Image-Guided Radiation Therapy (IGRT)
Image-guided radiation therapy (IGRT) is a technology that enables radiation oncologists to see a targeted tumor with improved clarity helps to maximize the potential of intensity-modulated radiation therapy (IMRT) and other advanced radiation therapy techniques that are intended to spare as much healthy tissue as possible. IGRT is accomplished in several different ways.
The physicians at the ROC offer daily ultrasound imaging to locate a tumor target in advance of radiation therapy treatment. A piece of equipment called BAT® (B-mode Acquisition and Targeting) combines an ultrasound probe and a 3-D tracking system to pinpoint targets rapidly and accurately as radiation therapy treatment begins. The accuracy of this equipment enables dramatic reduction of target margins. As a result, the amount of healthy tissue exposed to radiation can be reduced, minimizing the incidence of side effects. This technology is commonly used to treat prostate cancers.
Electronic Portal Imaging
The ability to verify a patient's treatment position with confidence is necessary for accurate delivery of radiotherapy treatment. Electronic portal imaging is one technique used by the ROC to achieve such verification. Electronic portal imaging enables fast acquisition and instantaneous display of high-quality images, enabling patient positioning to be recorded throughout the treatment. The technology can identify patient positioning errors so corrective action can be taken.
In some situations, implanted markers offer the best means to achieve image-guided localization. Implanted gold markers are identified at the time of treatment with electronic portal imaging and specialized software. The implants help maintain precise target identification during treatment.
ExacTrak uses 2 x-ray tubes and detectors mounted in the treatment room to acquire images while the patient is in the treatment position. The pair of 2-dimensional x-ray images, taken before treatment begins, are compared to reference images to assure the treatment is on target each day. ExacTrak can be used for tumor targets throughout the body.
Cone Beam Computed Tomography (CBCT)
This capability enables the acquisition of a CT scan while the patient is in treatment position on the linear accelerator before the treatment is delivered. Full 3-dimensional image data is collected and compared to reference images. This system assures the treatment is on target each day. Cone Beam CT can be used for tumor targets throughout the body.
Calypso - 'GPS for the Body'
Instead of using images for locating the tumor target, Calypso uses tiny, implanted, Beacon electromagnetic transponders. About the size of a grain of rice, these Beacons can be located very accurately and continuously through a process similar to GPS navigation. Calypso assures the treatment is on target before treatment each day. In addition, continuous tracking of the Beacons assures the treatment remains on target during the treatment. Calypso is commonly used in the treatment of prostate cancer. It's use for other treatments is being explored.