Ultrasound Guided Robotics for Prostate Brachytherapy.ppt

Report
Nathaniel Hayward
Department of Medical Biophysics
The University of Western Ontario
Supervisor: Aaron Fenster
• The most commmon non-skin cancer among Canadian men
• 25, 500 men will be diagnosed this year
•4, 400 of these cases will be fatal
•Treatments of Prostate Cancer
• Irradiation of Prostate Externally:
•Troubled Urination, Irritation
• Complete Prostatectomy:
•Incontinence, Impotence, Altered Bowel Habits
•Prostate Brachytherapy:
• Troubled Urination (Short-Term),Impotence
Standard Brachytherapy Procedures
Needle Pre-Loaded
with Iodine25 Seeds
Bladder
• Used to treat early localised prostate cancer tumours
•Utilises implantation of radioactive seeds
•Seeds deliver a local high-dose radiation that decreases
•Less damaging than other irradiation techniques as the
seeds are implanted directly into the prostate
Standard Brachytherapy Procedures
3-D Ultrasound Method
• Sound Waves sent and received at different angles
•Returning echoes are processed by a computer which
reconstructs a 3-D image
•Works much like a CT scan that utilises multiple x-rays
(true image)
Standard Brachytherapy Procedures
Image Quality vs. Real-Time
• There is a trade-off between quality and how fast the
image is processed.
• Why is this important?
The Problem
• Needles are guided parallel to TRUS transducer
•5mm increments limit lateral positioning
•Prostate changes position during procedure
• Need constant adjustment, Labour intensive for physician
•Enlarge Prostates – sections occluded by patients pubic arch
•Parallel insertion completely miss these areas and lead to
insufficient dose coverage
• Allows for testing of brachytherapy procedures
•Prostate mold is cast from a stereo-lithograph of a real patient
•Mold injected with molten agar and left to cool (Clear)
•Background agar is created to fill the rest of the box (Opaque)
The Solution
•Image-guided robotics receiving real-time updates
•Removes problem of pubic arch interference
•Previous Attempts have distinct advantages
•Respective procedures are still invasive
•Current project utilises physician
•Robot loads, and positions needle
Needle
Needle
Robot Accuracy
MTE
CT
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CT
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MTE
US
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US
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•Evaluation of Mean Target Accuracy involves:
a) Guide the needle to a 3D target
b) Record the location of the needle within the image
NGE 
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NLE 
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Needle Accuracy vs. Resolution
Robot Accuracy
• Needle accuracy of actual target vs. “true” measurement
and measurement using 3D-guided Robotics
Future Work
• Testing on human subjects
•Give a better feel for different sized prostates and
accuracies
• Reduce the size of the robot
•Portability, Improve physician accuracy
• Improve design to work with larger angles
•Increases success of brachytherapy especially in
patients with enlarged prostates
Acknowledgements
• Aaron Fenster - Supervisor
•Adam Krasinski- Supervisor
• Jeffrey Bax
•David Smith
•Laura Bartha
•Jacques
Montreuil
•Shi Sherebrin
•Lori Gardi
•Chandima
Edirisinghe
References
• Bax J, Fenster A, Montreuil J, Gardi L, Smith D. Apparatus And Method
For Guiding Insertion of a Medical Tool. US Patent Application
No: 11/427,121: Filed June 28, 2007 (Pending).
• Fenster A, Downey DB, Cardinal HN. Three-dimensional ultrasound
imaging. Physics in Medicine & Biology. 2001 ;46R67-R99.
•D.W. Rickey, P.A. Picot, D.A. Christopher, and A. Fenster, “A Wall-less
Vessel Phantom for Doppler Ultrasound Studies,” Ultrasound in
Med. & Biol 21(9), pp.1163-1176, 1995.

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