Adjuvant intensity-modulated proton therapy in malignant pleural mesothelioma A comparison with intensity-modulated radiotherapy and a spot size variation assessment

作者：Lorentini S; Amichetti M; Spiazzi L; Tonoli S; Magrini S M; Fellin F; Schwarz M^*

来源：Strahlentherapie und Onkologie, 2012, 188(3): 216-225.

DOI：10.1007/s00066-011-0038-3

• Intensity-modulated proton therapy
• Intensity-modulated radiation therapy
• Mesothelioma
• Spot size
• NTCP analysis

Purpose. Intensity-modulated radiation therapy (IMRT) is the state-of-the-art treatment for patients with malignant pleural mesothelioma (MPM). The goal of this work was to assess whether intensity-modulated proton therapy (IMPT) could further improve the dosimetric results allowed by IMRT. %26lt;br%26gt;Patients and methods. We re-planned 7 MPM cases using both photons and protons, by carrying out IMRT and IMPT plans. For both techniques, conventional dose comparisons and normal tissue complication probability (NTCP) analysis were performed. In 3 cases, additional IMPT plans were generated with different beam dimensions. %26lt;br%26gt;Results. IMPT allowed a slight improvement in target coverage and clear advantages in dose conformity (p %26lt; 0.001) and dose homogeneity (p = 0.01). Better organ at risk (OAR) sparing was obtained with IMPT, in particular for the liver (D-mean reduction of 9.5 Gy, p = 0.001) and ipsilateral kidney (V-20 reduction of 58%, p = 0.001), together with a very large reduction of mean dose for the contralateral lung (0.2 Gy vs 6.1 Gy, p = 0.0001). NTCP values for the liver showed a systematic superiority of IMPT with respect to IMRT for both the esophagus (average NTCP 14% vs. 30.5%) and the ipsilateral kidney (p = 0.001). Concerning plans obtained with different spot dimensions, a slight loss of target coverage was observed along with sigma increase, while maintaining OAR irradiation always under planning constraints. %26lt;br%26gt;Conclusion. Results suggest that IMPT allows better OAR sparing with respect to IMRT, mainly for the liver, ipsilateral kidney, and contralateral lung. The use of a spot dimension larger than 3 x 3 mm (up to 9x9 mm) does not compromise dosimetric results and allows a shorter delivery time.

• 出版日期2012-3