anatomy of fluoroscopy & ct fluoroscopy equipment l04
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IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment L04. Educational objectives. How is fluoroscopy equipment designed? - PowerPoint PPT PresentationTRANSCRIPT
Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
L04
IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists)
using Fluoroscopy
Educational objectives
• How is fluoroscopy equipment designed?
• What are the different factors that influence the X ray output from a fluoroscopic system?
• What are the new developments in fluoroscopy equipment?
2IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Fluorescent screen with leaded glass
Early (Screen Only) Fluoroscopy
3IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Modern Image Intensifier based fluoroscopy system
4IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Components of C-arm equipment
Camera
Image Intensifier
X-ray TubeFilters
Collimators
Optics
Generator &AutomaticBrightnessControl
Grid
5IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
From: R Kruger et al, Spine 2003
Bi-plane C-arm setup
6IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
A Modern Bi-Plane C-Arm with Flat Panel Detectors
X ray Tubes
Flat panelImage Receptors
7IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Multi-purpose C-arm Fluoroscopy System
Image Intensifier
X ray tube
8IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Over-couch vs Under-couch X ray Tubes
Image Intensifier
X ray Tube fixed under table
Image Intensifier
X ray Tube fixed over table
9IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Over-couch vs Under-couch X ray Tubes
• Under-Table X ray tube system subject the operator to much less scattered radiation than do over-table X ray tube systems.
• It is therefore preferable to have the X ray tube mounted below the table when purchasing fixed configuration systems.
10IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
The Image Intensifier (II)
Its function is to
• Convert X rays into visible light
• Increase the image brightness so it is visible to the camera and recording devices
11IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Automatic Brightness Control (ABC)
• Adjusts X ray intensity to produce image of predefined brightness
• Adjusts kV and mA in various ways to achieve predefined image brightness.
• Normally adjusts kV with associated adjustment in mA
12IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Theory of Operation – ABC
Camera
Iris/Diaphragm
Optics
Image Intensifier
Grid
FilterX ray Tube kV,mAK
AutomaticBrightnessControl
Collimator
Generator
ImageBrightnessFeedback
Table
Monitor
Reference Brightness
13IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Automatic Exposure Control and
Patient Thickness
kV
mA
Filtration
Focal Spot Size
Pulse Width
VerySmall
Small Medium Large VeryLarge
Patient size
Imaging modes
Fluoroscopy versus Acquisition,Magnification, Dose level
Synonyms:MAGZoom Field View (FOV)Image Intensifier field size
Magnification
16IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Smaller Image Intensifier Mode (“MAG”) has better resolution
6” 9”
0.15 mm / pixel vs. 0.23 mm/pixel
… but higher exposure to patient and staff
Magnification
17IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Radiation Output and Mag Modes
• Exposure Rate change = (old FOV)2/(new FOV)2
• Example: go from 40 cm to 30 cm
• 402/302 = 1.77
• So the smaller FOV will need 1.77x more radiation for the same image brightness
18IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
ABC increases patient dose for increased MAG
Normal, 40 cm FOV, 1 dose unit MAG 1, 33 cm FOV, 1.46 dose units
MAG 2, 23 cm FOV, 3.0 dose units MAG 3, 17 cm FOV, 5.5 dose units19
(+) mode increases dose by 50% compared to normal.(-) mode decreases dose by 50% compared to normal.
13 cm17 cm
23 cm
Low Fluoro,No MAG
High Fluoro,MAG 2
> 10 fold more exposure rate
20IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Can you tell ……….Which image is FLUOROSCOPY, which one is ACQUISITION?
Fluoroscopy vs Image Acquisition
21IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Continuous display of images, normally without recording, except last image hold (LIH)
Discrete or multiple images recorded in sequence. Commonly known as runs or cine runs
Fluoroscopy
Image Acquisition
> 10 fold more exposure rate22
IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
RadiationDose
ImageQuality
Better image quality with higher radiation dose reaching the image receptor.
Tradeoff: higher patient and staff dose!!
23IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
ALARAAs Low As Reasonably Achievable
No known safe limit of magnitude of radiation exposure
Patients
Professionalstaff
Physicians
24IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Pulsed Fluoroscopy
Pulsed fluoroscopy
26IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
• What is beam filtration?• Absorber placed between source and object
• Will preferentially absorb the lower energy photons
• Patient skin dose reduction
Effect of filtration
27IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
LowFiltrationSpectrum
Effect of filtration
Inte
nsit
y
Photon energy, keV
With increased filter and increased mA
For equal kVpIncreased mean beam energy
28IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
kVp
IncreasedMean Energy
Effect of filtration
• Additional Cu filters can reduce the skin dose by more than 70%.
• Some systems offer variable extra filtration (0.2 mm - 0.9 mm) that is automatically set according to patient weight and angulation of the C-arm.
29IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Dose Area Product (DAP)meter
Other important elements
Collimator
30IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Collimator
31IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Collimation confines the X ray beam to an area of the user’s choice.
Collimator
32IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Why is narrowing the field-of-view beneficial?1. Reduces exposure to patient by reducing volume of
tissue at risk2. Reduces scatter radiation at image receptor to improve
image contrast3. Reduces scatter radiation to in-room personnel4. Reduces potential overlap of fields when beam is
reoriented
Collimator
33IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Dose Rates and Aging Equipment
• Image Intensifier efficiency at converting X rays to light reduces over time. Thus the image becomes dimmer.
• Via the ABC, Image Intensifier input doses rates go up to compensate. (Patient and staff doses also increase.)
• A service engineer can open optical iris of TV camera to compensate, but at some stage no further adjustment available & image intensifier replacement needs to be considered.
34IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
C-arm Control Panel
kVp, mA display “Radiation on” warning Tube temperature alarm Image transfer controls Procedure timer
On Off
Manual fluoro
Automatic fluoro
Pulsed fluoro
Fluoro dose modeLow / high
Manual controlsMAG/Zoom/II field size
Image acquisition/
35IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
New developments
• Flat panel detectors
• CT fluoroscopy
• Mobile CT in operation theatre
36IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Flat panel detector
Flat panel detector instead of image intensifier
Camera
Image Intensifier
X-ray TubeFilters
Collimators
Optics
Generator &AutomaticBrightnessControl
Grid
For the user, dose level, MAG, filters and other parameters remain more or less the same
37IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Flat panel detector: bi-plane system
38IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
CT Fluoroscopy – real-time CT
• Staff enters CT room during acquisition
Needle holder
Biopsy mediastinal mass
39
Core biopsies, precise needle placement, fluid collection aspirations, drainage, local drug injection, RF ablation, lumbar nerve root blocks, vertebroplasty, arthrography, etc
Applications
UsersRadiologist, pneumologist, orthopedic surgeon, anesthetist
Patient skin dose rates typical > 10 times higher than in C-arm fluoroscopy
CT Fluoroscopy – real-time CT
40IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
10 mA paediatrics, 10-40 mA chest, 40-50 mA abdominal
Typical tube current settings in CTF
Staff protectionStandoff needle device to increase distance to primary beam
CT Fluoroscopy – real-time CT
41IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
CT in the operating theatre
• CT based surgical navigation – mobile system
• Staff leaves room during acquisition
42IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
CT in the operating theatre
• Also works in 2D conventional fluoroscopy mode
3D mode delivers radiation dose to patients that is comparable to that of a 64 slice CT scanner.
2D mode delivers radiation dose to patients and staff comparable to that of a conventional C-arm system
43IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment
Thank you
44IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L04. Anatomy of Fluoroscopy & CT Fluoroscopy Equipment