Presenter of 1 Presentation
TEMPORAL RESOLUTION REQUIREMENTS FOR MEASURING THE KINETICS OF OXYGEN DEPLETION DURING FLASH RADIOTHERAPY, BASED ON A 3D COMPUTATIONAL MODEL OF BRAIN VASCULATURE
Abstract
Background and Aims
FLASH has been shown to improve the therapeutic ratio of RT. The mechanism behind this effect has been partially explained by the ROD hypothesis. However, to better understand the contribution of oxygen, it is necessary to measure O2 in-vivo during FLASH irradiation. This study’s goal is to determine the temporal resolution required to accurately measure the rapidly changing oxygen concentration in FLASH RT.
Methods
We conducted a computational simulation of oxygen dynamics using a real vascular model constructed from a public fluorescence microscopy dataset. The dynamic distribution of oxygen tension (po2) was modeled by a PDE considering oxygen diffusion, metabolism, and ROD. The underestimation of ROD due to oxygen recovery was evaluated assuming either complete or partial depletion and a range of parameters such as oxygen diffusion, consumption, vascular po2, and vessel density.
Results
The O2 concentration recovers rapidly after FLASH RT. Assuming a temporal resolution of 0.5s, the estimated ROD is only 50.7% and 36.7% of its actual value in cases of partial and complete depletion. Additionally, the underestimation of ROD strongly depends on the vascular density. To estimate ROD rate with 90% accuracy, temporal resolution on the order of milliseconds is required considering the uncertainty in parameters involved.
Conclusions
The rapid recovery of O2 poses a great challenge for in-vivo ROD measurements in FLASH RT. Temporal resolution on the order of milliseconds is recommended for ROD measurements in the normal tissue. Further work is warranted to investigate whether the same requirements apply to ROD measurements in tumors, given their irregular vasculature.
Author Of 1 Presentation
TEMPORAL RESOLUTION REQUIREMENTS FOR MEASURING THE KINETICS OF OXYGEN DEPLETION DURING FLASH RADIOTHERAPY, BASED ON A 3D COMPUTATIONAL MODEL OF BRAIN VASCULATURE
Abstract
Background and Aims
FLASH has been shown to improve the therapeutic ratio of RT. The mechanism behind this effect has been partially explained by the ROD hypothesis. However, to better understand the contribution of oxygen, it is necessary to measure O2 in-vivo during FLASH irradiation. This study’s goal is to determine the temporal resolution required to accurately measure the rapidly changing oxygen concentration in FLASH RT.
Methods
We conducted a computational simulation of oxygen dynamics using a real vascular model constructed from a public fluorescence microscopy dataset. The dynamic distribution of oxygen tension (po2) was modeled by a PDE considering oxygen diffusion, metabolism, and ROD. The underestimation of ROD due to oxygen recovery was evaluated assuming either complete or partial depletion and a range of parameters such as oxygen diffusion, consumption, vascular po2, and vessel density.
Results
The O2 concentration recovers rapidly after FLASH RT. Assuming a temporal resolution of 0.5s, the estimated ROD is only 50.7% and 36.7% of its actual value in cases of partial and complete depletion. Additionally, the underestimation of ROD strongly depends on the vascular density. To estimate ROD rate with 90% accuracy, temporal resolution on the order of milliseconds is required considering the uncertainty in parameters involved.
Conclusions
The rapid recovery of O2 poses a great challenge for in-vivo ROD measurements in FLASH RT. Temporal resolution on the order of milliseconds is recommended for ROD measurements in the normal tissue. Further work is warranted to investigate whether the same requirements apply to ROD measurements in tumors, given their irregular vasculature.