A comparison of treatment planning techniques for low dose rate (LDR) prostate brachytherapy

Connolly, David; Sands, Gordon; Winter, H; Foley, Mark; Kleefeld, Christoph

doi:10.1016/j.ejmp.2021.01.040

Cited by 1 publication

(1 citation statement)

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“…Inter-observer variations are generally more significant than intra-observer variations when contouring the prostate, and therefore, inter-observer uncertainty values were exclusively tabulated. Further, inter-modality differences due to using TRUS images for prostate contouring have shown not to be significant compared to the gold standard of MRI and are within inter-observer variations of MRI [4], except for the prostate width, which is distorted due to the presence of the TRUS probe [41][42][43][44][45]. Considering the probe is left in place for the entire treatment for this patient, a consistent distortion was always present; therefore, uncertainty due to the choice of TRUS imaging was not considered.…”

Section: Uncertainties Componentsmentioning

confidence: 98%

Being certain about uncertainties: A robust evaluation method for high-dose-rate prostate brachytherapy treatment plans including the combination of uncertainties

Kennedy

Douglass

Santos

2022

Preprint

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In high-dose-rate (HDR) prostate brachytherapy the combined effect of uncertainties cause a range of possible dose distributions deviating from the nominal plan, and which are not considered during treatment plan evaluation. This could lead to dosimetric misses for critical structures and overdosing of organs at risk. A robust evaluation method to assess the combination of uncertainties during plan evaluation is presented and demonstrated on one HDR prostate ultrasound treatment plan retrospectively. A range of uncertainty scenarios are simulated by changing six parameters in the nominal plan and calculating the corresponding dose distribution. Two methods are employed to change the parameters, a probabilistic approach using random number sampling to evaluate the likelihood of variation in dose distributions, and a combination of the most extreme possible values to access the worst-case dosimetric outcomes. One thousand probabilistic scenarios were run on the single treatment plan with 19.0% of scenarios passing all eight clinical objectives. The prostate D90 had a standard deviation of 4.7%, with the worst case decreasing the dose by up to 27.6%. The urethra D10 was up to 38% higher than planned in the worst case. All DVH metrics in the probabilistic scenarios were found to be within acceptable clinical constraints for the plan under statistical tests for significance. The clinical significance of the results from the robust evaluation method presented on any individual treatment plan needs to be compared in the context of a historical data set that contains patient outcomes with robustness analysis data to ascertain a baseline acceptance.

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