1. FLUOROSCOPY EQUIPMENT

2. Learning Objectives
By the end of this Lecture the student will be able to:
Differentiate between fluoroscopic and radiographic examinations
List the basic components of the fluoroscopic system and identify the function of each component
Describe a typical basic fluoroscopic image Intensifier
Describe advantages of image intensified fluoroscopy over conventional screen fluoroscopy
Identify uses of dynamic and static fluoroscopic recording systems
Discus digital fluoroscopic image acquisition
Differentiate between conventional fluoroscopy, image intensifier
fluoroscopy, and digital fluoroscopy

3. References Websites http://www.e-radiography.net/
Bushberg, The Essentials of Physics and Medical
Imaging, Williams & Wilkins Publisher.
Positioning in Radiography: By k.C.Clarke.
Text book of radiographic positioning and related
anatomy;bykenneth L.Bontrager,5th edition
Websites

4. FLUOROSCOPY History Purpose: Invented by Thomas A. Edison in 1896
Conventional film radiography is restricted to static
patient exams. If dynamic events need to e studied such
as movement contrast materials through gastrointestinal
tract (GIT) the image must be viewed directly using a
dynamic method.
Purpose:
To perform dynamic studies.
Visualize anatomical structures in real time or motion.
View the motion and function of anatomic organs.

5. Fluoroscopic systems Conventional fluoroscopic systems
Earliest fluoroscopic systems used phosphor screens where the transmitted x-ray caused scintillations that were viewed directly.

6. Fluoroscopic systems Direct Fluoroscopy
In older fluoroscopic examinations radiologist stands behind screen and view the image.

7. Fluoroscopic systems Conventional fluoroscopic systems
The images of this type were of very poor quality for a number of reasons:-
- Poor light output by the fluorescent screen
- Low efficiency of the light conversion
mechanism
- Poor spatial resolution
for that fluorescent screens are no longer used since they gave high radiation dose to the operator.

8. Fluoroscopic with image intensifiers
What is an Image Intensifier ?
A complex electronic imaging device that receives the remnant beam and converts it to light and increases the intensity of the light.
The image intensifier tube is contained in a glass envelope in a vacuum and mounted in a metallic container which provides protection for the components.

9. Fluoroscopic with image intensifiers

10. Image Intensifier Schematics
Fluoroscopic with image intensifiers
Image Intensifier Schematics

11. Input Phosphor Constructed of cesium iodide.
Responsible for converting the incident photon’s energy to a burst of visible light photon.
Similar to intensifying screens in cassettes.
Standard size varies from cm.
Normally used to identify the II tubes.

12. Photocathode Thin metal layer bonded directly to the input phosphor.
Usually made of Cesium and Antimony compounds that respond to light stimulation.
Responsible for Photoemission.
Electron emission after light stimulation
The number of electrons emitted is directly proportional to the intensity of light intensity of the incident x-ray photon.

13. Electrostatic Focusing Lenses
A series of lenses inside the II tube to maintain proper focus of the photoelectrons emitted from the photocathode.
They contain a positive charge.
They are located along the length of the II tube.
The focusing lenses assist in maintaining the kinetic energy of the photoelectrons to the output phosphor.

14. Output Phosphor
Usually constructed of zinc cadmium sulfide crystals. Serves to increase illumination of the images by converting photoelectrons to light photons.

15. Spot Film Device
Used to make permanent images during the radiographic examination.
Film is positioned b/w the patient and the image intensifier.
When the film is needed, the radiologist actuates the control that brings the cassette in position. This changes the tube from fluoroscopic mA to radiographic mA.
During fluoroscopy, the tube is operated at less than 5 mA.

16. TV MONITORS
This practical and efficient viewing system was employed because of the limitations of the mirror optic viewing system.
TV monitors:
1. Enables viewing by multiple persons.
2. Monitors may be located in remote locations other than the radiographic room.
3. Image brightness and contrast can be manipulated.
4. Images may be stored on different medium for reviewing at a later time.

17. Fluoroscopy -Modes of operation
Manual Mode
Allow the use to select the exact MA and KVp required
AEC Mode
Allow the unit to drive the KVp and MA to optimize dose and image quality
Pulsed Digital mode
Modifies the fluoroscopic output by cutting by cutting out exposure between pulses
With the pulsed mode, it can be set to produce less than the conventional 25 or 30 images per second. This reduces the exposure rate.

