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System and Method for Real-Time Applicator Position (RAP) Monitoring in High-Dose-Rate Brachytherapy
Using Infrared Camera and Infrared Markers
UIRF Case #: 2013-031
Inventors: Junyi Xia, Yusung Kim, and Timothy J. Waldron.
Background:
Brachytherapy is a cancer treatment that delivers radiation dose through an applicator positioned within the
body and close to the tumor. This procedure irradiates the tumor directly while sparing surrounding healthy
tissue. The course of treatment usually lasts only four weeks compared to six to seven weeks for external beam
radiation treatments. Brachytherapy is used for gynecological, breast, brain, head, neck, lung, eye, and prostate
cancers. Brachytherapy is often performed on an outpatient basis by itself or combined with other treatments,
such as external beam radiation, chemotherapy, or surgery.
There are two kinds of Brachytherapy. Permanent brachytherapy is primarily used in the treatment of prostate
cancer. This technique uses 60 to 120 Iodine-125 or Palladium-103 radioactive seeds that are implanted directly
into the cancer location, where they emit low-dose-rate (LDR) radiation throughout the treatment. Temporary
brachytherapy is primarily used for prostate, breast, and gynecological cancer using Iridium-192. This
procedure uses a high-dose-rate (HDR) source to deliver radiation into the tumor through thin needles or
applicators guided by a computer-controlled afterloader device. The radiation source leaves the patient at the
end of each treatment. Temporary brachytherapy is delivered in a series of fractions.
Kinect is a motion sensing input device by Microsoft. It enables users to interact with a natural user interface
using gestures and spoken commands. Microsoft released a Kinect software development kit for Windows that
allows developers to write Kinect applications in C++/CLI, C#, or Visual Basic.NET.
Technological Description:
This technology is to use a pair (or more) of self-calibrated infrared (IR) markers to monitor in real-time the
location and motion of an HDR brachytherapy applicator. The markers are placed on the applicator (itself
placed inside patient) and on the patients exterior for reference. The applicator motion is tracked using IRtracking algorithms that IR images acquired from IR cameras, such as Microsoft Kinect.
This tracking method is important in intracavitary brachytherapy because it allows clinicians for proper
corrections when unacceptable applicator displacements occur, thus minimizing the dosimetric uncertainties
that caused by the applicator positional differences between a treatment plan and delivery.
Advantages:
REAL-TIME PROBE TRACKING – the IR tracking system provides real-time applicator positioning
information at 8 frames per second and allows for adjustments of probe positioning should the HDR applicator
probe become displaced due to patient transfer.
HIGHLY ACCURATE MEASUREMENT – the tracking system can achieve sub-millimeter accuracy in
detecting applicator displacement.