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IGRT in Lung
Cancer
Dr Santam Chakraborty
Assistant Professor
Radiation Oncology
IGRT
Image Guided Radiotherapy
Describes a chain rather than a single process
“Exclusive” of the delivery process
Typicall...
T. Gupta, C. A. Narayan, Image-guided radiation therapy: Physician’s perspectives. J. Med. Phys. 37, 174–
182 (2012).
Why IGRT
S. S. Korreman, Image-guided radiotherapy and motion management in lung cancer. Br. J. Radiol. 88,
20150100 (2015...
Why IGRT ...
J.-J. Sonke, J. Lebesque, M. van Herk, Variability of four-dimensional computed tomography patient models. In...
Target Volume Changes due to Imaging
S. S. Korreman, Image-guided radiotherapy and motion management in lung cancer. Br. J...
FDG PET CT in Target Volume Delineation
Y. Zheng et al., FDG-PET/CT imaging for tumor staging
and definition of tumor volu...
IGRT Technology & Imaging
Image Guided RT
Ionizing Radiation Based Other Technologies
Planar Imaging Volumetric Imaging
KV...
IGRT Image Technologies
Technology Energy Type Accuracy Comments
EPID MV 2D 1-2 mm Surrogate imaging of soft tissue
KV Xra...
IGRT Issues in Lung Cancer
1. Lung tumors are difficult to see with megavoltage imaging.
1. Significant movement of the tu...
Difficulty in
Visualization
EPID based matching
Difficulty in
Visualization
Changes in
Volume
K. R. Britton et al., Assessment of Gross Tumor Volume Regression and Motion Changes
During Radiotherapy...
Changes in
Volume
L. A. Dawson, M. B. Sharpe, Image-guided radiotherapy: rationale, benefits, and limitations.
Lancet Onco...
Changes in
Volume
Ways to implement IGRT
IGRT Protocols
Offline Online
Q : Which one can correct for random errors?
➢ Large step
reduction
➢...
Basic points prior to Imaging
1. Reproducible comfortable positioning with immobilization
2. Tattoos help but skin marks m...
Bone Matching vs Soft Tissue Matching
M. Guckenberger, Image-guided Radiotherapy Based on Kilovoltage Cone-beam Computed T...
Good CBCT Match
Slide Image
courtesy Dr J P
Aggarwal
(TMH)
What to match on CBCT
4D-CBCT
https://www.aapm.org/meetings
/06ss/documents/SonkeConeBe
am.pdf
Systematic vs Random Error
Systematic error : Reproducible, consistent errors, occurring in the same
direction and of simi...
Example Systematic & Random Error
https://docs.google.com/spreadsheets/d/1_w1dJzakVPJeMqFFRr5PZs4MVmKrN4lFPIMr0tRHZWA/edit...
NAL correction
workflow
Example of a NAL protocol
Levels of IGRT implementation
0 1 2
RT Planning
Done more
accurately
(e.g. contrast /
PET CT /
4DCT)
3 4
Surrogate
based
m...
IGRT Lung Recommendation
Level 0 CT with contrast
PET CT for accurate target delineation
4DCT for accurate capture of moti...
Imaging Dose & consequences
Modality Effective Dose (mSv) Daily IGRT (30#)
Diagnostic Chest CT 6.4 -
EPID AP 3.6 246
EPID ...
Conclusions
● Image guided radiotherapy is an integral part of any conformal radiotherapy
program for lung cancer
● IGRT a...
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IGRT in lung cancer

A short overview of Image Guided Radiotherapy process in Lung Cancer presented at TMC Kolkata circa 2016. Basic principles and concepts as well as examples are outlined.

