Your SlideShare is downloading. ×
0
Causes of Noise in PET imaging
Causes of Noise in PET imaging
Causes of Noise in PET imaging
Causes of Noise in PET imaging
Causes of Noise in PET imaging
Causes of Noise in PET imaging
Causes of Noise in PET imaging
Causes of Noise in PET imaging
Causes of Noise in PET imaging
Causes of Noise in PET imaging
Causes of Noise in PET imaging
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Causes of Noise in PET imaging

1,009

Published on

Published in: Health & Medicine, Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
1,009
On Slideshare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
15
Comments
0
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide
  • (a) The decay of a neutron deficient, positron emitting isotope (b) the detection in coincidence of the annihilation photons within a time window of 2t ns © the glucose analogue deoxyglucose labelled with positron-emitter F-18 to form the radiopharmaceutical F-D-G (c) FDG is injected and detection of pair of annihilation photons is done by a multi-ring PET detector camera (e) collection of positron annihilation events into sinograms where each element of the sinogram represents # annihilations in specific projection direction (f) coronal section of a final reconstructed whole-body PET image mapping the utilization of FDG in the body
  • Transcript

    • 1. Causes  of  Image  Noise  in  PET   Vibha  Chaswal,  Ph.D.  
    • 2. Positron  Emission  Tomography  
    • 3. PET  imaging:  Ideal  case   = Annihilation event Positron emitting nucleus ϒ1   = event of detection of photon in the detector ring e+   Detector Ring Line of Response (LOR) ϒ2   Two simultaneous (within 6-12 ns time difference) events in the detector make a line of response.
    • 4. Data  arrangement   ϒ1   θ Angle (θ) Sinogram ϒ2   t (t, θ) Position (t) Count on a Line of Response gets mapped to the corresponding position in a sinogram.
    • 5. DeviaEons  from  Ideal  case  –  scaGer   events   True counts ϒ1   e+   Detector Ring True Line of Response (LOR) ϒ2   ϒ2`   = Annihilation event Detected scatter event’s misplaced LOR = event of detection of photon in the detector ring
    • 6. DeviaEons  from  Ideal  case-­‐  Random   counts   True counts ϒ1   +   Detector Ring False (LOR), contributed from two separate annihilation events ϒ2   = Annihilation event = event of detection of photon in the detector ring
    • 7. PET:  Noise   •  Background  noise:  ScaGer  events  map   misplaced  counts  to  the  sinogram  and   Random  events  map  false  or  spurious  counts   •  ScaGer  -­‐  Supress  with  collimaEon  and   detectors  with  beGer  energy  resoluEon   •  Randoms  -­‐  Supress  by  smaller  sampling   window  of  coincidence,  i.e.,  faster  scinEllator   detectors;  and  CollimaEon  
    • 8. Factors  affecEng  counts   •  Trues   ↑  as  radio-­‐nuclide  concentraEon  ↑  (the  good  stuff)   ↓  as  paEent  size  ↑  (absorpEon  and  scaGer  effects)   •  Randoms   ↑↑  as  count  rate  ↑  (varies  as  square  of  count  rate)    Effects  dominate  image  noise  at  high  injected  acEviEes    Reduce  by  faster  electronics,  faster  crystals   •  Sca/ers   ↓  with  collimaEon   (about  15%  for  2D  PET  and  50%  for  3D  PET)   Reduce  with  collimaEon   (energy  selecEon  not  efficient  in  PET)  
    • 9. PET  improvements  leading  to   improved  SNR   •  Faster  electronics   •  Faster  scinEllators:  shorter  coincidence  Eming   window,  reduced  dead  Eme,  improved  energy   resoluEon  window.     •  PET/CT  technology,  ACFs  from  CT  scan  (reduced   paEent  movement  related  noise  factors  from  long   transmission  scans),  total  scanning  Eme  reduced   to  10-­‐15  minutes.   •  Fourier  re-­‐binning  and  staEsEcally-­‐based   algorithms  
    • 10. Resources   •  DW  Townsend,  ‘Physical  principles  and   technology  of  clinical  PET  imaging’,  BJR,  March   2004,  Vol  33  (2)   •  Bushberg  book   •  J  A  Anderson,  ‘IntroducEon  to  PET/CT’,  CRCPD   winter  2004  meeEng  presentaEon  
    • 11. Thank  You!  

    ×