Proton therapy for malignant pleural mesothelioma after extrapleural pleuropneumonectomy.
OBJECTIVE
To perform comparative planning for intensity-modulated radiotherapy (IMRT) and proton therapy (PT) for malignant pleural mesothelioma after radical surgery.


METHODS
Eight patients treated with IMRT after extrapleural pleuropneumonectomy (EPP) were replanned for PT, comparing dose homogeneity, target volume coverage, and mean and maximal dose to organs at risk. Feasibility of PT was evaluated regarding the dose distribution with respect to air cavities after EPP.


RESULTS
Dose coverage and dose homogeneity of the planning target volume (PTV) were significantly better for PT than for IMRT regarding the volume covered by >95% (V95) for the high-dose PTV. The mean dose to the contralateral kidney, ipsilateral kidney, contralateral lung, liver, and heart and spinal cord dose were significantly reduced with PT compared with IMRT. After EPP, air cavities were common (range, 0-850 cm(3)), decreasing from 0 to 18.5 cm(3)/day. In 2 patients, air cavity changes during RT decreased the generalized equivalent uniform dose (gEUD) in the case of using an a value of < - 10 to the PTV2 to <2 Gy in the presence of changing cavities for PT, and to 40 Gy for IMRT. Small changes were observed for gEUD of PTV1 because PTV1 was reached by the beams before air.


CONCLUSIONS
Both PT and IMRT achieved good target coverage and dose homogeneity. Proton therapy accomplished additional dose sparing of most organs at risk compared with IMRT. Proton therapy dose distributions were more susceptible to changing air cavities, emphasizing the need for adaptive RT and replanning.
Krayenbuehl
Jerôme
J
Department of Radiation Oncology, Zurich University Hospital, Switzerland.
Hartmann
Matthias
M
Lomax
Anthony J
AJ
Kloeck
Stephan
S
Hug
Eugen B
EB
Ciernik
I Frank
IF
D000368:Aged; D005240:Feasibility Studies; D005260:Female; D006321:Heart / Q000528:radiation effects; D006801:Humans; D007668:Kidney / Q000528:radiation effects; D008099:Liver / Q000528:radiation effects; D008168:Lung / Q000528:radiation effects; D008297:Male; D008654:Mesothelioma / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D008875:Middle Aged; D010994:Pleura / Q000601:surgery; D010997:Pleural Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D011013:Pneumonectomy / Q000379:methods; D061766:Proton Therapy; D011832:Radiation Injuries / Q000517:prevention & control; D011859:Radiography; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D013116:Spinal Cord / Q000528:radiation effects; D047368:Tumor Burden; D011522:Protons
D011522:Protons