Radiation therapy, proton therapy, carbon-ion therapy — how they differ

All three are radiation therapy. What separates them is how much dose reaches the surrounding healthy tissue while delivering the same dose to the tumor, and how forcefully they break cancer cells apart.

Conventional radiation therapy

The foundation is external beam radiation therapy, delivering X-rays from outside the body. No radiation remains in the body once treatment ends, so there is no problem being around family or children. Intensity-modulated radiation therapy (IMRT) and stereotactic body radiation therapy (SBRT) are techniques that concentrate the dose to the shape of the tumor and spare the healthy tissue around it (National Cancer Information Center).

Proton therapy

Protons stop at a set depth and release their energy there in a concentrated burst (the Bragg peak). Almost no radiation reaches the healthy tissue beyond the tumor. Their biological effect in killing cancer cells is similar to that of conventional X-rays, and they are considered where protecting healthy tissue matters most, as in a growing child.

Carbon-ion therapy

Carbon ions are heavier than protons and break the DNA of cancer cells more forcefully, on both strands. They are also used against tumors that responded poorly to conventional X-rays, and Korea's first carbon-ion treatment began in 2023. That does not mean it is the better treatment for every cancer. The indications are defined, and for cancers that do not fit them, surgery or standard radiation therapy is the better choice.

Sources and notes

National Cancer Information Center (cancer.go.kr) · NCCN Guidelines for Patients (nccn.org) · Medical Korea (medicalkorea.or.kr). Under the Medical Service Act, this site does not cover which hospital has which equipment. This article provides general medical information. Diagnosis, treatment and outcomes vary with each person's condition; decisions should always be made in consultation with a physician.