A Monte Carlo study on the feasibility of real-time in vivo source tracking during ultrasound based HDR prostate brachytherapy treatments

Poder, Joel; Cutajar, Dean L; Guatelli, Susanna; Petasecca, Marco; Howie, Andrew; Bucci, Joseph; Carrara, M.; Rosenfeld, Anatoly B.

doi:10.1016/j.ejmp.2019.02.012

Cited by 9 publications

(7 citation statements)

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“…The predominant aim of these studies has been to detect and minimize the occurrence of discrepancies between planned and measured HDR prostate BT dwell positions. Much of this technological evolution has been focused on the development of novel radiation detectors and detector arrays for the purposes of in‐vivo source tracking 8–12 . The advantage of in‐vivo source tracking over traditional point‐based in‐vivo dosimetry is the ability to determine actually delivered (within measurement uncertainty) dwell positions in three‐dimensional (3D) coordinates, and also measure dwell times 8,10,12 .…”

Section: Introductionmentioning

confidence: 99%

“…Much of this technological evolution has been focused on the development of novel radiation detectors and detector arrays for the purposes of in-vivo source tracking. [8][9][10][11][12] The advantage of in-vivo source tracking over traditional point-based in-vivo dosimetry is the ability to determine actually delivered (within measurement uncertainty) dwell positions in three-dimensional (3D) coordinates, and also measure dwell times. 8,10,12 When combined with real-time imaging, in-vivo source tracking may allow for a "delivered" 3D dose distribution to be reconstructed, giving more clinically meaningful results.…”

Section: Introductionmentioning

confidence: 99%

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HDR prostate brachytherapy plan robustness and its effect on in‐vivo source tracking error thresholds: A multi‐institutional study

et al. 2022

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The purpose of this study was to examine the effect of departmental planning techniques on appropriate in-vivo source tracking error thresholds for high dose rate (HDR) prostate brachytherapy (BT) treatments, and to determine if a single in-vivo source tracking error threshold would be appropriate for the same patient anatomy. Methods: The prostate, rectum, and urethra were contoured on a single patient transrectal ultrasound (TRUS) dataset. Anonymized DICOM files were disseminated to 16 departments who created an HDR prostate BT treatment plan on the dataset with a prescription dose of 15 Gy in a single fraction. Departments were asked to follow their own local treatment planning guidelines. Source positioning errors were then simulated in the 16 treatment plans and the effect on dose-volume histogram (DVH) indices calculated. Change in DVH indices were used to determine appropriate in-vivo source tracking error thresholds. Plans were considered to require intervention if the following DVH conditions occurred: prostate V100% < 90%, urethra D0.1cc > 118%, and rectum tt Dmax > 80%. Results: There was wide variation in appropriate in-vivo source tracking error thresholds among the 16 participating departments, ranging from 1 to 6 mm. Appropriate in-vivo source tracking error thresholds were also found to depend on the direction of the source positioning error and the endpoint. A robustness parameter was derived, and found to correlate with the sensitivity of plans to source positioning errors. Conclusions: A single HDR prostate BT in-vivo source tracking error threshold cannot be applied across multiple departments, even for the same patient anatomy. The burden on in-vivo source tracking devices may be eased through improving HDR prostate BT plan robustness during the plan optimisation phase.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

HDR prostate brachytherapy plan robustness and its effect on in‐vivo source tracking error thresholds: A multi‐institutional study

et al. 2022

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“…Many approaches have been taken to track the source position that includes, scintillation/crystal-based detectors, two-dimensional diode arrays, flat panels, and pinhole collimator detectors. [10][11][12][13][14][15][16][17][18] All the above methods have been successful within phantom measurements to varying degrees, with source tracking accuracy falling between the range of less than 1 mm up to 5 mm. Additionally, many of these systems have not been validated clinically, apart from the flat panel detector.…”

Section: Introductionmentioning

confidence: 99%

Development of patient and catheter specific error thresholds for high dose rate prostate brachytherapy

Koprivec,

Belanger,

Beaulieu

et al. 2024

Medical Physics

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BackgroundIn‐vivo source tracking has been an active topic of research in the field of high‐dose rate brachytherapy in recent years to verify accuracy in treatment delivery. Although detection systems for source tracking are being developed, the allowable threshold of treatment error is still unknown and is likely patient‐specific due to anatomy and planning variation.PurposeThe purpose of this study was to determine patient and catheter‐specific shift error thresholds for in‐vivo source tracking during high‐dose‐rate prostate brachytherapy (HDRPBT).MethodsA module was developed in the previously described graphical processor unit multi‐criteria optimization (gMCO) algorithm. The module generates systematic catheter shift errors retrospectively into HDRPBT treatment plans, performed on 50 patients. The catheter shift model iterates through the number of catheters shifted in the plan (from 1 to all catheters), the direction of shift (superior, inferior, medial, lateral, cranial, and caudal), and the magnitude of catheter shift (1–6 mm). For each combination of these parameters, 200 error plans were generated, randomly selecting the catheters in the plan to shift. After shifts were applied, dose volume histogram (DVH) parameters were re‐calculated. Catheter shift thresholds were then derived based on plans where DVH parameters were clinically unacceptable (prostate V100 < 95%, urethra D0.1cc > 118%, and rectum Dmax > 80%). Catheter thresholds were also Pearson correlated to catheter robustness values.ResultsPatient‐specific thresholds varied between 1 to 6 mm for all organs, in all shift directions. Overall, patient‐specific thresholds typically decrease with an increasing number of catheters shifted. Anterior and inferior directions were less sensitive than other directions. Pearson's correlation test showed a strong correlation between catheter robustness and catheter thresholds for the rectum and urethra, with correlation values of –0.81 and –0.74, respectively (p < 0.01), but no correlation was found for the prostate.ConclusionsIt was possible to determine thresholds for each patient, with thresholds showing dependence on shift direction, and number of catheters shifted. Not every catheter combination is explorable, however, this study shows the feasibility to determine patient‐specific thresholds for clinical application. The correlation of patient‐specific thresholds with the equivalent robustness value indicated the need for robustness consideration during plan optimization and treatment planning.

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“…[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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A Monte Carlo study on the feasibility of real-time in vivo source tracking during ultrasound based HDR prostate brachytherapy treatments

Abstract: A Monte Carlo study on the feasibility of real-time in vivo source tracking A Monte Carlo study on the feasibility of real-time in vivo source tracking during ultrasound based HDR prostate brachytherapy treatments during ultrasound based HDR prostate brachytherapy treatments

Cited by 9 publications

References 30 publications

HDR prostate brachytherapy plan robustness and its effect on in‐vivo source tracking error thresholds: A multi‐institutional study

HDR prostate brachytherapy plan robustness and its effect on in‐vivo source tracking error thresholds: A multi‐institutional study

Development of patient and catheter specific error thresholds for high dose rate prostate brachytherapy

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

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