Organs-at-risk dose and normal tissue complication probability with dynamic trajectory radiotherapy (DTRT) for head and neck cancer

Bertholet, Jenny; Mackeprang, Paul-Henry; Loebner, Hannes A.; Mueller, Silvan; Guyer, Gian; Frei, Daniel; Volken, Werner; Elicin, Olgun; Aebersold, Daniel M.; Fix, Michael K.; Manser, Peter

doi:10.1016/j.radonc.2024.110237

Cited by 2 publications

(3 citation statements)

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“…Third, alongside patient-setup, machine-related uncertainties were investigated. This study substantially added to our treatment plan comparison [27] by extending the evaluation from the nominal to realistic uncertainty scenarios, recognizing robustness as an integral part of plan quality [37] .…”

Section: Discussionmentioning

confidence: 99%

“…This robustness study was based on DTRT and VMAT plans previously created for a treatment planning comparison for 46 patients with loco-regionally-advanced oropharyngeal carcinoma ( Supplementary Table A.1 ) [27] , enrolled in the UPFRONT-NECK trial (NCT02918955) between 12.2016 and 4.2022. The patients provided informed consent.…”

Section: Methodsmentioning

confidence: 99%

“…Uncertainties therefore impact also the NTCP. A previous large plan comparison for H&N cancer showed that DTRT improves OAR sparing for salivary glands and swallowing structures compared to VMAT, resulting in statistically significant lower NTCP for xerostomia and dysphagia [27] . However, the impact of patient- or machine-related uncertainties on the dosimetric plan quality was not investigated.…”

Section: Introductionmentioning

confidence: 94%

See 2 more Smart Citations

Robustness analysis of dynamic trajectory radiotherapy and volumetric modulated arc therapy plans for head and neck cancer

Loebner,

Bertholet,

Mackeprang

et al. 2024

Physics and Imaging in Radiation Oncology

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 94%

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Robustness analysis of dynamic trajectory radiotherapy and volumetric modulated arc therapy plans for head and neck cancer

Loebner,

Bertholet,

Mackeprang

et al. 2024

Physics and Imaging in Radiation Oncology

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Dosimetric optimization for dynamic mixed beam arc therapy (DYMBARC)

Zhu,

Guyer,

Bertholet

et al. 2024

Medical Physics

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BackgroundNon‐coplanarity and mixed beam modality could be combined to further enhance dosimetric treatment plan quality. We introduce dynamic mixed beam arc therapy (DYMBARC) as an innovative technique that combines non‐coplanar photon and electron arcs, dynamic gantry and collimator rotations, and intensity modulation with photon multileaf collimator (MLC). However, finding favorable beam directions for DYMBARC is challenging due to the large solution space, machine component constraints, and optimization parameters, posing a highly non‐convex optimization problem.PurposeTo establish DYMBARC and solve the pathfinding challenge by employing direct aperture optimization (DAO) to determine the table angles and gantry angle ranges of photon and electron arcs for different clinically motivated cases.MethodsThe method starts by generating a grid of beam directions based on user‐defined resolutions along the gantry and table angle axes for each beam quality considered. Beam directions causing collisions or entering through the end of CT are excluded. For electrons, a fixed source‐to‐surface distance of 80 cm is used to reduce in‐air scatter. Electron beam energies with insufficient range to reach the target or beam directions impinging on the table before reaching the patient are excluded. The remaining beam directions form the pathfinding solution space. Promising photon and electron MLC‐defined apertures, with associated monitor unit (MU) weights, are iteratively added using a hybrid‐DAO algorithm. This algorithm combines column generation to add apertures and simulated annealing to further refine aperture shapes and weights. Apertures are added until the requested number of paths are formed and the user‐defined maximum total gantry angle range is reached. Paths are resampled to a finer gantry angle resolution and subject to DAO for simultaneous optimization of beam intensities along the photon/electron arcs. Subsequent final dose calculation and MU weight reoptimization result in a deliverable DYMBARC plan. DYMBARC plans are created for three clinically motivated cases (brain, breast, and pelvis) and compared to DYMBARC variants: colli‐DTRT (dynamic collimator trajectory radiotherapy) using non‐coplanar photon arcs; and Arc‐MBRT (mixed beam radiotherapy) using photons and electrons but restricted to coplanar setup. Additionally, a manually defined volumetric modulated arc therapy (VMAT) setup serves as a reference clinical technique. Dose distributions, dose‐volume histograms, and dosimetric endpoints are evaluated. Dosimetric validation with radiochromic film measurements (gamma evaluation, 3% / 2 mm (global), 10% dose threshold) is performed on a TrueBeam system in developer mode for one case.ResultsWhile maintaining similar target coverage and homogeneity, DYMBARC reduced mean doses to organs‐at‐risk compared to VMAT by an average of 3.2, 0.5, and 2.9 Gy for the brain, breast, and pelvis cases, respectively. Similar or smaller mean dose reductions were observed for Arc‐MBRT or colli‐DTRT, compared to VMAT. Electron contributions to the mean planning target volume dose ranged from 2% to 34% for DYMBARC and from 11% to 40% for Arc‐MBRT. Measurement validation showed >99.7% gamma passing rate.ConclusionsDYMBARC was successfully established using a dosimetrically optimized pathfinding approach, combining non‐coplanarity with mixed beam modality. DYMBARC facilitated the determination of photon and electron contributions on a case‐by‐case basis, enhancing more personalized treatment modalities.

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Organs-at-risk dose and normal tissue complication probability with dynamic trajectory radiotherapy (DTRT) for head and neck cancer

Cited by 2 publications

References 44 publications

Robustness analysis of dynamic trajectory radiotherapy and volumetric modulated arc therapy plans for head and neck cancer

Robustness analysis of dynamic trajectory radiotherapy and volumetric modulated arc therapy plans for head and neck cancer

Dosimetric optimization for dynamic mixed beam arc therapy (DYMBARC)

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