First online real‐time evaluation of motion‐induced 4D dose errors during radiotherapy delivery

Ravkilde, T.; Skouboe, Simon; Hansen, Rune; Worm, E.; Poulsen, Per Rugaard

doi:10.1002/mp.13037

Cited by 32 publications

(39 citation statements)

References 36 publications

(94 reference statements)

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“…DoseTracker is an in‐house developed computer program for fast real‐time calculation of the dose delivered during radiotherapy to an arbitrary set of points within a body contour . Any motion can be included in the dose reconstruction by shifting each individual calculation point between consecutive dose increment calculations.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Real‐time motion‐including dose reconstruction has been demonstrated in simulated treatments and in phantom experiments . We previously created an in‐house developed software program, DoseTracker, with the intent of determining motion‐induced dosimetric errors in real time. The method and software have been validated in a phantom study for real‐time QA allowing conventional phantom‐based pretreatment QA to be applied as in‐treatment QA during active beams .…”

Section: Introductionmentioning

confidence: 99%

“…We previously created an in‐house developed software program, DoseTracker, with the intent of determining motion‐induced dosimetric errors in real time. The method and software have been validated in a phantom study for real‐time QA allowing conventional phantom‐based pretreatment QA to be applied as in‐treatment QA during active beams . Patient anatomy is, however, very different from the cylindrical phantom that DoseTracker emulates for in‐treatment QA and calculating dose on the real patient anatomy instead would be more desirable.…”

Section: Introductionmentioning

confidence: 99%

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Simulated real‐time dose reconstruction for moving tumors in stereotactic liver radiotherapy

Skouboe¹,

Poulsen²,

Muurholm³

et al. 2019

Medical Physics

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Purpose: In radiotherapy, tumor motion may deteriorate the planned dose distribution. However, the dosimetric consequences of the motion are normally unknown for individual treatments. We here present a method for real-time motion-including tumor dose reconstruction and demonstrate its use for simulated stereotactic body radiotherapy (SBRT) of patients with liver cancer previously treated with Calypso-guided gating. Methods: Real-time motion-including dose reconstruction was performed using in-house developed software, DoseTracker, on offline replays of previous clinical treatments. The patient cohort consisted of fifteen patients previously treated in our clinic with three-fraction SBRT to the liver using conformal or IMRT plans. The tumor motion at treatment was monitored with implanted electromagnetic transponders. The dose reconstruction was performed for both the actual gated treatments and simulated nongated treatments using a 21 Hz data stream containing accelerator parameters and the recorded motion. The dose was reconstructed in the same calculation points within the planning target volume (PTV) as used by the treatment planning system (TPS). The reconstructed doses were compared with calculations performed in the TPS, in which the motion was modeled as a series of isocenter shifts. The comparison included point doses as a function of treatment time and the dose volume histogram (DVH) for the clinical target volume (CTV). The motion-induced reduction in the dose to 95% of the CTV, DD 95% , and in the mean CTV dose, DD Mean , was compared between DoseTracker and the TPS for each simulated fraction. DoseTracker currently assumes water density within the patient contour, so for comparison, the TPS calculations were performed with both CT density and water density. The calculation times were additionally analyzed. Results: Dose reconstruction was carried out for ninety SBRT sessions with calculation volumes ranging from 9.9 to 366.4 cm 3 and median calculation times of 55-155 ms (equivalent to 18.2-6.5 Hz). Time-resolved trends of doses to a single calculation point in the patient were well replicated and dose differences between actual and planned calculations matched well. DD Mean had a range of À0.1%-30.7%-points and was estimated by DoseTracker with a root-mean-square deviation (RMSD) to the TPS calculations of 0.43%-points (water density) and 0.79%-points (CT density). Similarly, DD 95% had a range of 0.0%-35.2%-points and was estimated by Dose-Tracker with an RMSD of 0.80%-points (water density) and 1.33%-points (CT density). Dose-Tracker predicted losses in tumor dose coverage above 5%-points with high sensitivity (91.7%) and specificity (97.6%). Conclusions: Real-time dose reconstruction to moving tumors was demonstrated on offline replays of previous clinical treatments. DVHs of actually delivered dose are made available immediately after the end of treatment fractions. It shows promising results for liver SBRT with accurate estimation of

