Beam selection for stereotactic ablative radiotherapy using Cyberknife with multileaf collimation

Bedford, James L.; Ziegenhein, Peter; Nill, Simeon; Oelfke, Uwe

doi:10.1016/j.medengphy.2018.12.011

Cited by 10 publications

(14 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The selection of an appropriate trajectory for CKA4 lends itself to a beam selection algorithm for positioning control points. 3,8,15,[25][26][27] However, the chosen method must include an accurate collision model for the prevention of collisions between the robot and the patient or couch. 26 Consequently, this study uses a fixed trajectory for all cases.…”

Section: Discussionmentioning

confidence: 99%

“…The Cyberknife typically traverses through up to 100 beam positions during delivery of a fraction of radiotherapy . This provides for a very conformal dose distribution but usually takes a long time to deliver.…”

Section: Introductionmentioning

confidence: 99%

“…The Cyberknife typically traverses through up to 100 beam positions during delivery of a fraction of radiotherapy. 3 This provides for a very conformal dose distribution but usually takes a long time to deliver. In the last decade, delivery time has been considerably reduced on conventional C-arm linear accelerators by the introduction of volumetric modulated arc therapy (VMAT), wherein the gantry of the accelerator is moved through a range of positions with the treatment beam continuously on.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Treatment planning optimization with beam motion modeling for dynamic arc delivery of SBRT using Cyberknife with multileaf collimation

et al. 2019

Self Cite

View full text Add to dashboard Cite

Purpose The use of dynamic arcs for delivery of stereotactic body radiation therapy (SBRT) on Cyberknife is investigated, with a view to improving treatment times. This study investigates the required modeling of robot and multileaf collimator (MLC) motion between control points in the trajectory and then uses this to develop an optimization method for treatment planning of a dynamic arc with Cyberknife. The resulting plans are compared in terms of dose‐volume histograms and estimated treatment times with those produced by a conventional beam arrangement. Methods Five SBRT patient cases (prostate A — conventional, prostate B — brachytherapy‐type, lung, liver, and partial left breast) were retrospectively studied. A suitable arc trajectory with control points spaced at 5° was proposed and treatment plans were produced for typical clinical protocols. The optimization consisted of a fluence optimization, segmentation, and direct aperture optimization using a gradient descent method. Dose delivered by the moving MLC was either taken to be the dose delivered discretely at the control points or modeled using effective fluence delivered between control points. The accuracy of calculated dose was assessed by recalculating after optimization using five interpolated beams and 100 interpolated apertures between each optimization control point. The resulting plans were compared using dose‐volume histograms and estimated treatment times with those for a conventional Cyberknife beam arrangement. Results If optimization is performed based on discrete doses delivered at the arc control points, large differences of up to 40% of the prescribed dose are seen when recalculating with interpolation. When the effective fluence between control points is taken into account during optimization, dosimetric differences are <2% for most structures when the plans are recalculated using intermediate nodes, but there are differences of up to 15% peripherally. Treatment plan quality is comparable between the arc trajectory and conventional body path. All plans meet the relevant clinical goals, with the exception of specific structures which overlap with the planning target volume. Median estimated treatment time is 355 s (range 235–672 s) for arc delivery and 675 s (range 554–1025 s) for conventional delivery. Conclusions The method of using effective fluence to model MLC motion between control points is sufficiently accurate to provide for accurate inverse planning of dynamic arcs with Cyberknife. The proposed arcing method produces treatment plans with comparable quality to the body path, with reduced estimated treatment delivery time.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Treatment planning optimization with beam motion modeling for dynamic arc delivery of SBRT using Cyberknife with multileaf collimation

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…The Cyberknife currently delivers radiation from a number of static locations around the patient in a step-and-shoot arrangement. 8 However, a number of studies have demonstrated the potential for reduction in delivery time by the use of dynamic arc delivery, similar in nature to volumetric modulated arc therapy (VMAT), although from noncoplanar orientations as opposed to the more common coplanar arcs used for VMAT. For example, Kearney et al 9 describe a noncoplanar arc optimization algorithm for Cyberknife with a circular collimator.…”

