PO-0831: Multi isocentric 4-pi volumetric modulated arc therapy approach for head and neck cancer

Subramanian, S.; Chilukuri, S.; Subramani, V.; Kathirvel, M; Garg, Arun; Swamy, Shivakumar; Subramanian, Kritika; Fogliata, A.; Cozzi, Luca

doi:10.1016/s0167-8140(17)31268-9

Cited by 1 publication

(2 citation statements)

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“…Gayen et al [45] have found noncoplanar VMAT to be advantageous over coplanar VMAT both in sequential boost and simultaneous integrated boost techniques for sparing the shoulders and improving target coverage in 22 patients. Subramanian et al [5] compared coplanar VMAT to multi-isocentric non-coplanar VMAT in 25 patients obtaining average reductions in mean dose to the parotids, larynx, oral cavity and pharyngeal muscle between 3 and 5 Gy. This improved sparing may be partly because non-coplanar plans had 1.5-3 times as many arcs as coplanar ones whereas, in the present study, DTRT and VMAT plans had the same number of arcs/paths.…”

Section: Discussionmentioning

confidence: 99%

“…Non-coplanar radiotherapy can further improve OAR sparing [3] with, e.g., 4π-IMRT using up to 30 non-coplanar beams [4], non-coplanar VMAT with multiple arcs at static non-coplanar table angles [5], or non-coplanar dynamic trajectory radiotherapy (DTRT) with simultaneous gantry and table rotation during beam-on, with [6][7][8] or without [9,10] dynamic collimator rotation. The trade-off between estimated delivery time and dosimetric plan quality was explored for nasopharyngeal tumours finding non-coplanar dynamic trajectories to be dosimetrically beneficial over coplanar techniques at the cost of longer, yet acceptable, delivery times [11].…”

Section: Open Accessmentioning

confidence: 99%

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Organ-at-risk sparing with dynamic trajectory radiotherapy for head and neck cancer: comparison with volumetric arc therapy on a publicly available library of cases

et al. 2022

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Background Dynamic trajectory radiotherapy (DTRT) extends volumetric modulated arc therapy (VMAT) with dynamic table and collimator rotation during beam-on. The aim of the study is to establish DTRT path-finding strategies, demonstrate deliverability and dosimetric accuracy and compare DTRT to state-of-the-art VMAT for common head and neck (HN) cancer cases. Methods A publicly available library of seven HN cases was created on an anthropomorphic phantom with all relevant organs-at-risk (OARs) delineated. DTRT plans were generated with beam incidences minimizing fractional target/OAR volume overlap and compared to VMAT. Deliverability and dosimetric validation was carried out on the phantom. Results DTRT and VMAT had similar target coverage. For three locoregionally advanced oropharyngeal carcinomas and one adenoid cystic carcinoma, mean dose to the contralateral salivary glands, pharynx and oral cavity was reduced by 2.5, 1.7 and 3.1 Gy respectively on average with DTRT compared to VMAT. For a locally recurrent nasopharyngeal carcinoma, D0.03 cc to the ipsilateral optic nerve was above tolerance (54.0 Gy) for VMAT (54.8 Gy) but within tolerance for DTRT (53.3 Gy). For a laryngeal carcinoma, DTRT resulted in higher dose than VMAT to the pharynx and brachial plexus but lower dose to the upper oesophagus, thyroid gland and contralateral carotid artery. For a single vocal cord irradiation case, DTRT spared most OARs better than VMAT. All plans were delivered successfully on the phantom and dosimetric validation resulted in gamma passing rates of 93.9% and 95.8% (2%/2 mm criteria, 10% dose threshold). Conclusions This study provides a proof of principle of DTRT for common HN cases with plans that were deliverable on a C-arm linac with high accuracy. The comparison with VMAT indicates substantial OAR sparing could be achieved.

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Section: Discussionmentioning

confidence: 99%