A real-time dosimetry study in radiation therapy using an electronic portal imaging device (EPID) to evaluate treatment quality assurance

Quality assurance and quality control are integral elements in radiation therapy for cancer patients, the purpose of which is to ensure the high quality of radiation therapy for patients so that the treatment results are optimal. In this regard, the aim of the current research is real-time dosimetry with an electronic portal imaging device to obtain the midplane dose. Intracorporeal dosimetry is one of the quality control methods and the most direct method for monitoring the dose delivered to the patient during radiation therapy, which is the biggest challenge in radiation therapy. Intracorporeal dosimetry is usually performed in the initial stages or during treatment; that if an error occurs in any of the treatment steps, this error is identified and it is possible to compensate for it and continue the treatment correctly. In the present study, the midplane dose was obtained by three arithmetic mean, geometric mean, and transmission dose in the form of gate simulation, and its results were compared with the clinical data obtained from the practical part. After comparing all the results obtained from the applicable methods and summarizing the data compared to the current research, according to the passing of the acceptance criteria in the comparison of the practical part and the simulation, it can be said that doing dosimetry using Epid is an acceptable method to move forward. A comprehensive system for more accurate dosimetry calculations in radiotherapy centers that are equipped with EPID. According to the results obtained from the practical part as well as the simulation of the project, the results with gamma index less than 1% were presented for Midplan.