18. Fluoroscopy Units
Smaller facilities may use one fluoroscopic system for a wide variety of procedures
Larger facilities have several units dedicated to specific applications, such as:
Gastrointestinal units
Remote fluoroscopy rooms
Peripheral angiography units
Cardiology catheterization units
Biplane angiography units
Mobile fluoroscopy – C arms units

19. Fluoroscopy Units 1/An over table model
Where the x-ray tube is placed above the table top, and the image intensifier under the table surface.

20. Fluoroscopy Units 2/An under table model
Where the x-ray tube is placed under the table surface , and the image intensifier over the table top.

21. Fluoroscopy Units
An under table model

22. Fluoroscopy Units
The table have the ability to tilt from horizontal to vertical

23. Fluoroscopy Units 3/Single or bi-planar cine –fluoroscopy model
Where the x-ray tube and image intensifier are fixed to c-arms.
Mostly used in surgical theatres.

24. Fluoroscopy Units
Remote control systems

25. Digital Fluoroscopy
Digital fluoroscopy is currently most commonly configured as a
conventional fluoroscopy system
This method uses digital detector technologies (eg, flat-panel
"direct" detection of x rays and charge- coupled device technology)
The analog video signal is converted to a digital
format with an analog-to-digital converter (ADC).

26. Radiation Protection General Rule (ALARA Principle) As Low Reasonably
Achievable

27. Radiation Protection
more exposure
Time
Longer usage

28. Radiation Protection TIME
Take foot off fluoro pedal if physician is not viewing the TV monitor
Use last image hold (freeze frame)
Five-minute timer
Use pulsed fluoro instead of continuous fluoro
Pulsed Low-Dose provides further reduction with respect to Normal
Dose continuous mode:
Use record mode only when a permanent record is required
Record beam-on time for review

29. Radiation Protection Distance
Distance is large factor for reducing exposure.
Inverse Square law
“ When you double the distance the exposure rate is decreased by 4 times ”

30. Radiation Protection DISTANCE - One step back from tableside:
cuts exposure by factor of 4
- Move Image Int. close to patient:
less patient skin exposure less
scatter
- Source to Skin Distance (SSD):
38 cm for stationary fluoroscopes
30 cm for mobile fluoroscopes

31. Radiation Protection X-ray Tube Position
Position the X-ray tube under the patient not above the patient.
The largest amount of scatter radiation is produced where the x-ray beam enters the patient.
By positioning the x-ray tube below the patient, you decrease the amount of scatter radiation that reaches your upper body.

32. Radiation Protection Shielding
Increasing the amount of shielding around a source of radiation will decrease the amount of radiation exposure.
To avoid scatter Be sure to shield all directions. - +
Shielding

33. Radiation Protection Lead aprons: cut exposure by factor of 20
SHIELDING
Lead aprons: cut exposure by factor of 20
Proper storage (hanging vs. folding)

34. Part No...., Module No....Lesson No
Module title
Radiation Protection
Protection tools
Eye goggles
curtain
Lead Apron
thyroid shield
IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

35. Radiation Protection Collimation
Collimate tightly to the area of interest.
Reduces the patient’s total entrance skin exposure.
Improves image contrast.
Scatter radiation to the operator will also decrease.

36. Radiation Protection Safety in Fluoroscopy
Familiarity with specific fluoro units
Factors influencing dose:
patient size
kVp, mA and time
tube - patient distance (SSD)
Image Intensifier - patient distance
image magnification vs. patient dose
x-ray field collimation
oblique's vs. perpendicular views

37. Radiation Protection Safety in Fluoroscopy
Standard Operating Procedures
- each clinical protocol / procedure
- modes of operation, image recording
- emphasis on minimizing duration
- risk / benefit on a case-by-case basis
Equipment quality control
- periodic PMs
- prompt calibrations
- post radiation output values
- check aprons, shields, gloves annually

38. Final Summary Golden rules”
Radiation Protection
Final Summary Golden rules”
Keep the II close to the patient
Do not overuse magnification modes
Keep the x-ray tube at maximal distance from patient
Use higher kVp where possible
Wear protective aprons and radiation monitors, and know where scatter is highest
Keep your distance, as far as is practicable