title: Stability of 18F-deoxyglucose uptake locations within tumor during radiotherapy for NSCLC: a prospective study.
abstract: OBJECTIVE
  Because individual tumors are heterogeneous, including for (18)F-deoxyglucose (FDG) uptake and, most likely, for radioresistance, selective boosting of high FDG uptake zones within the tumor has been suggested. To do this, it is critical to know whether the location of these high FDG uptake patterns within the tumor remain stable during radiotherapy (RT).
  
  
  METHODS
  Twenty-three patients with Stage I-III non-small-cell lung cancer underwent repeated FDG positron emission tomography computed tomography scans before radical RT (Day 0) and at Days 7 and 14 of RT. On all scans, the high and low FDG uptake regions were autodelineated using several standardized uptake value thresholds, varying from 34% to 80% of the maximal standardized uptake value. The volumes and overlap fractions of these delineations were calculated to demonstrate the stability of the high FDG uptake regions during RT.
  
  
  RESULTS
  The mean overlap fraction of the 34% uptake zones at Day 0 with Days 7 and 14 was 82.8% +/- 8.1% and 84.3% +/- 7.6%, respectively. The mean overlap fraction of the high uptake zones (60%) was 72.3% +/- 15.0% and 71.3% +/- 19.7% at Day 0 with Days 7 and 14, respectively. The volumes of the thresholds varied markedly (e.g., at Day 0, the volume of the 60% zone was 16.8 +/- 20.3 cm(3)). In contrast, although the location of the high FDG uptake patterns within the tumor during RT remained stable, the delineated volumes varied markedly.
  
  
  CONCLUSIONS
  The location of the low and high FDG uptake areas within the tumor remained stable during RT. This knowledge may enable selective boosting of high FDG uptake areas within the tumor.
authors.affiliation: Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, University Hospital Maastricht, Dr. Tanslaan 12, Maastricht, The Netherlands. Hugo.Aerts@maastro.nl
authors.forename: Hugo J W L
authors.initials: HJ
authors.lastname: Aerts
authors.forename: Geert
authors.initials: G
authors.lastname: Bosmans
authors.forename: Angela A W
authors.initials: AA
authors.lastname: van Baardwijk
authors.forename: Andre L A J
authors.initials: AL
authors.lastname: Dekker
authors.forename: Michel C
authors.initials: MC
authors.lastname: Oellers
authors.forename: Philippe
authors.initials: P
authors.lastname: Lambin
authors.forename: Dirk
authors.initials: D
authors.lastname: De Ruysscher
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000532:radiotherapy; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000532:radiotherapy; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods; D011446:Prospective Studies; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*; D011879:Radiotherapy Dosage; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18