title: The impact of PET/CT scanning on the size of target volumes, radiation exposure of organs at risk, TCP and NTCP, in the radiotherapy planning of non-small cell lung cancer.
abstract: OBJECTIVE
  To compare radiotherapy plans made according to CT and PET/CT and to investigate the impact of changes in target volumes on tumour control probability (TCP), normal tissue complication probability (NTCP) and the impact of PET/CT on the staging and treatment strategy.
  
  
  BACKGROUND
  Contemporary studies have proven that PET/CT attains higher sensitivity and specificity in the diagnosis of lung cancer and also leads to higher accuracy than CT alone in the process of target volume delineation in NSCLC.
  
  
  METHODS
  Between October 2009 and March 2012, 31 patients with locally advanced NSCLC, who had been referred to radical radiotherapy were involved in our study. They all underwent planning PET/CT examination. Then we carried out two separate delineations of target volumes and two radiotherapy plans and we compared the following parameters of those plans: staging, treatment purpose, the size of GTV and PTV and the exposure of organs at risk (OAR). TCP and NTCP were also compared.
  
  
  RESULTS
  PET/CT information led to a significant decrease in the sizes of target volumes, which had the impact on the radiation exposure of OARs. The reduction of target volume sizes was not reflected in the significant increase of the TCP value. We found that there is a very strong direct linear relationship between all evaluated dosimetric parameters and NTCP values of all evaluated OARs.
  
  
  CONCLUSIONS
  Our study found that the use of planning PET/CT in the radiotherapy planning of NSCLC has a crucial impact on the precise determination of target volumes, more precise staging of the disease and thus also on possible changes of treatment strategy.
authors.affiliation: Department of Oncology and Radiotherapy, University Hospital in Pilsen, alej Svobody 80, 304 60 Pilsen, Czech Republic.
authors.forename: Radovan
authors.initials: R
authors.lastname: Vojtíšek
authors.affiliation: Department of Oncology and Radiotherapy, University Hospital in Pilsen, alej Svobody 80, 304 60 Pilsen, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Mužík
authors.affiliation: Department of Radiation Oncology, Masaryk Memorial Cancer Institute in Brno, Žlutý kopec 543/7, 602 00 Brno, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Slampa
authors.affiliation: Department of Mathematics and Statistics, Faculty of Science, Masaryk University in Brno, Kotlářská 2, 611 37 Brno, Czech Republic.
authors.forename: Marie
authors.initials: M
authors.lastname: Budíková
authors.affiliation: Department of Oncology and Radiotherapy, University Hospital in Pilsen, alej Svobody 80, 304 60 Pilsen, Czech Republic.
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Hejsek
authors.affiliation: Department of Oncology and Radiotherapy, University Hospital in Pilsen, alej Svobody 80, 304 60 Pilsen, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Smolák
authors.affiliation: Department of Imaging Methods, University Hospital in Pilsen, alej Svobody 80, 304 60 Pilsen, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Ferda
authors.affiliation: Department of Oncology and Radiotherapy, University Hospital in Pilsen, alej Svobody 80, 304 60 Pilsen, Czech Republic.
authors.forename: Jindřich
authors.initials: J
authors.lastname: Fínek
keywords: NTCP; Non-small cell lung cancer; PET/CT; Radiotherapy planning; TCP