Özet:

OBJECTIVE The aim of the present study is the dosimetric comparison of intensity-modulated radiation therapy and volumetric arc therapy (VMAT) that are currently applied in the preoperative radiotherapy of locally advanced rectal cancer. METHODS Ten patients with locally advanced rectal cancer were recontoured according to defined protocol on computed tomography simulation that was previously scanned. Dosimetric comparison was performed for each patient with 7 and 9 fields intensity-modulated radiation therapy and VMAT. Compared dosimetric parameters were determined as doses of organs at risk, the total duration of treatment, target coverage, conformity index, homogeneity index, and the total monitor unit (MU). RESULTS All plans provided comparable dosimetric parameters for target volumes. Arc plans demonstrated a statistically significant benefit with lower doses on V15 and Dmean of the small bowel than intensity-modulated radiation therapy. Arc plans were obviously superior relating to measured volumes of the whole body, and plans with 7 field had the worst results. In addition, the reduction in total treatment time by approximately 60% was achieved in arc plans. CONCLUSION VMAT with short treatment duration and low MUs can be considered as providing a more comfortable and qualified treatment.

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