Extracranial Stereotactic Radiation Therapy, also known as Stereotactic Body Radiotherapy (SBRT), is a non-invasive method of delivering highly-focused radiation to a target within the body. This technology is being used in our practice to treat numerous conditions throughout the body that were previously unapproachable with conventional radiation or surgery. SBRT represents an excellent alternative to surgery for many patients who cannot undergo surgery or who prefer not to have surgery. This technology is one of the major advances in the field of surgery and oncology allowing our doctors to cure many diseases during a few, non-invasive treatments in our department. The most common diseases treated with SBRT include:
- Inoperable Lung Tumors
- Lung Metastases
- Spine Cancers
- Liver Tumors and Liver Metastases
- Pancreatic Tumors
- Adrenal Metastases
- Kidney Tumors
- Brain Tumors and Brain Metastases
ROA has by far the longest and most extensive experience with SBRT in Northern Virginia. SBRT can be performed using the CyberKnife® robotic radiosurgery system, which uses x-ray imaging and marker seeds to precisely target your tumor. The Trilogy® system can also perform computed tomography (CT) scans allowing doctors to use accurate imaging to guide treatment and avoiding the need for surgically implanted marker seeds.
One obstacle in treating tumors within the body is respiratory motion. To deliver an accurate, focused treatment while minimizing radiation to nearby healthy normal tissue, tumor motion as you breath must be accounted for in the treatment planning and delivery. ROA uses the most advanced equipment available to map the respiratory cycle during the target definition process. Once respiratory motion is taken into account, Trilogy® can perform respiratory-gating using a sophisticated system that controls the radiation beam in conjunction with the respiratory cycle. In addition, the CyberKnife® uses the Synchrony® Respiratory Tracking System to track the tumor motion in real-time during treatment, allowing you to breathe comfortably and naturally while receiving radiation. This allows ROA doctors to treat lung, liver, and pancreatic lesions with the greatest accuracy possible.
Typical SBRT Procedure
Step 1. Consultation
After a comprehensive consultation with one of our radiation oncologists that specializes in SBRT the appropriate imaging studies will be ordered to best visualize the tumor. Overall patient management and imaging studies are generally reviewed at our many multidisciplinary tumor boards where input is obtained from staff radiologists, pathologists, surgeons, and medical oncologists.
Step 2. Imaging Acquisition for Target Definition
The patient will report to the radiation oncology department where a custom immobilization device will be fashioned to achieve reproducible positioning and to minimize respiratory motion. Once the patient is positioned appropriately a CT scan will be obtained through that will be targeted. This data acquisition creates a 3D reference system that allows the target to be localized in relationship to 3D space in reference to the immobilization device. In some situations, marker seeds will be placed into or near the tumor by a team of specialists at least 1 week before the CT scan to help with more accurately targeting the tumor.
Step 3. Image Fusion
Once the CT data is loaded into our treatment planning system we then use fusion technology to correlate the CT data with images from an MRI, ultrasound, or PET scan to allow the most accurate visualization of the tumor
Step 4. Treatment Planning
After the target has been carefully defined, taking into account respiratory motion, the ROA doctor will sit down with our SBRT physicist to determine the optimal beam arrangements, shapes, angles, and weightings to treat the tumor while minimizing the dose to surrounding normal tissues.
Step 5. The Treatment
On the treatment days the patient is brought into the radiation treatment room and positioned on the treatment machine in their custom immobilization device. Image guidance is then performed to confirm patient positioning and localize the target at the time of treatment. Once these steps are completed the radiation is delivered. Your tumor can generally be treated in one to five sessions, allowing for minimize interruption of your daily activities. SBRT is a painless treatment and there is usually no recovery time required after this procedure.