The CyberKnife® Radiosurgery Solution: Early stage Bronchogenic Carcinoma:
Radiation Dose/Therapeutic Margin
Due to its unique tumor tracking capability, the CyberKnife® device has a published accuracy of one millimeter (14), with a much sharper dose fall off at the target volume margin, effectively rendering the high dose radiation margin more “scalpel-like,” allowing a far smaller normal tissue expansion around the target lesion. This margin reduction causes much better sparing of critical adjacent tissues from the high dose volume, allowing a substantial radiobiologic dose escalation within the target volume, resulting in the published safe delivery of >=60Gy total dose in 3 treatments, delivered in less than one week (12).
Large radiation dose per treatment is known as hypofractionation, and represents a tissue ablative radiation approach, safely administered only with an extremely precise device. Delivering 60 Gy in 3 treatments instead of the customary 30 treatments results in a radiation biological dose equivalent that is 50-100% larger, depending upon the biologic characteristics of the targeted cell population, translating to a higher probability of complete tumor eradication.
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