ESTRO 2023 - Abstract Book

S1816

Digital Posters

ESTRO 2023

b)

Conclusion In conclusion, our experience showed that Tomotherapy in helical modality provides a large proportion of optimal plans in terms of PTV coverage and OARs sparing, in a challenging population of postmastectomy patients with IBR. The learning curve showed that five years apart the rate of optimal plans was increased along with a decrease in the number of compromised plans. This analysis could be a useful platform to compare dose constraints between similar studies and to further refine them to optimize helical PMRT.

PO-2045 CyberKnife with InCise MLC versus VMAT with FFF in SBRT for Prostate cancer: A dosimetric comparison

W. Phongprapun 1 , P. Chanwichu 1 , W. Sittiwong 1 , S. Kunchitshoulakul 1 , P. Dankulchai 1

1 Siriraj Hospital, Radiation oncology, Bangkok, Thailand

Purpose or Objective Prostate cancer is one of the most common cancers in men. Stereotactic body radiation therapy (SBRT) is a technique to deliver high doses with high accuracy and precision in a few fractions. Cyberknife (CK) is one option of radiotherapy machine that is capable of delivering SBRT for prostate cancer; however, the cost per unit is relatively high and the availability of CK was limited in a few radiotherapy centers. Volumetric Modulated Arc Therapy (VMAT) technique to deliver SBRT plan was an appealing alternative option to SBRT delivered by CK. The objective of this study is the dosimetric comparison between CK-SBRT and VMAT-SBRT treatment in prostate cancer Materials and Methods Twenty prostate cancer patients treated by CK M6 were selected and replanned using VMAT. Dose prescription to prostate was 36.25 Gy in 5 fractions. For the CK, plans were generated by Incise MLC instead of fixed or Iris cone to reduce the treatment time. For VMAT, plans were generated for TrueBeam STx with the 'high definition' 120-leaf multileaf collimator(HD120-MLC) and used two partial arcs (200-160 clockwise arcs with collimator angle15 and 160-200