Penalization of aperture complexity in inversely planned volumetric modulated arc therapy

Younge, K. C.; Matuszak, Martha M.; Moran, Jean M.; McShan, Daniel L.; Fraass, Benedick A.; Roberts, D. A.

doi:10.1118/1.4762566

Cited by 95 publications

(122 citation statements)

References 30 publications

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“…When compared to the plan using a MSW of 0.5 cm, the mean MU reductions in the plans using MSWs of 1.0 and 1.5 cm were 15.2% and 21.9%, respectively, while the total control points were decreased by 2.9% and 8.8%, respectively. Previous studies showed that decreasing the MUs for treatment delivery reduces the constraint factor of the leaves’ trajectories, complexity of intensity‐modulated radiation therapy plans, and treatment time 14, 15, 16, 17. Hence, as the MSW increases and VMAT plan complexity decreases, the therapeutic efficiency may improve as well.…”

Section: Discussionmentioning

confidence: 99%

A study of minimum segment width parameter on VMAT plan quality, delivery accuracy, and efficiency for cervical cancer using Monaco TPS

Wang

Chen

Zhu

et al. 2018

J Applied Clin Med Phys

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PurposeThe purpose of this study was to study the influence of the minimum segment width (MSW) on volumetric modulated arc therapy (VMAT) plan quality, delivery accuracy, and efficiency for cervical cancer treatment.MethodsNineteen patients with cervical cancer were randomly selected to design VMAT plans. Three VMAT plans were generated for each patient incorporating MSWs of 0.5, 1.0, and 1.5 cm while other planning parameters remained constant using the Monaco treatment planning system (TPS) with 6 MV X rays delivered from an Elekta Synergy linear accelerator. Plan quality and delivery efficiency were evaluated based on dose‐volume histograms (DVHs), control points, monitor units (MUs), dosimetric measurement verification results, and plan delivery time.ResultsExcept for the small difference in target dose coverage and maximum dose, there were no statistically significant differences between the other dosimetric parameters in the planning target volumes. The 1.0 and 1.5 cm MSW plans showed lower maximum doses to the spinal cord than the 0.5 cm plan; doses to other organs at risks were similar regardless of MSWs. The mean reductions of total MUs when compared with the 0.5 cm plan were 14.5 ± 6.1% and 20.9 ± 7.9% for MSWs of 1.0 and 1.5 cm, respectively. The calculated gamma indices using the 3% and 3 mm criteria were 96.2 ± 0.6%, 97.0 ± 0.6%, and 97.6 ± 0.6% for the 0.5, 1.0 and 1.5 cm MSW plans, respectively. The plan delivery times decreased with increasing MSWs (p < 0.05).ConclusionIncreasing the MSW allows for improved plan delivery accuracy and efficiency without significantly affecting the VMAT plan quality. MSWs of 1.0 and 1.5 cm improved the plan quality, delivery accuracy, and efficiency for cervical VMAT radiation therapy.

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Section: Discussionmentioning

confidence: 99%

A study of minimum segment width parameter on VMAT plan quality, delivery accuracy, and efficiency for cervical cancer using Monaco TPS

Wang

Chen

Zhu

et al. 2018

J Applied Clin Med Phys

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“…Also, a large decrease in plan modulation not only improves delivery efficiency, but also potentially decreases planning and quality assurance time or difficulty. [12][13][14][15] The patients undergoing hypofractionated treatment for tumors of the thorax and abdomen are more prone to have respiratory motion. These respiratory motions in the SBRT cases are manageable with the systems like Active Breathing Coordinator, respiratory gating, forced shallow breathing, etc., as per patient's comfort.…”

Section: Discussionmentioning

confidence: 99%

“…Young et al have discussed the use of edge penalty during optimization that reduces the required MUs up to 30% by avoiding the creation of complex apertures and increases accuracy of dose delivery with gamma passing rate from 79.5% to about 95.4%. 12 Hence the creation of such smaller segments can be controlled with sequencing parameters by the segmentation of theoretical fluence into deliverable MLC segments. The minimum segment width parameter in the segmentation process has a significant role in the creation of segments with different sizes and shapes.…”

Section: Introductionmentioning

confidence: 99%

Influence of segment width on plan quality for volumetric modulated arc based stereotactic body radiotherapy

Nithiyanantham¹,

Mani²,

Subramani³

et al. 2014

Reports of Practical Oncology & Radiotherapy

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“…With the transfer of these patients to the EDGE, a marked increase in plan modulation was observed, visualized both in the MLC‐leaf trajectory sequence in the Eclipse treatment planning system (TPS) as well as quantified by the number of monitor units (MU) and our in‐house VMAT complexity metric 3, 4. We also observed a sudden increase in plans failing patient‐specific quality assurance with the ArcCHECK (Sun Nuclear Corporation, Melbourne, FL, USA).…”

Section: Introductionmentioning

confidence: 99%

The impact of a high‐definition multileaf collimator for spine SBRT

Younge

Kuchta

Mikell

et al. 2017

J Applied Clin Med Phys

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PurposeAdvanced radiotherapy delivery systems designed for high‐dose, high‐precision treatments often come equipped with high‐definition multi‐leaf collimators (HD‐MLC) aimed at more finely shaping radiation dose to the target. In this work, we study the effect of a high definition MLC on spine stereotactic body radiation therapy (SBRT) treatment plan quality and plan deliverability.Methods and MaterialsSeventeen spine SBRT cases were planned with VMAT using a standard definition MLC (M120), HD‐MLC, and HD‐MLC with an added objective to reduce monitor units (MU). M120 plans were converted into plans deliverable on an HD‐MLC using in‐house software. Plan quality and plan deliverability as measured by portal dosimetry were compared among the three types of plans.ResultsOnly minor differences were noted in plan quality between the M120 and HD‐MLC plans. Plans generated with the HD‐MLC tended to have better spinal cord sparing (3% reduction in maximum cord dose). HD‐MLC plans on average had 12% more MU and 55% greater modulation complexity as defined by an in‐house metric. HD‐MLC plans also had significantly degraded deliverability. Of the VMAT arcs measured, 94% had lower gamma passing metrics when using the HD‐MLC.ConclusionModest improvements in plan quality were noted when switching from M120 to HD‐MLC at the expense of significantly less accurate deliverability in some cases.

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Penalization of aperture complexity in inversely planned volumetric modulated arc therapy

Abstract: The use of the edge penalty during optimization has the potential to markedly improve dose delivery accuracy for VMAT plans while still maintaining high quality optimized dose distributions. The penalty regularizes aperture shape and improves delivery efficiency.

Cited by 95 publications

References 30 publications

A study of minimum segment width parameter on VMAT plan quality, delivery accuracy, and efficiency for cervical cancer using Monaco TPS

A study of minimum segment width parameter on VMAT plan quality, delivery accuracy, and efficiency for cervical cancer using Monaco TPS

Influence of segment width on plan quality for volumetric modulated arc based stereotactic body radiotherapy

The impact of a high‐definition multileaf collimator for spine SBRT

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