fotoniterapia

Fotoniterapia, or photon therapy, is a form of radiotherapy that uses high-energy photons to treat malignant tumors and, in some cases, non-cancerous conditions. The most common delivery is external beam radiotherapy, where beams of X-rays or gamma rays are directed at a target from outside the body, typically produced by linear accelerators or gamma-ray sources such as cobalt-60. Treatments are usually given in multiple sessions (fractions) over several weeks to maximize tumor control while limiting normal-tissue toxicity.

The therapeutic effect arises from ionizing photons depositing energy along their path, causing DNA damage that can kill or halt the multiplication of cancer cells. Because healthy tissues also receive some dose, treatment planning is essential. Modern planning uses CT simulation, delineation of target volumes and organs at risk, and optimization of dose distributions with multiple beam angles and shielding. Techniques include 3D conformal radiotherapy, intensity-modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT), and image-guided radiotherapy (IGRT). Stereotactic approaches, such as stereotactic body radiotherapy (SBRT) and stereotactic radiosurgery (SRS), deliver high doses in few fractions with sub-millimeter accuracy. Some SRS systems use photon beams from dedicated devices (e.g., Gamma Knife or LINAC-based systems).

Indications span a wide range of cancers, including brain, head and neck, lung, breast, prostate, and pelvic tumors, as well as metastatic disease and palliative scenarios. Photon therapy is also used in select non-oncologic conditions, such as treatment of certain vascular malformations or trigeminal neuralgia with radiosurgery. Benefits include non-invasiveness and precise dose localization, while risks involve acute and late side effects to nearby organs, dependent on treatment site and total dose.

Advances continue to refine accuracy, reduce toxicity, and expand indications, maintaining photon therapy as a central pillar of cancer treatment.