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Comparison of X-rays, Protons, and Heavy Ions
| Parameter | X-rays | Protons | Carbon Ions |
|---|---|---|---|
| Volume of irradiated normal tissue | Large | Small | Smallest |
| Biological effectiveness | |||
| In normal tissue | Low | Low | Low |
| In tumor tissue | Low | Low | High |
| Targeting precision | Low | High | Highest |
| System cost | Low | High | Highest |
| Worldwide centers, No. | Thousands | 55 | 10 |
| Worldwide treated patients, estimate | Millions | 120 000 | 15 000 |
