Procedures

Image Guided Radiation Therapy (IGRT) and Tracking/Localization

Image-guided radiation therapy (IGRT) is a technology that enables radiation oncologists to target the tumor with millimeter accuracy. It 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. In some situations, implanted gold markers offer the best means to achieve image-guided localization. Markers are identified at the time of treatment to maintain precise target identification during therapy.  IGRT is accomplished in several different ways as described below.

ExacTrac

ExacTrac^® uses special equipment mounted in the treatment room to acquire images while the patient is in the treatment position. X-ray images, taken before treatment begins, are compared to reference images to assure the treatment is on target each day.

Cone Beam Computed Tomography

This capability enables acquisition of a fast, low dose CT scan while the patient is in treatment position on the linear accelerator before the treatment is delivered. 3D image data is collected and compared to reference images. This system assures the treatment is on target. 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® technology uses tiny, implanted, beacon electromagnetic transponders. About the size of a grain of rice, these beacons can be located accurately and continuously through a process similar to GPS navigation. Calypso® assures the treatment is on target during treatment each day. Calypso® is commonly used in the treatment of prostate cancer. Its use for other treatments is being explored.

KV Imaging

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 is 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 is one technique used by radiation oncology team for accurate delivery of radiotherapy treatment. Electronic portal imaging is 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 before the dose of radiation is delivered.