Investigation of variability in image acquisition and contouring during 3D ultrasound guidance for partial breast irradiationReport as inadecuate

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Radiation Oncology

, 9:35

Cancer imaging and new preclinical diagnostics in radiation oncologyClinical Radiation Oncology


BackgroundThree-dimensional ultrasound 3DUS at simulation compared to 3DUS at treatment is an image guidance option for partial breast irradiation PBI. This study assessed if user dependence in acquiring and contouring 3DUS operator variability contributed to variation in seroma shifts calculated for breast IGRT.

MethodsEligible patients met breast criteria for current randomized PBI studies. 5 Operators participated in this study. For each patient, 3 operators were involved in scan acquisitions and 5 were involved in contouring. At CT simulation CT1, a 3DUS US1 was performed by a single radiation therapist RT. 7 to 14 days after CT1 a second CT CT2 and 3 sequential 3DUS scans US2a,b,c were acquired by each of 3 RTs. Seroma shifts, between US1 and US2 scans were calculated by comparing geometric centers of the seromas centroids. Operator contouring variability was determined by comparing 5 RT’s contours for a single image set. Scanning variability was assessed by comparing shifts between multiple scans acquired at the same time point US1-US2a,b,c. Shifts in seromas contoured on CT CT1-CT2 were compared to US data.

ResultsFrom an initial 28 patients, 15 had CT visible seromas, met PBI dosimetric constraints, had complete US data, and were analyzed. Operator variability contributed more to the overall variability in seroma localization than the variability associated with multiple scan acquisitions 95% confidence mean uncertainty of 6.2 mm vs. 1.1 mm. The mean standard deviation in seroma shift was user dependent and ranged from 1.7 to 2.9 mm. Mean seroma shifts from simulation to treatment were comparable to CT.

ConclusionsVariability in shifts due to different users acquiring and contouring 3DUS for PBI guidance were comparable to CT shifts. Substantial inter-observer effect needs to be considered during clinical implementation of 3DUS IGRT.

KeywordsBreast cancer 3D ultrasound Image guided radiotherapy Electronic supplementary materialThe online version of this article doi:10.1186-1748-717X-9-35 contains supplementary material, which is available to authorized users.

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Author: Anthony Landry - Tanya Berrang - Isabelle Gagne - Carmen Popescu - Tracy Mitchell - Hazel Vey - Letricia Sand - Siew Yan 


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