title: Use of standardized uptake value thresholding for target volume delineation in pediatric Hodgkin lymphoma.
abstract: OBJECTIVE
  A limitation of [(18)F] 2-fluoro-2-deoxy-d-glucose positron emission tomography (FDGPET) in radiation planning for Hodgkin lymphoma (HL) is significant variability in delineation of tumor volume. One approach to reduce variability is to apply automatic or semiautomatic segmentation methods such as thresholding based on a percent tumor maximum standardized uptake value (SUVmax). Here, we apply various tumor SUVmax thresholds and examine their effects in involved field radiation therapy (IFRT) and involved site radiation therapy (ISRT) target volumes.
  
  
  METHODS
  PET/computed tomography data sets were reviewed for 16 pediatric and young adult patients treated with IFRT. The following percent tumor SUVmax thresholds were applied to the prechemotherapy PET: 15%, 20%, 25%, 30%, 35%, and 40%. Clinical target volumes for IFRT and ISRT plans were manually generated based on these threshold volumes (CTVPET) and compared with clinical target volumes generated using the standard qualitative visual method (CTVQVM). Treatment plans were generated, doses to normal structures were compared, and the optimum threshold, defined as the CTVPET that corresponded to the percent overlap closest to 100% when compared with the CTVQVM, was determined.
  
  
  RESULTS
  On average, there was a 7.6-fold increase in PET volume between 40% and 15% SUVmax. When the 6 SUVmax thresholds were applied in the design of target volumes for IFRT, 2 of 16 patients had a change in treatment volume. There was a 2.4-fold increase in ISRT CTVs generated based on the 15% and 40% SUVmax, which translated into a clinically significant decrease in dose to normal structures when the ISRT plans that were generated using the 15% SUVmax volumes were compared with the 40% SUVmax. In most patients, the optimum threshold was SUVmax 15%.
  
  
  CONCLUSIONS
  Accurate target volume delineation with [(18)F] 2-fluoro-2-deoxy-d-glucose PET in HL is challenging and may require more precise and reproducible segmentation methods as we move toward more conformal therapies.
authors.affiliation: Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Walker
authors.affiliation: Department of Radiology, Division of Nuclear Medicine, Johns Hopkins Hospital, Johns Hopkins University School of Medicine, Baltimore, Maryland; Department of Radiation Oncology, Freiberg University, DKFZ-German Cancer Consortium Partner Site Freiburg, Freiburg, Germany.
authors.forename: Alin
authors.initials: A
authors.lastname: Chirindel
authors.affiliation: Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland; Department of Radiology, Division of Nuclear Medicine, Johns Hopkins Hospital, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Hobbs
authors.affiliation: Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Minh-Phuong
authors.initials: MP
authors.lastname: Huynh-Le
authors.affiliation: Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Moore
authors.affiliation: Department of Radiology, Division of Nuclear Medicine, Johns Hopkins Hospital, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Steve Y
authors.initials: SY
authors.lastname: Cho
authors.affiliation: Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland. Electronic address: sterezak@jhmi.edu.
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Terezakis
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D006689:Hodgkin Disease / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods; D055815:Young Adult
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18