title: Dosimetric inter-institutional comparison in European radiotherapy centres: Results of IAEA supported treatment planning system audit.
abstract: OBJECTIVE
  One of the newer audit modalities operated by the International Atomic Energy Agency (IAEA) involves audits of treatment planning systems (TPS) in radiotherapy. The main focus of the audit is the dosimetry verification of the delivery of a radiation treatment plan for three-dimensional (3D) conformal radiotherapy using high energy photon beams. The audit has been carried out in eight European countries - Estonia, Hungary, Latvia, Lithuania, Serbia, Slovakia, Poland and Portugal. The corresponding results are presented.
  
  
  METHODS
  The TPS audit reviews the dosimetry, treatment planning and radiotherapy delivery processes using the 'end-to-end' approach, i.e. following the pathway similar to that of the patient, through imaging, treatment planning and dose delivery. The audit is implemented at the national level with IAEA assistance. The national counterparts conduct the TPS audit at local radiotherapy centres through on-site visits. TPS calculated doses are compared with ion chamber measurements performed in an anthropomorphic phantom for eight test cases per algorithm/beam. A set of pre-defined agreement criteria is used to analyse the performance of TPSs.
  
  
  RESULTS
  TPS audit was carried out in 60 radiotherapy centres. In total, 190 data sets (combination of algorithm and beam quality) have been collected and reviewed. Dosimetry problems requiring interventions were discovered in about 10% of datasets. In addition, suboptimal beam modelling in TPSs was discovered in a number of cases.
  
  
  CONCLUSIONS
  The TPS audit project using the IAEA methodology has verified the treatment planning system calculations for 3D conformal radiotherapy in a group of radiotherapy centres in Europe. It contributed to achieving better understanding of the performance of TPSs and helped to resolve issues related to imaging, dosimetry and treatment planning.
authors.affiliation: North Estonia Medical Centre, Department of Radiotherapy , Tallinn , Estonia.
authors.forename: Eduard
authors.initials: E
authors.lastname: Gershkevitsh
authors.forename: Csilla
authors.initials: C
authors.lastname: Pesznyak
authors.forename: Borislava
authors.initials: B
authors.lastname: Petrovic
authors.forename: Joseph
authors.initials: J
authors.lastname: Grezdo
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Chelminski
authors.forename: Maria
authors.initials: M
authors.lastname: do Carmo Lopes
authors.forename: Joanna
authors.initials: J
authors.lastname: Izewska
authors.forename: Jacob
authors.initials: J
authors.lastname: Van Dyk
mesh_terms: D005060:Europe; D006801:Humans; D007390:International Agencies; D008485:Medical Audit; D011785:Quality Assurance, Health Care; D011874:Radiometry / Q000592:standards*; D011880:Radiotherapy Planning, Computer-Assisted / Q000592:standards*; D020266:Radiotherapy, Conformal / Q000592:standards*