Computing Dose to Circulating Blood Cells Using Whole-Body Blood Flow Simulations
J Shin1*, S Xing1, A Hammi1,J Pursley1, C Correa Alfonso2, J Withrow2, S Domal2, W Bolch2, H Paganetti1, C Grassberger1, (1) Mass General Hospital and Harvard Medical School, Boston, MA (2) University of Florida, Gainesville, Florida
Presentations
TU-EF-TRACK 4-4 (Tuesday, 7/27/2021) 3:30 PM - 5:30 PM [Eastern Time (GMT-4)]
Purpose: To develop a time-dependent computational method to estimate dose to circulating blood from radiation fields for any treatment site.
Methods: Two independent dynamic models were implemented: one describing the spatiotemporal distribution of blood particles (BPs) in organs and a second describing the time-dependent radiation field delivery. A whole-body blood flow network based on blood volumes and flow rates from ICRP Publication 89 was simulated to produce the spatiotemporal distribution of BPs in organs across the entire body using a discrete-time Markov process. Constant or time-varying transition probabilities were applied to the Markov process and their impact on transition time was investigated. The impact of treatment time and different anatomical sites was investigated using a liver and brain cancer patient. The impact on the blood dose-volume histograms (bDVHs) was assessed using bDVH metrics (V0Gy, V0.05Gy, D2%).
Results: Simulations revealed different dose levels to the circulating blood for brain compared to liver even for similar field sizes due to the different blood flow properties of the two organs. For the constant probability model, the volume of blood receiving any dose (V0Gy) after a single radiation fraction increases from 1.2% for 1s delivery time to 25.8% for 120s for brain and from 10% (1s) to 55.8% (120s) for liver, respectively. With time-dependent probability, V0Gy increases from 1.2% to 20.9% for brain and from 10% to 48.7% for liver, respectively. Changes in V0.05Gy show a similar pattern, while D2% decreases with longer delivery time. Unexpectedly, delivering the dose using a realistic time structure for every field only changes the bDVH negligibly compared to delivering the entire dose distribution over the treatment time.
Conclusion: This publicly available framework estimates patient-specific dose to circulating blood cells based on organ DVHs and enables studying the impact of different treatment plans, dose rates, and fractionation schemes.
Funding Support, Disclosures, and Conflict of Interest: This study was supported by NCI R01 CA248901, NCI R21 CA241918, and NCI R21 CA248118.
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