Rad 31 Digital Fluoroscopy
Digital Fluoroscopy (DF)
Digital x-ray imaging system that produces a series of dynamic images with use of an area x-ray
beam and an image intensifier
Operating Console
Contains alphanumeric & special function keys for entering patient data & communicating with
the computer
In addition, computer interactive video controls, a pad for cursor, and region-of-interest
manipulation
Digital Fluoroscopy Imaging System
During DF, the under-table x-ray tube actually operates in radiographic mode
Tube current is measured in hundreds of mA (instead of less than 5 mA, which is used in
conventional fluoro)
Computed Radiography (CR)
Cassette cased – DR – that uses storage phosphor plates to produce projections images
CR can be used in standard radiographic rooms (like film/screen system)
Must have:
1. CR cassettes
2. Phosphor plates
3. CR reader
Computed Radiography (CR)
There is a photostimulable phosphor plate placed inside the CR cassette
Plate usually made of Barium Fluorohalide with Europium as an activator
When x-rays strike the phosphor, so light is given off (like in screens), but also some energy is
deposited within the phosphor to create the latent image
The phosphor plate is then fed through the CR reader
Computed Radiography (CR)
RELEASING THE LATENT IMAGE:
One or more laser lights are used to scan over the plate causing the electrons to return to their
original state & emitting light in the process
This light is picked up by a photomultiplier tube & converted into an electrical signal
The electrical signal is sent through an analog-to-digital converter to produce a digital image
that is sent to the reviewing station
Digital Radiography (DR)
Cassette-less system
Uses an x-ray absorber material coupled to a flat panel detector or a CCD to form the image
Existing rooms need to be retrofitted with these devices if a new DR room is not installed
, Digital Radiography (DR)
No cassettes
The image acquisition device is built in:
A. To the table or wall stand
B. Enclosed in a portable device
2 types of acquisition methods:
1. Indirect capture
2. Direct capture
Image Acquisition
Flat panel – when the flat panel is used as the IR, once it is exposed, it is read immediately, &
the image is projected until next image is acquired
Interrogation time – time required for x-ray tube to be switched on and reach selected kVp and
mA
Extinction time – time required for the x-ray tube to be switched off
Pulse progressive fluoroscopy should be used routinely
Types of Image Receptors
1. Charged-coupled device
2. Flat panel image receptor
Charge-Couple Device (CCD)
CCD has a layer of crystalline silicon when illuminated, an electrical charge is generated, which
is then sampled, pixel by pixel, & manipulated to produce a digital image
Flat Panel Image Receptor (FPIR)
Consists of a photoconductor such as amorphous selenium which converts the x-ray photons
directly into electrical signals
Flat Panel Image Receptor (Cont)
Disadvantage - cost
Advantages – no cassettes needed
– easy to manipulate (lighter/durable)
– no lag
– no warm-up time
– no spatial distortion
– lowers patient dose
– no maintenance (unlimited life)
– high signal-to-noise ratio
– high spatial resolution
– high DQE (detective quantum efficiency)
Image Intensifier vs Flat Panel Image Receptor
Digital Fluoroscopy (DF)
Digital x-ray imaging system that produces a series of dynamic images with use of an area x-ray
beam and an image intensifier
Operating Console
Contains alphanumeric & special function keys for entering patient data & communicating with
the computer
In addition, computer interactive video controls, a pad for cursor, and region-of-interest
manipulation
Digital Fluoroscopy Imaging System
During DF, the under-table x-ray tube actually operates in radiographic mode
Tube current is measured in hundreds of mA (instead of less than 5 mA, which is used in
conventional fluoro)
Computed Radiography (CR)
Cassette cased – DR – that uses storage phosphor plates to produce projections images
CR can be used in standard radiographic rooms (like film/screen system)
Must have:
1. CR cassettes
2. Phosphor plates
3. CR reader
Computed Radiography (CR)
There is a photostimulable phosphor plate placed inside the CR cassette
Plate usually made of Barium Fluorohalide with Europium as an activator
When x-rays strike the phosphor, so light is given off (like in screens), but also some energy is
deposited within the phosphor to create the latent image
The phosphor plate is then fed through the CR reader
Computed Radiography (CR)
RELEASING THE LATENT IMAGE:
One or more laser lights are used to scan over the plate causing the electrons to return to their
original state & emitting light in the process
This light is picked up by a photomultiplier tube & converted into an electrical signal
The electrical signal is sent through an analog-to-digital converter to produce a digital image
that is sent to the reviewing station
Digital Radiography (DR)
Cassette-less system
Uses an x-ray absorber material coupled to a flat panel detector or a CCD to form the image
Existing rooms need to be retrofitted with these devices if a new DR room is not installed
, Digital Radiography (DR)
No cassettes
The image acquisition device is built in:
A. To the table or wall stand
B. Enclosed in a portable device
2 types of acquisition methods:
1. Indirect capture
2. Direct capture
Image Acquisition
Flat panel – when the flat panel is used as the IR, once it is exposed, it is read immediately, &
the image is projected until next image is acquired
Interrogation time – time required for x-ray tube to be switched on and reach selected kVp and
mA
Extinction time – time required for the x-ray tube to be switched off
Pulse progressive fluoroscopy should be used routinely
Types of Image Receptors
1. Charged-coupled device
2. Flat panel image receptor
Charge-Couple Device (CCD)
CCD has a layer of crystalline silicon when illuminated, an electrical charge is generated, which
is then sampled, pixel by pixel, & manipulated to produce a digital image
Flat Panel Image Receptor (FPIR)
Consists of a photoconductor such as amorphous selenium which converts the x-ray photons
directly into electrical signals
Flat Panel Image Receptor (Cont)
Disadvantage - cost
Advantages – no cassettes needed
– easy to manipulate (lighter/durable)
– no lag
– no warm-up time
– no spatial distortion
– lowers patient dose
– no maintenance (unlimited life)
– high signal-to-noise ratio
– high spatial resolution
– high DQE (detective quantum efficiency)
Image Intensifier vs Flat Panel Image Receptor
