Bone Marrow sparing VMAT in Whole Lung Irradiation

Background: Acute hematological toxicity is one of the side effects of whole lung irradiation(WLI) leading to interruption of treatment. With the novel radiotherapy techniques like Volume Modulated Arc Therapy (VMAT) it is possible to minimize treatment associated hematological side effects by sparing bone marrow. We report a new technique of Bone Marrow sparing VMAT (MS-VMAT) for WLI. Case Representation: We describe a 20-year male resident of Iraq, diagnosed as Giant cell tumor with pulmonary metastases, planned for 28.8 Gray/16 fractions to lung parenchymal nodules and 24 Gray/16 fractions to bilateral whole lungs using standard VMAT. After 7 fractions of radiotherapy patient developed Grade III hematological toxicity for which new plan was made with MS-VMAT. We generated three plans using standard anteroposterior-poseroanterior (AP-PA), VMAT and MS-VMAT. Dosimetric advantage was observed in MSVMAT over standard VMAT technique in terms of minimizing dose to bone marrow. Bone marrow sparing VMAT showed more sparing of marrow in vertebrae and sternum thereby minimizing the Grade III hematological toxicity. Conclusion: Effective bone marrow sparing may be possible with bone marrow sparing VMAT. Large scale randomized trials are needed to validate our results.