title: CT- versus coregistered FDG-PET/CT-based radiation therapy plans for conformal radiotherapy in colorectal liver metastases: a dosimetric comparison.
abstract: OBJECTIVE
  Our aim was to compare computed tomography (CT) and coregistered [(18)F]-fluorodeoxyglucose positron emission tomography CT-(FDG-PET/CT) based delineation of gross tumor volume (GTV) in unresectable colorectal liver metastasis (CRLM).
  
  
  METHODS
  Fifty-four patients with unresectable CRLM were enrolled but 16 were excluded due to detection of additional hepatic metastases in ten on PET/CT scans, precluding radiotherapy because of transcendent critical organ doses beyond tolerable limits; and of extrahepatic metastases in six. For 38 eligible patients, both CT and PET/CT images were acquired, and two 3D conformal plans were made using the CT and FDG-PET/CT fusion data sets. Radiotherapy plans (RTP) and doses to critical organs were analyzed.
  
  
  RESULTS
  Comparisons between two RTPs revealed need for change in GTV in 31 of 38 analyzable patients (81.6 %). In 25 (65.8 %) patients, GTV was significantly increased, with a median of 33.2 % (p < 0.001), whereas median 12.8 % decrease in six (15.8 %) (p < 0.001). There were no clinically meaningful differences in critical organ doses.
  
  
  CONCLUSIONS
  Coregistered FDG-PET/CT may improve delineation of GTV and theoretically reduce the likelihood of geographic misses in unresectable CRLM. Additionally, integration of FDG-PET/CT in the initial assessments of CRLM may spare almost one third of patients from potentially futile radical interventions.
authors: Department of Radiation Oncology, Adana Medical Faculty, Baskent University, Kisla Saglik Yerleskesi, 01120 Adana, Turkey. cemparlak@gmail.com
authors: Cem
authors: C
authors: Parlak
authors: Erkan
authors: E
authors: Topkan
authors: Serhat
authors: S
authors: Sonmez
authors: Cem
authors: C
authors: Onal
authors: Mehmet
authors: M
authors: Reyhan
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D015179:Colorectal Neoplasms / Q000473:pathology*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy* / Q000556:secondary; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods; D016896:Treatment Outcome
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18