Planning 4D intensity-modulated arc therapy for tumor tracking with a multileaf collimator

Niu, Yuxin; Betzel, G; Yang, X; Gui, Minzhi; Parke, William C.; Yi, B; Yu, C

doi:10.1088/1361-6560/aa56b7

Cited by 6 publications

(8 citation statements)

References 42 publications

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“…A robust and fast 3D tumor tracking algorithm based on 2D dynamic MRI will enable intrafractional tracking of target tumor when used with recently developed MR-LINAC’s. Combined with motion adaptive planning and treatment approaches (Keall et al 2001, Niu et al 2017), it can allow for margin reduction in PTV with high tumor tracking accuracy.…”

Section: Discussionmentioning

confidence: 99%

Simultaneous tumor and surrogate motion tracking with dynamic MRI for radiation therapy planning

Park¹,

Farah²,

Shea³

et al. 2018

Phys. Med. Biol.

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Respiration-induced tumor motion is a major obstacle for achieving high-precision radiotherapy of cancers in the thoracic and abdominal regions. Surrogate-based estimation and tracking methods are commonly used in radiotherapy, but with limited understanding of quantified correlation to tumor motion. In this study, we propose a method to simultaneously track the lung tumor and external surrogates to evaluate their spatial correlation in a quantitative way using dynamic MRI, which allows real-time acquisition without ionizing radiation exposure. To capture the lung and whole tumor, four MRI-compatible fiducials are placed on the patient's chest and upper abdomen. Two different types of acquisitions are performed in the sagittal orientation including multi-slice 2D cine MRIs to reconstruct 4D-MRI and two-slice 2D cine MRIs to simultaneously track the tumor and fiducials. A phase-binned 4D-MRI is first reconstructed from multi-slice MR images using body area as a respiratory surrogate and groupwise registration. The 4D-MRI provides 3D template volumes for different breathing phases. 3D tumor position is calculated by 3D-2D template matching in which 3D tumor templates in the 4D-MRI reconstruction and the 2D cine MRIs from the two-slice tracking dataset are registered. 3D trajectories of the external surrogates are derived via matching a 3D geometrical model of the fiducials to their segmentations on the 2D cine MRIs. We tested our method on ten lung cancer patients. Using a correlation analysis, the 3D tumor trajectory demonstrates a noticeable phase mismatch and significant cycle-to-cycle motion variation, while the external surrogate was not sensitive enough to capture such variations. Additionally, there was significant phase mismatch between surrogate signals obtained from the fiducials at different locations.

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Section: Discussionmentioning

confidence: 99%

Simultaneous tumor and surrogate motion tracking with dynamic MRI for radiation therapy planning

Park¹,

Farah²,

Shea³

et al. 2018

Phys. Med. Biol.

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“…This motion information can be used to simply deform the MLC aperture to follow the tumour motion, with no other changes [50,51].…”

Section: Motion Mitigation Methods In Ebrtmentioning

confidence: 99%

“…Finally, the two previously-published methods of 4D-VMAT optimization mentioned in Section 4.1 were considered: single trajectory optimization (STO) [52] and direct aperture deformation (DAD) [51]. The former method assumes that the patient's breathing motion is unchanging from one fraction to the next, while the latter makes no assumptions or provisions for the patient motion pattern, except to simply deform the aperture to follow the tumour motion.…”

Section: Comparison Of 4d Methodsmentioning

confidence: 99%

“…The design, implementation, validation, and evaluation of this 4D-VMAT plan optimization and delivery framework is done in Chapter 4. The resulting plans are compared to plans optimized using no motion compensation, MKO, as well as two motion tracking techniques: simple deformation of the MLC aperture to the motion of the tumour [51], and 4D-VMAT optimized under the assumption of a single fixed trajectory [52]. Particular attention is paid to the robustness of the plan quality, including adequate coverage of the target by the prescription dose, as well as maintaining a low dose to OARs.…”

