gms | German Medical Science

48th Meeting of the Particle Therapy Co-Operative Group

Particle Therapy Co-Operative Group (PTCOG)

28.09. - 03.10.2009, Heidelberg

Intensity Modulated Proton Therapy (IMPT) vs Intensity Modulated Radiation Therapy (IMRT)in malignant pleural mesothelioma (MPM): a dosimetric comparison

Meeting Abstract

  • S. Lorentini - Agenzia Provinciale per la Protonterapia, TRENTO, Italy
  • P. Hamer - A. O. Spedali Civili di Brescia, BRESCIA, Italy
  • M. Amichetti - Agenzia Provinciale per la Protonterapia, TRENTO, Italy
  • L. Spiazzi - A. O. Spedali Civili di Brescia, BRESCIA, Italy
  • S. Tonoli - A. O. Spedali Civili di Brescia, BRESCIA, Italy
  • S. Magrini - A. O. Spedali Civili di Brescia, BRESCIA, Italy
  • M. Schwarz - Agenzia Provinciale per la Protonterapia, TRENTO, Italy

PTCOG 48. Meeting of the Particle Therapy Co-Operative Group. Heidelberg, 28.09.-03.10.2009. Düsseldorf: German Medical Science GMS Publishing House; 2009. Doc09ptcog126

DOI: 10.3205/09ptcog126, URN: urn:nbn:de:0183-09ptcog1261

Published: September 24, 2009

© 2009 Lorentini et al.
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Outline

Text

Background: Recently the trimodality approach (neoadjuvant chemotherapy, extrapleural pneumonectomy and hemithoracic irradiation) is increasingly used for patients (pts) affected by MPM. With IMRT an increase in therapeutic dose to the pleural cavity and a reduction of doses to organs at risk (OAR) has been obtained. This study aims to observe if IMPT could further improve the dosimetric results allowed by IMRT.

Materials and methods: Data of 8 MPM pts (2 left, 6 right) were retrospectively selected. Two plans (one IMRT and one IMPT) were generated using the same software module (Hyperion), thus removing the bias of planning results produced with different optimization approaches. Delineated target volumes, OAR, and dose-volume constraints (reported in table below) of clinically delivered IMRT plans (planned in Plato, Nucletron) were retrieved and used to produce the new IMRT and IMPT plans. Beam delivery modalities were step and shoot for IMRT (6 MV Linac) and active spot scanning for IMPT (spot s = 3mm), respectively. Both techniques were optimized to deliver 50 Gy in 25 fractions to the planning target volume (PTV50) and in 3 cases 60 Gy, as simultaneous boost, to areas at increased risk of recurrence (PTV60). Quantitative comparison was based on DVH analysis.

Results: Results are presented in Table 1 [Tab. 1] as mean values calculated on all patients for each parameter.

Conclusions: IMPT allows for a slight improvement in target coverage and clear advantages in dose conformity and dose homogeneity. Better OAR sparing is obtained with IMPT, in particular for liver and omolateral kidney, together with a very large reduction of mean dose (the most important predictive parameter for lung toxicity) for the contralateral lung. Finally, IMPT plans show an evident decrease of integral dose with respect to IMRT.