What is SBRT and its main advantage?

• A. Brachytherapy; internal radiation source.
• B. Stereotactic body radiotherapy; a high-precision, high-dose-per-fraction radiotherapy for small targets; advantages include shorter treatment courses and steep dose gradients.
• C. Wide-field conventional radiotherapy; large targets.
• D. Intensity-modulated radiotherapy; modulates beam intensity across angles.

Answer: (B)

SBRT stands for stereotactic body radiotherapy, a approach that delivers very precise, high-dose radiation to a small tumor target in only a few treatment sessions. Achieving this level of precision relies on detailed imaging for planning, strict patient immobilization, and sophisticated delivery with multiple non‑coplanar beams or rapid arc therapy, creating a sharp dose fall-off so nearby healthy tissues receive much less radiation than the tumor.

The main advantage is this combination: you get a high biologically effective dose to a small target while sparing surrounding normal tissue due to the steep dose gradients, and you can complete treatment in a shorter overall course. This makes SBRT especially useful for small, well-defined tumors in areas like the lung, liver, or spine where precision is crucial.

It’s different from other forms of radiotherapy: brachytherapy uses an internal radiation source placed inside or near the tumor, wide-field conventional radiotherapy treats larger areas, and IMRT modulates beam intensity but SBRT emphasizes stereotactic precision and high dose per fraction with tight targeting.