期刊
CLINICAL ONCOLOGY
卷 33, 期 10, 页码 661-666出版社
ELSEVIER SCIENCE LONDON
DOI: 10.1016/j.clon.2021.04.012
关键词
Bone metastases; intensity-modulated radiotherapy; palliative care; rapid access; spine; volumetric modulated arc therapy
类别
The study aimed to develop a process for same-day contouring, planning, quality assurance, and delivery of VMAT for vertebral bone metastases in a rapid-access palliative radiotherapy program. By adjusting six main planning variables, the efficient combination was determined, allowing the treatment of thoracic and lumbar vertebral bone metastases to be completed in under 2 hours.
Aims: We aimed to develop a process for same-day contouring, planning, quality assurance and delivery of volumetric modulated arc therapy (VMAT) for vertebral bone metastases within our institution's rapid-access palliative radiotherapy programme. Materials and methods: Two thoracic (T6-7, T3-7) and two lumbar (L2-3, L1-5) targets were contoured on computed tomography images acquired from an anthropomorphic phantom and five patient scans. Inverse planning aimed to provide coverage of a prescribed dose of 8 Gy with a combined lung V2Gy < 25% and a combined kidney mean dose <2 Gy. Serial plans were created to identify an efficient combination of six main planning variables specific to our treatment planning system: (i) voxel size (3 mm versus 5 mm), (ii) Monte Carlo statistical uncertainty (1% per calculation versus 3% per control point), (iii) fluence smoothing (medium versus high), (iv) number of iterations of segment shape changes during optimisation (1 versus 5), (v) dose calculation algorithm (Monte Carlo versus pencil beam) and (vi) number of arcs (single versus multiple). Contouring, planning, quality assurance and treatment delivery were timed. Results: The combination of planning variables deemed efficient and appropriate was: a 3 mm voxel size, statistical uncertainty of 1% per calculation, medium fluence smoothing, five iterations of segment shape changes, Monte Carlo dose calculation and single full arc delivery. Patient scan contouring times ranged from 7 to 9 min (T6-7), 11-13 min (T3-7), 5-7 min (L2-3) and 8-10 min (L1-5) and planning times ranged from 9 to 15 min (T6-7), 13-25 min (T3-7), 18-25 min (L2-3) and 21-31 min (L1-5). Physics quality assurance times ranged from 15 to 21 min and beam-on times ranged from 3 to 6 min. Conclusions: The combined elements of VMAT for thoracic and lumbar vertebral bone metastases were completed in under 2 h. This new process makes same -day contouring, planning, quality assurance and treatment delivery of VMAT feasible within our rapid-access palliative radiotherapy programme. (c) 2021 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
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