Designing phantom for headandneck treatment verification: feasibility tests with bone and bone equiv

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Designing phantom for head-and-neck treatment
verification feasibility tests with bone and
(bone equivalent material incorporated) into
polymer gel

• J. emnická, V. Spevácek, T. Veselský, O. Koncek
  and J. Novotný Jr.

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Do we need an authentic phantom?
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Authentic phantom

• Various kinds of inhomogenities
• Similar properties to real tissues
• Accurate, reproducible and fast read out method
• MRI
• Practical usage
• Easy manipulation, versatility (different
  irradiation modalities)

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Authentic phantom

• Various kinds of inhomogenities
• Similar properties to real tissues
• Accurate, reproducible and fast read out method
• MRI
• Practical usage
• Easy manipulation, versatility (different
  irradiation modalities)

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Heterogeneity phantoms

• Dose mapping of inhomogeneities positioned in
  radiosensitive polymer gels. Hepworth et al. 1999
• Design and manufacture of head and neck phantom
  for the assessment of IMRT delivery with gel
  dosimetry. Meyeret et al. DOSGEL 2001
• Heterogenity phantoms for visualization of 3D
  dose distributions by MRI-based polymer gel
  dosimetry. Wanatabe. 2004
• (Study of density and stability of
  lung-equivalent gel. Clayes et al. DOSGEL 2006)
• Gamma Knife 3-D dose distribution near the area
  of tissue inhomogeneities by normoxic gel
  dosimetry. Isbakan et al. 2007
• Determination of dosimetric perturbations caused
  by aneurysm clip in stereotactic radiosurgery
  using gel phantoms and EBT-Gafrochromic films.
  Geso et al. 2008

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Bone implants and gel

• Set of real vertebrae
• Bone incorporation into polymer gel
• No special treatment (was not irradiated)
• Mechanical brushing distilled water
• Acetone distilled water

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Results
R2 s-1
Non irradiated, mechanical cleaning
1 T, Siemens Magnetom Expert 16 echoes TE 22.5
ms, TR 2000 ms, Coronal orientation Slice
thickness 5 mm Pixel 1 mm 2 acquistions 12 hours
from irr.
11.5 Gy, acetone
11.5 Gy, mechanical cleaning
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Authentic phantom

• Various kinds of inhomogenities
• Similar properties to real tissues
• Accurate, reproducible and fast read out method
• MRI
• Practical usage
• Easy manipulation, versatility (different
  situations - modalities)

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3D read out small sample
1T, CPMG, 16 echos, TE 22.5ms, TR 2000 ms, 9
acquisitions, slice thickness 2 mm, pixel 1 x 1
mm, Siemens Magnetom Expert
3T, TSE, 2 echoes (12, 775 ms), TR 11000ms,
pixel 1 x 1 mm, slice thickness 3 mm, 4
acquisitions, TF 65, Siemes Trio Tim
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(No Transcript)
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3D scanning of HN phantom filled with gelatine

• Turbo spin echo (2D, 3D) Multiple spin echo,
  1.5 T (Siemens Avanto)

1.5T, 32 echos, TE 30 ms, TR 10000 ms, 1
acquisition, slice thickness 3 mm, pixel 1 x 1
mm, Axial, Not optimized!!!!
1.5T, 2 echoes (32, 539 ms), TR 15000ms, 1
acquisition, pixel 1 x 1 mm, slice thickness 1
mm, TF 100, Sagittal
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3D scanning of HN phantom filled with gelatine

• Turbo spin echo (2D, 3D) Multiple spin echo,
  1.5 T (Siemens Avanto)

1.5T, 32 echos, TE 30 ms, TR 10000 ms, 1
acquisition, slice thickness 3 mm, pixel 1 x 1
mm, Axial
1.5T, 2 echoes (32, 539 ms), TR 15000ms, 1
acquisition, pixel 1 x 1 mm, slice thickness 1
mm, TF 100, Sagittal
MAX(profile) MIN(profile) /
MEAN(profile)100 18
Variation of R2 within the scanned slices 4
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Conclusions

• Promising results with bone implants
• Mechanically cleaned
• Bone equivalent material ( other tissues)
• MR scanning
• TSE for small samples
• HN Phantom
• multiple spin echo
• susceptibility effects different materials

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Thank you for attention