Story highlights After decades of battling one of the world's biggest killers, the treatment of cancer is still an inexact science

Successful treatments such as chemotherapy work by killing the cancer cells, but they also destroy healthy tissue

In Belgium, one company is pioneering a new therapy that targets cancers with proton radiation

The machines cost as much as $125 million, but the company is developing a smaller system for hospitals

(CNN) Even after decades of battling one of the world's biggest killers, the treatment of cancer is still an inexact science.

Successful methods such as chemotherapy work by killing the cancer cells, but they also destroy healthy tissue.

Health practitioners have been searching for a magic bullet that goes straight to the source of the cancer -- and everything from monoclonal antibodies, which carry cancer drugs direct to cancer cells, to straight surgery to cut out tumors have been used with varying degrees of success.

In Belgium, engineer and nuclear physicist Yves Jongen is pioneering a new therapy that targets cancers with proton radiation; a therapy that offers precision and minimal side effects.

"I started to designing equipment (for) proton therapy of cancer -- that was a radically new idea," Jongen told CNN.

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