Purpose: A planning study was performed for helical tomotherapy treatment. We evaluated the maximum achievable protection of organs at risk (OARs) in patients with malignant pleural mesothelioma after pleurectomy with simultaneous optimal target coverage.
Materials and methods: The datasets of 13 patients were included. The applied dose to the planning target volume (PTV) was 50.4 Gy with single doses of 1.8 Gy per fraction. Presuming optimal target coverage, we evaluated the applied dose to the OARs with special regard to the contralateral lung.
Results: For left-(lsRT)/right(rsRT)-sided radiotherapy, target coverage for the PTV showed a D98 (mean) of 49.37/49.71 Gy (98.0%/98.6%) and a D2 (mean) of 54.19/54.61 Gy (107.5%/108.3%). The beam-on time was kept below 15 min. The achieved mean dose (D50) to the contralateral lung was kept below 4 Gy for lsRT and rsRT. With regard to the other organs at risk the applied doses were as follows: mean dose (lsRT): ipsilateral kidney (Dmean) 13.03 (5.32-22.18) Gy, contralateral kidney (Dmean) <2.0 Gy, heart (Dmean) 22.23 (13.57-27.72) Gy, spinal cord D1 <Gy; mean dose (rsRT): ipsilateral kidney (Dmean) 10.22 (6.30-18.04) Gy, contralateral kidney (Dmean) <2.1 Gy, heart (Dmean) 8.02 (6.0-10.38) Gy, spinal cord D1 <35.5 Gy.
Conclusion: With helical tomotherapy, postoperative treatment for malignant pleural mesothelioma after pleurectomy achieves good target coverage combined with simultaneous dose sparing to the (especially contralateral) OARs.
Keywords: Dose constraints; IMRT; Pleural mesothelioma; Postoperative treatment; Sparing organs at risk.