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The effect of prone and supine treatment positions for the pre-operative treatment of rectal cancer on organ-at-risk sparing and setup reproducibility using volumetric modulated arc therapy

BACKGROUND AND PURPOSE: To compare organ-at-risk doses and setup reproducibility using the prone and supine orientations in volumetric modulated arc therapy (VMAT) for rectal cancer. MATERIALS AND METHODS: Seventeen consecutive rectal cancer patients undergoing preoperative radiation were selected a...

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Detalles Bibliográficos
Autores principales: Kim, Anthony, Karotki, Aliaksandr, Presutti, Joe, Gonzales, Glen, Wong, Shun, Chu, William
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5715653/
https://www.ncbi.nlm.nih.gov/pubmed/29202879
http://dx.doi.org/10.1186/s13014-017-0918-5
Descripción
Sumario:BACKGROUND AND PURPOSE: To compare organ-at-risk doses and setup reproducibility using the prone and supine orientations in volumetric modulated arc therapy (VMAT) for rectal cancer. MATERIALS AND METHODS: Seventeen consecutive rectal cancer patients undergoing preoperative radiation were selected and setup in either the prone (N = 8) or supine (N = 9) position. All patients were treated using posteriorly-applied VMAT. Bladder and small bowel dose and cone beam CT (CBCT) reproducibility metrics were retrospectively collected. RESULTS: Dose metrics for bladder and small bowel did not show significant differences between the prone and supine orientations. The prone data had a trend for smaller irradiated volumes than supine for the small bowel at lower doses—V20 (prone: 135 ± 99 cm(3); supine: 201 ± 162 cm(3)) and V30 (prone: 78 ± 71 cm(3); supine: 105 ± 106 cm(3)). At higher doses, the trend reversed as exemplified by the small bowel V50.4 (prone: 20 ± 28 cm(3); supine: 10 ± 14 cm(3)). CBCT data showed that rotational errors in pitch and roll were significantly larger for the prone vs. supine orientation (pitch: 2.0° ± 1.3° vs. 0.8° ± 1.1° p < 0.001; roll: 1.0° ± 0.9° vs. 0.3° ± 0.5°, p < 0.001). CONCLUSIONS: Bladder and small bowel doses were not significantly different when comparing VMAT plans developed for the prone and supine orientations. The supine orientation demonstrated improved setup reproducibility.