Efficacy of robust optimization plan with partial‐arc <scp>VMAT</scp> for photon volumetric‐modulated arc therapy: A phantom study

Miura, Hideharu; Ozawa, Shogo; Nagata, Yasushi

doi:10.1002/acm2.12131

Cited by 15 publications

(10 citation statements)

References 18 publications

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“…Robust optimization was initially introduced for intensity-modulated proton therapy (IMPT) to ensure adequate target dose coverage to account for position and proton range uncertainties [23]. It has been available for x-ray beam in radiation therapy treatment planning system recently [24]. A 4D robust optimization method was introduced by Liu et al to further reduce the impact of uncertainties including intra-fraction organ motion and shape changing to treat lung cancer [25].…”

Section: Methodsmentioning

confidence: 99%

Simulation of dosimetry impact of 4DCT uncertainty in 4D dose calculation for lung SBRT

Gang

Ding

et al. 2019

Radiat Oncol

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BackgroundDue to the heterogeneity of patient’s individual respiratory motion pattern in lung stereotactic body radiotherapy (SBRT), treatment planning dose assessment using a traditional four-dimensional computed tomography (4DCT_traditional) images based on a uniform breathing curve may not represent the true treatment dose delivered to the patient. The purpose of this study was to evaluate the accumulated dose discrepancy between based on the 4DCT_traditional and true 4DCT (4DCT_true) that incorporated with the patient’s real entire breathing motion. The study also explored a novel 4D robust planning strategy to compensate for such heterogeneity respiratory motion uncertainties.MethodsSimulated and measured patient specific breathing curves were used to generate 4D targets motion CT images. Volumetric-modulated arc therapy (VMAT) was planned using two arcs. Accumulated dose was obtained by recalculating the plan dose on each individual phase image and then deformed the dose from each phase image to the reference image. The “4 D dose” (D4D) and “true dose” (Dtrue) were the accumulated dose based on the 4DCT_traditional and 4DCT_true respectively. The average worse case dose discrepancy () between D4D and Dtrue in all treatment fraction was calculated to evaluate dosimetric /planning parameters and correlate them with the heterogeneity of respiratory-induced motion patterns. A novel 4D robust optimization strategy for VMAT (4D Ro-VMAT) based on the probability density function(pdf) of breathing curve was proposed to improve the target coverage in the presence of heterogeneity respiratory motion. The data were assessed with a paired t-tests.ResultsWith increasing breathing amplitude from 5 to 20 mm, target , increased from 1.59,1.39 to 10.15%,8.66% respectively. When the standard deviation of breathing amplitude increased from 15 to 35% of the mean amplitude, , increased from 4.06,3.48 to 10.25%,6.63% respectively. The 4D Ro-VMAT plan significantly improve the target dose compared to VMAT plan.ConclusionWhen the breathing curve amplitude is more than 10 mm and standard deviation of amplitude is higher than 25% of mean amplitude, special care is needed to choose an appropriated dose accumulation approach to evaluate lung SBRT plan target coverage robustness. The proposed 4D Ro_VMAT strategy based on the pdf of patient specific breathing curve could effectively compensate such uncertainties.

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Section: Methodsmentioning

confidence: 99%

Simulation of dosimetry impact of 4DCT uncertainty in 4D dose calculation for lung SBRT

Gang

Ding

et al. 2019

Radiat Oncol

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“…Similar observations were reported by Miura et al . [ 26 ] Their phantom based study in PTV, they showed that nonrobust volumetric-modulated arc therapy (VMAT), are less robust than robustly optimized CTV-based VMAT plans for set up uncertainties. Our study points out the need to consider robust optimization-based IMRT plans and also that robust evaluation should be performed before clinical selection of IMRT and proton plans.…”

Section: Discussionmentioning

confidence: 99%

The role of plan robustness evaluation in comparing protons and photons plans - An application on IMPT and IMRT plans in skull base chordomas