Section: Proposed Solution and Thesis Overviewmentioning

confidence: 99%

“…Two particular 4D-VMAT optimization methods will be investigated more closely in this study: single trajectory optimization (STO) [52] and direct aperture deformation (DAD) [51]. In STO it is assumed that the patient's breathing motion during delivery is known at the optimization stage, and does not change from one fraction to another.…”

Section: Introductionmentioning

confidence: 99%

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A Framework for the Robust Delivery of Respiratory Motion Adaptive Arc Radiotherapy

Christiansen¹

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ALERT‐RA: an aperture library‐enabled real‐time respiratory motion adaptive framework for 4D‐VMAT

Christiansen

Heath

2022

Medical Physics

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Purpose To develop a framework for robust optimization of real‐time respiratory motion adaptive VMAT treatment plans, and to evaluate the robustness of resulting plans to variations in tumor trajectory during delivery. Methods The proposed framework is called aperture library‐enabled real‐time robust adaptation (ALERT‐RA). A patient‐specific library of optimized MLC apertures is defined for each combination of gantry angle and respiratory phase. The method assumes that the tumor is tracked in real‐time throughout delivery, and the aperture corresponding to the current phase and gantry angle will be delivered. The aperture library is optimized by considering all possible tumor trajectories determined by a probabilistic respiratory motion model. Plan robustness to trajectory variations was evaluated by sampling a trajectory, and determining the corresponding dose, from the respiratory model for each fraction. The cumulative dose of the full treatment course was simulated 50 times. Percentile dose–volume histograms (PDVHs) were computed from these simulated treatments. The resulting plan quality and robustness of this method were compared to other previously published motion 4D‐VMAT methods, including: an optimized tracking approach that assumes reproducible tumor motion, conformal tracking with aperture deformation, and a motion‐encompassing method. Two fractionation schemes were tested to determine the possible effect on robustness: a conventional fractionation of 66 Gy in 33 fractions, and an SBRT course with 60 Gy in 5 fractions. Results When considering target coverage, the ALERT‐RA method was found to produce a plan which was more robust than those produced using the optimized or conformal tracking methods. Using the PDVH analysis, the 5th and 95th percentiles of the prescription dose volume for the conventionally fractioned plan were found to be (respectively) 79% and 82% for the optimized tracking approach, 81% and 83% for the conformal tracking approach, and 92% and 97% using the new ALERT‐RA method. The motion‐encompassing plan was slightly more robust than the ALERT‐RA plan, with 5th and 95th percentiles at 94% and 95%, respectively. This came at a cost of higher dose to OARs, with the volume of lung receiving 5 Gy or more equal to 48% for the motion‐encompassing plan versus 44% for the ALERT‐RA plan. For the SBRT plan, the conformal tracking plan was similarly not robust, with 5th and 95th percentiles of the prescription dose volume equal to 88% and 89%. The optimized tracking SBRT plan gave values of 93% and 95%, and the motion‐encompassing plan 94% and 95%, while the ALERT‐RA gave values of 93% and 96%. The volume of lung receiving 20 Gy or more was slightly higher for the optimized tracking and motion‐encompassing plans compared to the ALERT‐RA plan, at 15%, 15%, and 14%, respectively. Conclusions Compared to other motion‐adaptive VMAT approaches, the ALERT‐RA algorithm is capable of delivering high‐quality plans which are robust to variations in tumor motion trajectories.

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Planning 4D intensity-modulated arc therapy for tumor tracking with a multileaf collimator

Cited by 6 publications

References 42 publications

Simultaneous tumor and surrogate motion tracking with dynamic MRI for radiation therapy planning

Simultaneous tumor and surrogate motion tracking with dynamic MRI for radiation therapy planning

A Framework for the Robust Delivery of Respiratory Motion Adaptive Arc Radiotherapy

ALERT‐RA: an aperture library‐enabled real‐time respiratory motion adaptive framework for 4D‐VMAT

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