Stereotactic body radiotherapy (SBRT)

Stereotactic body radiotherapy (SBRT) is a means of administering radiotherapy to a tumor from different directions.

SBRT provides radiotherapy from many different locations around the body. The radiation beams ultimately meet at the tumor, resulting in the highest dose of radiation being effected to the tumor core, as opposed to the surrounding tissue. This ultimately results in a reduction of side effects caused by absorption of radiation in surrounding tissue.

SBRT is largely used in the treatment of very small cancers, including lung, lymph nodes and spinal cord tumors.

This therapy has multiple steps in the procedure plan, starting with a CT scan. A PET scan or MRI may also be required, focussing on the area of the body that ultimately needs  treatment. The data from all the preceding scans is then directly calibrated into the radiotherapy planning computer software. The computer software will then co-ordinate radiation beams to follow the shape of the tumor in close proximity, all the while making sure that the total tumor area is inside the radiotherapy field, and ultimately avoiding all healthy tissue. This further diminishes the risk of side effects.

The radiographer will administer markings on the body, making sure that the same area is treated at subsequent sessions. Moulds or masks may also be used during treatment, keeping the target area in place. Metal markers (fiducial markers) may also be inserted in or near the tumor, making sure that the treatment area is targeted with the utmost precision.

Different machines may be used to give SBRT, however the goal remains the same–the delivery of higher doses of radiation therapy to a specific target area.

SBRT is often a preferred treatment option, as it is a minimally invasive technique. Due to the accuracy of this method of treatment, fewer sessions are therefore required. SBRT treatment is delivered in 1 to 5 sessions, compared to 5 to 8 weeks with standard treatment. The therapy combines three dimensional imaging with highly targeted x-ray beams, concentrated on the tumor from different angles.

This form of treatment is particularly effective in treating small, well defined tumors in inoperable or surgically challenging locations. It is highly effective in treatment of localised tumors with pinpoint accuracy.