radiation protection in diagnostic and interventional radiology l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
RADIATION PROTECTION IN DIAGNOSTIC AND INTERVENTIONAL RADIOLOGY PowerPoint Presentation
Download Presentation
RADIATION PROTECTION IN DIAGNOSTIC AND INTERVENTIONAL RADIOLOGY

Loading in 2 Seconds...

play fullscreen
1 / 16

RADIATION PROTECTION IN DIAGNOSTIC AND INTERVENTIONAL RADIOLOGY - PowerPoint PPT Presentation


  • 192 Views
  • Uploaded on

IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology. RADIATION PROTECTION IN DIAGNOSTIC AND INTERVENTIONAL RADIOLOGY. Part 19.06: Optimization of protection in Mammography Practical exercise. Overview.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'RADIATION PROTECTION IN DIAGNOSTIC AND INTERVENTIONAL RADIOLOGY' - avent


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
radiation protection in diagnostic and interventional radiology

IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology

RADIATION PROTECTION INDIAGNOSTIC ANDINTERVENTIONAL RADIOLOGY

Part 19.06: Optimization of protection in Mammography

Practical exercise

overview
Overview
  • To be able to apply quality control protocol to mammography equipment
  • To measure, by different methods, the focal spot size of a mammographic installation
  • Interpretation of results

19.06 : Optimization of protection in Mammography

focal spot size required equipment
Focal spot size – Required equipment

1 - Star pattern

2 - Resolution bar

pattern

3- Pinhole and

slit camera

6X magnifying loupe and reticule

19.06 : Optimization of protection in Mammography

focal spot size star pattern 1
Focal spot size (star pattern) (1)
  • The focal spot size measurement is intended to determine its physical dimensions at installation or when resolution has markedly decreased. For routine quality control the evaluation of spatial resolution is considered adequate
  • A magnified X-ray image of the test device is produced using a mammography screen-film cassette

19.06 : Optimization of protection in Mammography

focal spot size star pattern 2
Focal spot size (star pattern) (2)
  • Select the focal spot size, 28 kV, and an mAs to obtain an optical density between 0.80 and 1.40 (measured in the central area of the image)
  • The image should be imaged at the reference point of the image plane, which is located at 60 mm from the chest wall side and laterally centred

19.06 : Optimization of protection in Mammography

focal spot size star pattern 2 cont d
Focal spot size (star pattern) (2) (cont’d)
  • Remove the compression device and place the test stand on top of the bucky (breast table)
  • Place the test device on top of the cassette

19.06 : Optimization of protection in Mammography

focal spot size star pattern 2 cont d8
Focal spot size (star pattern) (2) (cont’d)
  • According the IEC norm :
    • a nominal 0.3 focal spot should not exceed 0.45 mm in width and 0.65 mm in length
    • a nominal 0.4 focal spot should not exceed 0.60 mm in width and 0.85 mm in length

19.06 : Optimization of protection in Mammography

focal spot size star pattern 2 cont d9
Focal spot size (star pattern) (2) (cont’d)
  • The focal spot dimensions can be estimated from the 'blurring diameter' on the image (magnification 2.5 to 3 times) of the star pattern
  • The distance between the outermost blurred regions is measured in two directions: perpendicular and parallel to the tube axis

19.06 : Optimization of protection in Mammography

focal spot size star pattern 2 cont d10
Focal spot size (star pattern) (2) (cont’d)

The focal spot size is calculated as:

where :

θ : the angle of the radiopaque spokes (1° or 0.5°),

Dblur : the diameter of the blur.

Mstar : the magnification factor determined by taking the ratio of the diameter of the star pattern on the acquired image (Dimage) to the diameter of the star pattern (Dstar)

19.06 : Optimization of protection in Mammography

focal spot size slit camera 1
Focal spot size (slit camera) (1)
  • To determine the focal spot dimensions (f) with a slit camera, a 10 μm slit is used.

Note: Produce two magnified images (magnification 2.5 to 3 times) of the slit perpendicular and parallel to the tube axis.

  • The dimensions of the focal spot are derived by measuring each image using an a 6X magnifying loupe with a reticule and correcting for the magnification factor according to:

f = F/Mslit

19.06 : Optimization of protection in Mammography

focal spot size slit camera 1 cont d
Focal spot size (slit camera) (1) cont’d

where:

F : the width of the slit camera

(Mslit) :the magnification factor determined by measuring the distance from the slit to the plane of the film (dslit-to-film) and the distance from the focal spot to the plane of the slit (dfocal spot-to-slit)

Mslit = dslit-to-film /dfocal spot-to-slit

NB:The method requires a higher exposure than the star pattern method.

19.06 : Optimization of protection in Mammography

focal spot size pinhole 1
Focal spot size(pinhole) (1)
  • To determine the focal spot dimensions (f) with a pinhole, a 30 μm gold-platinum alloy pinhole is used.

Note: Produce a magnified image (magnification 2.5 to 3 times) of the pinhole.

  • The dimensions of the focal spot are derived by measuring the image with a 6X magnifying loupe and a reticule, and correcting for the magnification factor according to:

f = F/Mpinhole

19.06 : Optimization of protection in Mammography

focal spot size pinhole camera images of focal spot
Focal spot size Pinhole camera images of focal spot

19.06 : Optimization of protection in Mammography

focal spot size pinhole 1 cont d
Focal spot size(pinhole) (1) cont’d

where:

F :the size of the imaged focal spot.

Mpinhole: the magnification factor determined by measuring the distance from the pinhole to the plane of the film (dpinhole-to-film) and the distance from the focal spot to the plane of the pinhole (dfocal spot-to-pinhole)

Mpinhole= dpinhole-to-film /dfocal spot-to-pinhole

NB:The method requires a higher exposure than

the star pattern method.

19.06 : Optimization of protection in Mammography

where to get more information
Where to Get More Information

European protocol for the quality control of the physical and technical aspects of mammography screening. http://euref.org/index.php?option=com_phocadownload&view=category&id=1&Itemid=8

American College of Radiology Mammography Quality Control Manual, Reston VA, 1999.

Quality Control in Diagnostic Imaging, Gray JE, Winkler NT, Stears J, Frank ED. Available at no cost. http://www.diquad.com/QC%20Book.html

19.06 : Optimization of protection in Mammography