Estimation of Rectal Dose Using Daily Megavoltage Cone-Beam Computed Tomography and Deformable Image Registration

Assessment of cumulative external beam and intracavitary brachytherapy organ doses in gynecologic cancers using deformable dose summation

“…Estimating the uncertainty of OAR doses due to inter-fraction variation is beyond the scope of this work. Such an analysis requires daily on board cone beam CT together with deformation image registration tools for dose accumulation and was recently performed for prostate cancer [18]. Other potentially confounding factors include intra-fraction source and organ motion [19] which is not considered in this work.…”

Prostate external beam radiotherapy combined with high-dose-rate brachytherapy: dose-volume parameters from deformably-registered plans correlate with late gastrointestinal complications

“…A common uncertainty associated with EBRT, HDR and other radiotherapy techniques is inter-fraction motion of patient anatomy [51][52][53][54]. In response to this uncertainty, it is becoming more common for institutions to adopt repeat imaging over the course of prostate cancer treatment to correct for inter-fraction motions and improve the correspondence between planned dose and delivered dose [53,55].…”

“…A consideration for prostate EBRT in this study is rectum motion and variable rectum contents confounding the accuracy of rectum dose distributions obtained from single static planning CTs [52,56,57]. A variety of methods have been used to estimate the impact of interfraction motion on rectum dose parameters and doseresponse modelling for prostate EBRT [8,52,[58][59][60][61].…”

“…A variety of methods have been used to estimate the impact of interfraction motion on rectum dose parameters and doseresponse modelling for prostate EBRT [8,52,[58][59][60][61]. To obtain appropriate mean estimates for the difference in EBRT rectum dose between the single CT based values and the motion-corrected values this study analysed the results of another study [52] that used the same registration software and registration algorithm. Consequently, compared to the motion-corrected values the single CT based values may be conservative estimates by 3.9 % for the D 2% and 5.8 % for the equivalent uniform dose [52].…”

“…However, shifting of dose values identified as significant are likely as the single CT based estimates were mostly identified as being systematically different to the motioncorrected values [52,54]. The influence of inter-fraction on delivered doses is likely to be important when considering dose constraints recommended by studies where planned dose tends to be less than delivered dose.…”