Characterization of RespiratoryInduced Kidney Motion Using 4DCT

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Characterization of Respiratory-Induced Kidney
Motion Using 4DCT

• A retrospective analysis of 20 patients

Presented by Xiao-Yue Han
Date 17 October 2008
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Agenda

• Era of conformal radiotherapy IMRT
• Precision versus accuracy
• The problem of breathing
• Intra-fraction organ and tumor motion
• Retrospective analysis of kidney motion
• Aims, methods, results, conclusions
• Future research directions

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CONFORMAL RADIOTHERAPY
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That one looks a bit fancier.
http//news-service.stanford.edu/news/2007/april18
/med-accelerator-041807.html
http//www.varian.com/us/oncology/radiation_oncolo
gy/clinac/clinac_ix.html
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Implications of conformal radiotherapy

• IMRT
• s
• Highly sculpted/precise dose
• Enhanced therapeutic ratio
• Normal tissue sparing
• -s
• Cost
• Tedious, Tx time
• Necessitates greater accuracy
• Pt positioning/immobilization ? interfraction
• ??? ? intrafraction

http//varian.mediaroom.com/file.php/141/Dosedist
ribIMRTprostate.jpg
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THE PROBLEM OFBREATHING
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Abdominal organs are tightly packed
http//intensivecare.hsnet.nsw.gov.au/five/images/
abdominalorgans.jpg
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Abdominal structures move

• Organ migration
• Tumor shrinkage
• Respiration

RESPIRATORY MOTION CAN BE DELETERIOUS
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4DCT KIDNEY STUDY
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Aims

• To assess the extent of respiratory-induced
  kidney motion in the superior-inferior,
  anterior-posterior, and lateral-medial dimensions
• To evaluate respiratory-induced volumetric
  changes in the kidneys

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Methods

• Retrospective
• 20 pts
• 7 f, 10 m, 3 unk.
• 6 pts age range 43-78 y, 14 pts unk.
• 1 diseases Lung, liver, lower GI
• FB 4DCT sim on 4-slice Phillips or GE scanner,
  2.5-3mm
• No immobilizers, supine
• Images binned, IP derived
• 560 kidney contours total
• WACOM on Varian Eclipse Tx Planning
• MATLAB CERR for data analysis/processing

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Process Flowchart
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DATA
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What is the relationship between L/R?
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Conclusions

• p2p respiratory-induced kidney motion is greatest
  in the superior-inferior dimension (right skewed
  distribution)
• p2p volume change (deformation) of the kidney was
  related to size of kidney

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Limitations

• Only 20 pts
• Centroid motion
• 4DCT emergent technology
• Artifact
• Binning
• Not controlled for age or BMI

Chen, et al., Seminars in Radiation Oncology, Vol
14, No 1 ( January), 2004 pp 19-26
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FUTURE RESEARCHDIRECTIONS
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Future Research Directions

• Automated contouring
• Generate a lot more data a lot faster
• Robustness of observed data over time
• Multiple 4DCT scans over time, no Tx
• Multiple 4DCT scans over time, Tx
• Novel ways of understanding dynamic positioning
  of organs/tumor volumes
• Density distribution of structures
• Real-time motion surrogates
• What about the centers w/o 4DCT?

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Acknowledgements

• OHSU
• Charles R. Thomas, Jr.
• Charlotte D. Kubicky
• Martin Fuss
• Jayashree Kalpathy-Cramer
• UTHSCSA
• Clifton D. Fuller

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QUESTIONS
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