Validation of automated post-adjustments of HDR prostate brachytherapy treatment plans by quantitative measures and oncologist observer study

Dohlmar, Frida; Morén, Björn; Sandborg, Michael; Smedby, Örjan; Valdman, Alexander; Larsson, Torbjörn; Tedgren, Åsa Carlsson

doi:10.1016/j.brachy.2022.12.008

Cited by 1 publication

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“…Clinical comparisons and validation of the spatial optimization model 5 have previously been done in two studies. The first 5 contained a dosimetric comparison between clinically used and optimized treatment plans, and the second 10 was an extensive oncologist observer study based on a larger patient data set. In the latter study, eight oncologists compared clinical treatment plans with spatially optimized plans, and the optimized plans were preferred in a majority of the cases.…”

Section: Introductionmentioning

confidence: 99%

Technical note: Evaluation of a spatial optimization model for prostate high dose‐rate brachytherapy in a clinical treatment planning system

et al. 2023

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Background Spatial properties of a dose distribution, such as volumes of contiguous hot spots, are of clinical importance in treatment planning for high dose‐rate brachytherapy (HDR BT). We have in an earlier study developed an optimization model that reduces the prevalence of contiguous hot spots by modifying a tentative treatment plan. Purpose The aim of this study is to incorporate the correction of hot spots in a standard inverse planning workflow and to validate the integrated model in a clinical treatment planning system. The spatial function is included in the objective function for the inverse planning, as opposed to in the previous study where it was applied as a separate post‐processing step. Our aim is to demonstrate that fine‐adjustments of dose distributions, which are often performed manually in today's clinical practice, can be automated. Methods A spatial optimization function was introduced in the treatment planning system RayStation (RaySearch Laboratories AB, Stockholm, Sweden) via a research interface. A series of 10 consecutive prostate patients treated with HDR BT was retrospectively replanned with and without the spatial function. Results Optimization with the spatial function decreased the volume of the largest contiguous hot spot by on average 31%, compared to if the function was not included. The volume receiving at least 200% of the prescription dose decreased by on average 11%. Target coverage, measured as the fractions of the clinical target volume (CTV) and the planning target volume (PTV) receiving at least the prescription dose, was virtually unchanged (less than a percent change for both metrics). Organs‐at‐risk received comparable or slightly decreased doses if the spatial function was included in the optimization model. Conclusions Optimization of spatial properties such as the volume of contiguous hot spots can be integrated in a standard inverse planning workflow for brachytherapy, and need not be conducted as a separate post‐processing step.

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Section: Introductionmentioning

confidence: 99%