A comprehensive evaluation of adaptive daily planning for cervical cancer HDR brachytherapy

Abstract

The purpose of this study was to evaluate adaptive daily planning for cervical cancer patients who underwent high‐dose‐rate intracavitary brachytherapy (HDR‐BT) using comprehensive interfractional organ motion measurements. This study included 22 cervical cancer patients who underwent 5 fractions of HDR‐BT. Regions of interest (ROIs) including high‐risk clinical tumor volume (HR‐CTV) and organs at risk (OARs) were manually contoured on daily CT images. All patients were clinically treated with adaptive daily plans (ADP), which involved ROI delineation and dose optimization at each treatment fraction. Single treatment plans (SP) were retrospectively generated by applying the first treatment fraction's dwell times adjusted for decay and dwell positions of the applicator to subsequent treatment fractions. Various existing similarity metrics were calculated for the ROIs to quantify interfractional organ variations. A novel similarity (JRARM) score was established, which combined both volumetric overlap metrics (DSC, JSC, and RVD) and distance metrics (ASD, MSD, and RMSD). Linear regression was performed to determine a relationship between interfractional organ variations of various similarity metrics and D2cc variations from both plans. Wilcoxon signed‐rank tests were used to assess ADP and SP by comparing EQD2thinmathspaceD2cc(α/β=3) for OARs. For interfractional organ variations, the sigmoid demonstrated the greatest variations based on the JRARM, DSC, and RMSD metrics. Comparisons between paired ROIs showed differences in metrics at each treatment fraction. RVD, MSD, and RMSD were found to be significantly correlated to D2cc variations for bladder and sigmoid. The comparison between plans found ADP provided lower EQD2 D2cc of OARs than SP. Specifically, the sigmoid demonstrated statistically significant dose variations (p=0.015). Substantial interfractional organ motion occurs during HDR‐BT based on comprehensive measurements and may significantly affect D2cc of OARs. Adaptive daily planning provides improved dose sparing for OARs compared to single planning with the extent of sparing being different among OARs.PACS number(s): 87.55.D, 87.55.de, 87.55.kh, 87.57.nj

AAPM task group report 303 endorsed by the ABS: MRI implementation in HDR brachytherapy—Considerations from simulation to treatment

“…When available, and following commissioning, use of 3D applicator models is recommended. If available, verification imaging is recommended when a patient transfer is required as part of the treatment workflow to account for potential patient movement or disturbance of the applicator(s). The dosimetric significance of this potential motion remains controversial, and is dependent on the type of implant (e.g., intracavitary versus interstitial), sedation, and the immobilization equipment utilized 185–188 . For instance, motion can be minimized with tighter packing although this may require the administration of anesthesia. Develop a plan with an MRI physicist and/or vendor to ensure SAR limits are not exceeded in special situations such as when a patient is anesthetized/sedated or has an implanted device. Work with an MRI physicist and /or vendor to develop a QA program for the MRI scanner (e.g., image quality, image geometry, image transfer integrity, orientation).…”

Four-Dimensional Image-Guided Adaptive Brachytherapy for Cervical Cancer: A Systematic Review and Meta-Regression Analysis

“…In general, not only the volumes of the targets and OARs, but also the topography change. Meerschaert et al evaluated the similarity between fraction 1 and fractions 2-5 for HR-CTV and OARs in 22 cervical cancer patients who received 5 fractions of HDR brachytherapy (35). The results showed that the mean Dice similarity coefficient values of the HR-CTV, bladder, rectum, and sigmoid were 0.4-0.5, 0.6-0.7, 0.5, and 0.3-0.4, respectively.…”

Feasibility Study of Robust Optimization to Reduce Dose Delivery Uncertainty by Potential Applicator Displacements for a Cervix Brachytherapy

“…The incorporation of applicator displacement worst-case scenarios into the robust optimization with the use of a MAD function may enable the robust optimization approach to minimize the dose delivery uncertainty in a single plan approach for HDR brachytherapy treatment planning. Meerschaert et al [55] found the importance of adaptive planning method for cervical cancer HDR brachytherapy; however, a simulation device is not routinely available in some institution. Hence, a robust optimization method with a multi-objective genetic algorithm in a single plan approach for minimizing dose delivery uncertainty by potential applicator displacements was proposed.…”