This project will study the incorporation of individual patient related geometric uncertainties in the calculation,compilation and treatment of optimized radiotherapy dose distributions. Even advanced treatment planningtechniques nearly always rely on population-based rules to ensure that the majority of patients receiveadequate dose in the face of positioning errors and organ motion. This 'one size fits all' approach potentiallypenalizes patients who exhibit exceptionally large variation in position or motion, requiring more intensivemeasures to ensure adequate target volume coverage. However, it also penalizes a substantial proportion ofpatients with less uncertainty in their target position, who through the use of smaller margins would be atlesser risk for treatment related toxicity or eligible for higher tumor dose. We believe that a new combinedapproach involving a) dose computation strategies that already include the effects of geometric uncertainties,b) rigorous in-room methodologies for rapidly assessing target and patient configuration and c) accountingfor delivered dose and its influence on subsequent treatment delivery optimization will yield improvementsin efficient and accurate dose delivery, optimally tailored for each patient. Thus, the project's specific aims areto 1) implement general clinical frameworks for inclusion of patient related setup uncertainties and organmotion into the computation of dose distributions, 2) assess improvements in accuracy achieved through inroom,on-treatment measurement and action, 3) investigate human anatomic changes over short and longtime periods and how to accumulate dose to date using this information, and 4) determine the best ways toreact to differences between what is seen at treatment and what had been planned. In addition to bettertailoring overall treatments, these investigations will help determine how much complexity (in modeling,measurement and intervention) is actually beneficial for a given patient, thus helping to establish the mostefficient use of advanced in-room imaging resources within the radiotherapy community.
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