et al. 2020

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Purpose: To analyze robustness of treatment plans optimized using different approaches in intensity modulated proton therapy (IMPT) and investigate the necessity of robust optimization and evaluation in intensity modulated radiotherapy (IMRT) plans for skull base chordomas. Materials and Methods: Two photon plans, standard IMRT and robustly optimized IMRT (RB-IMRT), and two IMPT plans, robustly optimized multi field optimization (MFO) and hybrid-MFO (HB-MFO), were created in RayStation TPS for five patients previously treated using single field uniform optimization (SFO). Both set-up and range uncertainties were incorporated during robust optimization of IMPT plans whereas only set-up uncertainty was used in RB-IMRT. The dosimetric outcomes from the five planning techniques were compared for every patient using standard dose volume indices and integral dose (ID) estimated for target and organs at risk (OARs). Robustness of each treatment plan was assessed by introducing set-up uncertainties of ±3 mm along the three translational axes and, only in protons, an additional range uncertainty of ±3.5%. Results: All the five nominal plans provided comparable and clinically acceptable target coverage. In comparison to nominal plans, worst case decrease in D 95% of clinical target volume-high risk (CTV-HR) were 11.1%, 13.5%, and 13.6% for SFO, MFO, and HB-MFO plans respectively. The corresponding values were 13.7% for standard IMRT which improved to 11.5% for RB-IMRT. The worst case increased in high dose (D 1% ) to CTV-HR was highest in IMRT (2.1%) and lowest in SFO (0.7%) plans. Moreover, IMRT showed worst case increases in D 1% for all neurological OARs and were lowest for SFO plans. The worst case D 1% for brainstem, chiasm, spinal cord, optic nerves, and temporal lobes were increased by 29%, 41%, 30%, 41% and 14% for IMRT and 18%, 21%, 21%, 24%, and 7% for SFO plans, respectively. In comparison to IMRT, RB-IMRT improved D 1% of all neurological OARs ranging from 5% to 14% in worst case scenarios. Conclusion: Based on the five cases presented in the current study, all proton planning techniques (SFO, MFO and HB-MFO) were robust both for target coverage and OARs sparing. Standard IMRT plans were less robust than proton plans in regards to high doses to neurological OARs. However, robust optimization applied to IMRT resulted in improved robustness in both target coverage and high doses to OARs. Robustness evaluation may be considered as a part of plan evaluation procedure even in IMRT.

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“…Previous studies compared the robustness of CMRO and PTV-based optimization by shifting the planning CT without dose re-calculation, implicitly assuming dose invariance, which could lead to bias in favor of PTV-based optimization [5] or by systematic shifts with a dose recalculation could lead to bias in favor of CMRO [28]. By evaluating the dose on daily CBCTs, the EAGD accounts for geometrical variations and is very close to the actually given dose and not biased towards CMRO or PTV-based optimization.…”

Section: Discussionmentioning

confidence: 99%

Composite minimax robust optimization of VMAT improves target coverage and reduces non-target dose in head and neck cancer patients

Wagenaar

Kierkels

Free

et al. 2019

Radiotherapy and Oncology

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Background and purpose To assess the potential of composite minimax robust optimization (CMRO) compared to planning target volume (PTV)-based optimization for head and neck cancer (HNC) patients treated with volumetric modulated arc therapy (VMAT). Materials and methods Ten HNC patients previously treated with a PTV-based VMAT plan were studied. In addition to the PTV-plan a VMAT plan was created with CMRO. For both plans an adapted planning strategy was also investigated, including a plan adaptation during the third week of treatment. The PTV-plans and CMRO-plans (adapted and non-adapted) were evaluated by means of the estimated actually given dose (EAGD). Therefore, the dose was calculated on daily acquired CBCTs, mapped onto the planning CT and accumulated. The plans were compared by dosimetric parameters and normal tissue complication probabilities (NTCPs) for tube feeding dependence, grade 2-4 dysphagia and xerostomia. The accuracy of CBCT-based dose accumulation was further quantified by comparisons of dose accumulation on weekly verification CTs. Results On average, CMRO significantly increased (1.5 Gy) the D 98% of the EAGD to the clinical target volume and significantly decreased the mean dose of the ipsilateral parotid (2.8 Gy), inferior pharynx constrictor muscle (0.7 Gy) and the oral cavity (0.8 Gy). This translated into significantly reduced NTCP of tube feeding dependence (0.9%) and xerostomia (2.8%). The differences in EAGD derived from evaluation CTs or CBCTs were minimal. Conclusion Minimax robust optimization led to improved target coverage and dose reduction in organs at risk in HNC patients treated with VMAT.

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Efficacy of robust optimization plan with partial‐arc VMAT for photon volumetric‐modulated arc therapy: A phantom study

Cited by 15 publications

References 18 publications

Simulation of dosimetry impact of 4DCT uncertainty in 4D dose calculation for lung SBRT

Simulation of dosimetry impact of 4DCT uncertainty in 4D dose calculation for lung SBRT

The role of plan robustness evaluation in comparing protons and photons plans - An application on IMPT and IMRT plans in skull base chordomas

Composite minimax robust optimization of VMAT improves target coverage and reduces non-target dose in head and neck cancer patients

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