In this study, it was aimed to evaluate the performance and reliability of 3-dimensional (3D) in vivo electronic portal imaging device (EPID)-based dosimetry in radiotherapy (RT) of patients with gynecological cancer.
METHODS
The dose distributions and in vivo dosimetry results of patients with endometrial (n=10) and cervical
(n=10) cancer who underwent external pelvic RT in our department were analyzed retrospectively. The
RT planning and 3D in vivo dosimetry data were obtained from the treatment planning system and the
iViewDose® (Elekta, Crawley, UK) in vivo quality assurance system. In addition, patient-specific phantom
measurements were carried out for each patient with the Alderson Rando phantom. The results
were evaluated with 3D gamma analysis method using iViewDose® software. We obtained γmean, γ1%, and
γγ1% values for each patient with the analysis. Acceptance criteria for these parameters were taken as 0.7,
2.0, and 90%, respectively.
RESULTS
The phantom measurements showed that all treatment plans were applicable. All patients met the passing
criteria for ?mean, ?1%, and ??1%. The mean gamma passing rate was 95.1%±1.7 and 96.3%±2.9 for
patients with endometrial and cervical cancer, respectively.
CONCLUSION
The EPID-based in vivo dosimetry seems to be usable in clinical routine in the treatment of gynecological
cancers. However, field size is the most important limitation of in vivo EPID dosimetry in cases
requiring extended field RT.