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How does intensity-modulated radiation therapy shape radiation around a tumor?

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linear accelerator; external beam radiation therapy — radiation therapy External beam radiation therapy (also known as external beam teletherapy, or long-distance therapy) being delivered using a machine known as a linear accelerator.

Intensity-modulated radiation therapy (IMRT) is a specialized form of conformal radiation therapy that shapes radiation to match the specific contours of a tumor. It achieves this precision by utilizing a large number of small radiation fields controlled by tiny leaves, known as collimators.1

These collimators act as shutters that can block specific parts of the treatment field, allowing the machine to modulate the intensity of the radiation beam. By adjusting these fields, IMRT delivers a high dose of ionizing radiation directly to the tumor while effectively sparing the surrounding healthy tissues. Because this technique requires extreme accuracy, clinicians often use patient immobilization and image guidance to account for any movement of the tumor or internal organs during the treatment process.1