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Real‐time motion‐including dose estimation of simulated multi‐leaf collimator‐tracked magnetic resonance‐guided radiotherapy.

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Title: Real‐time motion‐including dose estimation of simulated multi‐leaf collimator‐tracked magnetic resonance‐guided radiotherapy.
Authors: Persson, Emilia1 (AUTHOR) emilia.persson@icr.ac.uk, Goodwin, Edmund1 (AUTHOR), Eiben, Björn1 (AUTHOR), Wetscherek, Andreas1 (AUTHOR), Nill, Simeon1 (AUTHOR), Oelfke, Uwe1 (AUTHOR)
Source: Medical Physics. Mar2024, Vol. 51 Issue 3, p2221-2229. 9p.
Subjects: Workflow software, Photon beams, Electron density, Radiotherapy, Drug dosage, Dose-response relationship (Radiation), Magnetic resonance, Radiotherapy safety
Geographic Terms: Stockholm (Sweden), Monaco
Abstract: Background: Real‐time dose estimation is a key‐prerequisite to enable online intra‐fraction treatment adaptation in magnetic resonance (MR)‐guided radiotherapy (MRgRT). It is an essential component for the assessment of the dosimetric benefits and risks of online adaptive treatments, such as multi‐leaf collimator (MLC)‐tracking. Purpose: We present a proof‐of‐concept for a software workflow for real‐time dose estimation of MR‐guided adaptive radiotherapy based on real‐time data‐streams of the linac delivery parameters and target positions. Methods: A software workflow, combining our in‐house motion management software DynaTrack, a real‐time dose calculation engine that connects to a research version of the treatment planning software (TPS) Monaco (v.6.09.00, Elekta AB, Stockholm, Sweden) was developed and evaluated. MR‐guided treatment delivery on the Elekta Unity MR‐linac was simulated with and without MLC‐tracking for three prostate patients, previously treated on the Elekta Unity MR‐linac (36.25 Gy/five fractions). Three motion scenarios were used: no motion, regular motion, and erratic prostate motion. Accumulated monitor units (MUs), centre of mass target position and MLC‐leaf positions, were forwarded from DynaTrack at a rate of 25 Hz to a Monte Carlo (MC) based dose calculation engine which utilises the research GPUMCD‐library (Elekta AB, Stockholm, Sweden). A rigid isocentre shift derived from the selected motion scenarios was applied to a bulk density‐assigned session MR‐image. The respective electron density used for treatment planning was accessed through the research Monaco TPS. The software workflow including the online dose reconstruction was validated against offline dose reconstructions. Our investigation showed that MC‐based real‐time dose calculations that account for all linac states (including MUs, MLC positions and target position) were infeasible, hence states were randomly sampled and used for calculation as follows; Once a new linac state was received, a dose calculation with 106 photons was started. Linac states that arrived during the time of the ongoing calculation were put into a queue. After completion of the ongoing calculation, one new linac state was randomly picked from the queue and assigned the MU accumulated from the previous state until the last sample in the queue. The queue was emptied, and the process repeated throughout treatment simulation. Results: On average 27% (23%–30%) of received samples were used in the real‐time calculation, corresponding to a calculation time for one linac state of 148 ms. Median gamma pass rate (2%/3 mm local) was 100.0% (99.9%–100%) within the PTV volume and 99.1% (90.1%–99.4.0%) with a 15% dose cut off. Differences in PTVDmean, CTVDmean, RectumD2%, and BladderD2% (offline‐online, % of prescribed dose) were below 0.64%. Beam‐by‐beam comparisons showed deviations below 0.07 Gy. Repeated simulations resulted in standard deviations below 0.31% and 0.12 Gy for the investigated volume and dose criteria respectively. Conclusions: Real‐time dose estimation was successfully performed using the developed software workflow for different prostate motion traces with and without MLC‐tracking. Negligible dosimetric differences were seen when comparing online and offline reconstructed dose, enabling online intra‐fraction treatment decisions based on estimates of the delivered dose. [ABSTRACT FROM AUTHOR]
Copyright of Medical Physics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
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  Label: Title
  Group: Ti
  Data: Real‐time motion‐including dose estimation of simulated multi‐leaf collimator‐tracked magnetic resonance‐guided radiotherapy.
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  Data: <searchLink fieldCode="AR" term="%22Persson%2C+Emilia%22">Persson, Emilia</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> emilia.persson@icr.ac.uk</i><br /><searchLink fieldCode="AR" term="%22Goodwin%2C+Edmund%22">Goodwin, Edmund</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Eiben%2C+Björn%22">Eiben, Björn</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Wetscherek%2C+Andreas%22">Wetscherek, Andreas</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Nill%2C+Simeon%22">Nill, Simeon</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Oelfke%2C+Uwe%22">Oelfke, Uwe</searchLink><relatesTo>1</relatesTo> (AUTHOR)
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  Data: <searchLink fieldCode="JN" term="%22Medical+Physics%22">Medical Physics</searchLink>. Mar2024, Vol. 51 Issue 3, p2221-2229. 9p.
