Stereotactic body radiation therapy (SBRT) is a technique designed to deliver radiation therapy very precisely to tumors anywhere in the body. Such advancement in accuracy of radiation treatments allows higher doses of radiation to be delivered in a shorter period of time (typically 3 to 5 treatments carried out over the course of 1 to 2 weeks vs. a standard 40-day treatment regimen) thus potentially improving the likelihood of killing the cancer cells of a tumor and helping to reduce side effects for patients.
We use SBRT for the treatment of small tumors in the lung and liver. Usually small tumors of the lung are removed by a surgeon. However, many patients have other medical problems that prevent them from undergoing surgery. For patients with small lung tumors who are not able to undergo surgery, we now can offer them SBRT.
St Elizabeth’s Medical Center also offers linear accelerator based stereotactic radiosurgery (SRS) which provides radiation in the form of a highly focused beam applied in multiple sweeps around the lesion. This highly accurate form of treatment is ideal for the treatment of certain types of tumors. This method uses either a single session treatment called stereotactic radiosurgery (SRS) or multiple treatment sessions called fractionated stereotactic radiotherapy (STRT), with each offering advantages for appropriately selected patients.
Both stereotactic radiosurgery and stereotactic radiotherapy are non-invasive treatments that use pencil-thin beams of radiation generated by a special linear accelerator to administer treatment effectively allowing higher doses of radiation to be delivered. Due to the ability to deliver higher doses of radiation to the treatment area, patient motion must be controlled. For immobilization purposes, a head frame is attached to the patient's skull through the use of specially designed pins until the treatment session is finished. There is little or no discomfort during the actual treatments which can be performed on an outpatient basis without many of the usual risks and side effects associated with surgery.
Part of the linear accelerator called a gantry rotates around the patient, delivering radiation beams from different angles. The ability to rotate 360° around the patient enables the very small beams with varying intensity to be aimed at the tumor from multiple angles. The radiation treatment being delivered to the patient can be modulated continuously throughout treatment without interrupting the gantry movement. By shaping and modulating a highly focused treatment beam, the dose to the tumor is more concentrated, in turn sparing surrounding healthy tissue better.
SRS differs from existing techniques because it delivers dose to the whole volume, rather than slice by slice. With SRS, areas of the brain for which other therapies or conventional surgery are ineffective, can be successfully treated.