Which statement best differentiates external beam therapy from brachytherapy in Radiant's context?

• A. External beam therapy delivers radiation from outside the body.
• B. Brachytherapy places radioactive sources inside or near the treatment area.
• C. External beam uses implants
• D. Chemotherapy is used

Answer: (B)

The key distinction is where the radiation source is located relative to the tumor. External beam therapy delivers radiation from outside the body, using machines like a linear accelerator to shoot beams through the body from multiple directions. Brachytherapy places the radioactive sources inside or very close to the treatment area, delivering a high dose directly to the tumor with a rapid fall-off to protect surrounding tissue. The statement that describes placing radioactive sources inside or near the treatment area best captures this essential difference. The other ideas don’t define the core location difference (implants belong to brachytherapy, not external beam, and chemotherapy is a separate treatment modality).