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IGRT in lung cancer

  1. 1. IGRT in Lung Cancer Dr Santam Chakraborty Assistant Professor Radiation Oncology
  2. 2. IGRT Image Guided Radiotherapy Describes a chain rather than a single process “Exclusive” of the delivery process Typically “onboard” guidance utilized Leads to action that improves / verifies accuracy
  3. 3. T. Gupta, C. A. Narayan, Image-guided radiation therapy: Physician’s perspectives. J. Med. Phys. 37, 174– 182 (2012).
  4. 4. Why IGRT S. S. Korreman, Image-guided radiotherapy and motion management in lung cancer. Br. J. Radiol. 88, 20150100 (2015).
  5. 5. Why IGRT ... J.-J. Sonke, J. Lebesque, M. van Herk, Variability of four-dimensional computed tomography patient models. Int. J. Radiat. Oncol. Biol. Phys. 70, 590–598 (2008).
  6. 6. Target Volume Changes due to Imaging S. S. Korreman, Image-guided radiotherapy and motion management in lung cancer. Br. J. Radiol. 88, 20150100 (2015).
  7. 7. FDG PET CT in Target Volume Delineation Y. Zheng et al., FDG-PET/CT imaging for tumor staging and definition of tumor volumes in radiation treatment planning in non-small cell lung cancer. Oncol. Lett. 7, 1015–1020 (2014). ● 35% have change in stage assignment ● Fused CT / PET result in target volume changes in 60% ● Reduced variability seen in GTV delineation between observers.
  8. 8. IGRT Technology & Imaging Image Guided RT Ionizing Radiation Based Other Technologies Planar Imaging Volumetric Imaging KV Fluoro / X ray MV Fluoro / X ray KV CT MV CT Electromagnetic Tracking Optical Surface Tracking Ultrasound Tracking MRI based Tracking
  9. 9. IGRT Image Technologies Technology Energy Type Accuracy Comments EPID MV 2D 1-2 mm Surrogate imaging of soft tissue KV Xray KV 2D 1-2 mm Better resolution w.r.t. EPID CBCT KV 3D < 1mm Volumetric “slow” scan. MVCT MV 3D < 1mm Can be useful for adaptive radiotherapy Stereoscopic Xray KV 2D < 1mm Useful in tumor tracking. Oblique angles. USG - 3D 3 mm Main utility in prostate cancers Surface - 2D 1 mm Surface based optical tracking and localization Transponders - 2D - Independent system for tumor tracking
  10. 10. IGRT Issues in Lung Cancer 1. Lung tumors are difficult to see with megavoltage imaging. 1. Significant movement of the tumor in all 3 directions in addition to “hysteresis” 1. Significant changes in the course of treatment 1. Lung motion is independent of bony motion
  11. 11. Difficulty in Visualization
  12. 12. EPID based matching
  13. 13. Difficulty in Visualization
  14. 14. Changes in Volume K. R. Britton et al., Assessment of Gross Tumor Volume Regression and Motion Changes During Radiotherapy for Non–Small-Cell Lung Cancer as Measured by Four- Dimensional Computed Tomography. International Journal of Radiation Oncology*Biology*Physics. 68, 1036–1046 (2007).
  15. 15. Changes in Volume L. A. Dawson, M. B. Sharpe, Image-guided radiotherapy: rationale, benefits, and limitations. Lancet Oncol. 7, 848–858 (2006).
  16. 16. Changes in Volume
  17. 17. Ways to implement IGRT IGRT Protocols Offline Online Q : Which one can correct for random errors? ➢ Large step reduction ➢ Limited workload ➢ Mean error correction ➢ Allows larger dose through smaller margins ➢ Daily error correction
  18. 18. Basic points prior to Imaging 1. Reproducible comfortable positioning with immobilization 2. Tattoos help but skin marks mobile over bone (~ 5 mm) 3. Laser alignment is must 4. Rigid couchtop with indexed immobilization 5. Assume setup is incorrect unless proven otherwise
  19. 19. Bone Matching vs Soft Tissue Matching M. Guckenberger, Image-guided Radiotherapy Based on Kilovoltage Cone-beam Computed Tomography — A Review of Technology and Clinical Outcome. European Oncology & Haematology. 07, 121 (2011).
  20. 20. Good CBCT Match Slide Image courtesy Dr J P Aggarwal (TMH)
  21. 21. What to match on CBCT
  22. 22. 4D-CBCT https://www.aapm.org/meetings /06ss/documents/SonkeConeBe am.pdf
  23. 23. Systematic vs Random Error Systematic error : Reproducible, consistent errors, occurring in the same direction and of similar magnitude. It affects the dose distribution by producing a “miss” Defined as the AVERAGE of a set of displacement. Random error: Varies in direction and magnitude in each fraction. It affects the dose distribution by producing a “blur” Defined as the STANDARD DEVIATION of a set of displacements
  24. 24. Example Systematic & Random Error https://docs.google.com/spreadsheets/d/1_w1dJzakVPJeMqFFRr5PZs4MVmKrN4lFPIMr0tRHZWA/edit?usp=sharing
  25. 25. NAL correction workflow
  26. 26. Example of a NAL protocol
  27. 27. Levels of IGRT implementation 0 1 2 RT Planning Done more accurately (e.g. contrast / PET CT / 4DCT) 3 4 Surrogate based matching using bony anatomy Matching based on target anatomy (implanted markers / volumetric) Adjustment / correction for intrafraction motion Adaptive Radiotherapy National Cancer Action Team, “National Radiotherapy Implementation Group Report IGRT Final Guidance for Implementation and Use” (NHS, 2012), (available at link).
  28. 28. IGRT Lung Recommendation Level 0 CT with contrast PET CT for accurate target delineation 4DCT for accurate capture of motion For all patients Level 1 Planar imaging with matching to reliable bony surrogate ± volumetric imaging weekly (tumor morphology / volume changes)* Pancoast tumors 3DCRT Level 2 Imaging with offline matching and NAL pathway with target volume matching (volumetric / fiducial) ± volumetric imaging weekly (tumor morphology / volume changes)* All other lung tumors 3DCRT Level 2 Imaging with daily online correction with target volume matching (volumetric / fiducial) Complex IMRT / Boost or reduced margins Level 3 Intrafraction motion monitoring SABR National Cancer Action Team, “National Radiotherapy Implementation Group Report IGRT Final Guidance for Implementation and Use” (NHS, 2012), (available at link).
  29. 29. Imaging Dose & consequences Modality Effective Dose (mSv) Daily IGRT (30#) Diagnostic Chest CT 6.4 - EPID AP 3.6 246 EPID Lat 4.6 KV CBCT 24.6 738 KV XVI (Elekta) 8.1 243 Estimated life-time probability of 2nd malignancy : 1.2% - 3.7% M. J. Murphy et al., The management of imaging dose during image-guided radiotherapy: Report of the AAPM Task Group 75. Med. Phys. 34, 4041–4063 (2007).
  30. 30. Conclusions ● Image guided radiotherapy is an integral part of any conformal radiotherapy program for lung cancer ● IGRT allows safer radiotherapy in terms of OAR dose reduction. ● IGRT however needs specialized equipment and expertise ● A team effort is needed for commissioning and implementation ● Physics and Technologists need to be a part of the team !!

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