is used in analogue fluoroscopy.
The ______ screen is used in analogue fluoroscopy.
Signup and view all the answers
Flat panel devices are thin film transistor (TFT) arrays that are rectangular in format and are used as ______ detectors
Flat panel devices are thin film transistor (TFT) arrays that are rectangular in format and are used as ______ detectors
Signup and view all the answers
CsI, a ______ is used to convert the incident x-ray beam into light
CsI, a ______ is used to convert the incident x-ray beam into light
Signup and view all the answers
TFT systems have a ______ at each detector element which converts light energy to an electronic signal
TFT systems have a ______ at each detector element which converts light energy to an electronic signal
Signup and view all the answers
Flat panel detectors would replace the image ______, video camera, and other peripheral devices
Flat panel detectors would replace the image ______, video camera, and other peripheral devices
Signup and view all the answers
Digital fluoroscopy uses ______ panel detectors to convert x-ray energy into an electronic signal
Digital fluoroscopy uses ______ panel detectors to convert x-ray energy into an electronic signal
Signup and view all the answers
The ______ of digital fluoroscopy allows for real-time image acquisition and display
The ______ of digital fluoroscopy allows for real-time image acquisition and display
Signup and view all the answers
Study Notes
Image Detection Systems
- Indirect image detection: x-rays are converted to visible light, then to electric charges, and finally to an electric signal
- Examples: CCD systems, a-Si indirect detectors, and CsI-scintillator with a-Si switching diodes or TFT-readout
CCD Systems
- Use a scintillator like gadolinium disulphide to convert x-rays to visible light
- Light is collected by optics to demagnify the 35x45cm2 film to 2-4 cm2 CCD
- Visible light is converted into charge that is amplified and readout
a-Si Indirect Detectors
- CsI-scintillator with a-Si switching diodes or TFT-readout
- 100 m pixel size, giving ~5 lp/mm
Direct Detection
- Also called flat panel detectors (FPD)
- Charge proportional to the x-rays received is stored on a capacitor
- The charges are conducted out by transistors one row at a time and subsequently amplified, multiplexed, and digitized
- The readout is very fast
a-Se Direct Detection
- Direct image detection
- X-ray photoconductor layer (usually amorphous selenium) converts x-rays to charge
- An applied electric field directs the charges to the charge collection electrodes
Spot-Film Devices and Cine-Radiography Cameras
- Attach to the front of the II and produce conventional radiographic screen-film images
- Better resolution than images produced by II
- Cine-radiography cameras attach to a port and can record a very rapid sequence of images on 35-mm film
Fluoroscopy Modes of Operation
- Continuous fluoroscopy: continuously on x-ray beam, 0.5 – 4 mA or higher, display at 30 frames/sec, 33 msec/frame acquisition time
- High dose rate fluoroscopy: specially activated fluoroscopy, 20 R/min is the maximum legal limit, audible signal required to sound
- Pulsed fluoro: series of short x-ray pulses, 30 pulses at ~10 msec per pulse, exposure time is shorter, reduces blurring from patient motion
- Last-frame hold: when the fluoroscopist takes their foot off the fluoroscopy pedal, the last live image is shown continuously
- Road mapping: software-enhanced variant of the last-frame-hold feature, useful for advancing catheters through tortuous vessels
Digital Image Quality
- Gray levels at a constant 512 x 512 matrix size
- The purpose of the automatic brightness control (ABC) is to keep the brightness of the image constant at the monitor
Flat Panel Digital Fluoroscopy
- Replace image intensifier
- Flat panel devices are thin film transistor (TFT) arrays that are rectangular in format and are used as x-ray detectors
- CsI, a scintillator, is used to convert the incident x-ray beam into light
- TFT systems have a photodiode at each detector element which converts light energy to an electronic signal
Type of Detector
- Indirect detection systems: the X-rays are absorbed in a phosphor layer and produce light photons which convert into electric charges in a photo detector and then to an electric signal
- Direct detection systems: the X-ray photons directly convert into charges (electron-hole pairs) and thus to an electric signal in a photoconductor
- Direct photon counting systems: single photons are counted, i.e.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz covers the principles of digital radiography image detection systems, including Sectra Microdose Mammography, Xcounter, and CCD systems.
