SBRT

Stereotactic body radiotherapy (SBRT) is a form of external beam radiotherapy that delivers high doses of ionizing radiation to a clearly defined tumor target in a small number of treatment sessions, typically one to five. SBRT relies on rigid immobilization, precise imaging, and advanced motion management to achieve millimeter accuracy and minimize dose to surrounding healthy tissue.

Planning and delivery involve a dedicated treatment planning CT, 3D conformal or intensity-modulated techniques, and image-guided verification at each session. Techniques such as fiducial markers, respiratory gating, breath-hold, or real-time tumor tracking are used to account for breathing and organ motion.

Dose and fractionation vary by tumor site and size. Common regimens include 50 Gy in 5 fractions, 54-60 Gy in 3-5 fractions, or 40-60 Gy in 3-4 fractions for liver or pancreas lesions. Spinal metastases are sometimes treated with 16-24 Gy in 1-3 fractions. The overall biologically effective dose is higher than conventional radiotherapy, enabling rapid tumor control.

Indications include early-stage non-small cell lung cancer in medically inoperable patients, solitary or limited metastatic lesions (oligometastatic disease) in liver, lung, spine, pancreas, kidney, adrenal glands, and other sites. SBRT is distinct from stereotactic radiosurgery (SRS), which is typically used for brain lesions.

Outcomes reported in selected diseases show high local control rates and favorable short-term toxicity profiles when delivered by experienced teams and with careful patient selection. However, toxicity to surrounding organs and long-term effects can occur, depending on location, dose, and fractionation.

Limitations include the need for specialized equipment and multidisciplinary planning, close comanagement of movement and dose to nearby critical structures, and limited suitability for large, diffuse, or previously irradiated lesions.