Özet:

OBJECTIVE Central nervous system (CNS) tumors are the most common solid organ tumors in children. We aimed to compare two modern radiotherapy techniques in target volumes and doses received by organs at risk (OAR). METHODS Eleven patients who had undergone 3D conformal radiotherapy (3DCRT) with the indication of craniospinal radiation therapy (CSRT) were included. OAR and target volumes were defined. The planned target volume (PTV) was PTV of the brain and PTV of the entire spine. A total of 36 Gy at 1,8 Gy/fraction was given to all patients. Intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) plans were prepared. RESULTS At mean doses of optic nerve, thyroid, esophagus, heart and oral cavity; VMAT was significantly superior to IMRT. At mean doses of lungs and kidneys; IMRT was better than VMAT. Dmax of VMAT was at lower limits for all OAR. Regarding low doses received by the body, IMRT was better in V2 and V5; while VMAT was better in V15 and V20. For PTV, V95 was 99% and 97%, and V107 was 2.6% and 4% in IMRT and VMAT, respectively. Regarding monitor units (MU), VMAT revealed significantly lower MU than IMRT. CONCLUSION Two techniques are suitable treatment choices for CSRT and may be utilized to diminish the late adverse effects of radiation and to increase disease-free survival rates in patients receiving CSRT. Nevertheless, the risk of secondary cancer development should be kept in mind.

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