Imaging for Radiotherapy delivery and verification

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Imaging for Radiotherapy delivery and verification

  1. 1. Imaging  for  Planning  and   Treatment  Verifica4on   (Rota&on  7)   Mentor:  Ryan  Flynn,  Ph.D.     (12/16/09  –  01/15/10)   By      Vibha  Chaswal,  Ph.D.   2/24/14   1  
  2. 2. Syllabus   PHEW!!!!!!!   2/24/14   2  
  3. 3. EPID  QA   •  Uniformity  versus  thickness  (across  flat-­‐field   images)   •  SNR  versus  thickness  of  solid  water   •  MTF   •  CNR   •  SNR   •  EPID’s  alignment  with  gantry  isocenter   2/24/14   3  
  4. 4. Addi4onal   •  •  •  •  •  CNR  vs  Thickness  vs  Dose   Effect  of  filtraRon  on  images   MTF  calculaRon  validaRon   Contrast  calculaRons  for  Air  &  Bone  in  water     DidacRc     2/24/14   4  
  5. 5. EPID  QA:  Image  Uniformity  vs  Thickness   2/24/14   5  
  6. 6. 1 3 5 4 2 Uniformity  (Normalized  mean  PV  in  an  ROI)   Image  Uniformity  vs  Solid  Water  Thickness   1.010   0.980   0.950   ROI_1  (top)     ROI_2    (boaom)   ROI_3  (right)   ROI_4  (leb)   ROI_5  (center)   0.920   0.890   0.860   0.830   0.800   0   2/24/14   5   10   15   20   Solid  Water  Thickness  (cm)   25   30   35   6  
  7. 7. EPID  QA:  Signal-­‐to-­‐Noise  raRo  vs  Thickness   2/24/14   7  
  8. 8. 2/24/14   8  
  9. 9. Signal-­‐to-­‐Noise  Ra4o  vs  Thickness  of  SW  slab   300   250   SNR   200   150   100   50   0   0   5   10   15   20   25   30   35   Sold  Water  Thickness  (cm)   2/24/14   9  
  10. 10. EPID  QA:     Imaging  Parameters   (SNR,  CNR,  MTF,  Dose  dependence)   2/24/14   10  
  11. 11. Material   Physical   density  (g/cm3)   PVC   1.00   Al   2.6   Pb   11.34   0.23 lp/mm 5 mm lead 15 mm PVC QC - 3V Phantom s/n 104 0.43 lp/mm 15 mm Al 11 mm Pb 0.76 lp/mm 0.2 lp/mm 0.1 lp/mm 7.5 mm Pb 2/24/14   11  
  12. 12. MTF Calculation Validation 2/24/14   Droege R.T, Morin R. L, ‘A practical method to measure MTF of scanners’, Med. Phys. 9(5), 1982 12  
  13. 13. EPID spatial resolution: MTF Calculation lp/mm   0.1   663.45   0.2   1342.163   0.23   2066.66   0.43   MTF  measured  using  QC-­‐3V  phantom     Std  Dev   2315.17   0.76   2825.81   1.20   1.00   MTF   0.80   0.60   0.40   0.20   0.00   0   2/24/14   0.1   0.2   0.3   0.4   0.5   line-­‐pairs/mm  (lp/mm)   0.6   0.7   0.8   13  
  14. 14. Imaging  Parameters:  SNR   Region   Physical   density  (g/ cm3)   Depth    (cm)   Radiological  Path-­‐ length   (g/cm2)   1  (Pb)   11.34   0.75   8.505   2  (PVC)   1   1.5   1.5   3  (Pb)   11.34   0.5   5.67   4  (Al)   2.6   1.5   3.9   5  (Pb)   11.34   1.1   12.474   6  (Pb)   11.34   0.75   8.505   SNR  versus  Radiological  Path-­‐length   SNR  (standard  devia4on)   140   120   100   80   60   40   20   0   0   2/24/14   2   4   6   8   10   Radiological  pathlength  (g/cm2)   12   14   14  
  15. 15. SNR  analysis  ROIs  1  &  6   ROI 1 2/24/14   ROI 6 15  
  16. 16. EPID  QA:  CNR  vs  Thickness  vs  Dose   10-QC-10 1MU 2MU 3MU (QC-3V as tumor inside varying solid water thickness patients) 10 cm 20-QC-10 1MU 2MU 3MU 30-QC-10 1MU 2MU 3MU 20 cm 30 cm 2/24/14   16  
  17. 17. CNR  of  QC-­‐3  phantom  vs  Radiological  Thickness   (for  different  doses  and  solid  water  thicknesses)    60.00     Contrast-­‐to-­‐Noise  Ra4o  w.r.t.  15mm  PVC   1 MU 2 MU  50.00     10 cm 3 MU  40.00      30.00     20 cm  20.00     30  cm    10.00      -­‐         0   2   4   6   8   10   12   14   Radiological  Thickness  (g/cm2)   2/24/14   17  
  18. 18. EDPI QA: EPID Alignment (Oncor A) Gantry 0 degree Gantry 90 degree 2/24/14   18   Gantry 270 degree, Gantry 180 degree
  19. 19. Fig 4(c): Gantry 180 degree, distance measurements between x-retic and e-retic. 2/24/14   Fig 4(d): Gantry 180 degree, distance measurements between x-retic and e-retic at the central ISIS sphere region that coincides with radiation isocenter; note that distance between x-retic and e-retic is 2.3mm, which is more than the tolerance value of 2mm. Hence, EPID is not aligned within specifications at 19   Gantry angle 180-degrees.
  20. 20. Fig 4(e): Gantry 180 degree, distance measurements between x-retic and center of pinhole of ISIS. Fig 4(f): Gantry 180 degree, distance measurements between e-retic and center of pinhole of ISIS. 2/24/14   20  
  21. 21. Clinical  ObservaRon   •  •  •  •  •  •  Whole  brain  x  1   Head  and  neck  x  2  (MVCBCT)     Pelvis  x  1  (portal)  x  3  (MVCBCT)     Thoracic  x  1  (portal)  x  2  (MVCBCT)     Extra-­‐cranial  lung  x  1  (MVCBCT)     Supine  Breast  x  1  (portal)   2/24/14   21  
  22. 22. Treatment Verification: MVCBCT Extra-Cranial Lung Head & Neck 2/24/14   Pelvic 22  
  23. 23. Treatment Verification: Portal Imaging Reference DRR Right Lat Treatment day Right lat portal image Whole Brain DRR Registered DRR and portal image Pelvic DRR Reference Planning PA DRR 2/24/14   Treatment day PA portal image Registered PA images 23  
  24. 24. Thoracic DRR Reference Planning AP setup DRR Reference Planning Left Anterior Oblique field DRR at Gantry 45-deg Reference Planning field DRR Left Lat Gantry 90-deg Reference Planning Right Anterior Oblique field DRR 2/24/14   at Gantry 344.9-deg Treatment day AP double exposure portal image Treatment day Left Anterior Oblique field portal image at Gantry 45-deg Registered AP DRR and portal images Registered Left Anterior Oblique DRR and portal images Treatment day Left Lat field portal image at Gantry 90- Registered Left Lat DRR and portal images deg Treatment day Right Anterior Oblique field portal image at Gantry 344.9-deg Registered Right Anterior Oblique DRR and portal 24   images
  25. 25. THANK  YOU!!!!!   2/24/14   25  

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