Quantifying the effect of seed orientation in postplanning dosimetry of low‐dose‐rate prostate brachytherapy

Fekete, Charles-Antoine Collins; Plamondon, M.; Martin, André-Guy; Vigneault, Éric; Verhaegen, Frank; Beaulieu, Luc

doi:10.1118/1.4895012

Cited by 18 publications

(19 citation statements)

References 47 publications

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“…This effect has been shown to cause < 2% differences in D 90 for LDR prostate implants with conventional seeds. 83,84 However, the magnitude and spatial extent of these dose calculation errors are larger for this source model (i.e., L = 1.00 cm) than for sources having L ≤ 0.4 cm. Consequently, no CON / an (r) are recommended for this source model.…”

Section: A73 Model Cs10 Anisotropy Functionsmentioning

confidence: 91%

Supplement 2 for the 2004 update of theAAPMTask Group No. 43 Report: Joint recommendations by theAAPMandGEC‐ESTRO

et al. 2017

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Cs (IsoRay Medical model CS-1 Rev2). Observations are included on the behavior of these dosimetry parameters as a function of radionuclide. Recommendations are presented on the selection of dosimetry parameters, such as from societal reports issuing consensus datasets (e.g., TG-43U1, AAPM Report #229), the joint AAPM/IROC Houston Registry, the GEC-ESTRO website, the Carleton University website, and those included in software releases from vendors of treatment planning systems. Aspects such as timeliness, maintenance, and rigor of these resources are discussed.Links to reference data are provided for radionuclides (radiation spectra and half-lives) and dose scoring materials (compositions and mass densities). The recent literature is examined on photon energy response corrections for thermoluminescent dosimetry of low-energy photon-emitting brachytherapy sources. Depending upon the dosimetry parameters currently used by individual physicists, use of these recommended consensus datasets may result in changes to patient dose calculations. These changes must be carefully evaluated and reviewed with the radiation oncologist prior to their implementation.

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Section: A73 Model Cs10 Anisotropy Functionsmentioning

confidence: 91%

Supplement 2 for the 2004 update of theAAPMTask Group No. 43 Report: Joint recommendations by theAAPMandGEC‐ESTRO

et al. 2017

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“…It is possible that a single false positive or false negative detection may not have significant effects on the dose–volume calculations, because of the low dose of an individual seed. Finally, the information on seed orientation gained through MR‐only seed localization may improve the accuracy of the dose calculations by allowing the use of anisotropic dose distributions …”

Section: Discussionmentioning

confidence: 99%

Challenges in MR‐only seed localization for postimplant dosimetry in permanent prostate brachytherapy

et al. 2017

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Purpose: An MR-only postimplant dosimetry workflow for low dose rate (LDR) brachytherapy could reduce patient burden, improve accuracy, and improve cost efficiency. However, localization of brachytherapy seeds on MRI scans remains a major challenge for this type of workflow. In this study, we propose and validate an MR-only seed localization method and identify remaining challenges. Methods and materials: The localization method was based on template matching of simulations of complex-valued imaging artifacts around metal brachytherapy seeds. The method was applied to MRI scans of 25 prostate cancer patients who underwent LDR brachytherapy and for whom postimplant dosimetry was performed after 4 weeks. The seed locations found with the MR-only method were validated against the seed locations found on CT. The circumstances in which detection errors were made were classified to gain an insight in the nature of the errors. Results: A total of 1490 of 1557 (96%) seeds were correctly detected, while 67 false-positive errors were made. The correctly detected seed locations had a high spatial accuracy with an average error of 0.8 mm compared with CT. A majority of the false positives occurred near other seeds. Most false negatives were found in either stranded configurations without spacers or near other seeds. Conclusions: The low detection error rate and high localization accuracy obtained by the complexvalued template matching approach are promising for future clinical application of MR-only dosimetry. The most important remaining challenge is robustness with regard to configurations of multiple seeds in close vicinity, such as in strands of seeds without spacers. This issue could potentially be resolved by simulating specific configurations of multiple seeds or by constraining the treatment planning to avoid these configurations, which could make the proposed method competitive with CTbased seed localization.

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“…First, the SPOT PROÔ system that was employed to calculate the final dose statistics for both IPSA and SGA used the 1D formalism; therefore, the same was used for the SGA code for consistency sake. Second, a recent study performed by Fekete et al (30) has shown that the seed orientation does not affect main clinical dosimetric quantities of interest in a statistically significant way for the clinical target volume and urethra. For the target structure, dosimetric constraints were represented by two sets of dose points, surface and volume.…”

Section: Formulation Of Objective Functionmentioning

confidence: 98%

An open-source genetic algorithm for determining optimal seed distributions for low-dose-rate prostate brachytherapy

et al. 2015

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Quantifying the effect of seed orientation in postplanning dosimetry of low‐dose‐rate prostate brachytherapy

Abstract: Based on the results from this study, seed orientations have no significant impact of CTV and urethra dose metrics but can affect OARs that are external to the CTV.

Cited by 18 publications

References 47 publications

Supplement 2 for the 2004 update of theAAPMTask Group No. 43 Report: Joint recommendations by theAAPMandGEC‐ESTRO

Supplement 2 for the 2004 update of theAAPMTask Group No. 43 Report: Joint recommendations by theAAPMandGEC‐ESTRO

Challenges in MR‐only seed localization for postimplant dosimetry in permanent prostate brachytherapy

An open-source genetic algorithm for determining optimal seed distributions for low-dose-rate prostate brachytherapy

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