Cancer is one of the leading causes of death in the world. Next to surgery and chemotherapy, radiotherapy is one of the most used treatment modalities for cancer. About 50% of the patients with cancer will be treated with radiotherapy during the management of their disease. In radiotherapy, ionizing radiation is used to kill proliferating tumor cells. As an unwanted (but sometimes unavoidable) side-effect, delivery of ionizing radiation to the patient may also lead to damage to healthy tissues. Generally, the total dose is delivered in a number of daily fractions. In between fractions, the healthy tissues can often more effectively repair part of the damage than tumors. Hence, the cumulative damage to tumor tissue is higher than for normal tissue when exposed to the same total dose in a large number of fractions. For most tumors and healthy tissues, this differential repair effect is enhanced with higher numbers of fractions.

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B.J.M. Heijmen (Ben)
Erasmus University Rotterdam
Erasmus MC: University Medical Center Rotterdam

de Pooter, J.A. (2008, October 16). Plan optimization for stereotactic radiotherapy. Erasmus University Rotterdam. Retrieved from