Testing 3D Ultrasound with Image-Guided Robotics for

Prostate Brachytherapy

Nathaniel HaywardDepartment of Medical BiophysicsThe University of Western Ontario

Supervisor: Aaron Fenster

Prostate Cancer• 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

Bladder

Needle Pre-Loaded with Iodine25 Seeds

Standard Brachytherapy Procedures

Prostate Brachytherapy

• 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?

• 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

The Problem

Prostate Phantom Testing

• 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)

Needle Needle

•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

The Solution

Robot Accuracy

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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

• Jeffrey Bax•David Smith•Laura Bartha•Jacques Montreuil•Shi Sherebrin•Lori Gardi•Chandima Edirisinghe

• Aaron Fenster - Supervisor•Adam Krasinski- Supervisor

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.