A Review Study of Possible Errors in the Process of Dose Delivery of Intensity Modulated Radiation Therapy (IMRT)

Intensity Modulated Radiation Therapy (IMRT) is one of the modern technologies of external radiotherapy, which underwent widespread clinical adoption in medical centers. Modern radiotherapy makes use of new technologies in design, treatment, and delivery systems. However, despite the advantages of IMRT compared to previous methods, radiotherapy errors are still an obstacle to achieving the desired dose distribution. In this paper, effective errors of the IMRT technique, together with the sensitivity of different quality assurance (QA) procedures in diagnosis are investigated and classified. According to these studies, in addition to the importance of human errors in delivery and patient positioning, beam correction device errors are other most effective sources of delivery errors, responsible for 35% to 50% of radiotherapy uncertainties. Thus, IMRT QA methods such as diode detectors, films, electronic portal images, log files, and artificial intelligence methods have been used extensively to investigate the MLC leaf positioning errors. Moreover, uncertainties of treatment couch design and MLC modeling in TPS should not be underestimated, since numerous studies have demonstrated that various couch tops include non-negligible beam attenuation, ranging from 4% to 9% for a gantry angle of 0. Whereas posterior oblique beams are often used in the IMRT process. This article aims to highlight the importance of recognition and correction of radiotherapy uncertainties and reduce possible accidents during an IMRT process by precisely knowing various IMRT QA procedures.