Avoidance sectors to reduce dosimetric impact of an irreproducible pannus on setup uncertainty in prostate SBRT VMAT: A case study

Hubley, Emily; Shukla, Geeta; Vakhnenko, Yelena; Den, Robert B.; Harrison, A

doi:10.1016/j.meddos.2018.05.003

Cited by 3 publications

(2 citation statements)

References 6 publications

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“…Similar strategies could be applied to CSI to minimize dose to adjacent OARs. Many studies have demonstrated the utilisation of avoidance sectors in VMAT planning to minimize radiation exposure to the OARs, a technique that could be adapted for the avoidance of critical structures in CSI as well [ 6 – 7 ].…”

Section: Introductionmentioning

confidence: 99%

Optimising craniospinal irradiation for medulloblastoma: a dosimetric comparison of two VMAT planning methods

Thakur,

Bansal,

Sudan

et al. 2024

ecancer Journal

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Background Craniospinal irradiation (CSI) poses a challenging planning process because of the complex target volume. Traditional 3D conformal CSI does not spare any critical organs, resulting in toxicity in patients. Here the dosimetric advantages of volumetric-modulated arc therapy (VMAT) using partial arc and avoidance sectors are compared with each other in planning in adult patients undergoing CSI to develop a clinically feasible technique that is both effective and efficient. Patient and methods Eight adult patients treated with CSI were retrospectively identified. In total 16 plans were made. We generated two plans for each patient: 1. VMAT plan using partial arc, namely VMAT_pa. 2. VMAT plan using avoidance sectors, namely VMAT_as. The dose prescribed was 36 Gy in 20 fractions. The dose-volume histogram for planning target volume (PTV) and organs at risk (OAR) (lens, eye, heart, thyroid, lungs, liver, gonads and kidneys) were analysed and compared. Dose parameters of mean dose, V 95% , and V 107% for the PTV were evaluated. Results The median length of PTV is 65.58 cm (45.8–79.5). The volume of PTV receiving 95% of the dose (V95%) in both the plans are 97.51% (VMAT_as) and 97.99% (VMAT_pa) ( p = 0.121) while V107% are 0.733 and 0.742 for VMAT_as and VMAT_pa, respectively ( p = 0.969). The doses of OARs such as lens, eye, liver and gonads were comparable. The mean heart dose was 10.4 and 9.0 Gy in VMAT_as and VMAT_pa plans, respectively ( p = 0.005). Significant lower doses to the thyroid, kidneys and lungs were seen in VMAT plans using avoidance sectors. Conclusion This study provides a practically useful VMAT planning method for the treatment of CSI and illustrates the ability of VMAT using avoidance sectors to generate highly conformal and homogeneous treatment plans for CSI, while limiting the dose to the relevant OARs.

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Section: Introductionmentioning

confidence: 99%

Optimising craniospinal irradiation for medulloblastoma: a dosimetric comparison of two VMAT planning methods

Thakur,

Bansal,

Sudan

et al. 2024

ecancer Journal

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“…There are various approaches proposed to improve VMAT plan by introducing partial arc or full arc with avoidance sectors to avoid the portion of the arc which contributes relatively less. (Rossi et al, 2016;Hubley et al, 2018;Elith et al, 2014;Huang et al, 2015;Chan et al, 2015;Wala et al, 2012;Rana et al, 2013). Eventually it reduces the treatment time and OAR dose by eliminating the gantry rotation angles, where limited beam modulation is required.…”

Section: Introductionmentioning

confidence: 99%

A Novel Method for Improving VMAT Plan Quality and Deliverability

Ramar

Meher

2022

Asian Pac J Cancer Prev

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Background: A new VMAT method called "Augmented Arc" (or simply Aug Arc) is proposed. The aim of this study is to demonstrate the validity of the proposed method in different clinical cases. Basically, Aug Arc refers to the portion(s) of the VMAT arc that is augmented with an additional arc to improve the plan quality. The Aug Arc portions in the Arc is determined using an objective function-based scoring method called "ψ -score". Methods: To validate our approach, we have applied it in four clinical cases: Lung, Abdomen, Gynecologic (Gyn) and Pancreas. Basically, for Lung and Pancreas cases, four sets of plans were created, which are: (1) Single arc plan (S Arc), (2) Double arc plan (D Arc), (3) Partial Arc plan without Aug Arc (P Arc) and (4) Partial plan with Aug Arc (P+Aug Arc). For Abdomen and Gyn cases, three sets of plans were created, which are: (1) Single arc plan (S Arc), (2) Double arc plan (D Arc) and(3) Single Arc with Aug Arc (S+Aug Arc). To compute the "ψ -score", an initial optimization was performed by using full Arc with 4-degree gantry spacing. Subsequently, Aug Arc portions were identified using the ψ -score plot in the single arc and partial arc scenarios. Results: The study finds that the proposed method is useful to improve the plan quality and plan deliverability for both centrically and non-centrically located tumors in terms of reducing the OAR dose, monitor units, beam on time and low dose volume without compromising the target coverage. Conclusion: The results indicate that the proposed approach could strike a balance between full double arc and single arc or partial arc in such a way that the planner can find a sweet spot of delivery parameters that result in optimal plan quality.

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Sparing lung tissue with virtual block method in VMAT planning for locally advanced non-small cell lung cancer

et al. 2022

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Avoidance sectors to reduce dosimetric impact of an irreproducible pannus on setup uncertainty in prostate SBRT VMAT: A case study

Cited by 3 publications

References 6 publications

Optimising craniospinal irradiation for medulloblastoma: a dosimetric comparison of two VMAT planning methods

Optimising craniospinal irradiation for medulloblastoma: a dosimetric comparison of two VMAT planning methods

A Novel Method for Improving VMAT Plan Quality and Deliverability

Sparing lung tissue with virtual block method in VMAT planning for locally advanced non-small cell lung cancer

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