Room: Exhibit Hall | Forum 4
Purpose: During Intensity Modulated Radiation Therapy (IMRT) treatment plan optimization, the Quantitative Analyses of Normal Tissue Effects in the Clinic (QUANTEC) recommendations are employed to strategically guide planners towards optimized treatment plans. When QUANTEC criteria are met, plan optimization is completed. However, further sparing of the organs at risk (OAR) might be possible if further optimization is allowed. An application is purposed that will assess the patient anatomy and produce a theoretical dose distribution that is used as a guide to assist dosimetrists achieving the best possible plan or to evaluate the efficacy of the dose objectives for each patient prior to the initiation of the planning process.
Methods: The application was developed using MATLAB. It incorporates patient CT data and contoured OARs along with recalculated dose fall off, to generate a theoretical dose distribution (TDD). Generated TTDs are based on the requested prescription and account for tissue heterogeneity. Dose is initially created for the PTV region and emanates to its surroundings using pre-calculated dose falloff. Physicians can review and alter the TDD to modify OAR sparing (change DVH lines or isodose lines) while keeping ideal PTV coverage.
Results: Ten previously treated prostate patient plans were initially evaluated. The TDD showed that there could be regions within the patient volume where further optimization could improve sparing of OARs. Such regions were mostly in the low dose region. It was also found that OARs distal to the PTV not included in the optimization could be better spared if objectives were assigned to them and were part of the optimization process.
Conclusion: This application establishes an effective preliminary option for treatment planners and offers guidance in achieving greater healthy tissue sparing. Results have demonstrated proof of concept and further improvements to the application are planned to incorporate feasible guidance with better predictability.
TH- External beam- photons: dose computation engines- deterministic