Radiation therapy uses high-energy beams to target and destroy cancer cells. Stereotactic Body Radiation Therapy (SBRT) is an advanced form of this treatment, known for its precision. This article explains SBRT, how it works, the conditions it treats, and what patients can expect.
What is SBRT?
SBRT, or Stereotactic Body Radiation Therapy, is a specialized external beam radiation treatment. It delivers highly concentrated radiation doses to a specific, targeted tumor. Unlike conventional radiation therapy, which uses many smaller doses over several weeks, SBRT delivers much larger doses per session. This allows for a shorter overall treatment period, often concluding in just a few days to two weeks. SBRT is a non-surgical procedure, targeting small, well-defined tumors with intense radiation. Its aim is to destroy cancer cells while minimizing exposure to surrounding healthy tissues and organs.
The Precision of SBRT Delivery
SBRT achieves its precision through advanced imaging and sophisticated delivery systems. Before treatment, detailed three-dimensional (3D) or four-dimensional (4D) images of the tumor are acquired using CT, MRI, or PET scans. These images provide a precise map of the tumor’s location, size, and shape, allowing radiation oncologists to create a customized treatment plan.
Specialized software uses these images to design how radiation beams will be delivered. Linear accelerators (linacs) direct multiple high-dose radiation beams from various angles. These beams converge precisely at the tumor, concentrating the highest dose on cancerous cells. This focused delivery minimizes radiation exposure to adjacent healthy tissues and organs. The precision of SBRT allows for a higher dose per session, known as hypofractionation, meaning fewer treatment sessions are required, often one to five.
Conditions Treated with SBRT
SBRT is commonly used for various small, well-defined cancers. It offers a treatment option for patients unsuitable for surgery due to health reasons or tumor location. Primary cancers frequently treated include early-stage lung, prostate, liver, and kidney cancer. For early-stage lung cancer, SBRT can be as effective as surgery in some cases.
SBRT is also employed for metastatic lesions, which are cancers that have spread from their original site. Common areas for SBRT treatment of metastases include the spine, lung, and liver. Its precision allows it to effectively target tumors in difficult-to-reach locations or those near sensitive organs.
What to Expect During SBRT Treatment
The SBRT treatment journey begins with a planning phase to ensure accuracy. Patients undergo simulation scans (CT, MRI, or PET) to create detailed images of the tumor and surrounding anatomy. During this phase, custom immobilization devices, such as molds or casts, are often created to ensure the patient remains in the exact same position for every treatment session. This precise positioning helps maintain the accuracy of radiation delivery.
Actual SBRT treatment sessions are typically short, lasting between 15 to 60 minutes. The procedure is painless; patients lie on a treatment table while the machine delivers radiation. A radiation therapist operates the equipment from a separate room, observing the patient through a screen and communicating via an intercom. The number of treatment sessions is usually few, ranging from one to five, delivered over one to two weeks.
Side effects from SBRT are generally mild and temporary, varying depending on the treated area. Common short-term effects include fatigue, skin irritation at the treatment site, or, if the tumor is near the stomach or liver, nausea or diarrhea. Following treatment, patients typically resume their daily activities quickly, and follow-up appointments are scheduled to monitor the tumor’s response and overall recovery.