Radiobiological Comparison of Volumetric Modulated Arc Therapy, 3D Conformal Proton Therapy and Intensity Modulated Proton Therapy for Lung Cancer
M Sullivan1, H Jin2, A Lau3*, S Ahmad4, (1) University of Oklahoma-Health Sciences Center, Oklahoma City, OK, (2) Baylor Scott & White Health, Temple, TX, (3) ,Edmond, OK, (4) University of Oklahoma Health Sciences Center, Oklahoma City, OK
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PO-GePV-T-123 (Sunday, 7/10/2022) [Eastern Time (GMT-4)]
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Purpose: To compare radiobiological characteristics of 3D conformal proton therapy (3DCPT), static aperture intensity modulated proton therapy (IMPTs), and volumetric modulated arc therapy (VMAT) in patients with lung cancer.
Methods: Ten patients with lung cancer were chosen, all of whom had treatment plans created for each of the mentioned modalities. The Varian Eclipse system was used for VMAT and 3DCPT; while RaySearch RayStation was used for IMPTs treatment planning. The parameters used in this comparison were equivalent uniform dose (EUD), tumor control probability (TCP), and normal tissue complication probability (NTCP). The radiobiologic variables chosen and varied to observe their effect on these parameters were α/β ratio (3 and 6), SF2, or the cell survival fraction at 2 Gy, (0.3,.0.5 and 0.7) and CCD, or the clonogenic cell density, (1000, 10000).
Results: Average EUD relative to prescription dose for 3DCPT plans: 1.017, for IMPTs: 1.026, for VMAT: 1.026. Average TCPs for each modality were found to be approximately 100% and average NTCPs for heart, spinal cord and contralateral lung were found to be very close to 0% irrespective of radiobiologic variables and treatment modalities.
Conclusion: No significant statistical differences were found in this study among all these modalities in the context of lung cancer, using TCP and NTCP as comparing parameters. These parameter values are not absolute, rather relative and can only predict relative superiority of treatment plan performance among modalities. EUDs were compared and, on average, were closer to the prescription dose for 3D conformal proton therapy plans.
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