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  Data: <searchLink fieldCode="DE" term="%22Workflow+software%22">Workflow software</searchLink><br /><searchLink fieldCode="DE" term="%22Photon+beams%22">Photon beams</searchLink><br /><searchLink fieldCode="DE" term="%22Electron+density%22">Electron density</searchLink><br /><searchLink fieldCode="DE" term="%22Radiotherapy%22">Radiotherapy</searchLink><br /><searchLink fieldCode="DE" term="%22Drug+dosage%22">Drug dosage</searchLink><br /><searchLink fieldCode="DE" term="%22Dose-response+relationship+%28Radiation%29%22">Dose-response relationship (Radiation)</searchLink><br /><searchLink fieldCode="DE" term="%22Magnetic+resonance%22">Magnetic resonance</searchLink><br /><searchLink fieldCode="DE" term="%22Radiotherapy+safety%22">Radiotherapy safety</searchLink>
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  Data: <searchLink fieldCode="DE" term="%22Stockholm+%28Sweden%29%22">Stockholm (Sweden)</searchLink><br /><searchLink fieldCode="DE" term="%22Monaco%22">Monaco</searchLink>
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: Background: Real‐time dose estimation is a key‐prerequisite to enable online intra‐fraction treatment adaptation in magnetic resonance (MR)‐guided radiotherapy (MRgRT). It is an essential component for the assessment of the dosimetric benefits and risks of online adaptive treatments, such as multi‐leaf collimator (MLC)‐tracking. Purpose: We present a proof‐of‐concept for a software workflow for real‐time dose estimation of MR‐guided adaptive radiotherapy based on real‐time data‐streams of the linac delivery parameters and target positions. Methods: A software workflow, combining our in‐house motion management software DynaTrack, a real‐time dose calculation engine that connects to a research version of the treatment planning software (TPS) Monaco (v.6.09.00, Elekta AB, Stockholm, Sweden) was developed and evaluated. MR‐guided treatment delivery on the Elekta Unity MR‐linac was simulated with and without MLC‐tracking for three prostate patients, previously treated on the Elekta Unity MR‐linac (36.25 Gy/five fractions). Three motion scenarios were used: no motion, regular motion, and erratic prostate motion. Accumulated monitor units (MUs), centre of mass target position and MLC‐leaf positions, were forwarded from DynaTrack at a rate of 25 Hz to a Monte Carlo (MC) based dose calculation engine which utilises the research GPUMCD‐library (Elekta AB, Stockholm, Sweden). A rigid isocentre shift derived from the selected motion scenarios was applied to a bulk density‐assigned session MR‐image. The respective electron density used for treatment planning was accessed through the research Monaco TPS. The software workflow including the online dose reconstruction was validated against offline dose reconstructions. Our investigation showed that MC‐based real‐time dose calculations that account for all linac states (including MUs, MLC positions and target position) were infeasible, hence states were randomly sampled and used for calculation as follows; Once a new linac state was received, a dose calculation with 106 photons was started. Linac states that arrived during the time of the ongoing calculation were put into a queue. After completion of the ongoing calculation, one new linac state was randomly picked from the queue and assigned the MU accumulated from the previous state until the last sample in the queue. The queue was emptied, and the process repeated throughout treatment simulation. Results: On average 27% (23%–30%) of received samples were used in the real‐time calculation, corresponding to a calculation time for one linac state of 148 ms. Median gamma pass rate (2%/3 mm local) was 100.0% (99.9%–100%) within the PTV volume and 99.1% (90.1%–99.4.0%) with a 15% dose cut off. Differences in PTVDmean, CTVDmean, RectumD2%, and BladderD2% (offline‐online, % of prescribed dose) were below 0.64%. Beam‐by‐beam comparisons showed deviations below 0.07 Gy. Repeated simulations resulted in standard deviations below 0.31% and 0.12 Gy for the investigated volume and dose criteria respectively. Conclusions: Real‐time dose estimation was successfully performed using the developed software workflow for different prostate motion traces with and without MLC‐tracking. Negligible dosimetric differences were seen when comparing online and offline reconstructed dose, enabling online intra‐fraction treatment decisions based on estimates of the delivered dose. [ABSTRACT FROM AUTHOR]
– Name: AbstractSuppliedCopyright
  Label:
  Group: Ab
  Data: <i>Copyright of Medical Physics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.)
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RecordInfo BibRecord:
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    Identifiers:
      – Type: doi
        Value: 10.1002/mp.16798
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        Text: English
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        Type: general
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      – SubjectFull: Electron density
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      – SubjectFull: Radiotherapy
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      – SubjectFull: Drug dosage
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      – SubjectFull: Magnetic resonance
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      – SubjectFull: Monaco
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      – TitleFull: Real‐time motion‐including dose estimation of simulated multi‐leaf collimator‐tracked magnetic resonance‐guided radiotherapy.
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              M: 03
              Text: Mar2024
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              Y: 2024
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