{"title":"Dosimetric Effects Due to Inter-Observer Variability of Organ Contouring When Utilizing a Knowledge-Based Planning System for Prostate Cancer","authors":"Han Liu, Christopher Amaloo, B. Sintay, D. Wiant","doi":"10.4236/IJMPCERO.2021.102005","DOIUrl":null,"url":null,"abstract":"Purpose: Radiotherapy is a widely accepted standard of care for early-stage prostate \ncancer, and it is believed that the plan quality and treatment outcome are \nassociated with contour accuracy of both the target and organs-at-risk (OAR). \nThe purposes of this study are to 1) assess geometric and dosimetric \nuncertainties due to inter-observer contour variabilities and 2) evaluate the \neffectiveness of geometric indicators to predict target dosimetry in prostate \nradiotherapy. Methods: Twenty prostate patients were selected for this \nretrospective study. Five experienced clinicians created unique structure sets \ncontaining prostate, seminal vesicles, bladder, and rectum for each patient. A \nfully automated script and knowledge-based planning routine were utilized to \ncreate standardized and unbiased plans that could be used to evaluate changes \nin isodose distributions due to inter-observer variability in structure \nsegmentation. Plans were created on a “gold-standard” structure set, as well as \non each of the user-defined structure sets. Results: Inter-observer \nvariability of contours during structure segmentation was very low for clearly \ndefined organs such as the bladder but increased for organs without \nwell-defined borders (prostate, seminal vesicles, and rectum). For plans \ngenerated with the user-defined structure sets, strong/moderate correlations \nwere observed between the geometric indicators for target structure agreement \nand target coverage for both low-risk and intermediate-risk patient groups, \nwhile OAR indicators showed no correlation to final dosimetry. Conclusions: Target delineation is crucial in order to maintain adequate dosimetric coverage \nregardless of the associated inter-observer uncertainties in OAR contours that \nhad a limited impact upon final dosimetry.","PeriodicalId":14028,"journal":{"name":"International Journal of Medical Physics, Clinical Engineering and Radiation Oncology","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2021-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"2","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"International Journal of Medical Physics, Clinical Engineering and Radiation Oncology","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.4236/IJMPCERO.2021.102005","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 2
Abstract
Purpose: Radiotherapy is a widely accepted standard of care for early-stage prostate
cancer, and it is believed that the plan quality and treatment outcome are
associated with contour accuracy of both the target and organs-at-risk (OAR).
The purposes of this study are to 1) assess geometric and dosimetric
uncertainties due to inter-observer contour variabilities and 2) evaluate the
effectiveness of geometric indicators to predict target dosimetry in prostate
radiotherapy. Methods: Twenty prostate patients were selected for this
retrospective study. Five experienced clinicians created unique structure sets
containing prostate, seminal vesicles, bladder, and rectum for each patient. A
fully automated script and knowledge-based planning routine were utilized to
create standardized and unbiased plans that could be used to evaluate changes
in isodose distributions due to inter-observer variability in structure
segmentation. Plans were created on a “gold-standard” structure set, as well as
on each of the user-defined structure sets. Results: Inter-observer
variability of contours during structure segmentation was very low for clearly
defined organs such as the bladder but increased for organs without
well-defined borders (prostate, seminal vesicles, and rectum). For plans
generated with the user-defined structure sets, strong/moderate correlations
were observed between the geometric indicators for target structure agreement
and target coverage for both low-risk and intermediate-risk patient groups,
while OAR indicators showed no correlation to final dosimetry. Conclusions: Target delineation is crucial in order to maintain adequate dosimetric coverage
regardless of the associated inter-observer uncertainties in OAR contours that
had a limited impact upon final dosimetry.