Evaluation of jaws-only intensity modulated radiation therapy treatment plans using Octavius 4D system

Abstract

Introduction: Jaws-Only Intensity modulated radiation therapy (JO-IMRT) is a technique uses the collimator jaws of the linear accelerator (LINAC) to delivery of complex intensity patterns. In previous studies, pretreatment patient specific quality assurance for those JO-IMRT were also performed using ionization chamber, MapCHECK2, and Octavius 4D and good agreements were shown. The aim of this study is to further verify JO-IMRT plans in 2 different cases: one with the gantry angle set equal to beam angle as in the plans and the other with gantry angle set to zero degree. Materials and Methods: Twenty-five JO-IMRT, previously verified, were executed twice for each plan. The first one used a real gantry angle, and the second one used a 0° gantry angle. Measurements were performed using Octavius 4D 1500. Results: The results were analyzed using Verisoft software. The results show that the Gamma average was 97.32 ± 2.21% for IMRT with a 0° gantry angle and 94.72 ± 2.67% for IMRT with a true gantry angle. Conclusion: In both cases, gamma index of more than 90% were found for all of our 25 JO-IMRT treatment plans.

Dosimetric comparison of intensity-modulated radiation therapy (IMRT) and field-in-field (FIF) technique for head-and-neck cancer

“…The QA is very important to consider the feasibility of the application of this technique before treatment. 25 Our measurements showed that the dose distributions planned using IMRT TPS are accurate and suitable for treatment delivery. It is interesting to note that all 20 plans of this study passed the requirements based on our established pass criteria (γ-index criterion of 3%/3 mm and pass rates of 96•65 ± 0•86%).…”

Assessment of the Dosimetric Index from IMRT and Rapid arc Plan for Oropharyngeal Cancer with Simultaneous Integrated Boost (SIB) Technique in Combination with EUD-based NTCP and TCP Radiobiological Models

“…The maximum dose for the brain stem and spinal cord [33,34] and the mean dose for the parotids [35][36][37][38] were not statistically significant for either 7-field or 9-field IMRT (p > 0.05). The NTCP [39], effective volume, EUD, and NTID of the brainstem, spinal cord, and parotids were also not statistically significant (p > 0.05).…”