Room: AAPM ePoster Library
Purpose: To model the circulating blood in the whole body and use the model to demonstrate the interplay effect between treatment delivery and blood motion.
Method and Materials: The Visible Human Male dataset was used for model creation and VMAT TBI planning. Organs, heart chambers, and major blood vessels were manually contoured while tissues (bone, muscle, and adipose tissue, etc.) and small blood vessels were automatically segmented. Blood density and velocity were assigned to each organ and tissue. To model blood motion, a “particle” was randomly sampled from the blood distribution in the body and its movement trajectory was tracked. Each movement step was a random 3D vector with its length determined by the blood speed at the current particle location. If the movement step was permitted in this cardiac phase (e.g. blood in the aorta can only go to arteries in systole cardiac phase), the step was accepted with a probability based on the speed difference between new and old locations. Otherwise, the step was rejected. To demonstrate the interplay effect of blood circulation with dynamic beam delivery, a VMAT TBI plan consisting of 17 beams and 9 isocenters was created. The dose volume histogram to the “static” blood and dynamic blood model was compared.
Results: The motion of 10000 blood “particles” were simulated as a proof of concept. Dose to dynamic blood had larger variation compared with dose to “static” blood.
Conclusion: A motion model for the circulating blood in the whole body was created. The interplay effect of blood motion with dynamic delivery was studied using a multi-iso VMAT TBI plan.