Evaluation of Different External Radiation Therapy Techniques for the Treatment of Malignant Pleural Mesothelioma After Extrapleural Pleuropneumonectomy

Abstract

ratio and beam output. Finally, a hypothetical treatment of a 2-cm diameter target located at a depth of 11 cm and near the pancreas was simulated on patient CT images using an optimized kV x-ray source and compared to a dose distribution generated with a 6 MV beam. Results: MC simulated depth-dose curves of the existing large-area x-ray source agreed with film measurements to within 5%. Beam energy and filtration, target thickness, collimator hole geometry, and treatment SSD had the largest effect on the quality of dose distributions in terms of both target-to-skin ratio and beam output. An optimized kV x-ray source design for the 4-cm diameter target resulted in target-to-skin ratio of 5.2 and D50 of 19.5 Gy delivered in 30 minutes. For the 5 mm-diameter target, the target-to-skin ratio increased to 11.2 and D50 in 30 minutes exceeded 35 Gy. The MC models of treatment coverage for a target near the pancreas demonstrated that optimized kV and 6 MV treatment plans delivered comparable doses to critical structures. The integral dose delivered by the kV x-ray source was similar to the integral dose delivered by the 6 MV beam due to the fast fall-off of kV beams. Conclusion: A novel radiation therapy kilovoltage x-ray source has been modeled and optimized using Monte Carlo simulations. Due to its unique design, the source delivers conformal doses of radiation to deep-seated tumors with dosimetric parameters and treatment times acceptable for clinical use. A hypothetical clinical scenario showed that treatment plans with the novel cost-effective kV x-ray source have the potential to match treatment plans generated with commonly used 6 MV beams. Author Disclosure: M. Bazalova: None. E. Graves: None. B. Wilfley: None. M. Weil: P. Ownership Other; yes. Q. Leadership; yes.