Section: Introductionmentioning

confidence: 99%

“…The choice of trajectory is a key aspect of arc delivery, but as trajectory selection is an extensive subject, the reader is referred to previous studies for details. 8,10,15 In the present study, a previously investigated arc trajectory 15 is used to provide suitable dynamic baseline plans in the known range of collision-free operation of the Cyberknife robot. Based on published data and other estimates from Accuray, the expected variations in dose rate, leaf positioning, and robot target position are established and incorporated into models of these parameters (Fig.…”

Section: Introductionmentioning

confidence: 99%

Dosimetric accuracy of delivering SBRT using dynamic arcs on Cyberknife

2020

Self Cite

View full text Add to dashboard Cite

Purpose: Several studies have demonstrated potential improvements in treatment time through the use of dynamic arcs for delivery of stereotactic body radiation therapy (SBRT) on Cyberknife. However, the delivery system has a finite accuracy, so that potential exists for dosimetric uncertainties. This study estimates the expected dosimetric accuracy of dynamic delivery of SBRT, based on realistic estimates of the uncertainties in delivery parameters. Methods: Five SBRT patient cases (prostate Aconventional, prostate Bbrachytherapy-type, lung, liver, partial left breast) were retrospectively studied. Treatment plans were produced for a fixed arc trajectory using fluence optimization, segmentation, and direct aperture optimization. Dose rate uncertainty was modeled as a smoothly varying random fluctuation of AE 1.0%, AE2.0% or AE 5.0% over a time period of 10, 30 or 60 s. Multileaf collimator uncertainty was modeled as a lag in position of each leaf up to 0.25 or 0.5 mm. Robot pointing error was modeled as a shift of the target location, with the direction of the shift chosen as a random angle with respect to the multileaf collimator and with a random magnitude in the range 0.0-1.0 mm at the delivery nodes and with an additional random magnitude of 0.5-1.0 mm in between the delivery nodes. The impact of the errors was investigated using dose-volume histograms. Results: Uncertainty in dose rate has the effect of varying the total monitor units delivered, which in turn produces a variation in mean dose to the planning target volume. The random sampling of dose rate error produces a distribution of mean doses with a standard deviation proportional to the magnitude of the dose rate uncertainty. A lag in multileaf collimator position of 0.25 or 0.5 mm produces a small impact on the delivered dose. In general, an increase in the PTV mean dose of around 1% is observed. An error in robot pointing of the order of 1 mm produces a small increase in dose inhomogeneity to the planning target volume, sometimes accompanied by an increase in mean dose by around 1%. Conclusions: Based upon the limited data available on the dose rate stability and geometric accuracy of the Cyberknife system, this study estimates that dynamic arc delivery can be accomplished with sufficient accuracy for clinical application. Dose rate variation produces a change in dose to the planning target volume according to the perturbation of total monitor units delivered, while multileaf collimator lag and robot pointing error typically increase the mean dose to the planning target volume by up to 1%.

show abstract

Evolutionary Machine Learning in Medicine

Lones,

Smith

2023

Genetic and Evolutionary Computation

View full text Add to dashboard Cite

Beam selection for stereotactic ablative radiotherapy using Cyberknife with multileaf collimation

Cited by 10 publications

References 39 publications

Treatment planning optimization with beam motion modeling for dynamic arc delivery of SBRT using Cyberknife with multileaf collimation

Treatment planning optimization with beam motion modeling for dynamic arc delivery of SBRT using Cyberknife with multileaf collimation

Dosimetric accuracy of delivering SBRT using dynamic arcs on Cyberknife

Evolutionary Machine Learning in Medicine

Contact Info

Product

Resources

About