1. Spot Filming
Cinefluorography
Fluoro Room Shielding
Radiation Areas

2. Spot Filming Spot Film Cassettes
Uses conventional radiographic cassettes.
Bypasses image intensifier for direct exposure.
Uses mA > 100 X that of photofluoro camera.

3. Spot Filming Spot Film Cameras Image the output phosphor of II.
Same mA as fluoroscopy (1-3 mA typically).
Exposes one frame/exposure.
Uses 70, 90, or 100/105 mm film size.
As you increase film size, increase image quality and patient dose.
Method of choice for spot filming compared to spot film cassettes.

4. Spot Filming Total Overframing Overframing Exact Framing Underframing
Framing (matching II output size to film area)
Total Overframing
Overframing
Exact Framing
Underframing

5. Framing and Patient Dose Reduction
Underframing
Exact Framing
Int. image = small dimension of frame
No part of image lost
Only 58% of frame used
Fluoro image < frame
Should be avoided
P. 31

6. Framing and Patient Dose Reduction
Total Overframing
Overframing
Image circle > short film dimension
Part of image lost
Circular image = diameter of frame
All of film used
39 % of image wasted

8. Cinefluorography
The process of recording fluoro images on movie (cine) film.
Film sizes
16 and 35 mm
The larger the film size, the greater the resolution and greater the patient dose.

9. Film Size
12.6 mm
30 mm

10. Cinefluorography Synchronization Framing Frequency
Camera shutter timed to the same frequency as the x-ray pulses.
Shutter open only during x-ray pulses.
Framing Frequency
Number of exposed frames/second.
Divisions or multiples of 60 Hz line rate.
Examples: 7.5, 15, 30, 90, 120 frames/second.

11. 35 mm Cine Camera

12. Shutter Synchronization

13. Cinefluorography, cont’d
Framing Frequency
Patient Exposure
Directly proportional to framing frequency.
P. 30

14. Cinefluorography, cont’d
Framing Frequency
Patient Exposure Conversions
2000 mR/frame X 1 mR/1000 mR = 2 mR/frame
2 mR/frame X 30 frames/second X 60 seconds/minute = 3,600 mR/minute
3,600 mR/minute X 1 R/1000 mR = 3.6 R/minute
P. 30

15. Cinefluorography, cont’d
F-number
Number indicating the ratio of the focal length of the camera lens to the diameter of the lens.
F-number = Focal Length of Lens/Diameter of Lens
The smaller the f-number = more light into the camera and less patient exposure.
P. 30

16. Focal length of lens

17. Focal length of lens
Lens Diameter
F-num = 50 mm / 20 mm = F 2.5

18. F-numbers Iris diaphragm
The smaller the f-number - the larger the aperture opening.
The larger the f-number - the smaller the aperture opening.

19. Depth of field

20. QA Concerns Spot Film and Cine Cameras
Beam and image size match within 3 % of SID
A small aperture (large f-number) will require greater patient exposure but result in low noise image.
Patient entrance exposures of rads or more.
P. 110

21. Structural Fluoro Room Shielding Provisions
Barriers
Primary
A barrier to attenuate the useful beam to the required degree.
Secondary
Used to attenuate stray (scattered and leakage) radiation to the required degree.
Useful Beam
Radiation that passes through window, aperture, or cone.
Stray Radiation
Leakage and secondary radiation. No useful purpose.
p. 121

22. Primary/Secondary Barriers
Exception would be in R/F room where all walls would be a primary barrier.
(Source: Principles of Imaging Science and Protection. Thompson, Hattaway, Hall, Dowd, 1994)

23. Structural Fluoro Room Shielding Provisions
Tube Leakage
Maximum 1 meter is 0.1 R/hour.
Half-Value Layer (HVL)
Thickness of material that reduces beam exposure rate by half of original value.
Tenth-Value Layer (TVL)
Thickness of material that reduces beam exposure rate to 1/10 of original value.

25. Tube Leakage
1 meter
Maximum permissible =
0.1 5 mA

26. Radiation Areas Radiation Area High Radiation Area Controlled Area
Any area where whole body dose could be = or > rem/1 hr. at 30 cm from source.
High Radiation Area
Any area where whole body dose could be = or > 0.1 rem/1 hr. at 30 cm from source.
Controlled Area
Any area where radiation safety rules enforced.
Unrestricted Area
An area in which access is neither limited nor controlled.

27. Radiation Areas, cont’d.
Restricted Area
Any area where access is limited by the licensee to protect individuals against undue risks from radiation exposure.

28. Unrestricted/Controlled Areas

29. Unrestricted
Area
Controlled
Area

30. QC-Semi-annual checks
Spot film
Film
Cine Processor
Cameras
Flare
Exposure Timer
Image Lag
Film-Screen Contac t
QC-Semi-annual checks
mAs Linearity
Image Quality
Grid
Exposure Reproducibility
Alignment
Phototimers
Linearity
Cine Film Processor
Spot Film- Cine Image
Camera Exposures
Cine Film Exposure
Spot Film
Beam Limitation
Resolution – Distortion
Film

31. Video Recording of Fluoroscopic Image
Video Tape
Video Disc
Laser Disc CD
Electronic Radiography
DVD

32. Video Tape Advantages Instant Replay No increase in patient exposure
Disadvantages Poor image quality Fixed framing rate- 30 frames/sec.

33. Video Disc (Electronic Radiography)
Advantages Last image freeze “sticky fluoroscopy” Instantaneous imaging Short exposure times 95% dose reduction during fluoro Variable framing rates – 1-30 frames/sec. Multiple image storage Random access of images
Disadvantages None significant

36. The End