Error detection thresholds for routine real time in vivo dosimetry in HDR prostate brachytherapy

Mason, J.; Henry, Ann; Bownes, Peter

doi:10.1016/j.radonc.2020.04.058

Cited by 9 publications

(3 citation statements)

References 14 publications

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“…shifts in other directions) are simulated and their effect on different clinical parameters is investigated. Real-time automatic error detection could be possible if these action limits are determined before the treatment occurs, however this probably has to be patient-, plan-, or possibly even catheter specific (Mason et al 2020). When defining the action limits, the uncertainty of the system has to be Figure 10.…”

Section: Discussionmentioning

confidence: 99%

Time-resolved clinical dose volume metrics, calculations and predictions based on source tracking measurements and uncertainties to aid treatment verification and error detection for HDR brachytherapy—a proof-of-principle study

van Wagenberg,

Voncken,

van Beveren

et al. 2024

Phys. Med. Biol.

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Objective. High-dose-rate (HDR) brachytherapy lacks routinely available treatment verification methods. Real-time tracking of the radiation source during HDR brachytherapy can enhance treatment verification capabilities. Recent developments in source tracking allow for measurement of dwell times and source positions with high accuracy. However, more clinically relevant information, such as dose discrepancies, is still needed. To address this, a real-time dose calculation implementation was developed to provide more relevant information from source tracking data. A proof-of-principle of the developed tool was shown using source tracking data obtained from a 3D-printed anthropomorphic phantom. Approach. Software was developed to calculate dose-volume-histograms (DVH) and clinical dose metrics from experimental HDR prostate treatment source tracking data, measured in a realistic pelvic phantom. Uncertainty estimation was performed using repeat measurements to assess the inherent dose measuring uncertainty of the in vivo dosimetry (IVD) system. Using a novel approach, the measurement uncertainty can be incorporated in the dose calculation, and used for evaluation of cumulative dose and clinical dose-volume metrics after every dwell position, enabling real-time treatment verification. Main results. The dose calculated from source tracking measurements aligned with the generated uncertainty bands, validating the approach. Simulated shifts of 3 mm in 5/17 needles in a single plan caused DVH deviations beyond the uncertainty bands, indicating errors occurred during treatment. Clinical dose-volume metrics could be monitored in a time-resolved approach, enabling early detection of treatment plan deviations and prediction of their impact on the final dose that will be delivered in real-time. Significance. Integrating dose calculation with source tracking enhances the clinical relevance of IVD methods. Phantom measurements show that the developed tool aids in tracking treatment progress, detecting errors in real-time and post-treatment evaluation. In addition, it could be used to define patient-specific action limits and error thresholds, while taking the uncertainty of the measurement system into consideration.

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Section: Discussionmentioning

confidence: 99%

Time-resolved clinical dose volume metrics, calculations and predictions based on source tracking measurements and uncertainties to aid treatment verification and error detection for HDR brachytherapy—a proof-of-principle study

van Wagenberg,

Voncken,

van Beveren

et al. 2024

Phys. Med. Biol.

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show abstract

“…Several groups with well-developed IVD systems have recognised the value of source tracking, either by measuring the individual 3D source positions or by measuring implant movements relative to the in vivo dosimeter. [4][5][6][7][8] Other groups have performed source tracking via other methods of directly measuring the source position with detectors including fluoroscopy, pinhole cameras, magnetic resonance, or 2D arrays. [3,[9][10][11][12][13][14] Some of the source tracking approaches have been demonstrated clinically, [3,7,9,15] or in principle [5,6,8,[10][11][12][13]16].…”

Section: Introductionmentioning

confidence: 99%

“…[4][5][6][7][8] Other groups have performed source tracking via other methods of directly measuring the source position with detectors including fluoroscopy, pinhole cameras, magnetic resonance, or 2D arrays. [3,[9][10][11][12][13][14] Some of the source tracking approaches have been demonstrated clinically, [3,7,9,15] or in principle [5,6,8,[10][11][12][13]16].…”

Section: Introductionmentioning

confidence: 99%

MaxiCalc: A tool for online dosimetric evaluation of source-tracking based treatment verification in HDR brachytherapy

2022

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Source tracking is becoming a more widely used approach in HDR brachytherapy treatment verification. While it provides a sensitive method to detect deviations from the treatment plan during delivery, it does not show the clinical significance of any detected changes. By incorporating a tool that calculates volumetric doses and DVH indices from measurements, source tracking systems can be expanded to assess dosimetric significance of any deviations from the plan. Methods: The source tracking dose calculation tool, MaxiCalc, was developed in MATLAB. Validation was performed by comparing doses and DVH indices calculated in MaxiCalc to those calculated by the clinical TPS, for several test plans and 10 clinical plans. Clinical implementation was demonstrated by calculating volumetric doses from a clinical source tracking event.Results: MaxiCalc showed excellent agreement with the clinical TPS for point and volumetric doses (mean difference < 0.01% and 0.1% respectively). MaxiCalc calculates dosimetrically equivalent plans to the TPS with agreement < 0.3% for all DVH indices except PTV V200%. Small differences seen for the clinical source tracking event were consistent with the known tracking uncertainties enabling them to be quantified for clinical decision making. Calculations are fast, enabling real-time use. Conclusions: MaxiCalc is an independent tool that calculates doses and DVH indices from dwells measured with any clinical HDR brachytherapy source tracking system. This extends the capabilities of source tracking systems from determining discrepancies in positions or times during delivery to assessing the dosimetric impact of any detected deviations, allowing for more comprehensive treatment verification and evaluation.

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Quantifying clinical severity of physics errors in high-dose rate prostate brachytherapy using simulations

et al. 2021

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Error detection thresholds for routine real time in vivo dosimetry in HDR prostate brachytherapy

Cited by 9 publications

References 14 publications

Time-resolved clinical dose volume metrics, calculations and predictions based on source tracking measurements and uncertainties to aid treatment verification and error detection for HDR brachytherapy—a proof-of-principle study

Time-resolved clinical dose volume metrics, calculations and predictions based on source tracking measurements and uncertainties to aid treatment verification and error detection for HDR brachytherapy—a proof-of-principle study

MaxiCalc: A tool for online dosimetric evaluation of source-tracking based treatment verification in HDR brachytherapy

Quantifying clinical severity of physics errors in high-dose rate prostate brachytherapy using simulations

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