Optimal adaptive IMRT strategy to spare the parotid glands in oropharyngeal cancerReportar como inadecuado

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1 LTSI - Laboratoire Traitement du Signal et de l-Image 2 LIST - Laboratory of Image Science and Technology Nanjing 3 CRIBS - Centre de Recherche en Information Biomédicale sino-français 4 National Key Laboratory for Electronics Measurement Technology 5 CRLCC - CRLCC Eugène Marquis

Abstract : PurposeIn oropharyngeal cancer adaptive radiation therapy ART, this study aimed to quantify the dosimetricbenefit of numerous replanning strategies, defined by various numbers and timings of replannings, withregard to parotid gland PG sparing.Material and methodsThirteen oropharyngeal cancer patients had one planning and then six weekly CT scans during the sevenweeks of IMRT. Weekly doses were recalculated without replanning or with replanning to spare the PG.Sixty-three ART scenarios were simulated by considering all the combinations of numbers and timings ofreplanning. The PG cumulated doses corresponding to -standard- IMRT and ART scenarios wereestimated and compared, either by calculating the average of weekly doses or using deformable imageregistration DIR.ResultsConsidering average weekly doses, the mean PG overdose using standard IMRT, compared to the planneddose, was 4.1 Gy. The mean dosimetric benefit of 6 replannings was 3.3 Gy. Replanning at weeks 1, 1-5,1-2-5, 1-2-4-5 and 1-2-4-5-6 produced the lowest PG mean doses, 94% of the maximum benefit beingobtained with 3 replannings.The percentage of patients who had a benefit superior to 5 Gy for thecontralateral PG was 31% for the three-replannings strategy. The same conclusions were found using DIR.ConclusionEarly replannings proved the most beneficial for PG sparing, three replannings weeks 1-2-5,representing an attractive combination for ART in oropharyngeal cancer.

Autor: Pengcheng Zhang - Antoine Simon - Bastien Rigaud - Joël Castelli - Juan David Ospina Arango - Mohamed Nassef - Olivier Henry - J

Fuente: https://hal.archives-ouvertes.fr/


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