Flouroscopy

Question 1

What is Luminescence

Answer 1

When material absorb energy and emit light

Two categories: fluorescence and phosphorescence

Question 2

What is flouroscence

Answer 2

the light is emitted very quickly in milliseconds

Question 3

What is phosphorescence

Answer 3

The light Is emitted more slowly

Question 4

Process of Luminescence

Answer 4

x-ray hit phosphor material containing valence band electrons
electrons promoted to a higher energy level
they drop back quickly or slowly
Light is emitted

Question 5

What is fluoroscopy

Answer 5

imaging technique that uses X-rays to obtain real-time moving images of the interior of an object.

Question 6

Components of the fluoroscopic imaging chain

Answer 6

x-ray tube
x-ray generator: high freq units and high output
image receptor: image intensifier or amorphous selenium flat panel detector
x-ray table
image monitoring system
connection for X-ray tube and imaging system

Question 7

What is charge coupled devices

Answer 7

Photosensitive silicon chops that can be used to convert light to a digital video iamge

Question 8

advantages of CCDs

Answer 8

does not produce artefacts like conventional fluoro
greater sensitivity to light
lower patient dose
no warm up required

Question 9

What is an image intensifier

Answer 9

a device which is used to convert incident radiation to a light image to be viewed, recorded and photographed

Question 10

components or elements of image intensifier

Answer 10

input phosphor or photocathode
electrostatic focusing lense
accelerating anode
output phosphor

Question 11

Input phosphor

Answer 11

made of glass with coat of caesium iodide CsI crystals
converts photons to light photons
CsI is used because; higher resolution, greater packing density

Question 12

Electrostatic focusing lenses

Answer 12

Set of positively charged electrodes placed inside the surface of the glass envelope
Focus and accelerate the electrons as they travel towards the output phosphor

Question 13

Anode

Answer 13

Allows passage of electrons to output phosphor

Positively charged electrode that attracts the electron towards the output phosphor

Question 14

Multifield image intensifier or magnifcation technique

Answer 14

Allows fluoroscopy image to be magnified electronically

Question 15

Disadvantage of MII/Magnification technique

Answer 15

due to the decrease in minification gain, mA must be increased to main image brightness
significant increase in patient dose
FOV decreased

Question 16

types of multifield intensifiers

Answer 16

Dual focus: 2 different FOVs

Tri focus: allows for a choice of 3 input phosphor

Question 17

magnification in flat panel detectors

Answer 17

magnification performed simply by digitally enlarging the display
slight loss of resolution
no increased patient dose

Question 18

Image intensifiers artefacts

Answer 18

Vignetting
Pincushion distortion
Veiling glare
S distortion

Question 19

What is vignetting

Answer 19

Decrease in image brightness at the lateral portions of image

Question 20

What is pincushion distortion

Answer 20

caused by projecting image from a curved surface onto a flat surface

Question 21

Veiling glare

Answer 21

Caused by light reflection from a window of output phosphor which reduces contrast

Question 22

S distortion

Answer 22

Warping of the image along an s-shaped axis caused by strong magnetic fields

Question 23

Applications of Fluoroscopic imaging

Answer 23

barium studies
Endoscopic studies (ERCP)
fertility studies (HSG)
angiographic studies
interventional studies
cardiac studies
orthopaedic procedures

Question 24

methods for digital flouroscopy - image intensifier tube digital fluoroscopy systems

Answer 24

standard fluoroscopic units feed the image from the television camera directly to the monitor for immediate viewing
analogue signals from camera is first sent through an ADC then through a microprocessor circuit which processes the image

Question 25

methods for digital flouroscopy - flat panel digital fluoroscopy systems

Answer 25

uses similar flat-panel image detectors to those used in DDR systems
flat-panel detectors replace the II and TV camera combination and feeds the image info directly to an image processor

Question 26

Digital fluoroscopy- image display

Answer 26

digitally generated image can be displayed on the monitor either monocrome grey-scale images or with bi-stable images
bistable images is which the pixels are either black or white with no shades of grey

Question 27

monitor scan display modes

Answer 27

continuous flouroscopy mode
pulsed interlaced scan mode
pulsed progressive scan mode
slow scan mode

Question 28

Advantages of Digital fluoroscopy

Answer 28

last frame hold
road mapping
digital temporal fitting
image enhancement
image restoration

Question 29

Considerations for flat-panel detectors

Answer 29

read out rate
pixel element size
pixel fill factor

Question 30

mobile fluoroscopic equipment components

Answer 30

two units: intensifier/flat-panel detectors and workstation unit
intensifier consists of a c-arm: variety of movements and an x-ray tube
workstation unit: various handles for movement and positioning, power switch and exposure switch, controls for radiographic settings and PACS system connection

Question 31

mobile fluoroscopic equipment components cont.

Answer 31

advanced image quality enhancement software
abilty to save and swap images between monitors
contrast controls
brake pedal
x-ray tube: stationary and rotating anode

Question 32

mobile fluoroscopic equipment components cont 2

Answer 32

generator and range of exposures

TV camera