PurposeIntracavitary brachytherapy is integral in the treatment of cervical cancer.
Because of interfraction variation, the current standard is replanning with
every fraction. This study aimed to determine whether there was a difference
in relative dosimetry if the source position and dwell time of the first
fraction were applied to subsequent fractions.Materials and MethodsThe authors performed a retrospective review of charts and films from 2007 to
2012. Eligible cases were patients with cervical cancer treated with
brachytherapy with the same dose prescription to point A. Replanning was
done on the first set of orthogonal plates. Source position and dwell time
were subsequently applied to the remaining fractions using actual films.ResultsTwenty-nine patients were included in this study. The results showed that
cervical, rectal, and bladder dose between the actual plan and the
hypothetical plan were not statistically different. In the hypothetical
plan, the source activity and dwell time of the first plan were applied to
the orthogonal films of the subsequent fractions and showed no significant
difference in all dose points.ConclusionThe results of this study showed proof of concept of the safety of using the
source position and dwell time of the first plan for subsequent fractions.
Until further studies are performed (also using three-dimensional planning
software), the concept should be considered investigational because of the
small sample size of the study. Until such research is performed, it is
still strongly recommended that replanning be performed with every fraction
whenever it is feasible.