BERKELEY, CA (UroToday.com) - Prostate cancer patients being treated with radiotherapy can now have their prostate position known to within 0.5mm during radiation treatment. Prostate cancer position is critical to accurate targeting of the radiation beam to avoid missing the tumour and irradiating healthy tissue. In a world first, a new prostate cancer-tracking system has been implemented in a 10-patient pilot study at the Royal North Shore Hospital. The technique, termed ‘KIM’ for kilovoltage intrafraction monitoring, uses x-rays during the radiation treatment to measure the position of markers implanted into the prostate though a novel 2D-to-3D calculation method. The system was originally conceived at Stanford University in 2008 by two of the investigators of this research, Drs. Keall and Poulsen, and is a collaboration between the University of Sydney, the Royal North Shore Hospital and Aarhus University in Denmark. In the current study, prostate cancer motion of over 10mm was seen during treatment.
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The overall accuracy of the system was higher than 0.5mm, better than other dedicated commercial prostate monitoring systems that can be purchased but have not been widely implemented in clinical practice. As well as being more accurate, an additional advantage of the KIM system over the dedicated systems is that it uses readily available radiation therapy equipment. So there is enormous potential for low-cost routine use of the system, worldwide.
“KIM is exciting for patients because it’s going to open up a new area of radiation oncology, real-time tumour tracking,” said Dr. Thomas Eade, a radiation oncologist at the Royal North Shore Hospital. “Further work and analysis is needed to decide on the appropriate patient groups, the benefits and its appropriate usage. But, it could potentially be available to all cancer radiotherapy patients who are treated using standard machines.”
Using the KIM system X-rays to measure the prostate motion adds a small amount of additional imaging dose delivered to the patient - approximately 1% of the treatment dose in the current studies, though there is potential for improvement. “KIM was implemented within the constraints of an existing clinical cancer radiotherapy system,” said Prof. Paul Keall, an NHMRC Australia Fellow at the University of Sydney and Principal Investigator of the research study. “We have several ideas to explore to make the system even more accurate with lower imaging dose.”
In the future, the research team plan to use the KIM information to pause the treatment when the prostate moves beyond a motion threshold, and ultimately to continuously align the radiation beam with the cancer throughout the treatment.
The research was supported primarily through an NHMRC Australia Fellowship grant. A paper based on this work has been published in the International Journal of Radiation Oncology Biology, Physics.
Written by:
Paul Keall, PhD as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
Radiation Physics Laboratory
Sydney Medical School and Institute of Medical Physics
School of Physics
University of Sydney
New South Wales, Australia
The research was supported primarily through an NHMRC Australia Fellowship grant. A paper based on this work has been published in the International Journal of Radiation Oncology Biology, Physics.
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