title: Tomotherapy PET-guided dose escalation: A dosimetric feasibility study for patients with malignant pleural mesothelioma.
abstract: OBJECTIVE
  The aim of this study was to investigate whether a safe escalation of the dose to the pleural cavity and PET/CT-positive areas in patients with unresectable malignant pleural mesothelioma (MPM) is possible using helical tomotherapy (HT).
  
  
  METHODS
  We selected 12 patients with MPM. Three planning strategies were investigated. In the first strategy (standard treatment), treated comprised a prescribed median dose to the planning target volume (PTV) boost (PTV1) of 64.5 Gy (range: 56 Gy/28 fractions to 66 Gy/30 fractions) and 51 Gy (range: 50.4 Gy/28 fractions to 54 Gy/30 fractions) to the pleura PTV (PTV2). Thereafter, for each patient, two dose escalation plans were generated prescribing 62.5 and 70 Gy (2.5 and 2.8 Gy/fraction, respectively) to the PTV1 and 56 Gy (2.24 Gy/fraction) to the PTV2, in 25 fractions. Dose-volume histogram (DVH) constraints and normal tissue complication probability (NTCP) calculations were used to evaluate the differences between the plans.
  
  
  RESULTS
  For all plans, the 95 % PTVs received at least 95 % of the prescribed dose. For all patients, it was possible to perform the dose escalation in accordance with the Quantitative Analysis of Normal Tissue Effects in the Clinic (QUANTEC) constraints for organs at risk (OARs). The average contralateral lung dose was < 8 Gy. NTCP values for OARs did not increase significantly compared with the standard treatment (p > 0.05), except for the ipsilateral lung. For all plans, the lung volume ratio was strongly correlated with the V20, V30, and V40 DVHs of the lung (p < 0.0003) and with the lung mean dose (p < 0.0001).
  
  
  CONCLUSIONS
  The results of this study suggest that by using HT it is possible to safely escalate the dose delivery to at least 62.5 Gy in PET-positive areas while treating the pleural cavity to 56 Gy in 25 fractions without significantly increasing the dose to the surrounding normal organs.
authors.affiliation: Medical Physics, Candiolo Cancer Institute - FPO, IRCCS, Turin, Italy. maggio.angelo@gmail.com.
authors.forename: Angelo
authors.initials: A
authors.lastname: Maggio
authors.affiliation: Medical Physics, Candiolo Cancer Institute - FPO, IRCCS, Turin, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Cutaia
authors.affiliation: Medical Physics, Candiolo Cancer Institute - FPO, IRCCS, Turin, Italy.
authors.forename: Amalia
authors.initials: A
authors.lastname: Di Dia
authors.affiliation: Medical Physics, Candiolo Cancer Institute - FPO, IRCCS, Turin, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Bresciani
authors.affiliation: Medical Physics, Candiolo Cancer Institute - FPO, IRCCS, Turin, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Miranti
authors.affiliation: Medical Physics, Candiolo Cancer Institute - FPO, IRCCS, Turin, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Poli
authors.affiliation: Radiotherapy Department, Candiolo Cancer Institute - FPO, IRCCS, Turin, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Del Mastro
authors.affiliation: Radiotherapy Department, Candiolo Cancer Institute - FPO, IRCCS, Turin, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Garibaldi
authors.affiliation: Radiotherapy Department, Candiolo Cancer Institute - FPO, IRCCS, Turin, Italy.
authors.forename: Pietro
authors.initials: P
authors.lastname: Gabriele
authors.affiliation: Medical Physics, Candiolo Cancer Institute - FPO, IRCCS, Turin, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Stasi
mesh_terms: D000368:Aged; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D008168:Lung / Q000528:radiation effects; D008297:Male; D008654:Mesothelioma / Q000401:mortality / Q000532:radiotherapy*; D008875:Middle Aged; D064847:Multimodal Imaging; D010997:Pleural Neoplasms / Q000401:mortality / Q000532:radiotherapy*; D049268:Positron-Emission Tomography; D011829:Radiation Dosage; D011874:Radiometry; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D015996:Survival Rate; D036542:Tomography, Spiral Computed
keywords: Dose escalation; Helical tomotherapy; PET imaging; Pleural malignant mesothelioma; Survival