Which radiotherapy technique is better for neoadjuvant treatment of rectal cancer: A dosimetric comparison

Year 2022, , 181 - 186, 30.05.2022

Aysegul Ucuncu Kefelı Aysegul Unal Karabey Umut Efe Dokurlar Berna Tırpancı Gulsah Ozkan Aykut Oguz Konuk Maksut Gorkem Aksu

https://doi.org/10.5472/marumj.1120583

Abstract

Objective: Our aim was to compare helical tomotherapy (HT) and volumetric modulated arc therapy (VMAT) plans with
3-dimensional conformal radiotherapy (3D-CRT) considering the planning target volume (PTV) and organs at risk (OARs) in rectal
cancer patients treated with neoadjuvant radiotherapy.

Patients and Methods: Thirty patients, previously treated with intensity modulated radiotherapy (IMRT) or 3D-CRT from January
2014 to February 2020 were selected and 3 plans were generated for each patient using VMAT, HT and 3D-CRT. Dosimetric
comparisons were made for each plan regarding PTV and OARs. Integral dose (ID) was calculated and beam on times were analyzed.

Results: The homogeneity index (HI) was significantly better in HT plans compared with VMAT and 3D-CRT plans (p<0.001),
conformity index (CI) was better in VMAT plans. For small bowel, high doses were higher in 3D-CRT plans (p <0.001). HT produced
lower doses for the bladder as compared to VMAT and 3D-CRT (p<0.005). The mean and maximum doses of bilateral femoral heads
were higher in 3D-CRT plans. Beam on times were longer and IDs were higher in HT plans (p<0.001).

Conclusion: Both VMAT and HT improved target homogeneity and conformity and decreased OAR doses compared to 3D-CRT.
Although, VMAT was the best method to decrease ID, HT produced better bladder sparing.

Keywords

Rectum cancer, Volumetric modulated arc therapy, Helical tomotherapy, 3-dimensional conformal radiotherapy, Plan comparison

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