2Department of Radiation Oncology, Okmeydanı Training and Research Hospital, İstanbul-Turkey
3Department of Medical Physics, Okmeydanı Training and Research Hospital, İstanbul-Turkey
4Department of Radiation Oncology, Avrupa Şafak Hospital, İstanbul-Turkey DOI : 10.5505/tjo.2018.1870 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.