Dosimetric Comparison of Intensity-Modulated Radiotherapy and Volumetric Arc Therapy for Rectal Cancer
Sedenay OSKEROĞLU KAPLAN1,Halil AKBÖRÜ2,Yunus SARALI3,Süleyman ALTIN2,Mustafa ÜNSAL2
1Department of Radiation Oncology, Mehmet Akif İnan Training and Research Hospital, Şanlıurfa-Turkey
2Department of Radiation Oncology, Okmeydanı Training and Research Hospital, İstanbul-Turkey
3Department of Medical Physics, Okmeydanı Training and Research Hospital, İstanbul-Turkey
DOI : 10.5505/tjo.2018.1870 OBJECTIVE
The aim of this study is dosimetric comparison of intensity modulated radiation therapy and volumetric arc therapy that are currently applied in the preoperative radiotherapy of locally advanced rectal cancer.

Ten patients with locally advanced rectal cancer were recontoured according to defined protocol on computed tomography simulation that were previously scanned. Dosimetric comparison was done for each patients with 7 and 9 fields intensity modulated radiation therapy and volumetric arc therapy. 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.

All plans provided comparable dosimetric parameters for target volumes. Arc plans demonstrated statistically significant benefit with lower doses on V15, Dmean of small bowel compared to 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. Besides the reduction in total treatment time by approximately 60% was achieved in arc plans.

Volumetric arc therapy with short treatment duration and low monitor units can be considered as providing a more comfortable and qualified treatment. Keywords : Intensity-modulated radiotherapy; preoperative chemoradiotherapy; rectal cancer; volumetric arc therapy