Download Contouring Structures and Targets in Radiation Oncology: New

Maria Golish, CMD, RTT, BS
Thank you auto-segmentation!!
• Had a limited role in early days of
Radiotherapy
• Mostly based in Diagnostic
Radiology department
• Slowly increased importance in
RT department
• Currently every step involves
Imaging
•
•
•
•
•
•
Diagnosis
Simulation
Treatment Planning
Physics QA
On treatment verification
Image guided treatment
Finding the edges of an anatomical
site or tumor and identifying that
as a structure
• Subjective
• Inconsistent
• Difficult to accomplish
when artifacts are present
• Time consuming
Involves combining multiple image sets
into one coordinate system
• Organ delineation software
• Can include multiple samples for
better outcome
• Models an organ’s shape using a
mesh of the structures surface
• Tools to add, edit, and modify
Screenshot courtesy of Philips Pinnacle³
Screenshot courtesy of Philips Pinnacle³
Step 1: Position mesh over organ
Step 2: Automatic adaptation of the
organ mesh₂
𝐸𝑡𝑡𝑡𝑡𝑡 = 𝑤𝑖𝑖𝑖 𝐸𝑖𝑖𝑖 + 𝐸𝑒𝑒𝑒
Screenshot courtesy of Philips Pinnacle³
Uses Gradient values
to define organ
surface
Video
courtesy of
Philips
Pinnacle³
Best fit vs Weighted average
A way of manipulating an image so the geometric
correspondence of 2 or more images is improved
Image courtesy of Mirada Medical, UK
Image courtesy of Mirada Medical, UK
Images courtesy of Mirada Medical, UK
Image courtesy of Mirada Medical, UK
Image courtesy of Mirada Medical, UK
Image courtesy of Philips Pinnacle³
Image courtesy of Philips Pinnacle³
Image courtesy of Mirada Medical, UK
The lymph node region in green was defined as
another region of interest.
Image courtesy of Mirada Medical, UK
Image courtesy of Mirada Medical, UK
So what structures am I supposed
to contour?
http://www.rtog.org/CoreLab/ContouringAtlases/Lung
Atlas.aspx
“CTGTV is the gross target volume
defined on CT, will be a composite
volume of the primary tumor mass
(GTVT) and nodal diseases (GTVN)”₃
http://www.rtog.org/CoreLab/ContouringAtlases/LungAt
las.aspx
“The primary tumor should be
contoured on CT images under a
standard lung window/level for its lung
borders and under a mediastinal
window/level for the borders adjacent
to mediastinum”₃
http://www.rtog.org/CoreLab/ContouringAtlases/LungAtl
as.aspx
Mandatory Critical Structures
•
•
•
•
Lung, Esophagus, & Spinal Cord
Brachial Plexus
Chest Wall
Pericardium, Heart and Great
Vessels
Brachial Plexus
“This is only required for patients with tumors of upper
lobes. Only the ipsilateral brachialplex is required. This
will include the spinal nerves exiting the neuroforamine
from top of C5 to top of T2. In contrast to prior RTOG lung
studies of contouring the major trunks of the brachial
plexus with inclusion of subclavian and axillary vessels,
this trial requests contouring the nerves according to the
CT anatomy on every other CT slice. The structure should
extend at least 3 cm above the PTV.”₃
Int. J. Radiation Oncology Biol. Phys., Vol. 72, No. 5, pp. 1362–1367,
2008
Int. J. Radiation Oncology Biol. Phys., Vol. 72, No. 5, pp. 1363, 2008
Conclusion
•
•
•
•
•
•
Image Registration
Image Segmentation
Model Based Segmentation
Auto-Segmentation with Atlases
Deformable Image Registration
RTOG Corelab contouring
assistance
Thank You!!





1) http://en.wikipedia.org/wiki/Image_registration
2) Michael R. Kaus, Todd McNutt, PhD, Jim Shoenbill,
MSc, Model-Based Segmentation, for treatment with
Pinnacle³ , Philips Medical Systems, August 2006, 4535983-04371
3)http://www.rtog.org/CoreLab/ContouringAtlases/Lun
gAtlas.aspx
4) WILLIAM H. HALL, M.D.,* MICHAEL GUIOU, PH.D.,* NANCY Y. LEE,
M.D.,y ARTHUR DUBLIN, M.D. et al.. DEVELOPMENT AND VALIDATION
OF A STANDARDIZED METHOD FOR CONTOURING THE BRACHIAL
PLEXUS: PRELIMINARY DOSIMETRIC ANALYSIS AMONG PATIENTS
TREATED WITH IMRT FOR HEAD-AND- NECK CANCER, Int. J.
Radiation Oncology Biol. Phys., Vol. 72, No. 5, pp. 1362–1367,
2008
5) Wu Zhou and Yaoqin Xie, Interactive Multigrid Refinement for
Deformable Image Registration, BioMed Research International,
Volume 5 September 2013, Article ID 532936