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Simulated real‐time dose reconstruction for moving tumors in stereotactic liver radiotherapy

Skouboe¹,

Poulsen²,

Muurholm³

et al. 2019

Medical Physics

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“…Advanced software developments yet to be clinically applied to standard cancer radiotherapy systems include real-time volumetric visualization of the anatomy as it evolves during treatment, e.g. Li et al, [7] real-time online dose reconstruction [8] and the ability to evaluate the motion-induced dose errors in real-time [9]. Combining these tasks with fast planning will facilitate volumetric real-time adaptation of the radiation beam to the dynamic patient and tumor anatomy.…”

mentioning

confidence: 99%

In Reply to Dahele and Verbakel

Keall

Nguyen

O’Brien

et al. 2019

International Journal of Radiation Oncology*Biology*Physics

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Your letter and your translational research work support the question posed in the review:[1] Are we at the tipping point for the era of real-time radiation therapy? Your research adds additional clinical evidence that real-time 3D IGRT can be performed on standard-equipped cancer radiation therapy systems. Indeed, had it been published or known to us before we wrote the review your clinical translation of the markerless spine tracking [2] would have been included as a fourth real-time 3D IGRT implementation on standard-equipped systems. Your additional retrospective work, based on clinical data, paves the way for further translation for markerless lung [3] and bronchus [4] tracking applications.

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Effect of an integral quality monitor on 4‐, 6‐, 10‐MV, and 6‐MV flattening filter‐free photon beams

Nguyen

Yokoyama

Kojima

et al. 2020

J Applied Clin Med Phys

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PurposeTo investigate the effect of an integral quality monitor (IQM; iRT Systems GmbH, Koblenz, Germany) on 4, 6, 10, and 6‐MV flattening filter‐free (FFF) photon beams.MethodsWe assessed surface dose, PDD20,10, TPR20,10, PDD curves, inline and crossline profiles, transmission factor, and output factor with and without the IQM. PDD, transmission factor, and output factor were measured for square fields of 3, 5, 10, 15, 20, 25, and 30 cm and profiles were performed for square fields of 3, 5, 10, 20, and 30 cm at 5‐, 10‐, and 30‐cm depth.ResultsThe differences in surface dose of all energies for square fields of 3, 5, 10, 15, 20, and 25 cm were within 3.7% whereas for a square field of 30 cm, they were 4.6%, 6.8%, 6.7%, and 8.7% for 4‐MV, 6‐MV, 6‐MV‐FFF, and 10‐MV, respectively. Differences in PDD20,10, TPR20,10, PDD, profiles, and output factors were within ±1%. Local and global gamma values (2%/2 mm) were below 1 for PDD beyond dmax and inline/crossline profiles in the central beam region, respectively. The gamma passing rates (10% threshold) for PDD curves and profiles were above 95% at 2%/2 mm. The transmission factors for 4‐MV, 6‐MV, 6‐MV‐FFF, and 10‐MV for field sizes from 3 × 3 to 30 × 30 cm2 were 0.926–0.933, 0.937–0.941, 0.937–0.939, and 0.949–0.953, respectively.ConclusionsThe influence of the IQM on the beam quality (in particular 4‐MV X‐ray has not verified before) was tested and introduced a slight beam perturbation at the surface and build‐up region and the edge of the crossline/inline profiles. To use IQM in pre‐ and intra‐treatment quality assurance, a tray factor should be put into treatment planning systems for the dose calculation for the 4‐, 6‐, 10‐, and 6‐MV flattening filter‐free photon beams to compensate the beam attenuation of the IQM detector.

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First online real‐time evaluation of motion‐induced 4D dose errors during radiotherapy delivery

Abstract: Real-time delivery-specific QA during radiotherapy of moving targets was demonstrated for the first time. It allows supervision of treatment accuracy and action on treatment discrepancy within 2 s with high sensitivity and specificity.

Cited by 32 publications

References 36 publications

Simulated real‐time dose reconstruction for moving tumors in stereotactic liver radiotherapy

Simulated real‐time dose reconstruction for moving tumors in stereotactic liver radiotherapy

In Reply to Dahele and Verbakel

Effect of an integral quality monitor on 4‐, 6‐, 10‐MV, and 6‐MV flattening filter‐free photon beams

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