Time-resolved QA and brachytherapy applicator commissioning: Towards the clinical implementation

Fonseca, Gabriel Paiva; Voncken, Robert; Hermans, J.; Verhaegen, Frank

doi:10.1016/j.brachy.2021.08.003

Cited by 6 publications

(5 citation statements)

References 17 publications

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“…The median dwell time differences between measured and planned dwell times in the first and last dwell position were 0.1 s and 0.060 s in our study, which coincide with results of Fonseca et al in a recent study [ 34 ]. They described differences less than 0.05 s for all dwell positions except for the first and the last position.…”

Section: Discussionsupporting

confidence: 92%

In Vivo Verification of Treatment Source Dwell Times in Brachytherapy of Postoperative Endometrial Carcinoma: A Feasibility Study

Herreros

Pérez‐Calatayud

Ballester

et al. 2022

JPM

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(1) Background: In brachytherapy, there are still many manual procedures that can cause adverse events which can be detected with in vivo dosimetry systems. Plastic scintillator dosimeters (PSD) have interesting properties to achieve this objective such as real-time reading, linearity, repeatability, and small size to fit inside brachytherapy catheters. The purpose of this study was to evaluate the performance of a PSD in postoperative endometrial brachytherapy in terms of source dwell time accuracy. (2) Methods: Measurements were carried out in a PMMA phantom to characterise the PSD. Patient measurements in 121 dwell positions were analysed to obtain the differences between planned and measured dwell times. (3) Results: The repeatability test showed a relative standard deviation below 1% for the measured dwell times. The relative standard deviation of the PSD sensitivity with accumulated absorbed dose was lower than 1.2%. The equipment operated linearly in total counts with respect to absorbed dose and also in count rate versus absorbed dose rate. The mean (standard deviation) of the absolute differences between planned and measured dwell times in patient treatments was 0.0 (0.2) seconds. (4) Conclusions: The PSD system is useful as a quality assurance tool for brachytherapy treatments.

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Section: Discussionsupporting

confidence: 92%

In Vivo Verification of Treatment Source Dwell Times in Brachytherapy of Postoperative Endometrial Carcinoma: A Feasibility Study

Herreros

Pérez‐Calatayud

Ballester

et al. 2022

JPM

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“…For each marker, IP acquisitions were made using the LINAC with the marker in the isocenter, to establish the pixel coordinates corresponding to the center of each marker (Fonseca et al 2021). This calibration procedure is needed, as the IP is also used for applicator QA in our clinic (Fonseca et al 2022). Therefore, the holder has to be removed periodically, and it is not assured that the markers are in the exact same location every time.…”

Section: Source Tracking Measurementmentioning

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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“…The radiotherapy field, the focus of this study, has seen the development of novel and centre-specific technologies as custom 3D printed applicators for brachytherapy, QA tools or patient-specific phantoms for imaging and dosimetry. (Fonseca et al 2022, Membrive Conejo et al 2021, Tino et al 2022.…”

Section: Introductionmentioning

confidence: 99%

Dual-energy CT evaluation of 3D printed materials for radiotherapy applications

et al. 2023

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Objective: There is a continuous increase in 3D printing applications in several fields including medical imaging and radiotherapy. Although there are numerous advantages of using 3D printing for the development of customized phantoms, bolus, quality assurance devices and other clinical applications, material properties are not well known and printer settings can affect considerably the properties (e.g. density, isotropy and homogeneity) of the printed parts. This study aims to evaluate several materials and printer properties to identify a range of tissue-mimicking materials. Approach: Dual-energy CT was used to obtain the effective atomic number (Zeff) and relative electron density (RED) for thirty-one different materials including different colours of the same filament from the same manufacturer and the same type of filament from different manufacturers. In addition, a custom bone equivalent filament was developed and evaluated since a high-density filament with a composition similar to bone is not commercially available. Printing settings such as infill density, infill pattern, layer height and nozzle size were also evaluated. Main results: Large differences were observed for HU (288), RED (>10%) and Zeff (>50%) for different colours of the same filament due to the colour pigment. Results show a wide HU variation (-714 to 1104), RED (0.277 to 1.480) and Zeff (5.22 to 12.39) between the printed samples with some materials being comparable to commercial tissue-mimicking materials and good substitutes to a range of materials from lung to bone. Printer settings can result in directional dependency and significantly affect the homogeneity of the samples. Significance: The use of DECT to extract RED, and Zeff allows for quantitative imaging and dosimetry using 3D printed materials equivalent to certified tissue mimicking tissues.

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Time-resolved QA and brachytherapy applicator commissioning: Towards the clinical implementation

Cited by 6 publications

References 17 publications

In Vivo Verification of Treatment Source Dwell Times in Brachytherapy of Postoperative Endometrial Carcinoma: A Feasibility Study

In Vivo Verification of Treatment Source Dwell Times in Brachytherapy of Postoperative Endometrial Carcinoma: A Feasibility 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

Dual-energy CT evaluation of 3D printed materials for radiotherapy applications

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